Functional diagnostics in orthodontics.
Why does an orthodontist need detailed diagnostics?
The main goal of diagnostics is to collect the necessary data about the patient's condition so that the orthodontist analyzes them and draws up a well-functioning treatment plan. Treatment started without a detailed step-by-step plan of action for the doctor and the patient will not lead to the desired result. It's like driving through the woods at night without a compass, flashlight or map.
Braces simply glued to your teeth are useless at best and likely to make things worse. In order to “pave” the patient a good route to his even and beautiful smile, the orthodontist needs certain information. It is collected and diagnosed.
What awaits the patient during the diagnosis at the orthodontist
For the patient, the diagnosis before the start of orthodontic treatment will take 30-40 minutes.
What is included in orthodontic diagnostics and why:
- Panoramic x-ray or orthopantomogram (OPTG)- shows a general view of the jaws and all teeth, including their roots, impacted teeth, wisdom teeth, extracted teeth, rudiments of teeth and bone condition.)
- Teleroentgenogram (TRG)- in the lateral projection and in the front (according to indications). Based on these images, the doctor determines the cause of the dentoalveolar anomaly, sees the ratio of the jaws and makes a conclusion whether this bite problem can be corrected only by orthodontic methods or whether a complex solution to the problem is needed together with maxillofacial surgeons.
- 3D scanning or taking impressions of the jaws to calculate their diagnostic models. The doctor must know the exact dimensions of the jaw, teeth, and their relationship in order to “find” a place for orthodontic treatment. Here lies the answer to the question - is it necessary to remove teeth. Based on 3D scanning, computer 3D modeling of the jaws and virtual treatment planning are performed.
- Photographing- portrait (because in the process of orthodontic treatment there is a change in the external appearance of the patient), intraoral (needed to track the dynamics of treatment).
- 3D analysis - computed tomography (CT) according to indications (unlike OPTG, which gives a 2-dimensional image, CT shows the spatial position of the teeth, their relative position and position in the jaw. In this picture, the doctor sees the inclination of the tooth, which in some cases is very important. CT is also indicated for periodontal diseases to determine the condition of the periodontal tissues).
- Video filming for fixing functional disorders in motion - when chewing, swallowing.
- Laser diagnostics of caries with the Diagnocam device
After the diagnosis, the doctor analyzes the data, makes the necessary calculations and draws up a detailed treatment plan for the patient. You need to understand that such a volume of work takes time and takes about 2 weeks.
How the orthodontist diagnoses - video
We draw up such a plan in a presentation, which the orthodontist discusses with the patient, explains and agrees. Only AFTER the plan is approved, treatment begins.
Examples of diagnostics at the orthodontist of our patients
Diagnosis at the orthodontist
from 6000 rub.
DISPLACE ALL FEARS AND MYTHS ABOUT ORTHODONTICS
NOW SIMPLE AS 1-2-3
Diagnosis is carried out by young and inexperienced orthodontists. An experienced doctor sees everything at a glance.
Paradoxically, such a view of diagnostics is found even in our age of computer technology, when everyone must understand the difference between data obtained by measuring high-precision instruments and determined “by eye”, with the participation of the notorious “human factor”.
Why are some patients sure that the doctor "by eye" will see and evaluate the condition of their jaws at the skeletal level? To put it literally, the difference between the result of a complete modern diagnostics and a “by eye” assessment is the same as between the conclusion of experts and the version of the investigation.
Modern orthodontics in the last decade has acquired very wide possibilities, and has become almost an exact science, but in order to use them, you need a deep analysis of the clinical situation with the help of modern high-precision equipment.
For diagnostics, you need a panoramic picture and casts - everything else is done simply to “pump out” additional money.
Let's think about what an orthodontist needs to know for such a movement of the patient's teeth in order to get the expected result? Most likely, you know that with the help of any orthodontic appliance, the orthodontist imparts the necessary force to the tooth, applying it at the right point and in the right direction - this is the principle of orthodontic treatment.
But how does the orthodontist know what force, how and where to apply?
To do this, he carries out rather complex geometric calculations, taking into account the biomechanics of the human body. It is clear that for such calculations it is necessary to have initial data - they are obtained during diagnostics. Unfortunately, OPTG and casts do not provide all the information necessary for calculations. Therefore, arguing with your orthodontist that part of the diagnosis is meaningless is useless - do you want his calculation to be accurate and correct for you?
The sooner the doctor reported the results of the diagnosis and treatment plan, the better it is.
There is a wonderful Russian proverb that fully reflects the meaning of this situation: “Hurry is needed when catching fleas!”. And intellectual work takes time. Analyzing the data obtained during the diagnosis and creating a treatment plan for a specific clinical case, the doctor, as we have already written above, conducts complex geometric and physical calculations, takes into account a lot of nuances and possible scenarios. This is a complex intellectual creative process that takes time. A high-quality, predictable and working “as it should” treatment plan cannot be invented overnight, and more than one Newtonian apple will not help here.
Very often, a consultation of several fellow orthodontists is required to draw up a treatment plan - as you know, one head is good, but two are better. Therefore, we strongly advise all potential orthodontist patients to be patient and not to rush your doctor, and, by the way, to be on your guard if, suddenly, the orthodontist offers you a final plan immediately after the consultation. That doesn't happen. Orthodontic treatment is long and financially expensive, so it is better to prepare for it properly, check everything, measure it 7 times, and then go to the result confidently and without unpleasant surprises.
Collecting the most complete information about the patient so that the orthodontist can make the correct diagnosis, understand how to treat the patient and satisfy his basic wishes.
Comprehensive diagnostics includes:
1. Photo protocol, assessment of smile and facial harmony
Plays an important role in monitoring changes and quality of treatment. During the consultation phase, photographs are needed to visualize the patient's problem. During the diagnostics, intraoral photographs are taken, photos of teeth in a closed, open state, at different angles of the face and smile - including the so-called "Emma test", which shows the patient how his teeth are usually seen during speech.
The younger the person, the more the upper incisors are visible when talking and the lower ones are not visible. With age, the soft tissues sink, lose their tone, and the upper teeth are less and less visible and the lower teeth are more and more visible. If a patient comes in for orthodontic treatment, then we pay attention to this, because we can change this and “rejuvenate” him in terms of perception during speech.
Up to 20 x-rays of teeth and face from different angles are taken for the patient
What is being evaluated?
- facial aesthetics
- Profile
- Bite and condition of teeth in their positions
- Center line ratio of incisors
- The width and arc of the smile (visibility and parallelism of the lip line)
- Condition of tooth enamel
The movement of the dentition can affect the position of the lips, so the orthodontist can reduce the aggravation of wrinkles by increasing the height of the bite. Decreasing the height of the bite leads to a greater likelihood of wrinkles, folds, which the doctor must take into account in the treatment plan.
2. Soft tissue and periodontal analysis
As a rule, at this stage, the orthodontist determines the symmetry of the gingival levels and checks the need for aesthetic correction of the gums, as well as the treatment of inflammatory diseases of periodontal tissues. Installation of braces is possible only after these issues are resolved.
3. Taking dental impressions
Now few people make calculations on models, they are created more formally. In general, all this can be done on computed tomography, subject to sufficient knowledge and skills of the orthodontist. Using plaster models, the orthodontist calculates the size of the teeth, the amount of space needed to move, looks at the proportionality of the teeth, whether restoration is required, how they will close after treatment.
Why do we continue to make casts at the Confidentiality Clinic?
At the Confidentiality clinic, we do not treat the patient so that he has even teeth and everything is fine only according to calculations. We treat so that the smile was beautiful in real life.
The first and most important reason- this is the need for models with indirect fixation.
The second reason- they make it possible to once again see some real object live, because CT and TRG are virtual things, and models make it possible to visually see the patient's bite.
It happens that an orthodontist in the process of treatment encounters some unexpected effect for him and is lost. At the Confidentiality clinic, we calculate everything “on the shore” in order to continue strictly according to the treatment plan, which was drawn up even before the fixation of the braces.
4. 3D cephalometric analysis of a CT image (a modern alternative to 2D TRH images)
Standard TRG analysis includes an assessment of the position of the teeth already in the space of the skull and how the teeth stand relative to the jaws, how the jaws are located relative to the skull, what size they are.
3D diagnostics is a much larger amount of information than what we see from TRG. Additionally, CT evaluates the position of each tooth in the bone tissue, the therapeutic condition of the teeth, the condition of the root canals of the pulpless teeth. It is possible to accurately assess the causes of the bite pathology and understand what caused it - a decrease in the size of the jaw or its displacement, only with the help of 3D diagnostics.
Without 3D computed tomography, a full-fledged diagnosis is impossible today - this one image replaces and unites everything.
Unfortunately, not all orthodontists have tomographs and are able to analyze 3D images. Now this is the gold standard of all diagnostics and a huge plus for the patient, because not only the orthodontist, but also any other doctors involved in the treatment can comprehensively approach a single verified treatment plan with just one CT scan.
5. Smile design (and virtual setup using Insignia)
It is not enough to collect information, it is necessary to analyze it. After the diagnosis, a detailed calculation is carried out using computer programs. For example, we calculate a teleroentgenogram using a special computer program, where all important points can be placed very accurately, and the program automatically calculates the angles of all jaws and the inclination of the teeth. This is really an accurate calculation, and not an approximate drawing on paper. The program for working with computed tomography allows you to extract various images of teeth at all possible angles and in all planes. In the calculation of TRG, we have already completely switched to 3D-cephalometric analysis.
Some orthodontists do not diagnose at all, some do, but formally, and do not rely on it, building a treatment plan immediately at the first visit.
We use the latest modern diagnostic methods, which makes it possible to build a verified prognosis and treatment plan. On average, the orthodontist needs from 1 to 1.5 weeks to analyze the information and draw up a treatment plan.
6. Diagnostic presentation.
After a comprehensive analysis, the orthodontist makes a detailed diagnostic presentation. It can be up to 100 or more slides with image cuts and a step-by-step architecture for building the result of orthodontic treatment. By opening it, any doctor from any other clinic will be able to assess the clinical situation of the patient.
A diagnostic presentation is a detailed, ready-made treatment plan that the patient can use even if he moves to another city and continues treatment with another doctor. In Russia, this approach is practiced by a few orthodontic clinics.
All this makes it possible to plan treatment, predict its timing and complexity. We do all the necessary preparation in advance for a clear understanding of the treatment process at the start, and not at its stages.
7. Discussion and choice of treatment plan
There is a special visit at Confidential called "Treatment Plan Discussion". At the diagnostic presentation, the orthodontist demonstrates to the patient the main points that require his attention:
- First of all, how to correct the patient's basic needs - crowding, position and inclination of the teeth.
- After that, the orthodontist points out to the patient other problematic points - perhaps those that the patient himself did not notice.
8. All patients want to know how much orthodontic treatment will cost.
A full diagnosis makes it possible to accurately announce the final amount of treatment to the patient, as the orthodontist understands the situation in detail and is confident in the treatment plan, and therefore in its cost. If additional medical manipulations are required, such as implantation, prosthetics, restorations, then this is discussed immediately. Qualitative preparation for orthodontic treatment minimizes the likelihood of the appearance of "pitfalls".
And all this is not only told to the patient, but also visually shown on the computer.
How is the patient's wishes taken into account in the diagnostic process?
- First of all, we ask what the patient does not like.
- With questions, we lead the patient to a more specific complaint.
For example, he doesn't like smiling. What exactly does the patient mean by the phrase “does not like the smile”? They may not like some separate tooth or the position of the teeth relative to each other, other patients - the color of the teeth. - When planning treatment, we proceed from the wishes of the patient.
It's understandable that everyone wants straight teeth, but there are times when a patient's requests can affect our plan.- If the patient does not want to place an implant, then the orthodontist considers the possibility of closing the gaps without prosthetics.
- If the patient does not like the displacement of the center line, the orthodontist calculates whether it is possible to move it.
- If the patient does not like the position of one canine, but at the same time he has disproportionate skeletal jaws among themselves. We can correct the position of the canine, but at the same time we understand that the bite itself will not improve, and this is one of the goals of orthodontic treatment. Not just straight teeth, but also a functional bite.
Therefore, we try to describe the whole situation to the patient and bring our treatment plan as close as possible to what he wants, if possible. If this is not possible, then we discuss what needs to be done additionally and what is the optimal result and treatment plan.
How often during the diagnostic process is it recommended that the patient visit another doctor and how are their comments taken into account?
If the orthodontist sees that only braces and moving teeth cannot achieve the desired treatment result or not satisfy the patient's request, then the patient is always given a referral to other clinic specialists:
- if you need to carry out prosthetics of one or more teeth
- if you need an implant
- if you need to work with periodontium
In any case, the orthodontist is obliged to involve the appropriate specialists.
In reality, adult patients often already have problems with their teeth, they have treated teeth, teeth with caries. It is obligatory to visit a hygienist and a dentist-therapist, as a minimum for installing braces - clean teeth without caries.
FGBOU VO "St. Petersburg State University" Department of Maxillofacial Surgery and Surgical Dentistry
Allowed to defend Head of Department
________________Professor Madai D.Yu.
(signature)
"___" ______________ 20___
FINAL QUALIFICATION WORK
ON THE TOPIC: Functional diagnostics in orthodontics
Completed by a student
Birtanova Natalia Gavrilovna
521groups
Scientific adviser:
Doctor of Medical Sciences, Professor Fadeev Roman Aleksandrovich
St. Petersburg
List of symbols……………………………………….3
Introduction ………………………………………………………………3
Chapter 1
Etiology and pathogenesis of dentoalveolar anomalies…………...6
Classification of dentoalveolar anomalies…………………..12
Methods for diagnosing dentoalveolar anomalies……………17
Clinical research methods………………………….17
1.3.3. Anthropometric research methods ………………..27
1.3.4. X-ray methods of research……….………….31
1.3.5. Functional research methods……………………..44
Chapter 2. Clinical population and research methods………57
2.1. Distribution by patient groups…………………………58
Chapter 3. Results of the study and their discussion………………66
3.1.1. The results of the study on kinesiography………………..66
3.2.1. The results of the study on sonography……………………73
3.2. Conclusion………………………………………………………76
3.2.1. Conclusions…………………………………………………………77
References…………………………………………………..….80
List of symbols
TMJ - temporomandibular joint.
WHO - World Health Organization
ZNA - dentoalveolar anomaly
MFR - maxillofacial area
TENS - transcutaneous electrical nerve stimulation.
Introduction.
Relevance.
The prevalence of dentoalveolar anomalies (DA) both among children and adults in Russia is quite high. According to various sources, it ranges from 41.1% to 95.3% (V. M. Bezrukov, 2000). The results of studies conducted by V. N. Trezubov, R. A. Fadeev, O. V. Barchukova (2003) indicate the occurrence of ASA among people aged 16–25 years of about 79%. No less common are AF and abroad. So, in Finland, according to M. L. Tuominen, R. J. Tuominen, 1994, the prevalence of AF is about 47%, according to U. Varrela, 2008 - 60%; in Denmark - 45% (K. R. Burgersdijk et al., 1991); Norway - 37% (L. V. Espeland, A. Steenvik, 1991); USA - 35% (V. M. Bezrukov et al., 2000). At the same time, in the general structure of AF among the European population, distal bite is more common - 24.5–37.5%, less often - deep bite - 13.4% (A.S. Shcherbakov, 1986). The prevalence of mesial bite among Europeans is up to 12% (N. G. Abolmasov, 1982), and open bite - 10.5% (Yu. L. Obraztsov, 1991).
Along with traditional diagnostic methods, such as: calculation of diagnostic models of the jaws, analysis of teleroentgenograms, evaluation of orthopantomograms, computed tomography, magnetic resonance imaging, modern dentistry uses methods of functional diagnostics.
The founders of the functional direction in dentistry abroad are A. Rogers (the founder of myogymnastics for dentoalveolar anomalies), R.R. Jenkelson (the founder of neuromuscular dentistry) and A. Gyzi, who described the transversal articular path, the author of the first individually adjustable articulator; in Russia - I.S. Rubinov
Functional methods are widely used in research work, but rarely used in clinical practice.
Purpose of the study– to study the diagnostic capabilities of functional diagnostic methods (kinesiography and sonography) in orthodontics.
Tasks.
To achieve this goal, the following tasks were set:
To assess the functional state of the masticatory apparatus in patients with various forms of dentoalveolar anomalies using kinesiography.
To assess the functional state of the temporomandibular joint in patients with various forms of dental anomalies using sonography.
To assess the functional state of the masticatory apparatus after TENS-therapy in patients with various forms of dentoalveolar anomalies using kinesiography.
To assess the functional state of the temporomandibular joint after TENS-therapy in patients with various forms of dentoalveolar anomalies using sonography.
The practical significance of the work. Functional diagnostics is the diagnosis of the state of the function of an organ or system of the body, the degree of its violation during pathological processes and recovery after treatment. Functional diagnostic methods in dentistry are based on measuring the physical properties of the examined tissues - electrical, optical, acoustic, etc. These properties are possessed by tissues of the dental pulp, periodontium and other tissues of the mandible. Diagnosis is based on the fact that the physical properties of biological tissues change during diseases. Knowing the indicators in the norm, it is possible to quantify the degree of disturbances in the studied tissues, which makes it possible to more accurately diagnose the severity and stage of the pathological process.
With the help of functional diagnostic methods after treatment, it is possible to objectively assess how much it was possible to restore the condition of the tissues under study. By re-determining their physical properties, one can trace the duration of the therapeutic effect. These methods make it possible to identify the reserve capabilities of the studied tissues in the norm and the degree of their loss in diseases. This allows predicting the success of treatment and the outcome of the disease.
Chapter 1. Literature Review.
Etiology and pathogenesis of dental anomalies.
By duration, this period can be divided into 2 parts:
It is also customary to single out endogenous (internal) and exogenous (external) factors of influence on the dentition.
Endogenous causes are divided into genetic, endocrine, chemical and physical effects on the fetus:
Genetic factors - the child inherits from parents some features of the structure of the dentition - the shape and size of the teeth, the anatomy of the jaws and soft tissues, the discrepancy between the size of the jaws and the size of the tooth may be due to the inheritance of the size of the mother's jaws and the size of the father's teeth, which can lead to a lack of space in the dentition (mismatch of wide teeth, narrow jaw). Also, hereditary diseases and malformations cause violations of the structure of the facial skeleton, quantitative and anatomical pathologies of the shape of the teeth and jaws. Hereditary diseases include congenital cleft lip, alveolar process, hard and soft palate; dysostoses, Shershevsky's disease, Crouzon's disease - the leading symptoms of which are congenital underdevelopment of the jaws; a combination of cleft palate and fistulas of the lower lip (Van der Wood syndrome); syndromes of Franceschetti, Goldenhar, Robin. Changes in enamel and dentin can be hereditary - imperfect amelogenesis and dentinogenesis, Stanton-Capedon syndrome, anomalies in the size of the jaws (macrognathia and micrognathia), anomalies in the position of the jaws in the skull (prognathia and retrognathia). Also hereditary can be - diastema, short frenulum of the tongue and lips, adentia.
Endocrine factors - the endocrine glands begin to function during fetal development, and it is the adrenal cortex - from the 8th week of embryonic development, the thyroid gland from the 12th week, and the secretory activity of the remaining endocrine glands and the hypothalamic - pituitary system begins from the 20-26th week of development fetus, therefore, a violation of their function can lead to anomalies of the dentoalveolar system. Congenital dysfunction of the adrenal cortex leads to accelerated development of the bones of the skull (the appearance of three between the teeth due to increased growth of the jaws), a violation of the timing of teething and a change in the milk bite. Hypothyroidism leads to late eruption of milk and permanent teeth (2-3 years), late formation of roots, changes in the shape and size of tooth crowns, adentia, multiple enamel hypoplasia, delayed development of the jaws and their deformation. In hyperthyroidism, there is a delay in the growth of the jaws in the sagittal direction. Along with the morphological change in the structure of the dentoalveolar system, the functions of the masticatory, temporal and tongue muscles change, which leads to a violation of the closure of the dentition. Hyperfunction of the parathyroid glands increases the contractile response of the masticatory and temporal muscles. Due to a violation of calcium metabolism, deformation of the jaw bones occurs, resorption of the interalveolar septa, thinning of the cortical layer of the bones of the skeleton.
Chemical and physical effects on the fetus. These include the stay of future parents in an unfavorable environment (saturation of air and water with chemical and bacteriological elements, increased radiation, sudden changes in ambient temperature, too high or too low temperature), taking medications during pregnancy, especially in the first trimester. Taking antibiotics, in particular tetracyclines, before pregnancy and during it leads to discoloration of the enamel (tetracycline teeth). Diseases of a pregnant woman (chronic, infectious, endocrine and others), fever, malnutrition, lack of vitamins and minerals, and many other reasons can lead to dentoalveolar changes, such as cleft lip, alveolar process, hard and soft palate, isolated or through fusion of the facial skeleton and many other anomalies in the development of the fetus. (L.S. Persin, V.M. Elizarova, S.V. Dyakova. 2003)
Prenatal common factors include an unfavorable environment, namely insufficient ultraviolet radiation, a lack of fluoride in drinking water, and an increased level of radiation. Work before and during pregnancy in a chemical plant, in a poorly isolated X-ray room, significant physical activity, a large number of stressful situations, especially in the first 3-4 months. Local factors - mechanical trauma to the fetus. The fetus is in the amniotic fluid, which protects it from concussions and shocks. Its amount normally changes at different periods of fetal development, by 6 months, gradually increasing, the volume reaches 2 liters, and by the end of pregnancy it decreases to 1 liter. Due to the increase in amniotic fluid, intra-amniotic pressure increases, which can lead to impaired blood supply to the fetus. If the volume of the amniotic fluid does not match, pressure can occur on different parts of the fetal body, including the maxillofacial region, and subsequently its deformations are formed. Also, excessive pressure of the mother's clothes on the stomach can lead to pathology of fetal development. Incorrect position, pressure of the amniotic fluid, amniotic cords can lead to violations of the dentoalveolar system. (V.N. Trezubov, A.S. Shcherbakov, L.M. Mishnev 2005)
Postnatal common factors include rickets, insufficient ultraviolet irradiation of the child, impaired calcium-phosphorus metabolism, difficulty in nasal breathing, pathology of the ENT organs, impaired function of masticatory and facial muscles, infectious diseases of childhood can also lead to deformation of the maxillofacial region, developmental delay jaws. Local postnatal causes of dentoalveolar anomalies should be considered from the start of breastfeeding. The newborn has a small lower jaw relative to the upper (infantile retrogeny). With natural feeding in the first year of life, its active growth occurs. To receive milk from the mother's breast, the baby pushes the lower jaw forward, grabbing the nipple with his lips. Negative pressure arises in the oral cavity and as a result of the work of the muscles that determine the movements of the lower jaw, the child receives milk from the mother's breast. With artificial feeding, the correct position of the head, the size of the nipple and the hole in it play an important role. Usually a large hole is made in the nipple, which means that swallowing movements predominate over sucking ones, therefore, there is a delay in the development of the lower jaw, since the muscles of the maxillofacial region do not take an active part in the act of sucking. If the head is thrown back during feeding, then the growth of the lower jaw is delayed and a distal bite is formed. The shape and length of the nipple disrupts the balance between the muscles of the tongue and the chewing muscles. Feeding a child after three years of age with only liquid and soft food often leads to dentoalveolar anomalies, since the dentoalveolar system remains without sufficient functional load. Changes in the dentoalveolar ratio are affected by the bad habits of the child:
Prolonged use of a pacifier.
Wrong position in a dream. Sleeping with the head thrown back contributes to the appearance of pathology in the sagittal plane, distal occlusion, a strong forward tilt of the head - mesial occlusion. Sleeping in a constant one position (on your side, with your hand under your cheek) leads to asymmetrical development of the jaws.
Incorrect posture, chin resting on a hard object.
Constant biting of any objects or laying between the teeth of the tongue, cheeks.
Mouth breathing.
Thumb sucking.
Incorrect chewing (chewing on one side, muscle hypertrophy on that side).
The action of the muscles of the maxillofacial region during swallowing, chewing, breathing and speech and the state of physiological rest is one of the most important factors influencing the correct formation of the dentition. The balance between antagonist and synergist muscles creates the conditions for its proper development. Violation of the myodynamic effect between the masticatory, temporal, buccal muscles, between the muscles of the floor of the mouth, the chin, the circular muscle of the mouth leads to various pathologies. Insufficiency of the function of the circular muscle of the mouth leads to an increase in the length of the upper dentition (distal occlusion), a change in the position of the lower lip, and a vestibular inclination of the incisors. Violation of the functional properties of the muscles of the tongue can lead to mesial or distal bite. Macroglossia - an increase in the size of the tongue leads to a violation of the growth of the upper and lower jaws. (F.Ya. Khoroshilkina 2006)
Examination in dentistry and, in particular, in orthodontics, as in other branches of medicine, is extremely important, since the entire further course of treatment depends on its quality. The characteristics of the examination are dictated by the age of the patient, which sometimes, especially in children, is decisive, both in terms of the psychological approach and the method of treatment in different phases of tooth development.
The value of a correct and thorough examination is sometimes underestimated, it is often carried out superficially, or limited to just examining the teeth. In order for a dental examination to fulfill its purpose, it must be carried out purposefully and systematically. It pays best to follow the same sequence in order to avoid that any of the important signs do not go unnoticed. The examination should include the following elements: 1) anamnesis and external examination of the patient, 2) extraoral examination, 3) intraoral examination, 4) additional (auxiliary) examination methods, and only after that the diagnosis is determined, the components of which are described on p. 56, and a treatment plan is outlined.
A general examination of a patient cannot, of course, be confused with an examination, for example, by an internist, which is resorted to only for certain indications. In most cases, an external examination (aspectio) and a few indicative questions are sufficient to get an idea of the patient's personality. Therefore, it is advantageous to combine this part of the examination with the anamnesis. Thus, it is possible to obtain information not only about the somatic state of the patient, but also about the mental state, information about which is especially important for the dentist.
When collecting anamnestic data, especially from a child, questions should be formulated in such a way that they are understandable and do not cause injury. Based on the behavior of children, you can get valuable information for the psychologically correct treatment of them. Sometimes an anamnesis concerning the immediate disturbances is sufficient. In young children, it is always important to check the history by asking parents.
Given that the main contingent of patients at the orthodontist are children, the most serious attention should be paid to psychological preparation for research. The concept of preparation means a set of measures designed to have a beneficial effect on the mental state of the child before treatment. It is not enough to just talk to the child and then act according to normal practice. It is necessary to prepare for each individual intervention, and psychological repression is inevitably intertwined with prevention. We must also not forget that the patient is subjected to mental influence not only under the influence of the doctor and nurse, but also under the influence of the entire organization of the reception.
In preschool age, the child in most cases already had to meet with the dentist. It is at this age that the child's readiness for fear and apprehension is great. The suggestibility of children in this age period is very significant, and it is very important to use it in a positive sense.
Emotionally, a school-age child gradually stabilizes and seeks to control the external manifestations of his feelings. Children from about 8 years of age onwards do not indeed, with few exceptions, cry or resist treatment. However, upon careful observation of their speech, facial expressions and general behavior, it turns out that they experience great fear. Starting from school age, the experience gained by the individual has a huge influence on the rest of his life, and it is impossible for it to accumulate if it has an unpleasant character.
The mental development of a child at school age requires the right psychological approach both in the family and from the dentist. Around the age of 12, the child is able to think logically and abstractly, and therefore it is necessary for him to properly explain the meaning of dental care.
During puberty and adolescence, the situation becomes even more difficult, as young people tend to get out of the influence of their educators and become independent in their views. A favorable circumstance at this age to reinforce a positive attitude towards dental care may be the emerging aesthetic feelings. Young people not only perceive the beauty of the work of art, but also begin to monitor their appearance, which can be used to persuade them to take good care of their teeth. It should be noted that a too “routine” approach with a few familiar sayings and jokes can have a negative impact, and therefore it is important to find out the interests of the patient already at the first visit and even note this in the outpatient chart At the next visit, the doctor can start a conversation with them. Even a child does not want to be just a “case”, a “detail on an assembly line”, and therefore a strict “individualization” of treatment is necessary, taking into account the emotional properties and reactions of the child.
Postnatal period: time of birth (term, term), height of the newborn, weight, head circumference, type of feeding, texture and chemical composition of food, early childhood diseases - measles, scarlet fever, dysentery, poliomyelitis, rickets, pathology of the upper respiratory tract; the state of the endocrine system, mental abilities, the general development of the child, posture, the presence of deformations of other parts of the body; condition of the gastrointestinal tract; playing sports; habitual sleeping posture, activities; type of breathing (nasal, oral), the presence of adenoid growths and enlargement of the tonsils, frequent runny nose, nasality.
Take into account the timing of eruption of milk and permanent teeth, early pathological processes, injuries and surgical interventions in the maxillofacial region, the timeliness of treatment of milk and permanent teeth (caries, pulpitis, periodontitis), untimely removal of milk teeth and the cause, timeliness and rationality of prosthetics, if necessary, bad habits.
Bad habits mean a variety of childhood habits that adversely affect the growth and development of the jaw and other facial bones and adjacent soft tissues. Such habits include sucking or biting a finger, tongue, lip, pencil, edge of a blanket, improper swallowing and breathing through the mouth, static habits of a certain body position during sleep, incorrect speech articulation, nocturnal and daytime bruxism, and other parafunctions.
Some bad habits associated with dysfunction of the dentoalveolar system are sometimes not noticed by children and parents themselves. The doctor is obliged to recognize them, pay attention to it and take appropriate measures. So, for example, a child's habit of chewing on one side is easily detected by the deposition of plaque and tartar on the non-working side. On the working side, an earlier change of teeth can be noted. Hasty chewing of food is sometimes accompanied by biting of the cheeks and tongue, which can be judged by areas of hemorrhage on the mucous membrane, more often in the region of the lateral teeth.
Careless eating is usually combined with the habit of improper swallowing (see Fig. 110, 111). It is very important to know how the child breathes. If he is used to breathing through his mouth, but tries to breathe through his nose, then this can be easily seen from the tense expression on his face, the auxiliary movements of the wings of the nose, labored inhalation and noisy exhalation. At the same time, the child gets tired very quickly and soon takes a deep breath through the mouth, getting relief. In the presence of a mechanical obstacle in the nose, chewing becomes arrhythmic, uneven, breath holding occurs, which can cause hypoxia. If there is a difficulty in nasal breathing, it is necessary to refer the patient to an otolaryngologist, if speech is disturbed, to a speech therapist, and if bad habits are identified in schoolchildren, to a neuropathologist or psychiatrist, since this can be not only the cause of the formation or aggravation of the dentoalveolar anomaly, but also neurotic syndrome.
In an extraoral examination, attention is primarily paid to the symmetry of the face and its parts, the possibility of free opening of the mouth. The distance between the dentition is measured, which is usually 4.5-5 cm. The configuration of the lower third of the face is often of great diagnostic value. Already by changing the morphological features of this part of the face, a correct diagnosis can be made: nasolabial and chin folds, corners of the mouth, the size of the oral fissure, the relationship between the lips, their configuration and line of contact, the type of chin (oblique back, medium or protruding).
All this characterizes one or another bite anomaly. For example, a flattened upper lip, a prominent chin, and a lower lip overlapping the upper lip are characteristic of an overbite. A pronounced chin-labial fold, an inverted lower lip, a sloping chin, a reduced lower third of the face are characteristic of the so-called bird face and are characteristic of lower micrognathia (see Fig. 79; 80, b).
Examination of the oral cavity. Evaluation of the dental formula and compliance with its age. On examination, anomalies of the teeth are revealed by their color and structure of tissues, shape, number, position. Pay attention to the shape of the alveolar and dental arches, the nature of their closure. When examining the dentition, the question often arises whether a tooth was removed, and if it was removed, then which one. If there is an unequal number of teeth on both sides of the midline, and there is no gap, then one of the teeth is removed, i.e. there is a defect or true adentia, and the gap has closed as a result of tooth movement.
When it comes to incisors and canines, it is easy to tell from the shape which tooth was extracted. Certain difficulties arise when it is necessary to distinguish the second milk molars from the first permanent ones. At the same time, the sixth tooth or the fifth milk tooth could be removed, in place of which the permanent molar moved. The issue is resolved according to the degree of their development and with the help of X-ray examination.
Having described the anomalies of individual teeth, they proceed to the study of the relationship of the dentition, and then the jaw bones are examined. In the region of the lateral teeth, one- or two-sided compression is noted, excessive or insufficient development of the alveolar process of these areas in the vertical direction, the shape of the palate is domed, flat or gothic.
The state of the mucous membrane is also examined: normal, inflamed or other pathological changes. The size and places of attachment of the frenulums of the lips and tongue, buccal bands, the shape of the slope of the alveolar processes and the depth of the vestibule of the oral cavity are assessed.
Examine the tongue, its relationship with the dentition at rest and when swallowing. During the examination, it is necessary to ask to show the tip of the tongue, the tremor of which may be a sign of increased activity of the thyroid gland. Reduced activity of the tip of the tongue, if there is no inflammation or neoplasm, is often due to a short frenulum.
To assess oral hygiene, the Oral Hygiene Index (OHI) or the Simplified Oral Hygiene Index (OHI-S) -- Green Vermillion (Fig. 59) are used.
Signs of bad habits can be polished edges on the teeth, periodontal disease of individual or groups of teeth, their mobility, rotation, lack of contact with antagonists. We should not forget that bad habits can also affect the state of the temporomandibular joints, which manifests itself in the form of pain or awkwardness, headache. By the type of deformation, one can assume the presence of one or another bad habit.
A very important factor is the preservation of milk teeth before their physiological change, the nature and time of existence of defects in the dentition and / or their deformations, and, if necessary, prosthetics. The nature of the movements of the lower jaw is determined (straight, evenly, translationally, jerkily, with displacement) when opening or closing the mouth. Attention is also paid to the displacement or, conversely, the alignment of the inter-incisal lines during the opening of the mouth. If necessary, palpation and auscultation of the temporomandibular joints are performed.
Apply clinical functional tests (Ilyina-Markosyan L.V.) for differential diagnosis of displacements of the lower jaw, helping to determine the direction of displacement and a possible cause (see Fig. 405, 406).
First trial (study at rest). When examining the patient's face (face and profile), pay attention to the position of the lower jaw at rest and during a conversation. Facial signs of malocclusion, if any, are revealed.
The second test (the study of habitual occlusion). The patient is offered to close the teeth without opening the lips. If there is a habitual displacement of the lower jaw, then facial features become more pronounced, in direct proportion to the magnitude of the displacement.
The third test (the study of lateral displacements of the lower jaw). The patient opens his mouth wide, and at the same time, facial features are studied, which are especially noticeable with the existing lateral displacement. Facial asymmetry in this case increases, decreases or disappears, depending on the cause.
The fourth test (comparison of habitual and central occlusion). The patient compares the teeth one by one in the central, habitual occlusion, and at the same time, the harmony of the face is compared. This test allows you to clarify the existing violations: the degree of displacement of the lower jaw, narrowing or expansion of the dentition, asymmetry.
To clarify the distal occlusion (prognathia), a clinical test according to Eshler-Bittner is used. The patient closes his teeth in habitual occlusion, and the doctor remembers the profile of the face. Then the patient is asked to push the lower jaw forward until the front teeth are directly closed and the sixth teeth are in a neutral ratio. If the profile improves, then the anomaly is due to underdevelopment of the lower jaw or its distal position. With a deterioration in the profile, the cause of the anomaly is the underdevelopment of the upper jaw and its dentition.
Muscle imbalance in the maxillofacial region affects the formation of the facial skeleton, the development and tone of the neck muscles. If you look at a standing person in profile, then the centers of gravity of his head, scapular-shoulder girdle, hips, knee joints and feet are, as a rule, on the same vertical line, which is characteristic of a harmoniously developed structure (see Fig. 120). With impaired posture, the following features are observed: forward tilt of the head, a change in the direction of gaze, a flat chest, a decrease in its anteroposterior size, a change in the angle of the ribs, scoliosis, protrusion of the abdomen, valvus (O-shaped) curvature of the legs, flat feet. Orthodontic treatment of such patients together with a general orthopedist improves posture or normalizes it. Violation of posture, in turn, creates the prerequisites for respiratory failure, especially with sagittal malocclusion.
The study of the morphology of the milk bite in young children is very difficult. Occlusion in the milk occlusion is characterized by frontal overlap within 1-2 mm, and during chewing, the movements of the lower jaw occur freely, with the distribution of the load evenly on all teeth.
With the correct ratio in the milk bite, the tip of the tubercle of the lower canines is located between the canines and the lateral incisors of the upper jaw. H. Taatz found that such closure occurs in 59% of probands, and this was called a neutral, or correct, relationship (Fig. 60). The situation when the top of the tubercle of the upper canine falls not exactly between the upper canines and lateral incisors, but is somewhat displaced backwards, A.Kantorowicz called the word “distalization”, which, in his opinion, indicates “distal” acting forces. H. Taatz found such "distalization" in 41% of the examined and tried to connect it with the ratio of the distal surfaces of the second milk molars (see Fig. 37.43).
She found that with a neutral ratio of canines, the molars are closed either with the presence of a mesial step (52%), or their distal surfaces are in the same plane (48%). At the same time, in the presence of "distalization" of the lower canines, the molars closed with the presence of a mesial step in 19% of children and almost with the same frequency (17%) there was a distal step, and in 64% the distal surfaces of the molars were in the same plane (Fig. 60 ).
Mesiodistal relationship between upper and lower milk canines
The average size of the second milk molars, if present
difference: + 0.67 mm + 1.17 mm + 0.95 mm
Rice. 60. The location of the distal surfaces of the dentition of the milk bite, depending on the width of the second milk molars (explanation in the text).
These data can serve as a prognostic sign of the possible formation of a distal occlusion in the future, namely: 1 - if the upper and lower canines contact "tubercle to tubercle", 2 - if, when measuring the model, there is a distance of about 2.0 mm between the distal surface of the upper and lower milk canines, 3 - if both dentitions end with a distal step or, at least, are in the same plane.
Thus, “distalization” cannot be associated with distal occlusion, since it occurs much more often, approximately in a ratio of 9:40, and does not require treatment. At the same time, the distal occlusion can be formed in the presence of other unfavorable circumstances, for example, when the jaw is narrowed (reduction of the transversal size) or when the frontal teeth protrude.
In permanent occlusion, the well-known Pont indices are used to assess the width of the dental arches, and another method is applicable to determine the transversal size of the dental arch of the milk occlusion: the measuring points on the upper jaw (see Fig. 61) are located in the deepest part of the masticatory groove of the first molars (anterior width ) and at the deepest point of the lingual-mesial groove of the second molar (posterior width). On the lower jaw, with a correct bite, the corresponding points are located on the buccal-distal cusps of the first molars (anterior width) and on the middle buccal cusps of the second molars (posterior width).
If we connect the obtained line of the anterior width with the Lo perpendicular to the labial surface (closer to the cutting edge) of the crown of the central incisors, we will obtain the length of the anterior section of the dental arch (see Fig. 61). In the clinic, this can be done using a conventional or orthodontic caliper. Table 1 presents data on this index.
A.M.Schwarz proposed an additional method for determining the shape of the dental arch in milk occlusion. Diagnostic models of the upper and lower jaws are oriented along the midline corresponding to the median palatine suture, and perpendicular to it along the line passing through the transverse fissures of the second molars (see Fig. 62). If a semicircle is drawn from the intersection point, then it should pass through the buccal tubercles of the primary molars, the tips of the canines and the cutting edges of the front teeth. Measurements of milk dentitions without diastemas and tremas showed that the transversal size of the dental arch is 2–3 mm smaller than with a dental arch with tremes and diastemas, although its shape still corresponds to a semicircle. The transverse dimension between the palatal surfaces of the second molars, according to Korkhaus and E. Neumann, should be at least 28 mm. Otherwise, the authors believe that there is an obstacle to growth.
Table 1
Indexes for milk bite with a fluctuation range of 5% (according to Eismann und Warnatsch)
|
Sum of incisor width SJ |
Anterior arch width 54:64 84:74 |
Posterior arch width 55:65 85:75 |
Anterior arch length |
|
Milk bite without primary spaces |
|||
|
Milk bite with primary gaps |
|||
For each person there is no exact, single shape of the dental arch. The definitions given by Mulreiter in relation to the lower and upper dentition, parabolic and semi-elliptical, respectively, are very approximate. However, there are attempts to geometrically build dentition based on the width of the teeth. The greatest preference is given to the Pont method, which, like the anthropological index of the head: width x 1 "" t, calculated 2 indices. What shape of the dental arch length should be created during treatment? First of all, you need to know the limits for correction.
Normally, there is a certain relationship between the zygomatic width of the face and the width of the dental arch of the upper jaw. Using the Pont index, you can get data on the size of the dental arches. To determine the zygomatic width, an obstetric compass is used (Fig. 63), which is installed 2–2.5 cm in front of the ear tragus. Since, according to Izar, for a skeletonized skull, the ratio “width of the dental arch / zygomatic width” is 1:2, it is necessary to make a correction for the thickness of the soft tissues, namely, in children of 6 years old “- 8 mm”, in older ones, up to 18 years old, must subtract 10 mm. For example, if a preschooler has a zygomatic width of 110 mm, then 8 mm is subtracted from this figure and divided by 2. This results in the width of the dental arch corresponding to this skull, namely 51 mm.
To determine the greatest width of the dental arch, it is necessary to measure the distance between the most protruding points of the buccal surface at the posterior edge of the primary molar (later the 1st, 2nd, 3rd permanent molars). A comparison between the true value and the due value (according to the Isar * and Pona indices) will clearly show whether the size of the dental arch corresponds to the type of skull or not.
Research and analysis of diagnostic control models. For a long time, scientists have paid attention to the need to study models of dentition, since it is not always possible to establish a diagnosis and treatment plan only on the basis of a clinical examination alone. In this regard, various methods for measuring models, determining indices and compiling tables have been proposed. In relation to the digital indicators of a normal dental arch, all kinds of deviations are determined.
The models reflect the clinical picture of the oral cavity, and the measurements taken on them help to determine the features of the existing anomaly or deformity. They are necessary when deciding on the removal of a particular tooth and the use of the most effective orthodontic appliance, they help to track the changes that occur during the treatment process and compare the results achieved.
This method is used as a laboratory supplement. In the clinic, impressions are obtained from both jaws of the patient, which must meet certain requirements: good impressions of the teeth, alveolar part, apical base, transitional fold, frenulum of the tongue and lips.
Based on the impressions obtained, models are prepared, preferably from durable varieties of gypsum. The base of the base of the model is made using rubber molds, or from other elastic materials, or using special shapers. You can cut the base so that its corners correspond to the line of the fangs, and the base is parallel to the chewing surfaces.
There are numerous devices that orient the models in relation to each other, the cranial part of the facial skeleton and the chin. On the models, the date of their receipt is marked, with a Roman numeral their primary, secondary ... etc., the patient's surname and initials, the number of the outpatient card. Such models are called diagnostic control (Fig. 65).
In order to make measurements on models, compasses of various designs are used (Fig. 66). In addition, other devices are used. For example, an orthocross (orthodontic cross, Fig. 67), which is a transparent celluloid or plastic plate, on which millimeter divisions are applied. This plate is placed on the model so that its midline coincides with the midsagittal plane of the model. Using the orthocross, you can establish the existing deviations in relation to the frontal and sagittal planes. Various orthometers, symmetroscopes (Fig. 67, c), symmetrographs, special tables are known. It should be noted that for everyday practice, the measuring instruments presented in Figure 66 are sufficient. Models are studied in relation to three mutually perpendicular planes (Figure 68).
Transversal measurements (deviations in relation to the sagittal plane). The discrepancy between the upper and lower dentition is often the result of their inadequate width. With an orthognathic bite, the buccal tubercles of the upper lateral teeth overlap the corresponding lower ones (see Fig. 69, /). With a narrowed upper dentition, its lateral teeth fit into the longitudinal intertubercular fissure of the lower lateral teeth and a bilateral buccal crossbite or bilateral vestibulocclusion is formed (Fig. 69, a). With an unevenly narrowed upper dental arch, there may be normal ratios of the upper and lower lateral teeth on one side, and reverse on the other, i.e. unilateral vestibulocclusion (Fig. 69, b); with an unevenly expanded upper dentition and an unevenly narrowed lower one, the lateral teeth of one side can be in an orthognathic ratio, and on the other, the upper teeth with their palatal surface touch the vestibular surfaces of the lower lateral ones, which is typical for unilateral linguo-occlusion (Fig. 69, c) . With an excessively wide upper jaw or a sharply narrowed lower jaw, the upper lateral teeth slip completely past the lower ones and a bilateral lingual crossbite or bilateral lingual occlusion is formed (Fig. 69, d).
Transversal deviations in the frontal area are determined based on the coincidence or mismatch of the median line between the central incisors of the upper and lower jaws. The cause of these deviations may be the lateral displacement of the upper or lower incisors in relation to the sagittal plane (edentia, supernumerary teeth, early extraction).
Given the value of the width of the dentition, Pont (Pont, 1907) developed an index of normal width. He found a certain pattern between the sum of the transverse dimensions of the four permanent incisors (SI) and the width of the dentition in the region of premolars and first molars. If SI is divided by the distance between the first premolars, molars and multiplied by 100, then we get
Measurement of the width of the dentition is made between certain points: on the upper jaw - between the middle of the fissures of the first premolars and first molars, and on the lower jaw - the points between the first and second premolars and between the distal-buccal tubercles of the first molar (Fig. 70) . With an orthognathic bite, the measuring points on the lower model overlap with the corresponding points on the upper one.
In practice, the Pona index is calculated as follows. The width of the 4 upper incisors is measured, each separately. The measurement can be made on models.
The resulting sum of the width of the incisors is multiplied by 100, divided by the premolar index (80) and a figure is obtained indicating the normal width of the dentition in the region of the premolars. For example, the sum of the width of the cutters is 32 mm * 100: 80 = 40 mm. Therefore, the normal width of the dentition in the region of the premolars is 40 mm with the width of the incisors = 32 mm. The normal width is determined accordingly in the area of the molars: 32 mm * 100: 64 = 50 mm.
The actual width of the dentition is measured on the patient or on models, and the narrowing or expansion is determined by the difference with the normal indicator in each case. To facilitate the work, so as not to determine the normal width of the dentition each time, it is advisable to use the table in Figure 70, in which the normal width of the dentition has already been calculated for one or another sum of the width of the upper incisors.
Data showing the width of the dentition according to the Pona index is not an unconditional indicator of anomalies. The index is only a guideline, especially since neither individual, nor gender, nor racial characteristics are taken into account in its value. Pont determined the index among the population of Southern France, and, according to Korkhaus, if this index is used for the population of Central Europe, then the width of the dentition is 1 mm larger.
N.G. Snagina established a relationship between the sum of the mesiodistal dimensions of 12 permanent teeth and the width of the dental arches. The width of the latter, according to her data, in the region of premolars is 39.2% of the size of 12 teeth, and in the region of molars - 50.4%.
In cases where not all upper incisors have erupted or are missing, the width of the dental arch can be determined by the sum of the transverse dimensions of the lower incisors, using the Ton index. R. Topp (1937) established the ratio of the width of the upper incisors to the lower ones as 1:0.74 or 4:3, i.e. Si/Si = 1.35.
Sagittal measurements (made in relation to the frontal plane). According to the classification of E. Engle, if the lateral teeth of the lower jaw are located in front of the upper ones by half the width of the premolars, i.e. if the middle of the mesio-buccal tubercle of the upper first molar fits into the groove between the buccal tubercles of the lower one of the same name, then this ratio of the dentition is designated as neutral (see Fig. 57, a).
table 2
Measurement table by Korkhaus
|
The sum of the width of the 4 top cutters (mm) |
The sum of the width of the 4 top cutters (mm) |
Length of the anterior segment of the upper dental arch (Lo) (mm) |
|
When the lower lateral teeth are located distally with respect to the upper, i.e. when the mesiobuccal tubercle of the sixth upper tooth is located in front of the groove between the buccal tubercles of the sixth lower tooth, then they speak of a distal occlusion (see Fig. 57, b, c). If the lower lateral teeth are located in front of the upper ones, i.e. the mesio-buccal tubercle of the upper sixth tooth is located behind the transverse intertubercular groove, i.e. between the lower sixth and seventh, then this ratio is considered a mesial occlusion (progeny).
The sagittal ratio of the lateral teeth in the position of central occlusion is usually marked on the models with vertical lines passing through the middle of the anterior buccal tubercle of the upper sixth tooth (see Fig. 57, 65).
Deviations in the group of anterior teeth are determined using average values that show the dependence of the width and length of the dental arch. The starting point for these measurements is a plane parallel to the frontal one. It passes through the middle of the fissures of the first premolars and crosses the midsagittal plane. A perpendicular is drawn from the labial surface of the upper central incisors to the indicated plane, which determines the length of the anterior segment of the upper dental arch (Fig. 71). Korkhaus established a certain relationship between the sum of the transverse dimensions of the four upper incisors and the length of the anterior section of the upper dental arch (Table 2). The data in Table 2, reduced by 2--3 mm, according to the thickness of the upper incisors, can be used to determine the length of the anterior section of the lower dental arch. This amendment can be ignored with a direct bite. Korkhaus measurements can be used in the study of anomalies caused by underdevelopment or excessive development of the anterior part of the jaws, vestibular deviation or inclination of the anterior teeth towards the palate.
H.Gerlach (1966), studying the ratio of the sizes of the upper and lower incisors, divided the dental arches into separate segments according to their functional affiliation. He drew a line connecting the mesial surfaces of the canines, and lines (right and left) connecting it with the distal surface of the first molars, thus obtaining three segments on each jaw - one anterior and two lateral (Fig. 72), ST - anterior upper segment, Si -- anterior lower segment; Lr -- right upper lateral segment (any lateral segment includes the canine, both premolars and the first molar); L1 -- left upper lateral; Lur -- right lower lateral, Lul -- left lower lateral.
The connection between the lateral segments is determined by the formula Lr = LI ± 3%, i.e. the sum of the mesiodistal dimensions of the right and left teeth is almost the same. The anterior upper segment corresponds to the sum of the widths of the four upper incisors. The anterior lower segment is equal to the product of the width of the lower incisors and the Ton index (1.35).
According to H. Gerlach, there is also a relationship between the size of the anterior and lateral segments. Ideal ratios can only be with an orthognathic bite, with a frontal overlap of 3 mm, when the size of the anterior segment is the same as the size of the lateral ones. The author also established a connection between the Ton index and the depth of the incisal overlap. So, with a direct bite, the anterior segment, due to the adaptation of the anterior teeth to such a closure, is shortened by 10% compared to the lateral segment. In this regard, for the level bite, an amendment was made to the Ton index, i.e. Si/Si = 1.22.
With an increase in the anterior segment compared to the lateral segment, the tendency to crowd the position of the teeth increases. With a larger anterior segment of the upper jaw compared to the lower one of the same name, deep incisal overlap is possible. Knowledge of such patterns is of great prognostic value in diagnosis. In other words, according to a certain ratio of segments, it is possible to draw a conclusion about the pathogenesis of some anomalies in the position of the teeth. The difference in the size of individual segments should be evaluated taking into account the entire segmental formula. Thus, an increase in the anterior segment can be combined with a decrease in the lateral one, but correct occlusal contacts are provided only if the total values of all upper and lower segments are equal.
Summarizing, we can assume that when analyzing diagnostic models, the following relationships should be taken into account: 1) anterior segment - lateral segments of the same jaw, 2) lateral segments of the upper jaw - lateral segments of the lower jaw, 3) anterior upper segment - anterior bottom segment.
Vertical measurements are taken in relation to the horizontal plane (see Fig. 68). The model is held in front of him at eye level so that the imaginary occlusal plane runs horizontally, touching the buccal cusps of the premolars and the mesiobuccal cusps of the first molars. Thus, it is possible to determine which teeth are located above or below this plane (see Fig. 73). The dentoalveolar elongation on the upper or lower jaw formed during this anomaly or deformation is called differently, namely, infraocclusion and supraocclusion, respectively. Dentoalveolar shortening on the upper jaw is supraocclusion, the same on the lower jaw is infraocclusion.
The degree of severity of the depth of the incisal overlap or the absence of closure (open bite) is determined in millimeters. An overlap exceeding 1/3 of the crown height, but with the preservation of the incisal-cusp contact, is called a deep incisal overlap.
The existing relationship between dentoalveolar anomalies and the shape of the hard palate dictates the need to measure the palatine vault in the sagittal, transversal directions and display it graphically in the form of a diagram. This can be done with a Korkhaus symmetrograph using the shear grating proposed by Van Loon (Fig. 74). The model of the upper jaw is installed with a reference point along the median palatine suture and fixed on the platform. When the clamping device is released, thin metal rods, resting against the plaster, repeat the shape of the palate, which is sketched on graph paper.
L.V. Ilyina-Markosyan simplified this by designing a special ruler with a slot in the middle, into which a movable rod with a scale is inserted. The ruler is placed alternately on the tubercles of the canines, premolars, molars and the height of the palate is measured.
Korkhaus measured the depth of the palate using a three-dimensional compass (see Fig. 66) from a straight line connecting the middle of the fissures of the first molars to the palatal suture perpendicular to the occlusal surface. He proposed to calculate the palate height index in relation to the length or width of the dental arch: palate height 100/dental arch length or palate height * 100/dental arch width. The length of the dental arch is determined using a soft wire or fishing line from the distal surface of the sixth tooth on one side, along the middle of the chewing surface of the lateral teeth and the cutting edges of the front teeth, to the distal surface of the sixth tooth on the opposite side. The height (depth) of the palate can also be determined on a teleroentgenogram in relation to the occlusal plane. The height (depth) of the palate can be measured using the apparatus shown in Figure 74.
Measurement of the apical basis of the jaws. Howes (1957) established the interdependence of dental and basal arches (apical basis) in orthognathic occlusion. According to the author, the width of the apical base in the area of the first premolars should be equal to the width of the dental arch or more by 1–2 mm. The width of the apical base of the upper jaw is measured in the area of the fossa canina, above the tops of the first premolars, and the width of the dental arch is measured between the tops of their buccal tubercles. The length of the apical base is measured along the midline from the apex of the palatine incisor papilla in the upper jaw and the contact point between the central incisors in the lower jaw to a line connecting the distal surfaces of the upper or lower first permanent molars.
On models, the length of the apical base is measured on the upper jaw from the point between the central incisors in the region of the neck from the palatal side, on the lower jaw - from the anterior rib of the cutting edge of the central incisors.
N.G. Snagina (1965) measured the width of the apical base on models of the upper jaw, setting the legs of the measuring instrument in the recesses at the level of the tips of the canine roots and first permolars. On the lower jaw, measurements were taken between the same teeth, 8 mm away from the level of the gingival margin. With a fairly high accuracy, the width of the apical basis can be measured on transverse sections of models (the section passes behind the canines, along the mesial surface of the first premolars).
Research by N.G. Snagina showed that there is a direct relationship between the value of the apical base and the dental arch,
Rice. 75. Hawley--Herber--Herbst graphical method for determining the shape of the dental arch: a - diagram construction scheme, b - application on the model.
Graphic methods of research. Gysi (1895), Hawley (1904), Herber, Herbst (1907) tried to depict the normal form of the dental arch in the form of graphic reproductions. However, the proposed charts were largely arbitrary, complex, and not supported by clinical studies.
To determine the shape of the dentition during the milk bite, the A.Schwarz method is convenient (see Fig. 61, 62). For permanent occlusion, the Hawley--Herber--Herbst diagram has become widespread, which should be drawn individually for each patient when planning and predicting treatment.
Hawley believed that the curve along which the 6 front teeth are located is a segment of the arc with a radius equal to the width of 3 teeth: the central, lateral incisors and canine. Hawley used Bonwill's equilateral triangle principle to define the lateral segments. But such a curve, with diverging side segments, is more like a parabola. Herber, using arithmetic calculations, constructed a curve of a normal dentition in the form of a semi-ellipse. Herbst went further and combined the Hawley curve and the Herber semi-ellipse, obtaining a diagram (Fig. 75), which most realistically reflects the normal shape of the dentition, which is constructed as follows.
The width of the central, lateral incisors and canine of the upper jaw is measured, and this size is the radius "AB" for describing the first circle from point B. Then the segments AC and AD are marked with the same radius from point A. The resulting CAD arc is the curve along which all the maxillary anterior teeth are located. To determine the location of the lateral teeth, an equilateral triangle is built. To do this, from point E - the place of intersection of the extended radius AB with the first (small) circle - draw straight lines through points C and D until they intersect with the tangent to the circle at point A, obtaining an equilateral triangle EFG.
With a radius equal to the side of this triangle, point O is marked from point A on the line AE and a second large circle is described from it. From point M (the intersection of the second circle with the diameter), the points H and J are marked with the radius AO on this circle. Then the point H is connected to C, and the point J is connected to the point D and the HCADJ curve is obtained, which, according to Hawley, corresponds to the upper dental arch .
Herbst has replaced the straight lines HC and JD with arcs CN and DP by drawing the diameter KL perpendicular to the diameter AM. Then the arc CN is described with radius LC from point L, and the arc DP is described with radius KD from point K. Thus, the resulting arc NCADP is the desired semi-ellipse of the normal upper dental arch.
Rice. 76.
For the lower dentition, the arch is drawn in a similar way, but the radius AB is reduced by 2 mm (thickness of the crowns of the upper front teeth) in orthognathic bite. Depending on the width of the 3 upper anterior teeth, several similar diagrams are drawn, the appropriate one is selected and compared with the model of a particular patient. This facilitates the application of diagrams in practice and the determination of various deviations in the dentition (Fig. 75, b). On the basis of these calculations, sets of orthodontic blowers were also created, which makes it possible to select the right one for treatment.
Cephalometric research method (measurements on the head). The purpose of the study is to elucidate the relationship of anomalies and deformities with various parts of the face and skull. Since ancient times, researchers have believed that in order to obtain aesthetically satisfactory results in orthodontic treatment, it is necessary to study the face and the location of the jaws in the skull. E. Angle in 1908 proposed a "line of harmony", which, with a satisfactory profile, should touch the points nasion, subnasale, gnathion (Fig. 76). But this technique has not found practical application.
The founder of the cephalometric method in orthodontics is the Dutch scientist Van Loon (1916). His method lies in the fact that the models of the jaws are installed in the face mask in a natural position and a model-mask is obtained, which is placed in a skull-holder cube with transparent walls. Van Loon denoted only two planes, one of which was borrowed from anthropology, namely the auricular or Frankfurt horizontal. Perpendicular to it is the second plane - mid-sagittal. This technique, due to its complexity and cumbersomeness, has also not received practical application.
A further development of the cephalometric method was the gnatostatic method proposed by P.Simon (1919). Gnatostat (from Greek gnathos - jaw and lat. status - state) - a device with which the location of models is determined in relation to three mutually perpendicular planes: the mid-sagittal plane passes along the palatine suture and divides the face in half; the ear-orbital, or Frankfurt, horizontal line passes through the orbital point and the upper edge of the external auditory opening; the frontal or orbital plane, perpendicular to the first two, passes through both orbital points (see Fig. 68). In orthodontics, skin and bone points are used for designations, adopted at the international conference of anthropologists in 1884 (Germany).
The P.Simon gnatostat apparatus consists of a facial arch connected to an impression tray and has four moving arrows installed on the auricular and inferoorbital points (see Fig. 77). With the help of a gnatostat, the base of the model is formed in accordance with the above planes, and thus the spatial orientation of the patient's dentition is simulated, which makes it possible to visualize the location of the jaws in the skull.
The technique is as follows: an impression tray for the upper jaw is filled with an impression mass and inserted into the mouth. After the impression has hardened, the assistant holds the spoon in this position, the handle of which is fastened to the rod. The facial arch is put on the latter, orienting it with arrows at the level of the Frankfurt horizontal along the points orbitale (or - the deepest point of the lower edge of the orbit) and tragion (t - a point on the upper edge of the ear tragus).
Rice. 77. Equipment and sequence of work in the manufacture of gnatostatic models according to P.Simon: a - gnatostat: / - standard metal impression spoon, 2 - metal rod, 3 - movable sleeve, 4 - hinge, 5 - orbital arch, 6 - arrows, 6 - installation of the gnatostat and taking impressions, c - installation of a ruler (a) with an engraving arrow (o) on the orbital arc and engraving of the orbital line on the cast (c), d - casting of the gnatostatic model (Simon).
On the patient's face, these points are preliminarily marked with a bold pencil or black paper circles are pasted.
Having arranged and fixed the arrows and the arc with screws, the movable sleeve is mixed close to the arc and everything is fixed. Then the arc with the rod is disconnected from the impression tray, the impression is removed from the mouth and reconnected in the same position. The line connecting the ends of the two middle arrows is the line of intersection of the Frankfurt horizontal with the orbital plane. To transfer this line to the surface of the cast, use a ruler (Fig. 11, c), which is applied to the sharp ends of the two arrows of the orbital arc. An arrow with a pointed end departs at a right angle from the middle of the ruler, which can move up and down and around the axis within the same plane. The ruler is laid so that the point of the arrow reaches the surface of the imprint (Fig. 77, c). When moving the arrow up and down and sideways, the tip leaves a mark on the surface of the print in the form of an engraved line. Then the orbital arc is replaced with a platform and the upper model is cast (Fig. 11, d). After the model is released from the cast, a drawn transverse line is found that passes through the tops of both canines, and the median plane is set along the palatal suture.
Rice. 78. Models of the jaws: a - normal, 6 - gnatostatic (explanation in the text).
Gnatostatic models made in this way have the following features: the upper plinth surface of the upper model corresponds to the Frankfurt horizontal, and the lower one is parallel to it; the distance between them is 8 cm; the rear surfaces of the models are parallel to the orbital plane and are at a distance of 4 cm from it. Models are drawn and studied using a symmetrograph. When comparing gnatostatic models with conventional ones, it can be seen that the occlusal curve on them is not the same. On gnatostatic models, it decreases anteriorly, i.e. goes with an inclination in relation to the Frankfurt horizontal (Fig. 78, b). If the upper canines coincide with the orbital plane - the norm, if ahead of it - prognathism and treatment should be directed to the upper jaw. If the upper canines are displaced beyond the frontal plane - medical manipulations on the lower jaw.
In the following decades, the P.Simon method was modified many times. In particular, V.N.Trezubov and E.N.Zhulev developed the technique of obtaining impressions from the upper jaw using a gnatostat and subsequent formation of plaster models. Today, this technique can be used with a conventional or special articulator equipped with a facial arch, with an individual or standard setting of the articular and incisal angles.
The emergence of new research methods, such as teleroentgenography, has reduced the importance and necessity of gnatostatic models.
For a long time, orthodontists have used various methods of anthropology for their research and determine the angles on the face and skull using compasses and rulers. For example, the angle formed from the intersection of lines going from the tragus of the ear and from the bridge of the nose to the subnasale point was used by the Dutch dentist R. Satreg for physiognomic study of the face and determination of racial characteristics. This angle was called the Camper's angle of the face, the magnitude of which was associated with the development of the brain and facial skull.
Analysis of face photographs. Photographs of the face profile have long been studied by authors using various methods. A purely aesthetic consideration of the "line of harmony" photographs was carried out by EAAngle (see Fig. 76). Then D.A. Kalvelis, Simon, Andresen, Izard, A. Kantorowicz, A. Schwarz were engaged in the analysis of faces in the photographs.
To study the configuration of the face before and after orthodontic treatment, photographs of 9x12 cm in size (profile and face) are prepared. Photographs of the face (face) are of diagnostic value in case of narrowing of the jaws, pronounced protrusion of the anterior part of the upper dentition, facial asymmetries, with deep and open bite. Profile photos help clarify the severity of distal, mesial, open and deep bite.
It is recommended to photograph the patient in three positions: with closed lips (front), with closed teeth in central occlusion and bare teeth (front) and in profile. When looking forward, the head is set straight so that the imaginary sagittal and orbital planes are perpendicular to the cabinet floor, and the Frankfurt horizontal is parallel to it. Lips and chin muscles should not be tense.
Rice. 79. Face profile analysis: / -- Frankfurt horizontal, 2 -- P.Simon orbital plane, 3 -- Dreyfus nasal plane, 4 -- A.Kantorowicz profile vertical.
To compare photographs, their identity is necessary, for which special devices are used - photostats and the same shooting conditions. When studying photographs (profile), the following lines are drawn: the Frankfurt horizontal, Simon's orbital plane, the Dreyfus nasal plane, A. Kantorovich's profile vertical (Fig. 79). The last three lines are parallel and intersect at right angles with the Frankfurt horizontal. For more accurate drawing of these lines, you can apply the mentioned points with a pencil or stick black paper circles before shooting.
Normally, the upper lip touches the Dreyfus line, the lower lip is somewhat spaced, and the chin is between the orbital and Dreyfus lines. Such a study can be carried out directly on the face using a profiloscope, if available. To determine the types of the head and face, various indices are proposed, determined from photographs (face), in particular, the Izar facial index (see Fig. 64).
The photographs also study the shape, size of the nose, chin, forehead, the height and severity of the lips, the profile of the mouth (Fig. 80). Photographs in many cases facilitate the diagnosis and preparation of a treatment plan, but do not give an idea of the shape and structure of the facial skeleton and the location of the jaws. Therefore, they should be compared with the data from the analysis of teleroentgenograms, supplementing also the results of stereophotogrammetry and holography.
However, photography must necessarily be carried out before orthodontic treatment in various positions (profile and front), with the patient's smile, on the right and left, dentitions closed and separately, including with the help of special mirrors. The resulting photographs, along with diagnostic models, orthopantomograms and teleroentgenograms, are necessary documentation that must be stored and requested before treatment, during and after the end of therapy.
X-ray methods of research are necessary to clarify the diagnosis, plan, prognosis of treatment and dynamic monitoring of its results. This is one of the most common research methods. At the same time, along with obtaining traditional X-ray images, intraoral digital (digital) radiography is being introduced into the practice of dental clinics, which provides a number of fundamentally new opportunities. Irradiation during digital radiography is reduced by 60--90% (Yudin PS et al., 2006), which reduces the anxiety of patients who also have the opportunity to see the image on the monitor screen themselves.
Intraoral contact radiography. Obtaining such radiographs of teeth and craniofacial bones is more difficult due to anatomical features and the possibility of layering. Therefore, for contact intraoral images, it is recommended to direct the tube of the X-ray tube at a certain angle for the teeth of the upper and lower jaws, using the isometric rule: the central beam passes through the top of the root of the removed tooth perpendicular to the bisector of the angle formed by the long axis of the tooth and the surface of the film (see Fig. 81 ). Deviation from this rule leads to a shortening or lengthening of the object, i.e. the image of the teeth is longer or shorter than the teeth themselves.
Rice. 80. Types of facial profile: a - orthognathic occlusion, b - with upper prognathia, c - with lower prognathia (progenia).
To comply with the rules of isometry, it is necessary to use certain angles of inclination of the X-ray tube when shooting different parts of the jaws. To shoot individual teeth or groups of them, there are certain features of the position of the x-ray film in the oral cavity, the inclination of the x-ray tube, the direction of the central beam and the point of contact of the top of the tube with the skin of the face, which are described in the manuals on dental radiology. Figure 82 shows a diagram of the projections of the tips of the roots of the teeth on the skin of the face.
Intraoral radiography "bite" is performed in cases where intraoral contact images are not possible (increased gag reflex, especially in children), if it is necessary to study large sections of the alveolar process, to assess the condition of the buccal and lingual cortical plates of the lower jaw and the floor of the mouth.
Extraoral (extraoral) radiography is used when it is necessary to assess areas of the upper and lower jaws, facial bones, temporomandibular joints, the image of which is not obtained on intraoral images or they are only partially visible. On extraoral images, the image of the teeth and their surrounding formations is less structural. Therefore, such images are used only in cases where it is not possible to obtain intraoral radiographs (increased gag reflex, lockjaw, etc.).
X-ray of the temporomandibular joints. Various methods are used to study the joints: the close-focus X-ray method, it is known as the "Parma method" - is performed with the mouth wide open, since a better image is obtained due to the elimination of the shadow of the zygomatic bone.
Rice. 81. Projection image of the tooth depending on Fig. 82. Scheme of the projection of the tops of the teeth roots from the direction of the central beam: 1 - lengthening on the skin of the face, tooth extraction - the central beam is directed perpendicular to the axis of the tooth; 2 - tooth shortening - the central beam is directed perpendicular to the film; 3 - isometric - the correct image of the tooth.
Sometimes the Schüller method is used, but even with this method there is a lot of distortion due to layers and the presence of many spherical surfaces. It is best to use tomography and sonography to study changes in the temporomandibular joint.
Tomography and sonography. These are additional methods of layer-by-layer study of the area under study, allowing you to obtain an image of a certain layer, avoiding the superposition of shadows that make it difficult to interpret radiographs. Special devices are used - tomographs or tomographic attachments. During the exposure, the patient is motionless, and the X-ray tube and film cassette move in opposite directions.
With the help of tomography, an X-ray image of a certain layer of bone at the desired depth can be obtained. This method is especially valuable for studying various pathologies of the temporomandibular joint, lower jaw, etc. Tomograms can be obtained in three projections: sagittal, frontal and axial. Pictures are taken in layers with a “step” of 0.5–1 cm, usually at a depth of 2–2.5 cm. At a rocking angle of 20°, the thickness of the layer under study is 8 mm, at 30, 45, and 60° it is 5.3, respectively; 3.5; 2.5 mm.
A layer-by-layer study with a small swing angle of the x-ray tube (5--12 °) is called zonografiya. In this case, the image of the studied area is obtained more clear and contrast. The technique is so called because it allows you to get an image not only of a separate layer, but of the whole zone of the object. At its core, sonography occupies an intermediate position between plain radiography and tomography. It differs from the first by the phenomenon of smearing of interfering shadows, and from the second by the fact that it preserves the overall x-ray picture of the area being filmed in the image.
One of the special types of sonography is panoramic tomography of the skull (see Fig. 84, 85), which is used to study the dentoalveolar system. This technique makes it possible to obtain an image of three-dimensional curved surfaces on a flat x-ray film. In a panoramic tomograph, either the patient and cassette rotate, or the tube and cassette rotate. Sonography is the method of choice, especially when it is necessary to obtain information about the ratio of the elements of the temporomandibular joint.
The scheme for measuring the parameters of the temporomandibular joint is shown in Figure 83. The width of the articular fossa at the base is determined along the line AB connecting the lower edge of the auditory canal with the top of the articular tubercle; the width of the articular fossa is also measured along the line SD, drawn at the level of the top of the mandibular head parallel to the line AB; the depth of the articular fossa - along the perpendicular KL, drawn from its deepest point to the line AB; the height of the mandibular head (degree of immersion) - along the perpendicular KM, restored from the highest point of the top of the head to the line AB (almost always coincides with KL); width of mandibular head AjBi; the width of the joint space at the base in front of AAi and behind - Bi B, as well as at an angle of 45 ° to the line AB from point K in the anterior (segment a), in the posterior (segment c) and in the upper (segment b); the angle of the degree of inclination of the posterior slope of the articular tubercle to the line AB (angle a).
Modern panoramic tomographs have separate programs for performing conventional orthopantomograms, sonograms of the temporomandibular joints, maxillary sinuses, middle third of the face, atlanto-occipital articulation, orbits with optic nerve holes, and facial skull in lateral projection.
The most complete, especially general information, is provided by orthopantomograms, which, although they have projection distortion due to the variability of the shape of the objects being photographed and do not clearly display the bone structure in the region of the anterior teeth, nevertheless, this is an indispensable method for diagnosing dentoalveolar anomalies. It allows you to study the size of the body and processes of the jaws, the asymmetry of the right and left halves of the facial skeleton, the lateral displacement of the lower jaw, the location of the hyoid bone, the size of the nasal cavity and maxillary sinuses.
The orthopantomogram may reflect the relationship of the dentition in the mesiodistal and vertical directions, the location of the mandibular heads in the articular fossae, the branches and angles of the lower jaw.
To obtain a panoramic image, the emitter (X-ray tube) and the receiver (X-ray film or digital semiconductor sensor) move around the patient's head along a certain trajectory (see Fig. 84). The speed of the beam movement determines which layer will be displayed on the film or will be perceived by the digital sensor.
The idea in this case is the same as when photographing a moving object. For example, a photographer shoots a car moving fast along a road surrounded by trees. If you firmly fix the camera, then the picture will have a clear image of trees and a completely blurry image of a car. If the apparatus moves at the speed of a car, then its image will be obtained and blurred - motionless objects (trees). The situation is practically the same in panoramic shooting - the emitter and receiver rotate relative to the patient's jaw, and the linear velocity of the layers located at different distances from the center of rotation will be different. Therefore, by moving the "camera" at different speeds, you can photograph different layers. This situation is depicted in Figure 84.
For metric studies on an orthopantomogram, it is customary to draw horizontal, vertical and oblique lines. To assess the development of the lower jaw according to orthopantomography data, A.N. Chumakov and S. Khazem proposed an improved method, which, unlike the existing ones, involves the use of not absolute values, but relative ones. For this purpose, a reference straight line is drawn tangentially connecting the mandibular heads in the joint.
Perpendiculars descend to this line or parallel to it from the following points: along the mesial surface of the central lower incisors, along the distal edge of the lower canines, along the distal edge of the first permanent molars of the lower jaw. After these lines are drawn, segments are formed (Fig. 85): 1) the length of the dentition (from the distal surface of the 36th to the distal surface of the 46th tooth); 2) the central segment (73, 32, 31, 41,42, 83rd teeth during the formation of a mixed dentition and 36, 32, 31,41,42,46th - in the permanent one); 3) anterior-left and right (31, 32, 73 and 41, 42, 83 in mixed dentition or 31, 32, 33 and 41, 42, 43 - in permanent); 4) lateral segments (36, 75, 74 and 46, 85, 84 in the period of formation of mixed dentition and in permanent - 36, 35, 34 and 44, 45, 46).
Using this technique, it is possible to determine the ratio of the projection of the central and lateral segments to the projection of the length of the dental arch and find out where, in which segment deviations in the development of the lower jaw occurred. By the size of the lateral segments, one can judge the symmetry of their development and determine the topography of dysplasia.
It should be noted that the interpretation of radiographs in children is much more demanding than in adult patients. The very personality of the child needs a more gentle and thoughtful application of this method. Difficulties, and sometimes mistakes, often occur from ignorance of age characteristics, the need to monitor the state of the rudiments of permanent teeth, their development, which is of great importance for the prevention and treatment of various disorders.
With radiography in children, the rule should be more generally that this method should not be used if clinical examination is sufficient. On the other hand, one should not miss the opportunity to make an early diagnosis with the help of radiography and prevent complications.
Teleroentgenography (long-distance radiography). The first work on radiographic anthropometry of the skull is considered to be the research of Pacini (1922). Then the works of H. Hofrath and B.H. Broadbent (1931) appeared. All these works were devoted mainly to the study of the structural features of the skull, as well as the ratio of its individual parts in the norm.
At present, the method of teleroentgenography has become firmly established in orthodontic practice, both abroad and in our country. By studying a teleroentgenographic image, it is possible to determine the features of the growth and development of the bones of the face. By comparing images before, during and after treatment, it is possible to determine the changes that occur in connection with the treatment.
To conduct teleroentgenography, a special device is needed that would allow for the correct and reliable fixation of the head of the subject in the desired position. For this purpose, a number of installations - cephalostats - have been proposed. Their principle is almost the same, and one of the components is a craniostat for fixing the head and a device for the cassette.
When receiving teleroentgenograms (TRG), certain rules must be observed. The distance between the X-ray tube and the film should be as large and constant as possible. Due to the large distance, distortion of the object being shot is minimized. Hence the name "teleroentgenography" - radiography at a distance. Various authors give unequal distances (from 30 cm to 4-5 m). At the Congress of American Orthodontists in Boston (1956), a standard distance of 1.5 m was adopted, and the exposure time was reduced to 0.2 s to reduce exposure.
In view of the fact that the materials published in the literature are based on the analysis of teleroentgenograms obtained at different settings and at different focal lengths, in order to compare the linear dimensions of the skull, it is necessary to know the image magnification factor. This must be determined by each researcher in relation to the survey technique. The calculation of the magnification factor can be done using the formula:
where A is magnification in percent, D is focus-to-film distance, d is object-to-film distance.
When evaluating linear measurements of various parts of the skull, it should be taken into account that the size of anatomical objects located at an angle to the shooting plane is distorted in accordance with parallax, i.e. offset of the image, in direct proportion to the value of this angle.
Before shooting, a paste from an aqueous solution of barium sulfate or a mixture of silver amalgam filings with glycerin is applied to the skin of the face along the mid-sagittal line with a soft kolinsky or squirrel brush in order to obtain the contours of the bone base and soft tissues on one film. Decoding and various measurements are carried out directly on the TRG using a negatoscope, or its drawing is transferred with ink to tracing paper and cellophane paper, there are also computer programs for decoding.
The literature describes many methods for the analysis of TRG, in which the authors propose a variety of schemes with up to 130 or more parameters. The authors of the book are more impressed by the method proposed by M.Z. Mirgazizov, A.P. Kolotkov and others, according to which the minimum number of decisive parameters is used for differential diagnostics. Based on the theory of probability, they determined the information content of the known X-ray cephalometric indicators, from which the most valuable ones were selected for each specific anomaly.
X-ray cephalometric diagnosis and treatment planning can be divided into 4 stages: confirmation of the preliminary diagnosis; differential diagnosis of clinical varieties of malocclusion; identification of the essence and morphological features of violations in the structure of the face and bite, inherent in one form or another, i.e. establishment of the final diagnosis; treatment planning.
The most commonly used method is A.M.Schwarz, who divided all measurements into craniometric, gnatometric and profilometric. We present the main points, planes and angles. As a guide, A.Schwarz proposed the plane of the base of the skull, namely its anterior part, as the most stable. The following points were used to determine the planes (Fig. 86, 87). Capital letters indicate bony points, small letters indicate points on the skin.
A. Cranial anthropometric points (bone and skin). Se (Sella) - a point in the middle of the entrance to the Turkish saddle; N (Nasion) -- the point of intersection of the nasolabial suture with the median plane; Or (Orbitale) - the lowest point of the lower edge of the orbit; Sna (Spina nasalis anterior) -- anterior nasal spine; Snp (Spina nasalis posterior) - the posterior nasal spine, this point is often poorly visible, therefore it is advisable to navigate along the lower edge of the fpp point and find it at the intersection of the latter with the contour of the palate; fpp (fissura pterygopalatine) - a point on the anterior wall of the pterygopalatine fossa, most protruding posteriorly in the form of a loop; Ro (Porion) - the upper edge of the external auditory canal; Co (condylon) -- the most cranial point on the convex surface of the mandibular head; Ss (Subspinale, according to Downs point A) - a point in the median plane, where the front edge of Sna passes into the wall of the alveolar process; sn (subnasale) - the point of transition of the lower part of the nose to the lip; Spm (supramentale, no Downs point B) - the most posteriorly located point along the midline in the region of the mental fold; Pg (Pogonion) - the most protruding point of the chin; Gn (Gnathion) - the lowest point of the symphysis of the lower jaw. Go (Gonion) - a point on the bisector of the angle at the intersection of the tangents to the lower edge of the jaw and to the posterior edge of the lower jaw branch.
Rice. 87.
B. Dental anthropometric points (see Fig. 89). Pi I -- the longitudinal axis of the upper central incisor is drawn through the middle of the root apex and its canal; Pi I -- longitudinal axis of the lower central incisor through the middle of the root apex and root canal. Similarly, it is possible to draw the longitudinal axes of all single-rooted teeth. Rto (5 - the longitudinal axis of the upper first molar is drawn through the middle of the intertubercular fissure, between the mesial and distal buccal roots; Pmu 6 - the longitudinal axis of the lower first molar is drawn between the roots and through the middle of the intertubercular fissure. Similarly, you can draw the longitudinal axes of all multi-rooted teeth .
When deciphering TRG, the following planes are used (planum, see Fig. 88, 89). The plane of the anterior part of the base of the skull NSe; the Frankfurt horizontal plane (FH) connecting the points Po and Or; SpP (plane of the base of the upper jaw) passes through the points Sna and Snp; Mp (the plane of the base of the lower jaw) passes through the points Gn and Go; the occlusal plane (Ocp) corresponds to the line of closing of the teeth and is drawn through the middle of the vertical of the incisal overlap so that at least three tubercles of the molars touch it; in the milk bite, this plane passes through the middle of the vertical of the incisal overlap and the tubercles of the second milk molars. Tangent to skin points sn (subnasale) and pg (pogonion) - T (tangent). Rp (nasal plane) - perpendicular from the skin point p to the plane Nse; Horn (orbital plane) - a straight line from the skin point og, parallel to Rp.
Rice. 88.
Rice. 89.
Total anterior face height (N--Gn), total mid-face height (Hfm) from a point in the middle of the Nse plane to a point in the middle of the Gn--Go line, total posterior face height (Hfp) from the Se point to the Go point, depth middle part of the face (Dmf) from a point in the middle of the line N--Gn to a point in the middle of the line Se--Go.
Having determined the points and planes, they proceed to the analysis of the lateral TRG, highlighting cranio-, gnatho- and profilometry. In each section, linear measurements and the ratio of their values, angular measurements are carried out.
Craniometry. The purpose of craniometric studies is to determine the location of the jaws and the temporomandibular joint in relation to the base of the skull. As a guideline for craniometry, the plane of the anterior part of the skull base (N--Se) is used. Options for the location of the jaws are determined by the values of the angles: facial, inclination and the angle of the "horizontal" (Fig. 89).
The front angle (1) is formed at the intersection of the lines NSe and NSs (internal lower angle), it is called the angle "F" (Facies - face). With orthognathic bite, on average, it is 85 ± 5 °.
The inclination angle "I" (2) (inclination - inclination, i.e. the angle of inclination of the dentition relative to the base of the skull) is formed at the intersection of the plane Pp and SpP (internal upper angle), and its average value is 85 °.
To determine the position of the articular head in relation to the base of the skull, the angle (3) is determined, which is formed at the intersection of the plane Pp and Po-Or (Frankfurt horizontal). According to A.Schwarz, this is the horizontal angle "H", which also affects the shape of the face profile.
Gnathometric studies make it possible to establish, with the help of certain measurements, important morphological features of various types of malocclusion. In this case, the measurements concern the dentoalveolar complex located between two basal planes - SpP (the plane of the base of the upper jaw) and MP (the plane of the base of the lower jaw). In practice, the following measurements are the most important (Fig. 89).
1. There is a certain dependence in the ratio of the length of the jaws. The length of the lower jaw is related to the length of the anterior part of the base of the skull (NSe) as 20:21 or 60:63. The length of the upper jaw relates to the length of the lower jaw in the same way as 2:3, i.e. the length of the upper jaw is 2/3 of the length of the lower. According to Korkhaus, the desired length of the lower jaw branch is related to the length of its body as 5:7, i.e. the length of the branch is 5/7 of the length of the body of the jaw. The difference in the desired and actual length of the jaws indicates the degree of their underdevelopment or overgrowth.
The degree of development of the jaws along the vertical (dentoalveolar height) is determined: in the area of the front teeth along the perpendicular from the cutting edge of the central incisors and in the area of the lateral ones - along the perpendicular from the middle of the chewing surface of the sixth and seventh teeth to the plane of the base of the corresponding jaw (SpP or Mp).
The angle formed by the two basal planes -- SpP and MP. It is called the basal angle, or angle "B", and it is equal to an average of 20 + 5 °. A reduced angle is a sign of well-developed masticatory muscles, and its increase indicates underdevelopment of the molars. A large basal angle always accompanies severe open bite. At the same time, an increase in the angle of the lower jaw is also observed.
The gonial angle, or the angle of the lower jaw, is formed at the intersection of the tangents to the lower edge of the lower jaw and the posterior surface of its branch. Its average value fluctuates within 123±10°. Its increase or decrease contributes to the aggravation of anomalies.
tr -- trichion -- scalp border
n -- skin point nasion
p -- skin point porionor = orbital point
H - horizontal line through points P and Og
sn - dermal nasal point
gn -- skin point of the symphysis of the lower jaw
Rp and Ro are perpendiculars to the horizontal H
KPF -- Kiefer-Profil-Feld (profile field)
Rice. 90. Scheme for interpretation of profilometric data.
The axial inclinations of the teeth (angles 4, 5, 7, 8) are measured in relation to their respective basal planes. For example, Pi X to SpP is 70°, etc. Average angles for upper central incisors, canines, and premolars are 70, 80, and 90°; for lower incisors and canines - 90° with a difference of ±5° (the angles of inclination of the central upper and lower incisors are measured from the outside, i.e. the lower external angle). If the axial inclination of the upper incisors is less than 65°, then they are in the protrusion position; if more than 75 ° - in the position of retrusion.
The continuation of the long axes of the upper and lower incisors until they intersect forms an inter-incisal angle (6) "ii". The measurement is taken inwards and the average value of the angle is 140+5°. The relative position of the incisors is affected by the value of the basal angle (SpP - MP).
Profilometry. Of no small importance in the profilometric study is the thickness of the soft tissues of the face, which can either compensate for the wrong profile or exacerbate it even more. Therefore, it is always necessary to take into account the thickness of soft tissues, which is especially important when choosing a treatment method. There are the following average data on the thickness of the soft tissues of the face profile when shooting at a distance of 2 m: the distance between the bone and skin points N--n = 7 mm; sn--Ss = 14--16 mm; spm--Spm=12mm; pg-- Pg = 15 mm (see fig. 88, 89).
Between the nasal and orbital planes there is a profile field KPF (Kiefer-Profil-Feld) (Fig. 90). Of particular practical importance is the profile angle "T", which is formed at the intersection of Pp and the line connecting pg and sn (pogonion and sub-nasale) (see Fig. 89). The angle "T" can be determined from the photograph. With an orthognathic bite, it runs along the center of the red border of the upper lip, touching the edge of the lower one, and is equal to an average of 10 °, but can also have a negative value.
The age of the patient and the appearance of ossification centers of the wrist. The development and growth of the jaw bones are intermittent, spasmodic and coincide with periods of active growth of the whole organism. Most clinicians consider orthodontic treatment to be most appropriate during periods of active growth of the facial skeleton. Its most intensive growth falls on the 1st, 3rd, 6th - 7th, 11th - 13th years of life.
Table 3
wrist bones
Rice. 91.
It is necessary to determine the correspondence between the dental and so-called "bone" age. Therefore, radiographs of the hands are used to identify such periods (Table 3, Fig. 91). Ossification of the hand and wrist is considered the standard of skeletal development. It is very important for the orthodontist to know when skeletal growth ends, because the variability of tooth age has a very significant range. The following criteria were recognized as the most reliable. The synostosis of the epiphyses with the diaphysis occurs at 15-19 years of age, of the nail phalanges at 13-18 years of age, and of the middle phalanges at 14-20 years of age.
Assessment of the stage of jaw growth according to the degree of formation of the cervical vertebrae. The degree of formation of the dentoalveolar system can be determined by the rule of growth of the cervical vertebrae proposed by McNamara "1, 2, 3 ...". On the teleroentgenogram, II-VI cervical vertebrae are taken into account. According to the author, there are 6 stages of the formation of the cervical vertebrae with a maximum level in 3-4 stages.
In the 1st stage, each vertebra has a trapezoid shape, rounded outlines, and a flattened lower border. In the 2nd, the concavity of the II vertebra appears, and the rest acquire a more rectangular shape. This means that less than a year remains before the peak of active growth of the lower jaw begins. In the 3rd stage, vertebrae II and III already have a semicircular concavity, which may be an indicator of active growth in the same year. In the 5th stage II-V, the vertebrae are depressed and more square in shape - growth is almost completed. At the 6th stage, II-VI, the vertebrae are square with concave upper and lower borders; growth is finally completed. The 4th stage is accompanied by the appearance of concavity in II, III and IV vertebrae. Growth potential is slightly lower than in the previous stage, and in girls it coincides with the beginning of monthly cycles.
Study of the functional state of the dentofacial system. The interdependence of form and function is manifested both during the period of development and formation of the dentoalveolar system, and throughout the life of a person. The dental system is constantly affected by various internal and external factors, under the influence of which the function and, accordingly, the shape of its constituent tissues and organs change: lips, cheeks, tongue, chewing and facial muscles, temporomandibular joints, soft palate, muscles of the floor of the mouth and throats. Such changes can adversely affect the condition of the dentition and jaws, resulting in a variety of bite anomalies and their combinations.
In order for orthodontic treatment to be successful and its results sustainable, it is necessary to pay attention not only to individual teeth, dentition and surrounding tissues, but also to the other components listed above, including the quality and way of pronouncing speech sounds. In orthodontics, various methods are used that determine the state of the dentoalveolar system and make it possible to judge the need for restructuring certain functions.
The performance of the complex functions of the periodontium would be impossible without the existence of a large number of nerve fibers and sensitive nerve endings in its tissue. The bulk of the nerve endings, as a rule, are embedded in the bundles of the dense connective tissue of the periodontium, although they can also be found in the layers of loose connective tissue. The periodontium is richest in sensory innervation in the region of the root apex. Significantly fewer nerve endings are observed in the periodontium of the cervical third of the root.
Periodontium with its numerous nerve endings, along with the oral mucosa and chewing muscles, is a reflexogenic field, the irritation of which can cause both intra- and extra-systemic reflexes. The latter include reflexes to the masticatory muscles, which regulate the strength of its contraction. From these positions, we can talk about the periodontium as a regulator of masticatory pressure.
Reflexes arising in the area of the dentoalveolar system, functional chewing links. When food enters the oral cavity, the receptors of tactile, temperature and taste sensitivity located in the mucous membrane are irritated. Further, impulses from receptors along the second and third branches of the trigeminal nerve enter the medulla oblongata, where the sensory nuclei are located. From these nuclei begins the second neuron of the sensitive part of the trigeminal nerve, which goes to the thalamus. The third neuron begins from the thalamus opticus, heading to the sensitive zone of the cerebral cortex, from where efferent impulses are also sent along the branches of the trigeminal nerve to the masticatory muscles. The corresponding nerve devices (muscle feeling) located in the chewing muscles regulate the movements of the lower jaw and the force of muscle contraction. All this reflex activity is subject to cortical influences.
The function of chewing muscles and neural reception are manifested depending on the position of individual groups of teeth in the dental arch. From this point of view, it is advisable to single out functional links in the region of the anterior and lateral teeth in the dentoalveolar system. The following units or parts are included in the chewing link (Fig. 92, 93): 1 - the supporting part (periodontium), 2 - the motor part (muscles), 3 - the neuroregulatory part, 4 - the corresponding zones of vascularization and innervation that provide nutrition to the organs and tissues of the chewing link and metabolic processes in them.
Normally, in the chewing link, there is a coordinated interaction between the supporting part (periodontium), the motor part (musculature) and the neuroregulatory part. In the coordination of the functions of the individual parts of the chewing link, an important role is played by the nervous reception of the masticatory muscles, periodontium and oral mucosa. Of the reflexes that occur in the area of the dentoalveolar system during chewing, the following can be distinguished: periodontomuscular, gingivomuscular, myotatic and mutually combined.
Chewing links can be classified depending on the state of their individual elements as follows. According to the condition of the supporting tissues: a chewing link with intact teeth, with an abnormal arrangement of teeth, with teeth affected by caries, periodontitis, with partial or complete absence of teeth, with dentures. In the process of chewing function, a combination of various reflexes takes place. The set of reflexes associated with bite separation, which plays an important role in the clinic of orthodontics, deserves special attention.
The periodontal muscle reflex manifests itself during chewing with natural teeth, while the force of contraction of the masticatory muscles is regulated by the sensitivity of the periodontal receptors.
The gingivomuscular reflex is carried out after the loss of teeth, when the force of contraction of the masticatory muscles is regulated by the receptors of the mucous membrane of the gums and alveolar processes (Fig. 93), on which the basis of the prosthesis or orthodontic apparatus relies.
Myotatic reflexes are manifested in functional conditions associated with stretching of the masticatory muscles (see Fig. 358). The beginning of the myotatic reflex is given by impulses that arise in receptors located directly in the masticatory muscles and in their tendons.
Rice. 92. Scheme of functional masticatory Fig. 93. Scheme of the masticatory link with regulation of the link: / - supporting part (periodontium), 2 - functions through the periodontomuscular reflex part (musculature), 3 - neuroregulatory from the upper jaw (/), through the gingival muscular part , 4 - system of blood vessels, lar reflex from the lower jaw (II), i.e. and trophic innervation. in the presence of a removable prosthesis or orthodontic plate.
These receptors are irritated when the muscles are stretched, as a result of which the latter contract reflexively. The more the lower jaw is lowered, the more the chewing muscles are stretched. In response to muscle stretching, their reflex contraction occurs; the process of muscle stretching is manifested in a change in their tone both in a static state and during function.
Physiological changes in teeth and periodontium. The shape, structure of the teeth and the condition of the periodontium are not constant; under the influence of various functional influences, they change under physiological conditions. These changes are manifested in erasure, in the appearance of mobility and displacement in the direction of the masticatory plane, in the occurrence of pathological bite, in exfoliation of the epithelium and in slight atrophy of the dental cells. As a result of erasing the chewing surface, the "working" places of the teeth are gradually polished, their steepness decreases, the grooves of the chewing surface become smaller and gradually disappear. As a result of erasing the chewing surface, sharp edges, enamel stripes appear on the teeth, and flat defects form in the dentin. This reduces the load on the periodontium during chewing, since much less force is required for chewing with sharp teeth. As a result of such abrasion, the bite becomes deeper, a much larger part of the chewing surfaces is in contact, and the horizontally directed force acting on the teeth is significantly reduced.
Erasing depends on the type of chewing, on the composition of the food and on the stability of the teeth. In the case of an orthognathic bite, more significant abrasion is found on the front teeth, with a deep bite - on the molars. According to the degree of erasure, conclusions can also be drawn regarding the age of a person. Until the age of 30, abrasion is limited to enamel, furrows appear on incisors, canines and crowns of molars. At the age of 40, in people who chew well, abrasion reaches the dentin, which is good because of the yellowish color. At the age of 50, the dentin on a larger surface becomes exposed and has a dark brown color, the crown of the tooth becomes slightly shorter. Age features of physiological erasure are shown in Figure 94. By the age of 70, in people who chew well, erasure approaches the tooth cavity.
Chewing efficiency and methods for its determination. One of the indicators of the state of the dental system is chewing efficiency. Some clinicians, in particular S.E. Gelman, use the term "chewing power" instead. But power in mechanics is the work done per unit of time, it is measured in kilograms. The work of the masticatory apparatus can be measured not in absolute units, but in relative ones, i.e. according to the degree of grinding food in the oral cavity in percent. Therefore, it is more correct to use the concept of "chewing efficiency". Thus, chewing efficiency should be understood as the degree of grinding of a certain amount of food in a certain time. Methods for determining chewing efficiency can be divided into static, dynamic (functional).
Static methods for determining chewing efficiency are used during a direct examination of the oral cavity, when the condition of each tooth and all available ones is assessed and the data obtained are entered into a special table in which the share of each tooth in the chewing function is expressed by the corresponding coefficient. Such tables have been proposed by many authors, but in our country the methods of N.I. Agapov and I.M. Oksman are more often used.
In the table of N.I.Agapov, the lateral incisor of the upper jaw was taken as a unit of functional efficiency (Table 4).
In total, the functional value of the dentition is 100 units. The loss of one tooth in one jaw is equated (due to the dysfunction of its antagonist) to the loss of two teeth of the same name. Table 4 (according to N.I. Agapov) does not take into account the wisdom teeth and the functional state of the remaining teeth.
Table 4
Table of coefficients of teeth according to N.I. Agapov
Table 5
Table of coefficients of teeth according to I.M. Oksman
I.M. Oksman proposed a table for determining the chewing ability of teeth, in which the coefficients are based on taking into account anatomical and physiological data: the area of the occlusal surfaces of the teeth, the number of tubercles, the number of roots and their sizes, the degree of alveolar atrophy and the endurance of the teeth to vertical pressure, periodontal conditions and reserve forces of non-functioning teeth. In this table, the lateral incisors are also taken as a unit of chewing efficiency, the wisdom teeth of the upper jaw (three-cusp) are valued at 3 units, the lower wisdom teeth (four-cusp) - at 4 units. In total, 100 units are obtained (Table 5). The loss of one tooth entails the loss of the function of its antagonist. In the absence of wisdom teeth, 28 teeth should be taken as 100 units.
Taking into account the functional efficiency of the chewing apparatus, an amendment should be made depending on the condition of the remaining teeth. With periodontal diseases and tooth mobility of I or II degree, their functional value is reduced by a quarter or half. With tooth mobility of the III degree, its value is zero. In patients with acute or exacerbated chronic periodontitis, the functional value of the teeth is reduced by half or equal to zero.
In addition, it is important to take into account the reserve forces of the dentition. To take into account the reserve forces of non-functioning teeth, the percentage of loss of chewing ability in each jaw should be additionally noted as a fractional number: in the numerator - for the teeth of the upper jaw, in the denominator - for the teeth of the lower jaw. The following two dental formulas are an example:
- 80004321
- 87654321
- 12300078
- 12345678
- 80004321
- 00004321
- 12300078
- 12300078
In the first formula, the loss of chewing ability is 52%, but there are reserve forces in the form of non-functioning teeth of the lower jaw, which are expressed by designating the loss of chewing ability for each jaw as 26/0%.
With the second formula, the loss of chewing ability is 59% and there are no reserve forces in the form of non-functioning teeth. The loss of chewing ability for each jaw separately can be expressed as 26/30%. The prognosis for the restoration of function in the second formula is less favorable.
To bring the static method closer to clinical diagnosis, V.K. Kurlyandsky proposed an even more detailed scheme for assessing masticatory efficiency, which was called an odontoperiodontogram. A periodontogram is a diagram-drawing in which data about each tooth and its supporting apparatus are entered. Data in the form of symbols obtained as a result of clinical examinations, X-ray studies and gnatodynamometry are entered into a special drawing scheme.
Functional (dynamic) methods for determining chewing efficiency. The effectiveness of the chewing function depends on a number of factors: the presence of teeth and the number of their articulating pairs, tooth decay and its complications, the condition of the periodontium and chewing muscles, the general condition of the body, neuro-reflex connections, salivation and the qualitative composition of saliva, as well as the size and consistency food bolus. With pathological phenomena in the oral cavity (caries and its complications, periodontitis and periodontal disease, defects in the dentition, dentoalveolar anomalies), morphological disorders are usually associated with functional insufficiency.
Chewing samples. Christiansen in 1923 first developed their technique. The subject is given to chew three identical cylinders of coconut. After 50 chewing movements, the subject spits out the chewed nuts into the tray; they are washed, dried at a temperature of 100° for 1 hour and sifted through 3 sieves with holes of different sizes. By the number of unsifted particles remaining in the sieve, the effectiveness of chewing is judged. The technique of Christiansen's chewing test was later modified in our country by S.E. Gelman in 1932.
Gelman's chewing test. S.E. Gelman proposed to determine the effectiveness of chewing not by the number of chewing movements, as Christiansen, but for a chewing time period of 50 s. A quiet environment is required to obtain a chewing sample. It is necessary to prepare packaged almonds, a cup (tray), a glass of boiled water, a glass funnel with a diameter of 15x15 cm, gauze napkins 20x20 cm in size, a water bath or pan, a metal sieve with holes of 2.4 mm, balance with weight.
The subject is given 5 g of almond kernels for chewing, and after the indication “start”, 50 seconds are counted. Then the subject spits the chewed almonds into the prepared cup, rinses his mouth with boiled water (if there is a removable denture, rinses it too) and also spits it into the cup. In the same cup, add 8-10 drops of a 5% sublimate solution, after which the contents of the cup are filtered through gauze over a funnel. The almonds remaining on the gauze are placed in a water bath to dry; while taking care not to overdry the sample, as it may lose weight. A sample is considered dried when its particles do not stick together during kneading, but separate. Particles of almonds are carefully removed from a gauze napkin and sifted through a sieve. With intact dentitions, the entire chewing mass is sifted through a sieve, which indicates 100% chewing efficiency. If there is a residue in the sieve, it is weighed and the percentage of violation of chewing efficiency is determined using the proportion, i.e. the ratio of the residue to the entire mass of the chewing sample. So, for example, if there are 1.2 g left in the sieve, then the percentage loss of chewing efficiency will be equal to:
5:100-1.2:x; x* (100-1.2): 5 = 24%.
Physiological chewing test according to Rubinov. I.S. Rubinov considers it more physiological to confine one grain of hazelnut weighing 800 mg for a chewing test. The chewing period is determined by the appearance of the swallowing reflex and is equal to an average of 14 s.
When a swallowing reflex occurs, the mass is spit into a cup; its further processing corresponds to the Gelman method. In cases of difficulty in chewing the nut kernel, I.S. Rubinov recommends using cracker for the sample; the time of chewing a rusk until the swallowing reflex appears is on average 8 s. At the same time, it should be pointed out that chewing a cracker causes a complex of motor and secretory reflexes that contribute to better absorption of the food bolus.
With various disorders in the oral cavity (carious destruction of teeth, their mobility, defects in the dentition, malocclusion, etc.), the chewing period is lengthened. Samples can also establish the effectiveness of prosthetics, depending on the design of prostheses and their quality.
L.M.Demner suggests weighing the entire chewed mass, both remaining in the sieve after sifting it, and passing through the sieve in order to identify the number of food particles remaining in the oral cavity or quietly swallowed during the chewing test.
However, there are shortcomings in conducting these tests. In the Christiansen method, the test is done after 50 chewing movements. This figure, no doubt, is arbitrary, because one person, depending on his chewing stereotype, needs 50 chewing movements to grind food, and another is enough, for example, 30. S.E. Gelman tried to regulate the test in time, but did not take into account that circumstance that different individuals grind food to varying degrees, i.e. some people swallow more chopped food, others less, and this is their individual norm.
Rice. 95. Ideal occlusion in orthognathic bite: two- and three-point contacts on the supporting tubercles of the teeth of the lower jaw and the antagonists of the upper jaw opposing them (indicated in yellow).
According to the method of I.S. Rubinov, chewing efficiency is judged by the time of chewing 0.8 g of hazelnut before the swallowing reflex appears. This technique is devoid of the above disadvantages, however, it makes it possible to judge the restoration of efficiency only with perfect adaptation to prostheses.
Determining the place of static and functional methods for studying the effectiveness of chewing in the clinic of orthodontics, it must be emphasized that it would be a mistake to oppose them on the basis that the former are called static, and the latter functional, as well as to replace some methods with others. Indeed, the static methods are based on gnathodynamometric methods, i.e. functional research.
From the standpoint of a systematic approach, the most important link in the masticatory apparatus is occlusion, which is recorded in various ways and is assessed only visually. We propose to determine the quantitative index of the occludedogram.
Method for determining the quantitative index of the occludedogram. To calculate the index of the occludedogram obtained with the help of clasp wax, a three-point system for evaluating each pair of antagonists is used.
The occludedogram index is determined taking into account 14 pairs of antagonist teeth:
score - there are no prints on the occludedogram.
points - fuzzy prints.
points - clear or through prints.
The occludedogram index is calculated by the formula: OCG index (%) = x
Numerator = sum of points (S)xl00. Denominator = highest score multiplied by the number of pairs of antagonistic teeth (n).
For orthognathic (physiological) occlusion (Fig. 95), OKG index = 100%. A lower value of the index indicates an uneven load and the presence of supracontacts.
Graphic methods for recording the movements of the lower jaw and the functional state of the muscles. Graphic registration of the movements of the lower jaw, on the basis of which articulators were built - the first mechanical models of the musculoskeletal system of the masticatory system, played a positive role. The design of dentures adapted to the simplest movements of the lower jaw, which immeasurably improved the quality of prosthetics, at the same time opened up new perspectives for the theory and practice of orthopedic dentistry. The solution of these problems required the involvement of modern functional research methods in the clinic of orthopedic dentistry.
The most fundamental studies of the biomechanics of the masticatory system have been carried out using mastication and electromyography.
Mastication. The masticatory stereotype depends on many conditions: the nature of bite and articulation, the extent and topography of dentition defects, the presence or absence of a fixed interalveolar height, and, finally, the constitutional and psychological characteristics of the patient. Masticography, which allows you to graphically record the dynamics of chewing and non-chewing movements of the lower jaw, is a method for objectively studying this stereotype. The first attempt to record the movements of the lower jaw using a kymograph was made by N.I. Krasnogorsky (1906). Then this technique has undergone many modifications and now looks relatively simple. In 1954, I.S. Rubinov proposed a device - a masti-kaciograph and developed a method for registering the movements of the lower jaw during chewing on a kymograph, which he called masticography.
Mastication is a graphic method of registering reflex movements of the lower jaw (from the Greek masticatio - chewing, grapho - writing). To use this method, apparatuses were constructed, consisting of recording devices, sensors and recording parts. The recording was made on a kymograph or on oscilloscope-graphic and strain gauge installations.
The most appropriate place for the installation of recording devices should be considered the chin region of the lower jaw, where soft tissues are relatively little displaced during function. In addition, the amplitude of movements of this part of the lower jaw during chewing is greater than its other sections, as a result of which the recording device captures them better. Experience with devices with several recording devices has shown that they are suitable for detailed studies only in a special laboratory. In this regard, a simpler and more convenient apparatus was designed - a masticatsiograph, which makes it possible to record the movements of the lower jaw on a kymograph under normal physiological conditions (Fig. 96).
Rice. 97. Mastication of one chewing period. I - state of rest, II - the phase of introducing food into the mouth, III - the initial phase of the chewing function, IV - the main phase of chewing, V - the phase of the formation of a lump and swallowing it, O - the moment of closing the dentition and crushing food , Oi, O2; -- moment of grinding food (time in seconds).
The device consists of a rubber balloon (B) placed in a special plastic case (A), which is attached to the chin region of the lower jaw with a bandage (C) with a graduated scale (E), showing the degree of pressure of the balloon to the chin. The balloon is connected by means of an air transmission (T) to the Marey* capsule (M), which makes it possible to record the movements of the mandible on the kymograph (K).
The use of the described technique showed that the recording of the chewing movements of the lower jaw is a series of successive wavy curves. The whole complex of movements associated with chewing a piece of food, from the beginning of its introduction into the mouth until the moment of swallowing, is characterized as the chewing period (Fig. 97). In each chewing period, five phases are distinguished. On the masticogram, each phase has its own characteristic record.
The first phase - the state of rest - corresponds to the period before the introduction of food into the mouth, when the lower jaw is motionless, the muscles are in minimal tone and the lower dentition is 2-3 mm apart from the upper one, i.e. corresponds to the resting position of the mandible. On the masticogram, this phase is indicated as a straight line at the beginning of the chewing period, i.e. isolines.
The second phase is the opening of the mouth and the introduction of food. Graphically, it corresponds to the first ascending knee of the curve, which starts immediately from the line of rest. The span of this knee depends on the degree of opening of the mouth, and the steepness of it indicates the speed of introduction into the mouth.
The third phase, the initial phase of the chewing function (adaptation), begins from the top of the ascending knee and corresponds to the process of adaptation to the initial crushing of a piece of food. Depending on the physical and mechanical properties of food, changes occur in the rhythm and range of the curve of this phase. During the initial crushing of a whole piece of food in one movement, the curve of this phase has a flat top (plateau), turning into a gentle downward knee - to the level of rest. With the initial compression of a piece of food due to several movements, by looking for the best place and position for crushing it, corresponding changes occur in the nature of the curve. Against the background of a flat top, there are a number of short undulating rises located above the level of the line of rest. The presence of a flat top in this phase indicates that the force developed by the chewing muscles did not exceed the resistance of the food and did not crush it. As soon as the resistance is overcome, the plateau turns into a descending knee. The initial phase of the chewing function, depending on various factors, can be displayed graphically as a single wave or as a combination of waves composed of several ascents and descents of different heights.
The fourth phase - the main phase of the chewing function - is graphically characterized by the correct periodic alternation of chewing waves. The masticatory wave includes all movements that are associated with one lowering and raising of the lower jaw until the teeth close. It is necessary to distinguish between the ascending knee, or the rise of the AB curve, and the descending knee, or the descent of the BS curve. The ascending knee corresponds to a complex of movements associated with lowering the lower jaw. The downward knee corresponds to the set of movements associated with the lifting of the lower jaw. The top of the masticatory wave B indicates the limit of the maximum lowering of the lower jaw, and the angle value indicates the speed of transition to the lifting of the lower jaw.
The nature and duration of these waves in the normal state of the dental system depend on the consistency and size of the piece of food. When chewing soft food, frequent, uniform rises and descents of masticatory waves are noted. When chewing solid food in the initial phase of the chewing function, there are more rare descents of masticatory waves with a more pronounced increase in the duration of the wave-like movement. Then the successive ups and downs of chewing waves become more frequent.
The lower loops between the individual waves (0) correspond to pauses when the lower jaw stops during the closing of the teeth. The size of these loops indicates the duration of the closed state of the dentition. The presence of contacts between the dentition can be judged by the level of the location of the lines of intervals or closure loops. The location of the closure loops above the level of the line of rest indicates the absence of contact between the dentition. When the chewing surfaces of the teeth are in or close to contact, the occlusion loops are located below the line of rest.
The width of the loop formed by the descending knee of one chewing wave and the ascending knee of the other registers the speed of the transition from closing to opening of the dentition. According to the sharp angle of the loop, it can be judged that the food was subjected to short-term compression. The larger the angle, the longer the compression of food between the teeth. The straight platform of this loop means the stop of the lower jaw during the crushing of food. A loop with a wave-like rise in the middle indicates rubbing of food during sliding movements of the lower jaw.
After the end of the main phase of chewing, the phase of the formation of a lump of food begins, followed by swallowing it. Graphically, this phase looks like a wave-like curve with a slight decrease in the height of the waves. The act of forming a lump and preparing it for swallowing depends on the properties of the food: the formation of a lump of soft food occurs in one step, the formation of a lump of solid, crumbly food takes place in several steps. Corresponding to these movements, curves are recorded on the kymograph tape.
After swallowing the food bolus, the state of rest of the masticatory muscles is again established. Graphically, it is displayed as a horizontal line. This state is the first phase of the next chewing period.
Electromyographic study of masticatory and facial muscles. Electromyography is a method of functional study of the muscular system, which allows you to graphically record muscle biopotentials. Biopotential - the potential difference between two points of living tissue, reflecting its bioelectrical activity. Registration of biopotentials allows you to determine the state and functionality of various tissues. For this purpose, a multichannel electromyograph and special sensors are used - skin electrodes.
The functional activity of the muscles of the perioral region often changes due to malocclusion, bad habits, oral breathing, improper swallowing, speech disorders, and poor posture. Neurogenic and myogenic causes may, in turn, contribute to the emergence and development of malocclusion.
Electromyography should be carried out with the assumption of diseases of the temporomandibular joint and the muscular system. By means of an electromyographic study, it is possible to determine the dysfunction of the masticatory and facial muscles during rest, tension and movements of the lower jaw, characteristic of various types of malocclusion.
It is desirable to record the activity of paired muscles at: 1) physiological rest; 2) stress, including compression of the dentition; 3) various movements of the lower jaw.
Electromyomasticography. In order to clarify the indicators of electrical oscillations of the masticatory muscles, corresponding to the individual phases of the masticatory period, the electromyography method was used in combination with mastication. With the help of a masticatiograph, the movements of the lower jaw are recorded, and with the help of diverting electrodes, biocurrents from the masticatory muscles are recorded. Using this method, it is possible to identify the insufficiency of the biopotentials of the masticatory muscles in certain areas of the masticogram. This method can be used to test the effectiveness of therapeutic interventions.
Mastication dynamometry. The forces developed by the masticatory muscles during the compression of the dentition are determined using gnatodynamometers of various designs. The indicators of gnathodynamometry are judged by the sensations of patients associated with pain or an unpleasant feeling. Such a subjective method of assessment leads to discrepancies in the indicators of gnathodynamometry.
The method for determining the force of chewing - mastication dynamometry (Rubinov IS, 1957) - is based on the use of natural nutrients of a certain hardness with simultaneous graphic registration of the chewing movements of the lower jaw. Previously, using a phagodynamometer, the efforts (in kilograms) required to grind a particular substance are determined. The name of the method - mastication dynamometry - indicates the measurement of chewing force, in contrast to gnatodynamometry - the measurement of the jaw compression force. According to the nature of the records of chewing food substances with a known hardness, one can judge the intensity of chewing.
Myotonometry. With various deviations from the norm, muscle tone changes. So, with complicated caries, the tone of the masticatory muscles proper at rest increases, which can serve as an additional symptom of dental disease. A device for measuring the tone of masticatory muscles (myotonometer) consists of a probe and a measuring scale in grams.
Using the method of myotonometry, it is possible to determine the indicators of the tone of the masticatory muscles in a state of physiological rest and during compression of the dentition. Muscle tone depends on the interalveolar height and varies according to the duration of bite separation from several hours and days to several weeks.
In order to identify the relationship between the tone of the masticatory muscles proper and the force developed by them, a combination of myotonometry and gnatodynamometry was used. The subject was asked to squeeze the sensor of the electronic gnatodynamometer with a certain force with his teeth, while the muscle tone was measured with the myotonometer (see Fig. 98). The study showed that muscle tone does not increase strictly in proportion to the strength developed.
The data show that the relationship between the tone of the masticatory muscles proper and the force of compression of the dentition is subject to individual fluctuations and that there is no direct relationship between the degree of increase in the tone of the proper masticatory muscles and the force of compression of the dentition.
Myography. The function of the striated muscles is studied using various instruments that record the thickening and reduction of the corresponding muscle groups during their contraction or relaxation. The myography method records the activity of muscles associated with a change in their thickness during isotonic and isometric contractions. In the process of chewing, the thickness of the muscles changes due to an increase and decrease in their tone. The myography method is used to account for reflex contractions (thickening and thickening) of the masticatory muscles. The introduction of myography into the clinic is promising for recording the function of mimic muscles in normal and pathological conditions.
Rheography is a method for studying pulse fluctuations in the blood filling of vessels of various organs and tissues, based on graphic registration of changes in the total electrical resistance of tissues. In dentistry, methods have been developed for studying blood circulation in the tooth - rheodentography, in periodontal tissues - rheoparodontography, and in the periarticular region - rheoarthrography. Rheography is used for early and differential diagnosis, evaluation of the effectiveness of treatment of various diseases. Research is carried out with the help of rheographs - devices that allow you to register changes in the electrical resistance of tissues and special sensors. The recording of the rheogram is carried out on writing instruments.
For reoparodontography, silver electrodes with an area of 3x5 mm are used, one of which is applied from the vestibular side (current), and the second (potential) - from the palatine or lingual side along the root of the tooth under study. This arrangement of electrodes is called transverse. The electrodes are fixed on the mucous membrane with medical glue or adhesive tape. Ground electrodes are attached to the earlobe. After connecting the sensors to the devices and after calibrating, they start recording. At the same time, for convenience of calculation, an electrocardiogram is recorded in lead II (Fig. 99, a) and a differential rheogram with a constant time of 10 s.
In the rheogram (RG), the ascending part is distinguished - the anacrota, the apex, the descending part - the catacrot, the incisura and the dicrotic zone (Fig. 99, b). A qualitative assessment of the RG consists of a description of its main elements and features (features): 1) the characteristic of the ascending part (steep, gentle, hump-shaped); 2) the shape of the top (sharp, pointed, flat, arched, double-humped, domed, in the form of a cock's comb); 3) the nature of the descending part (flat, steep); 4) the presence and severity of a dicrotic wave (absent, smoothed, clearly expressed, located in the middle of the descending part, in the upper third, close to the base of the curve); 5) the presence and location of additional waves on the descending part (number, location below or above the dicrotic wave).
A typical RG configuration is characterized by a steep ascending part, a sharp apex, a smooth descending part with a dicrotic wave in the middle and a clearly defined incisura. Quantitative analysis of RG is carried out using a triangle and a pencil. All amplitude indicators are expressed in millimeters, time (a, p, y) - in seconds.
To characterize the occlusal relationships, their possible latent and obvious violations, the method of graphic registration of the movements of the lower jaw by means of a functionograph is used (Fig. 100). An extraoral recording of the movements of the lower jaw is carried out - a functiogram - with simultaneous computer registration of the relief of the occlusal surface using the facial arch and articulators "Quick", "Stratos 200".
The installation of the functiograph is carried out as follows. A digitizer is attached to the front arc oriented along the Frankfurt horizontal (Fig. 100, 2), i.e. a touch manipulator, or a device for entering into a computer a graphic image of the movements of the lower jaw, consisting of an electronic "pen" and a screen-platform on which the recording is made. The electronic "pen" is rigidly fixed on an extraoral rod connected to a perforated metal intraoral vestibular plate. A heated thermoplastic mass is strengthened in the plate and superimposed on the dentition of the lower jaw so that the occlusal surface is free, which is checked by closing in the central occlusion.
From the position of central occlusion, the patient is asked to move the mandible into anterior occlusion, then back to posterior occlusion (posterior contact position). In turn, from the position of the central occlusion, the subject several times makes movements of the lower jaw to the right and left lateral occlusions. With lateral movements of the lower jaw, a recording known as the gothic angle is clearly indicated on the computer monitor screen. At the same time, several Gothic angles can be recorded on the monitor at some distance from each other, the tops of which correspond to the central ratio of the jaws (see Fig. 286). Through the tops of these Gothic corners, a line can be drawn connecting them. If it coincides with the middle sagittal line drawn on the monitor, then this indicates the symmetry and synchronism of movements in the temporomandibular joints. Based on these records, it is possible to assess the amplitude of movements of the lower jaw, possible disorders in the temporomandibular joint, and disharmony of the masticatory muscles.
The described electronic-mechanical functionograph was used to facilitate the analysis of the results of the study of the movements of the lower jaw and the programming of the articulator for an individual function. The central relationship of the jaws and the border movements of the lower jaw from this position can be accurately recorded and repeatedly reproduced both with the help of a functionograph and in an articulator. This technique allows you to control the correctness of the modeling of the occlusal surface in the manufacture of prostheses, selective grinding of teeth.
Summary. As a result of comprehensive research, the orthodontist receives a large amount of various information, including digital. This information must be systematized and presented in the form of a diagnosis, which should reflect functional, morphological and aesthetic disorders (for the structure of the diagnosis, see p. 56). After establishing the diagnosis, it is necessary to clarify the indications for treatment, specify its objectives, determine the scope and degree of difficulty, the sequence of application of various methods, device designs, and the ultimate goal of therapy. All this can be significantly accelerated, simplified, avoiding all sorts of errors and random errors with the help of special programs and computerized case histories.
Diagnosis in orthodontics is the first and one of the most important steps to create a beautiful smile. And if you want to get an excellent result, you can’t do without a diagnostic analysis of each specific case. And this must be done correctly and carefully. After all, it is not braces that treat at all, but a doctor. And he must clearly understand the goals of treatment and how to achieve them.
Do you want to have a beautiful smile? Then pay close attention to choosing a doctor.
Everything plays a role here: his qualifications, attention to detail, etc. In general, as in any serious business in life, the approach is the same: measure seven times, cut once :)
What is the diagnosis through the eyes of the patient?
Some 30 minutes spent in the clinic, which includes:
- Inspection.
- Taking photographs of the face and teeth.
- Removal of casts (impressions) of the jaws.
- Performing x-rays.
What is diagnostics through the eyes of the doctors of our clinic?
More than one (!) hour of work in the clinic to create a presentation after the diagnosis, which will contain conclusions on a large number of evaluation criteria. Why is this happening?
It should be understood that approaches to the analysis of diagnostic data are completely different for all doctors.
Someone does not conduct it at all and is ready to lay out a treatment plan immediately at the consultation without the slightest doubt. And this, in general, does not mean high qualification, rather the opposite.
For some doctors, one panoramic (overview) image and casts are enough. Which is also unacceptable for a modern orthodontist.
How will be correct?
Now we will tell you what steps our diagnostic presentation consists of.
1. Analysis of diagnostic models.
An electronic caliper calculates the space deficit for each tooth on the plaster model of the jaws. The data is transferred to the presentation.
2. Analysis of x-rays.
The data are calculated in special computer programs. On their basis, the main conclusions are drawn.
3. Assessment of periodontal status (level of gums and frenulums).
4. Assessment of facial parameters.
The main questions at this stage - is it possible to delete? Will it ruin the profile? Even if extraction is required due to bite, the face is always a priority.
5. Evaluation of the smile and visibility of the incisors at rest.
It is important to understand which teeth are more visible during a conversation - upper or lower. It has been proven that greater visibility of the upper teeth significantly makes the face look younger and more attractive. It works better than any anti-aging cream :) One of the basic goals of any treatment.
6. Smile width.
The more teeth you see in a smile, the wider and more open it appears.
The most charming smile is the one that follows the contour of the lower lip as much as possible. Also the basic goal of any treatment. More details about the canons of the beauty of a smile are written in our article - What is a beautiful smile.
8. Planning the positioning of brackets on the teeth according to the conclusions of the smile analysis.
As you can see, the half hour spent by the patient in the chair turns into a huge "behind the scenes" work for the thoughtful orthodontist.
Treatment planning is creative, painstaking work. Unfortunately, not all orthodontists nowadays fully understand this process. They are not ready to lay this foundation, without which it is impossible to build a good and stable treatment in the long run.
Orthodontics is not fixing braces. The teeth can be arbitrarily even, and the smile, nevertheless, remains very mediocre, the profile of the face - a spoiled removal "in the name of the teeth."
Our treatment directly affects the appearance, because the result remains with the patients forever! Therefore, the fundamental point in treatment is only the right choice of a doctor!
The main thing is to get into reliable, experienced hands. And if you are reading this, then you are already on the right track!
