Classification of modern filling materials. Materials for filling teeth

Filling is the restoration of the anatomy and function of the destroyed part of the tooth. Accordingly, the materials used for this purpose are called filling materials. Currently, due to the emergence of materials capable of recreating tooth tissue in its original form (for example, dentin - glass ionomer cements, (GIC) compomers, opaque shades of composites; enamel - fine hybrid composites), the term restoration is more often used - restoration of lost tissue tooth in its original form, i.e. imitation of tissues in color, transparency, surface structure, physical and chemical properties. Reconstruction means changing the shape, color, and transparency of the crowns of natural teeth.

Filling materials are divided into four groups.

1. Filling materials for permanent fillings:

1) cements:

a) zinc phosphate (Foscin, Adgesor original, Adgesor fine, Uniface, Viscine, etc.);

b) silicate (Silicin-2, Alumodent, Fritex);

c) silicophosphate (Silidont-2, Laktodont);

d) ionomer (polycarboxylate, glass ionomer);

2) polymer materials:

a) unfilled polymer-monomer (Acrylic Oxide, Carbodent);

b) filled polymer-monomer (composites);

3) compomers (Dyrakt, Dyrakt A P, F-2000);

4) materials based on polymer glass (Solitaire);

5) amalgams (silver, copper).

2. Temporary filling materials (aqueous dentin, dentin paste, Tempo, zinc-eugenol cements).

3. Materials for therapeutic pads:

1) zinc-eugenol;

4. Materials for filling root canals.

The properties of filling materials are considered in accordance with the requirements for filling materials.

Requirements for permanent filling materials

1. Technological (or handling) requirements for the initial uncured material:

1) the release form of the material must contain no more than two components that are easily mixed before filling;

2) after mixing, the material must acquire plasticity or consistency convenient for filling the cavity and forming an anatomical shape;

3) the filling composition after mixing must have a certain working time, during which it retains its plasticity and ability to form (usually 1.5–2 minutes);

4) the curing time (the period of transition from the plastic to the solid state) should not be too long, usually 5–7 minutes;

5) curing must occur in the presence of moisture and at a temperature not exceeding 37 °C.

2. Functional requirements, i.e. requirements for the cured material. The filling material in all respects should be close to those of the hard tissues of the tooth:

1) exhibit stable adhesion to the hard tissues of the tooth over time and in a humid environment;

2) exhibit minimal shrinkage during curing;

3) have a certain compressive strength, shear strength, high hardness and wear resistance;

4) have low water absorption and solubility;

5) have a coefficient of thermal expansion close to the coefficient of thermal expansion of hard dental tissues;

6) have low thermal conductivity.

3. Biological requirements: the components of the filling material should not have a toxic, sensitizing effect on tooth tissue and oral organs; the material in the cured state should not contain low molecular weight substances capable of diffusion and leaching from the filling; The pH of aqueous extracts from uncured material should be close to neutral.

4. Aesthetic requirements:

1) the filling material must match the color, shade, structure, and transparency of the hard tissues of the tooth;

2) the filling must be color stable and not change the quality of the surface during operation.

1. Composite materials. Definition, history of development

In the 40s XX century acrylic quick-hardening plastics were created, the monomer of which was methyl methacrylate, and the polymer was polymethyl methacrylate. Their polymerization was carried out thanks to the initiator system BPO-Amin (benzoyl and amine peroxide) under the influence of oral temperature (30–40 °C), for example Acrylicoxide, Carbodent. This group of materials is characterized by the following properties:

1) low adhesion to tooth tissues;

2) high marginal permeability, which leads to disruption of the marginal seal of the filling, the development of secondary caries and inflammation of the pulp;

3) insufficient strength;

4) high water absorption;

5) significant shrinkage during polymerization, about 21%;

6) discrepancy between the coefficient of thermal expansion and a similar indicator of hard dental tissues;

7) high toxicity;

8) low aesthetics, mainly due to changes in the color of the filling (yellowing) due to oxidation of the amine compound.

In 1962, R. L. BOWEN proposed a material in which BIS-GMA, with a higher molecular weight, was used as a monomer instead of methyl methacrylate, and quartz treated with silanes as a filler. Thus, R. L. BOWEN laid the foundation for the development of composite materials. In addition, in 1965, M. Buonocore made the observation that the adhesion of filling material to tooth tissue improves significantly after pre-treatment of enamel with phosphoric acid. These two scientific achievements served as prerequisites for the development of adhesive methods for the restoration of dental tissue. The first composites were macrofilled, with inorganic filler particle sizes ranging from 10 to 100 microns. In 1977, microfilled composites were developed (particle size of inorganic filler from 0.0007 to 0.04 microns). In 1980, hybrid composite materials appeared, in which the inorganic filler contains a mixture of micro- and macroparticles. In 1970, M. Buonocore published a report on filling fissures with a material that polymerizes under the influence of ultraviolet rays, and in 1977, the production of light-curing composites that polymerize under the influence of blue light (wavelength 450 nm) began.

Composite materials are polymer filling materials containing a finished, silane-treated inorganic filler of more than 50% by weight, therefore composite materials are called filled polymers in contrast to unfilled ones, which contain less than 50% inorganic filler (for example: Acrylic oxide - 12%, Carbondent - 43%).

2. Chemical composition of composites

The main components of composites are an organic matrix and an inorganic filler.

Classification of composite materials

There is the following classification of composite materials.

1. Depending on the particle size of the inorganic filler and the degree of filling, the following are distinguished:

1) macrofilled (conventional, macrofilled) composites. The particle sizes of inorganic filler are from 5 to 100 microns, the content of inorganic filler is 75–80% by weight, 50–60% by volume;

2) composites with small particles (microfilled). The particle size of inorganic filler is 1-10 microns;

3) microfilled (microfilled) composites. The particle sizes of inorganic filler are from 0.0007 to 0.04 microns, the content of inorganic filler is 30–60% by weight, 20–30% by volume.

Depending on the form of the inorganic filler, microfilled composites are divided into:

a) inhomogeneous (contain microparticles and conglomerates of pre-polymerized microparticles);

b) homogeneous (contain microparticles);

4) hybrid composites are a mixture of conventional large particles and microparticles. Most often, composites of this group contain particles ranging in size from 0.004 to 50 microns. Hybrid composites, which contain particles no larger than 1–3.5 μm, are classified as finely dispersed. The amount of inorganic filler by weight is 75–85%, by volume 64% or more.

2. Composites are distinguished according to their intended purpose:

1) class A for filling carious cavities of class I–II (according to Black);

2) class B for filling carious cavities of classes III, IV, V;

3) universal composites (non-homogeneous microfilled, finely dispersed, hybrid).

3. Depending on the type of initial form and method of curing, materials are divided into:

1) light-curing (one paste);

2) chemically curing materials (self-curing):

a) “paste-paste” type;

b) “powder-liquid” type.

Macro-filled composite materials

The first composite, proposed by Bowen in 1962, had quartz flour as a filler with particle sizes up to 30 microns. When comparing macrofilled composites with traditional filling materials (unfilled polymer-monomer), their lower polymerization shrinkage and water absorption, higher tensile and compressive strength (2.5 times), and lower coefficient of thermal expansion were noted. However, long-term clinical trials have shown that fillings made of macrofilled composites are poorly polished, change in color, and there is pronounced abrasion of the filling and the antagonist tooth.

The main disadvantage of macrophiles turned out to be the presence of micropores on the surface of the filling, or roughness. Roughness arises due to the significant size and hardness of the inorganic filler particles compared to the organic matrix, as well as the polygonal shape of the inorganic particles, so they quickly crumble during polishing and chewing. As a result, there is significant abrasion of the filling and the antagonist tooth (100–150 microns per year), fillings are poorly polished, surface and subsurface pores, they need to be eliminated (cleaning etching, washing, applying adhesive, polymerization of adhesive, application and polymerization of composite); otherwise they will stain. Next, the final finishing (polishing) of the filling is performed. First, rubber and plastic heads, flexible disks, strips, and then polishing pastes are used. Most companies produce two types of pastes for final finishing: for preliminary and final polishing, which differ from each other in the degree of abrasive dispersion. It is necessary to carefully study the instructions, since the polishing time for polishing pastes from different companies differs. For example: polishing pastes from Dentsply: polishing should begin with Prisma Gloss paste for 63 seconds on each surface separately. Polishing with this paste gives the surface a wet shine (the filling shines if it is moistened with saliva). Next, use the “Frisra Gloss Extra Fine” paste (also for 60 minutes on each surface), which will add a dry shine (when drying the tooth with an air jet, the shine of the composite is comparable to the shine of enamel). If these rules are not followed, it is impossible to achieve an aesthetic optimum. The patient must be warned that dry shine must be restored every 6 months. When filling cavities of classes II, III, IV, flosses are used to control the marginal fit of the filling in the gingival area, as well as to control the contact point. The floss is inserted into the interdental space without delay, but with great effort it slides along the contact surface. It should not tear or get stuck.

Ignoring the final flashing (lighting each surface of the restoration for 1 minute) may compromise the strength of the filling, resulting in possible chipping of the restoration.

Microfilled composites

Composites with small particles (microfilled) are close in properties to macrofilled ones, but due to the reduction in particle size, they have a higher degree of filling, are less susceptible to abrasion (about 50 microns per year) and are better polished. For filling in the frontal area, Visio-Fill, Visar-Fill, Prisma-Fill (light-curing) are recommended; in the area of chewing teeth, the following are used: P-10, Bis-Fil II (chemical curing), Estelux Post XR, Marathon, Ful-Fil , Bis-Fil I, Occlusin, Profil TLG, P-30, Sinter Fil (light curing).

In 1977, microfilled composites were created, which contain particles of inorganic filler 1000 times smaller than those of macrophiles, due to this their specific surface area increases 1000 times. Compared to macrophiles, microphilic composites are easily polished, have high color fastness (light-curing), and are less abrasive, since they are not characterized by roughness. However, they are inferior to conventional composites in strength and hardness, have a higher coefficient of thermal expansion, significant shrinkage and water absorption. The indication for their use is filling carious cavities in the frontal group of teeth (classes III, V).

A type of microfilled composites are inhomogeneous microfilled composites, which contain fine particles of silicon dioxide and microfilled prepolymers. In the manufacture of these composites, pre-polymerized particles (size about 18–20 μm) are added to the main mass containing microfilled particles; thanks to this technique, filler saturation is more than 80% by weight (for homogeneously microfilled materials, filling by mass is 30–40%), in Therefore, this group of materials is more durable, and it is used for filling frontal and lateral teeth.

Representatives of microfilled (homogeneous) composites are the following composites.

* see Table No. 5.

Hybrid composite materials

The inorganic filler is a mixture of conventional large particles and microparticles. Contact of an etching agent on an adjacent tooth, if it is not isolated by a matrix, can lead to the development of caries.

Acid damage to the oral mucosa leads to burns. The etching solution must be removed, and the mouth must be rinsed with an alkali solution (5% sodium bicarbonate solution) or water. In case of significant tissue damage, treatment is carried out with antiseptics, enzymes, and keratoplasty preparations.

After etching, it is necessary to exclude contact of the etched enamel with oral fluid (the patient should not spit, it is necessary to use a saliva ejector), otherwise the microspaces are closed with salivary mucin, and the adhesion of the composites deteriorates sharply. If the enamel is contaminated with saliva or blood, the etching process must be repeated (cleaning etching - 10 s).

After washing, the cavity should be dried with an air stream, the enamel becomes matte. If dentin etching was used, the principles of wet adhesion must be remembered. Dentin should not be overdried, it must be moist and sparkling, otherwise air enters the dentinal tubules, demineralized dentin; collagen fibers stick together (“spaghetti effect”), as a result of which the formation of the hybrid zone and cords in the dentinal tubules is disrupted. The result of the above phenomena may be the occurrence of hyperesthesia, and the strength of attachment of the filling to the dentin decreases.

At the filling stage, the following errors and complications are possible. Wrong choice of composite, ignoring indications for its use. It is unacceptable, for example, to use microfilled material on the chewing group of teeth due to low strength (or macrofilled material in the area of the front teeth due to unaesthetics.

*cm. Table No. 6. Representatives of fine hybrid composites.

Properties of composites

1. Technological properties:

1) the release form of chemically cured composites contains two composites (mixed before filling): “powder - liquid”, “paste - paste”. Light-curing ones have one paste, so they are more homogeneous, there is no air porosity, they are precisely dosed, unlike chemically curing ones;

2) after mixing, chemically cured composites acquire plasticity, which they retain for 1.5–2 minutes - working time. During this time, the plasticity of the material changes - it becomes more viscous. The introduction of material and its formation outside working hours lead to disruption of adhesion and loss of the filling. Consequently, chemically curing materials have limited working time, while photopolymers do not;

3) the curing time for chemically cured ones is on average 5 minutes, for photopolymers - 20–40 s, but for each layer, therefore the time for placing a filling from a photopolymer is longer.

2. Functional properties:

1) all composites have sufficient adhesion, which depends on etching, the type of bonds or adhesives used (etching increases the adhesion force of composites to enamel by 75%; enamel bonds provide an adhesion force to enamel of 20 MPa, and dentin adhesives create different adhesion forces to dentin in depending on the generation of the adhesive, which is for the I generation – 1–3 MPa; II generation – 3–5 MPa; III generation – 12–18 MPa; IV and V generations – 20–30 MPa);

2) chemically cured composites, mostly of the “powder-liquid” type, have the greatest shrinkage (from 1.67 to 5.68%). Photocurable - about 0.5–0.7%, which depends on the filler load: the more filler there is, the less shrinkage (macrophiles and hybrids have less shrinkage than microfilled ones); in addition, shrinkage of photopolymers is compensated by layer-by-layer curing, directional polymerization;

3) compressive and shear strength is greatest for hybrid and macro-filled composites, less for micro-filled ones, therefore they are used in the area of anterior teeth. Abrasion is greatest for macrofilled ones due to roughness - 100–150 microns per year, less for microfilled ones, minimal for finely dispersed hybrids - 7–8 microns per year and inhomogeneous microfilled ones. The wear rate of chemically cured composites is greater than that of light-cured ones, which is associated with internal porosity and a lower degree of polymerization;

4) water absorption is greatest in microfilled ones, which significantly reduces their strength, less in hybrids and macrophiles, since they contain less organic component and more filler;

5) the coefficient of thermal expansion is closest to that of solid tissues in macrofilled and hybrids due to the high filler content;

6) all composites have low thermal conductivity.

3. Biological requirements (properties). Toxicity is determined by the degree of polymerization, which is greater in photopolymers, and therefore they contain fewer low molecular weight substances and are less toxic. The use of dentinal adhesives of the IV and V generations makes it possible to do without isolating linings for moderate caries; for deep caries, the bottom is covered with glass ionomer cement. Chemically cured composites, as a rule, are equipped with enamel bonds, so it is suggested to use an insulating pad (for moderate caries) or an insulating and therapeutic pad (for deep caries).

4. Aesthetic properties. All chemically cured composites: change color due to the oxidation of benzoyl peroxide, macrofilled ones - due to roughness. When opening and necrectomy, the classical principles of surgical treatment of a carious cavity are used. If it is intended to use only enamel bonds (adhesives), then when forming a carious cavity it is necessary to follow traditional principles: the walls and bottom of the treated cavity must be at right angles, the formation of additional sites is carried out for cavities of classes II, III, IV. It is possible to completely abandon the classical principles of carious cavity formation in the case of using enamel-dentin adhesive systems. In this case, all dentin or part of it (in the case of applying gaskets to the bottom of the carious cavity) is used for adhesion to the composite.

At the stage of processing the edges of the enamel, it is necessary to create a bevel at an angle of 45° or more for cavities of classes III, IV, V, and then finish it with a fine-grained diamond bur. By creating a bevel, the active surface of the tooth enamel increases for adhesion to the composite. In addition, a smooth transition between composite and enamel is ensured, which makes it easier to achieve an aesthetic optimum. Failure to comply with these rules may result in the filling falling out and affecting its cosmetic appearance. In class I and II cavities, the enamel bevel is often not created, since the composite, which wears out faster than the enamel, wears out earlier, which worsens the marginal fit. In addition, the composite may chip on the chewing surface along the rebate line. Finishing the edges of the enamel is carried out in all cases when filling cavities of classes I–V. As a result, the enamel surface becomes smooth and uniform, since chips of enamel prisms that occur during the opening of the carious cavity are removed. The surface structureless layer of enamel covering the bundles of prisms is removed, which facilitates subsequent acid etching of the enamel. If finishing is not carried out, then chips of enamel prisms during the functioning of the filling lead to the formation of retention areas, which contributes to the accumulation of microorganisms, dental plaque and the development of secondary caries.

*cm. Table No. 7. Physical characteristics of some composite filling materials used to restore chewing teeth.

The dentist's task is not only to achieve an individual appearance, but also to provide for the variability of the color of natural teeth under any lighting conditions. The solution to this problem is possible if the doctor restores the tooth crown with materials that optically exactly imitate dental tissue:

1) enamel + surface enamel, enamel-dentin junction;

2) dentin + peripulpal dentin (does not imitate pulp).

Finally, artificial dental tissues must be incorporated into the restorative design within the topographic boundaries of natural dental tissues, such as:

1) center (cavity) of the tooth;

2) dentin;

Replicating the natural structure of the tooth is the essence of the biomimetic method of dental restoration.

The most complete imitation of the appearance of a crown is possible if the restoration model matches 4 parameters:

3) transparency.

4) surface structure.

3. Mechanism of adhesion of composites to dentin

Pathophysiological features of dentin:

1) dentin consists of 50% inorganic substance (mainly hydroxyapatite), 30% organic (mainly collagen fibers) and 20% water;

2) the surface of dentin is heterogeneous; it is penetrated by dentin tubules containing processes of odontoblasts and water. Water is supplied under pressure of 25–30 mmHg. Art., when dried, the amount of water increases, so the dentin of a living tooth is always wet and cannot be dried. The degree of dentin mineralization is heterogeneous. There are hypermineralized (peritubular) dentin and typemineralized (intertubular) dentin;

3) after preparation, the dentin surface is covered with a smear layer containing hydroxyapatites, collagen fragments, odontoblast processes, microorganisms, and water. The smear layer prevents the adhesive from penetrating into the dentin.

Taking into account the above features, to obtain a strong bond between dentin and composite it is necessary:

1) use hydrophilic low-viscosity adhesives (the use of hydrophobic viscous adhesives is unacceptable, since the dentin of a living tooth cannot be dried; in this case, an analogy can be drawn with applying oil paint to a wet surface);

2) remove the smear layer or saturate it and stabilize it. In this regard, dentinal adhesive systems can be divided into two types:

a) Type I – dissolving the smear layer and decalcifying dentin;

b) Type II – preserving and including a smear layer (self-conditioning).

Method for obtaining the bond between composites and dentin

1. Conditioning – treatment of dentin with acid to dissolve the smear layer, demineralize the surface dentin, and open the dentin tubules.

2. Priming – treatment of dentin with a primer, i.e. a solution of a low-viscosity hydrophilic monomer that penetrates demineralized dentin and dentinal tubules, forming cords. As a result, a hybrid zone is formed (micromechanical connection of the adhesive with dentin).

3. Application of a hydrophobic adhesive (bond), which provides a (chemical) bond with the composite.

When using Type I dentin adhesive systems, an acid solution (conditioner) is used to remove the smear layer. If it is a weak organic acid of low concentration (10% citric, maleic, EDTA, etc.), then the enamel is treated traditionally, i.e., 30–40% phosphoric acid. Currently, the method of total etching of enamel and dentin with a solution of 30–40% orthophosphoric acid is widespread. Acid etching of dentin does not have an irritating effect on the pulp, since during caries a zone of sclerotic dentin is formed; pulpitis observed after filling is most often associated with insufficient tightness of the filling.

4. Isolation.

5. Traditional cavity preparation with enamel bevel at an angle of 45°.

6. Medical treatment (70% alcohol, ether, 3% hydrogen peroxide are not used).

7. Application of therapeutic and insulating pads (for deep caries) and insulating pads for moderate caries. Glass ionomer cement should be preferred. Pads containing eugenol or phenol inhibit the polymerization process.

8. Etching the enamel. The etching gel is applied to the beveled enamel tap for 30–60 s (baby and pulpless teeth are etched for 120 s), then the cavity is washed and dried for the same time.

9. Mixing a two-component bond 1: 1, applying it to the etched enamel and gasket, spraying.

10. Mixing the main and catalytic paste 1: 1 for 25 s.

11. Filling the cavity. The time for using the prepared material is from 1 to 1.5 minutes. Polymerization time is 2–2.5 minutes after mixing.

12. Final processing of the filling.

Contraindications to the use of the material are allergic reactions and poor oral hygiene.

After applying the primer, a hydrophobic adhesive or bond is applied (on enamel and dentin), which provides a chemical bond with the composite.

Type II adhesives are called self-etching or self-conditioning; The primer contains, in addition to the low-viscosity monomer acetone or alcohol, acid (maleic acid, organic esters of phosphoric acid). Under the influence of a self-conditioning primer, partial dissolution of the smear layer occurs, opening of dentinal tubules and demineralization of surface dentin. At the same time, impregnation with hydrophilic monomers occurs. The smear layer is not removed, but is sprayed, and its sediment falls on the surface of the dentin.

After applying the self-conditioning primer, a hydrophobic bond is used. The disadvantage of this type of dentinal adhesives is their weak ability to etch enamel, therefore, at present, even when using these systems, a total etching technique is used.

Currently, fourth and fifth generation adhesive systems are used in dental practice. The IV generation is characterized by a three-stage processing: total etching, application of a primer, and then enamel bond. In V generation adhesives, the primer and adhesive (bond) are combined; the adhesion force of adhesives of the IV and V generations is 20–30 MPa.

IV generation adhesive systems:

1) Pro-bond (Caulk);

2) Opti-bond (Kеrr);

3) Scotchbond Multipurpose plus (3M);

4) All bond, All bond 2 (Bisco);

5) ART-bond (Coltenе), Solid bond (Heraeus Kulzer).

V generation adhesive systems:

1) One step (Bisco);

2) Prime and bond 2.0 (Caulk);

3) Prime and bond 2.1 (Caulk);

4) Liner Bond – II tm (Kuraray);

5) Single Bond (3M);

6) Suntaс Single bond (Vivadent);

7) Solo bond (Kеrr).

Polymerization of composites

The disadvantage of all composites is polymerization shrinkage, which ranges from approximately 0.5 to 5%. The reason for shrinkage is a decrease in the distance between monomer molecules as a polymer chain is formed. The intermolecular distance before polymerization is about 3–4 angstroms, and after it it is 1.54.

The polymerization reaction is triggered by heat, a chemical or photochemical reaction, which results in the formation of free radicals. Polymerization occurs in three stages: initiation, propagation and termination. The propagation phase continues until all free radicals have combined. During the polymerization process, shrinkage occurs and heat is generated, as with any exothermic reaction.

Composite materials have shrinkage in the range of 0.5–5.68%, while shrinkage in fast-hardening plastics reaches 21%. Polymerization shrinkage is most pronounced in chemically cured composites.

One-component adhesive Dyract PSA

The curing reaction initially occurs due to light-initiated polymerization of the composite part of the monomer, and then the acid part of the monomer reacts, leading to the release of fluorine and further cross-linking of the polymer.

Properties:

1) reliable adhesion to enamel and dentin;

2) marginal fit, like that of composites, but easier to achieve;

3) strength is greater than that of GIC, but less than that of composites;

4) shrinkage, like composites;

5) aesthetics and surface properties close to composites;

6) long-term release of fluoride.

Indications:

1) III and V classes of permanent teeth;

2) non-carious lesions;

3) all classes, according to Black, in baby teeth.

Dyract AP Properties:

1) particle sizes are reduced (up to 0.8 microns). This increased abrasion resistance, increased strength, fluoride release, and improved surface quality;

2) a new monomer is introduced. Increased strength;

3) the initiator system has been improved. Increased strength;

4) new adhesive systems Prime and Bond 2.0 or Prime and Bond 2.1 were used.

Indications:

1) all classes, according to Black, in permanent teeth, cavities of classes I and II, not exceeding 2/3 of the intertubercular surface;

2) to imitate dentin (“sandwich technique”);

3) non-carious lesions;

4) for filling baby teeth.

Thus, Dyract AR is similar in properties to microhybrid composites.

4. Requirements when working with composite material

The requirements are as follows.

1. Subject the light source to periodic inspection, since deterioration in the physical characteristics of the lamp will affect the properties of the composite. As a rule, the lamp has a luminous flux power indicator; if it does not, you can apply a layer of filling material to the mixing pad with a layer of 3–4 mm and polymerize it with light for 40 s. Then remove the layer of uncured material from below and determine the height of the fully cured mass. As a rule, the power density of polymerization lamps is 75-100 W/cm?.

2. Taking into account the limited penetrating power of light, filling the carious cavity and polymerization of the filling should be incremental, i.e., layer-by-layer, with the thickness of each layer no more than 3 mm, which contributes to more complete polymerization and reduced shrinkage.

3. When working with the material, it should be protected from extraneous light sources, especially from the light of the dental unit lamp, otherwise premature hardening of the material will occur.

4. Low-power lamps less than 75 W require a longer exposure and a reduction in layer thickness to 1–2 mm. In this regard, the increase in temperature below the surface of the filling at a depth of 3–2 mm can reach from 1.5 to 12.3 O C and lead to pulp damage.

5. To compensate for shrinkage, the directional polymerization technique is used.

Thus, photopolymers have the following disadvantages: heterogeneity of polymerization, duration and labor intensity of filling, the possibility of thermal damage to the pulp, high cost, mainly due to the high cost of the lamp.

Most of the disadvantages of photopolymers are associated with imperfections in the light source. The first photopolymers were cured with an ultraviolet emitter, later systems with longer wavelength light sources (blue light, wavelength 400–500 nm) were proposed, which were safe for the oral cavity, curing time was reduced from 60–90 s to 20–40 s, the degree of polymerization with a material thickness of 2–2.5 mm. Currently, the most promising light source is an argon laser, capable of polymerizing to great depth and width.

5. Mechanism of adhesion between composite layers

The construction of a restoration structure is based on gluing, which, according to its intended purpose, can be divided into gluing the restoration material with tooth tissue and gluing together fragments of the restoration material (composite or compomer), i.e., a layer-by-layer technique for constructing restorations. (Features of obtaining a reliable bond between the composite and enamel and dentin will be discussed in the section Adhesion of composites to enamel and dentin). The connection of fragments of the composite material with each other is due to the peculiarity of the polymerization of composites, namely the formation of a surface layer (LS).

The surface layer is formed as a result of polymerization shrinkage of the composite or compomer and inhibition of the process by oxygen.

Polymerization of chemically cured composites is directed towards the highest temperature, i.e., towards the pulp or the center of the filling, therefore chemically cured composites are applied parallel to the bottom of the cavity, since shrinkage is directed towards the pulp. The shrinkage of photopolymers is directed towards the light source. If you do not take into account the direction of shrinkage when using photopolymers, then the composite detaches from the walls or bottom, as a result, the insulation is broken.

The directional polymerization technique allows you to compensate for shrinkage.

I class. To ensure good connection of the composite with the bottom and walls, it is applied in oblique layers from approximately the middle of the bottom to the edge of the cavity on the chewing surface. First of all, the applied layer is illuminated through the corresponding wall (to compensate for polymerization shrinkage), and then irradiated perpendicular to the composite layer (to achieve the maximum degree of polymerization). The next layer is applied in a different direction and is also illuminated, first through the corresponding wall, and then perpendicular to the composite layer. This ensures a good marginal seal and prevents tearing of the filling edges due to shrinkage. When filling large cavities, polymerization is carried out from four points - through the cusps of the molars. For example: if the composite layer is first applied to the buccal wall, it is illuminated first through the buccal wall (20 s), and then perpendicular to the surface of the composite layer (20 s). The next layer is applied to the lingual wall and illuminated through the corresponding wall, and then perpendicularly.

II class. When filling, the most difficult thing is to create contact points and good marginal adaptation in the gingival part. For this purpose, wedges, matrices, and matrix holders are used. To reduce shrinkage, the gingival part of the filling can be made from a chemically cured composite, GIC, since its shrinkage is directed towards the pulp. When using a photopolymer, light-conducting wedges are used or light is reflected using a dental mirror, positioning it 1 cm below the level of the tooth neck at an angle of 45° to the longitudinal axis of the tooth.

III class. The layers are applied to the vestibular or oral walls, followed by illumination through the corresponding wall of the tooth on which the composite layer was applied. Then polymerize perpendicular to the layer. For example, if a layer of composite was first applied to the vestibular wall, then it is initially polymerized through the vestibular wall, and subsequently perpendicularly.

The gingival part of the filling in classes III and IV polymerizes similarly to class II.

V class. Initially, the gingival part is formed, the fillings of which are polymerized, directing the light guide from the gums at an angle of 45°. Shrinkage is directed towards the gingival wall of the cavity, resulting in a good marginal fit. Subsequent layers are polymerized by directing the light guide perpendicularly.

After polymerization of the last layer, finishing is carried out to remove the surface layer, which is easily damaged and permeable to dyes.

Under conditions of moist (not overdried) dentin, the adhesion force of oschch to dentin is up to 14 MPa.

When using GIC - Vitremer, a primer containing HEMA and alcohol is used to treat dentin.

The strength of GIC depends on the amount of powder (the more powder, the stronger the material), the degree of maturity, and the processing characteristics of the filler. For example, type II high-strength GIC (having inclusions of silver particles in crushed glass particles) and type III lining cements have the greatest strength.

GICs have low water absorption and solubility, which are related to the degree of cement maturity. The maturation of GIC, depending on the type of cement, occurs in different periods (from several weeks to several months).

The coefficient of thermal expansion is close to that of dentin.

When making cement radiopaque, the aesthetic properties (transparency) deteriorate, so cements for cosmetic work, as a rule, are not radiopaque.

Biological properties of GIC

GICs are low toxic to pulp, since they contain a weak organic acid. When the dentin thickness is more than 0.5 mm, no irritating effect on the tooth pulp is observed. In case of significant thinning of the dentin, it is covered with a therapeutic pad based on calcium hydroxide in a certain area.

GICs have an anti-caries effect due to the release of fluoride ions for several months; in addition, they are able to accumulate fluoride released from toothpastes during their use; GICs containing silver additionally release silver ions.

The aesthetic properties of GIC for cosmetic work are high; for high-strength cements and lining cements they are low due to the significant content of powder and fluorine ions.

Polycarboxylate cements

Powder: zinc oxide, magnesium oxide, aluminum oxide.

Liquid: 40% solution of polyacrylic acid.

The hardened material consists of zinc oxide particles bound by a gel-like zinc polyacrylate matrix. Calcium ions of dentin combine with the carboxyl groups of polyacrylic acid, and zinc ions “cross-link” polyacrylic acid molecules.

Properties: physical and chemical bond with hard tissues, slightly soluble in saliva (compared to CFC), non-irritating (the liquid is a weak acid), but has low strength and poor aesthetics. Used for insulating gaskets, temporary fillings, and fixation of crowns.

The ratio of liquid to powder is 1:2, mixing time is 20–30 s, the finished mass stretches behind the spatula, forming teeth up to 1 mm, and shines.

Insulating and healing pads

Composite materials are toxic to the dental pulp, so for moderate and deep caries, therapeutic and insulating pads are necessary. It should be noted that the toxicity of composites is related to the amount of residual monomer that can diffuse into the dentinal tubules and damage the pulp. The amount of residual monomer is greater in chemically cured composites, since the degree of their polymerization is lower compared to photopolymers, i.e. light-cured composites are less toxic. The use of dentinal adhesives of the IV and V generations (which reliably isolate the pulp and compensate for the shrinkage of composites) makes it possible to do without insulating pads in case of moderate caries, and in case of deep caries, therapeutic and insulating pads are applied only to the bottom of the cavity. The use of eugenol-containing cements is unacceptable, since eugenol inhibits polymerization. When filling canals with materials based on a resorcinol-formalin mixture and eugenol, an insulating lining made of phosphate cement, glass ionomer or polycarboxylate cement is applied to the canal mouth.

Medical pads

For deep caries, the use of calcium-containing therapeutic pads is indicated. Calcium hydroxide, which is part of their composition, creates an alkaline pH level of 12–14, as a result of which it has an anti-inflammatory, bacteriostatic effect (severe dehydration) and an odontotropic effect - it stimulates the formation of replacement dentin.

Therapeutic pads are applied only to the bottom of the cavity in the projection of the pulp horns in a thin layer. Increasing the volume and applying a gasket to the walls is undesirable due to low strength - 6 MPa (phosphate cement - 10 MPa) and poor adhesion, otherwise the fixation of the permanent filling will deteriorate. Etching of enamel and dentin is carried out after isolating the treatment pad with GIC (glass ionomer cement), since due to the high marginal permeability of the treatment pad, an acid depot is created under it, in addition, it is dissolved by acid.

There are one-component therapeutic pads with light (Basic-L) and chemical curing (Calcipulpa, Calcidont) and two-component chemical curing (Dycal, Recal, Calcimot, Live, Kaltsesil).

Insulating gaskets.

The following can be used as insulating gaskets:

1) zinc phosphate cements (ZPC): Foscin, Phosphate cement, Visphate, Viscine, Dioxyvisfate, Uniface, Adgesor, Adgcsor Fine. II. Ionomer cements (IC);

2) polycarboxylate: Superior. Carbcfme, Carboxyfme, Belokor;

3) glass ionomer (GIC).

*cm. Table No. 7. Glass ionomer cements.

Glass ionomer cements

The invention of GIC is credited to Wilson and Keith (1971).

Glass ionomer cements are materials based on polyacrylic (polyalkenic) acid and crushed aluminofluorosilicate glass. Depending on the type of initial form, the following are distinguished:

1) “powder – liquid” type (powder – aluminofluorosilicate glass, liquid – 30–50% solution of polyacrylic acid). For example, Master Dent;

2) the “powder - distilled water” type (polyacrylic acid is dried and added to the powder, which increases the shelf life of the material, facilitates manual mixing, and makes it possible to obtain a thinner film), so-called hydrophilic cements. For example, Stion APX, Base Line. Type of crust. For example, lonoseal, Time Line.

According to the curing method, the following powders are distinguished ( see table No. 8).

Glass ionomer cements are classified according to their intended purpose.

1 type Used for fixation of orthopedic and orthodontic structures (Aquameron, Aquacem, Gemcem, Fuji 1).

Type 2 – restorative cement for restoring defects in hard dental tissues:

1) type for cosmetic work. Work requiring aesthetic restoration with minor occlusal load (Chemfill superivjr, Vitremer. Aqua Ionofill).

2) for work requiring increased strength of fillings (Ketak-molar; Argion).

Type 3 – lining cements (Bond Aplican, Gemline, Vitrcbond, Vivoglas, Miner, Bond fotak, Ionobond, Ketak bond, Time Line, Stion APH, Base Line, lonoseal).

Type 4 – for filling root canals (Ketak endo aplican, Stiodent).

Type 5 – sealants (Fugi III).

Properties of GIC

1. Technological properties (uncured material). Mixing time is 10–20 s, after which the material acquires plasticity, retained for 1.5–2 min (for chemically cured materials).

2. Functional properties. Adhesion to enamel and dentin is of a chemical nature (A. Wilson, 1972) due to the combination of calcium ions of hard tooth tissues and carboxyl groups of polyacrylic acid. Necessary conditions for a strong bond are the absence of foreign substances: plaque, saliva, blood, smear layer on the surface of dentin, therefore, pre-treatment of enamel and dentin with a 10% solution of polyacrylic acid for 15 seconds, followed by rinsing and drying is necessary. The advantage of using polyacrylic acid is that it is used in cement and its residues do not affect the hardening process of the cement; in addition, calcium ions are activated in enamel and dentin.

As a result of finishing treatment, the surface is smooth, transparent, and shiny. Under different lighting (direct, transmitted, side light), the restoration is monolithic, the border with dental tissues is not visible. If an optical boundary between the dental tissues and the filling is detected (a white stripe, “crack in the glass”), it can be concluded that the bonding is broken; correction is necessary: etching is carried out, an enamel adhesive is applied, followed by curing.

Finally, a final lightening of all surfaces of the filling is carried out, thereby achieving the maximum degree of polymerization of the composite.

Thus, control tests for composite bonding:

1) when adding the composite, the portion should stick to the surface and come off the capsule or smoother;

2) after plastic processing, a portion of the composite does not separate from the bonded surface, but is deformed;

3) after finishing treatment there is a monolithic connection between the composite and dental tissues, there are no white tear strips.

GIC for cosmetic work (Vitremer, Kemfil Superior, Aqua Ionofil).

The ratio of powder to liquid is from 2.2: 1 to 3.0: 1 (if the liquid is polyacrylic acid) and from 2.5: 1 to 6.8: 1 (for materials mixed with distilled water).

The curing reaction of GIC can be represented as ionic cross-coupling between polyacrylic acid chains. In the initial curing phase, cross-links are formed due to calcium ions located on the surface of the particles. These divalent bonds are unstable and easily dissolve in water, and dehydration occurs when dried. The duration of the initial phase is 4–5 minutes. In the second phase - final curing - cross-links are formed between polyacrylic acid chains with the help of less soluble trivalent aluminum ions. The result is a hard, stable matrix that is resistant to dissolution and drying. The duration of the final curing phase is, depending on the type of cement, from 2 weeks to 6 months. Particularly significant absorption - loss of water - can occur within 24 hours, so insulation with varnishes is necessary for this period. A day later, the filling is treated, followed by isolating the filling with varnish (processing of high-strength cements and lining cements is possible after 5 minutes, since they acquire sufficient strength and resistance to dissolution). The length of curing time is determined by a number of factors:

1) Particle sizes matter (in general, cosmetic slow-hardening cements have particle sizes up to 50 microns, while types I and III with a faster curing reaction have smaller particles);

2) An increase in the amount of fluorine reduces ripening time, but impairs transparency.

3) Reducing the calcium content on the surface of the particles allows you to shorten the ripening time, but reduces the aesthetics of the material.

4) The introduction of tartaric acid reduces the amount of fluorine; such materials are more transparent.

5) The introduction of a light-activated composite matrix into the GIC composition reduces the initial curing time to 20–40 s.

Final curing of light-activated glass ionomer cements (GIC) occurs within 24 hours or more.

High-strength GIC (Argion, Ketak Molar)

An increase in strength is achieved by introducing amalgam alloy powder, but the physical properties change slightly.

A significant increase in strength and abrasion resistance is achieved by introducing about 40% by weight of silver microparticles into the composition, which are baked into glass particles - “silver metal ceramics”. Such materials have physical properties comparable to amalgam and composites, but are not so significant as to form the edge of the tooth and fill large lesions.

Mixing powder and liquid in a ratio of 4: 1, manual or capsule, administration with a stroker or syringe. The curing time is 5–6 minutes, during which resistance to dissolution is acquired and processing of the filling becomes possible. After processing, the cement is insulated with varnish.

Cements of this group are radiopaque and not aesthetic.

Adhesion to dentin is slightly reduced due to the presence of silver ions.

Indications for use:

1) filling of temporary teeth;

2) polymerization on the surface of the composite.

In its composition, PS resembles an unfilled adhesive system. In PS accessible to air penetration, the polymerization reaction is completely inhibited (if you place a chemical or light adhesive in the recess of the tray, you will notice that the layer located at the bottom is cured, which demonstrates the formation of PS and the penetration of oxygen to a certain depth). The surface of a portion of the composite polymerized with access to air is shiny and moist. This layer is easily removed, damaged, and permeable to dyes, so after completion of the restoration it is necessary to treat the entire accessible surface of the restoration with finishing tools to expose a durable, well-cured composite.

PS also plays an important positive role, creating the possibility of combining a new portion of the composite with a previously polymerized one. Based on this idea, the formation of the restoration is carried out in a certain sequence.

1. Checking for the presence of a surface layer inhibited by oxygen - the surface looks shiny, “wet”, the shine can be easily removed. When adding a portion of the composite, due to locally created pressure, the oxygen-inhibited layer is removed, and the portion of the applied composite is glued to the surface. If the composite reaches behind the instrument or capsule and does not stick, it means that the surface is contaminated with oral or gingival fluid or there is no PS. The introduced portion is removed and the adhesive surface treatment (etching, application of adhesive, polymerization) is repeated.

2. Plastic processing of a portion of the composite. The glued portion is distributed over the surface with patting movements directed from the center to the periphery, while the layer inhibited by oxygen is displaced. When the ambient temperature rises above 24 °C, the material becomes excessively plastic and fluid, and therefore does not transfer the pressure of the trowel; in this case, the layer inhibited by oxygen is not displaced. This may be the reason for the frequent delamination of restorations made in the summer or in a hot room. As a result of plastic processing, when trying to separate a portion of the composite with a tool, it is deformed, but does not separate. Otherwise, it is necessary to continue plastic processing.

3. Polymerization.

Lining cements

They are not transparent and not aesthetically pleasing, so they are covered with restorative materials. They cure quickly, becoming resistant to dissolution within 5 minutes, have chemical adhesion to enamel and dentin, which prevents marginal permeability, release fluoride, and are radiopaque.

The ratio of powder and liquid is from 1.5: 1 to 4.0 1.0; in a sandwich type structure, at least 3: 1, since a larger amount of powder increases strength and reduces curing time.

After 5 minutes they acquire sufficient strength, resistance to dissolution, and can be etched with 37% phosphoric acid simultaneously with the enamel. Mixed manually or in capsules, administered with a stroker or syringe.

When filling multiple cavities, GIC is introduced into one cavity and covered with another restorative material. If several cavities are filled at the same time, then to avoid overdrying, the GIC is insulated with varnish. The subsequent application of the composite should be layer-by-layer, following the directional polymerization technique to prevent separation of the GIC from the dentin. The strength is sufficient for dentin replacement followed by covering with another restorative material.

Some cements have sufficient strength and can be used for insulating gaskets; the criterion for suitability is the curing time (no more than 7 minutes).

Light-curing GIC contains 10% light-curing composite and hardens under the influence of a light activator in 20–40 s. The final curing time required for the polyacrylic chains to form and the cement to achieve its final strength is approximately 24 hours.

GICs modified with photosensitive polymers are less sensitive to moisture and dissolution (in the experiment - after 10 minutes). The advantage of such cements is also their chemical bond with the composite.

Stages of using glass ionomer cement:

1) cleaning the tooth. Color selection using a shade scale (if GIC is used for a permanent filling);

2) tooth isolation.

Mixing of components is carried out manually and using a capsule system, followed by administration with a stroker or syringe. The capsule mixing system followed by injection with a syringe allows you to reduce the level of porosity and evenly fill the cavity. Cure time: mixing time 10–20 sec, initial cure 5–7 min, final cure after several months. These properties cannot be changed without losing transparency. After initial curing, the cement is isolated with a protective varnish based on BIS-GMA (it is better to use a bond from light-activated composites), and the final treatment is carried out after 24 hours, followed by re-isolation with varnish.

Physical properties: GICs of the group under consideration are not sufficiently resistant to occlusal loads, therefore their scope of application is limited to cavities of classes III, V, erosions, wedge-shaped defects, cement caries, fissure sealing, filling of baby teeth, temporary filling, some can be used as a lining material ( if initial curing occurs within a period of no more than 7 minutes).

Radiopacity: Most cements in this group are not radiopaque.

Compomers

A new class of filling materials, introduced into practice since 1993. The term “compomer” is derived from two words “composite” and “ionomer”. The material combines the properties of composites and glass ionomers.

The adhesive bonding system, the polymer matrix, is taken from the composites; the chemical bond between the particles of glass (filler) and the matrix, the release of fluorine from the mass, the proximity of thermal expansion to the dental tissues are taken from the GIC. In particular, the Dyrect AR material contains both acidic groups and polymerizable resins in the monomer composition. Under the influence of light, polymerization of methacrylate groups occurs; subsequently, in the presence of water, the acid groups react with filler particles. Strength, hardness, and abrasion are consistent with microhybrid composites, which allows us to recommend Direct AR for the restoration of all groups of cavities and imitation of dentin when filling with composites.

The term “compomer” is associated by many with “Dyract”, which, indeed, was the first material of a new class. Currently, it has been improved and a new compomer is being produced - Dyract AR (anterior, posterior) with improved physical, chemical and aesthetic properties. Other representatives of this class include F 2000 (ЗМ), Dyract flow.

Composition of composites (using Dyract as an example):

1) monomer (qualitatively new);

2) composite resin (BIS-GMA) and polyacrylic acid GIC;

3) a special type of powder;

4) liquid (from 1.67 to 5.68%) and the least for light-curing composites (0.5–0.7%).

Chemically activated composites consist of two pastes or a liquid and a powder. These components include an initiator system of benzoyl peroxide and amine. When mixing a base paste containing amine and catalytic components, free radicals are formed, which trigger polymerization. The rate of polymerization depends on the amount of initiator, temperature and the presence of inhibitors.

The advantage of this type of polymerization is uniform polymerization, regardless of the depth of the cavity and the thickness of the filling, as well as short-term heat generation.

Disadvantages: possible errors during mixing (incorrect ratio of components), short working time for modeling a filling, impossibility of layer-by-layer application, darkening of the filling due to oxidation of the amine compound residue. In the process of working with such materials, the viscosity changes quickly, therefore, if the material is not introduced into the cavity within the working time, its adaptation to the walls of the cavity is difficult.

As a polymerization initiator in light-polymerizing composites, a light-sensitive substance is used, for example campferoquinone, which, under the influence of light with a wavelength in the range of 400–500 nm, is cleaved to form free radicals.

Light-activated materials do not require mixing, therefore they do not have the air porosity inherent in two-component chemically cured composites, i.e. they are more homogeneous.

Polymerization occurs on command, so the working time for modeling fillings is not limited.

Possible layer-by-layer applications significantly allow you to more accurately select the color of the filling. The absence of a tertiary amine will give the material color stability. Thus, photocuring composites are more aesthetically pleasing.

However, it should be taken into account that the degree of polymerization is non-uniform; polymerization shrinkage is directed towards the source of polymerization. The degree and depth of polymerization depend on the color and transparency of the composite, the power of the light source, and the exposure distance to the source. The closer the light source, the lower the concentration of underpolymerized groups.

Curing time – 5–6 minutes. Final polymerization after 24 hours, so after curing it must be protected with varnish (supplied), for example, Ketak Glaze, Final treatment after 24 hours.

The presented description is indicative and cannot take into account the peculiarities of the use of various representatives of a wide group of glass monomer cements, therefore in all cases their use must comply with the manufacturer’s instructions.

6. Methodology for working with chemically cured composite materials (using the example of the microphilic composite “Degufil”)

Before working with these composite materials, it is necessary to determine the indications for its use (depending on the classification of cavities, according to Black), the material in question is classes III, V; it is possible to fill cavities of other classes when preparing a tooth for permanent prosthetics.

1. Cleaning the tooth (fluoride-containing pastes are not used).

2. Color selection is made by comparison with the scale in daylight; The tooth must be cleaned and moisturized. The material in question contains pastes of color A 2 or A 3.

Total etching technique: an acid gel is applied first to the enamel and then to the dentin. The etching time for enamel is 15–60 s, and for dentin – 10–15 s. Rinse for 20–30 s. Drying – 10 s.

Advantages:

1) saving time - treatment of tooth tissue is carried out in one stage;

2) the smear layer and its plugs are completely removed, the tubules open, and relative sterility is achieved;

3) dentin permeability is sufficient for the formation of a hybrid zone.

Flaws:

1) when the etched dentin is contaminated, the infection penetrates into the pulp;

2) with a high degree of shrinkage of the composite, hyperesthesia is possible.

The technique of working with etched dentin has some peculiarities. Before etching, dentin contains 50% hydroxyapatite, 30% collagen and 20% water. After etching - 30% collagen and 70% water. During the priming process, water is replaced by adhesive and a hybrid zone is formed. This phenomenon is possible only if the collagen fibers remain moist and do not fall off, therefore water and air jets should be directed at the enamel, and only reflected ones at the dentin. After drying, the enamel is matte, and the dentin is slightly moisturized and sparkling (the so-called wet bonding concept). When dentin is overdried, collagen fibers collapse – the “spaghetti effect”, which prevents primer penetration and the formation of a hybrid zone (Edward Swift: connection with etched overdried dentin - 17 MPa, sparkling - 22 MPa).

The next step after conditioning is applying primer. The primer contains a low-viscosity hydrophilic monomer (for example, XEMA - hydroxyethyl methacrylate), which penetrates into moist dentin; glutaraldehyde (chemical bond with collagen, denatures, fixes, disinfects protein); alcohol or acetone (reduce the surface tension of water, facilitating deep penetration of the monomer). Priming time is 30 s or more. As a result of priming, a hybrid zone is formed - a zone of monomer penetration into demineralized dentin and tubules, the penetration depth is limited by the odontoblast process. If the composite shrinks significantly, negative pressure is created, causing tension on the appendix, which may cause postoperative sensitivity.

7. Method of using light-curing composite material

Stage I. Cleaning the surface of teeth from plaque and tartar.

Stage II. Selecting the color of the material.

Stage III. Isolation (cotton swabs, rubber dam, saliva ejector, matrices, wedges).

I V stage. Preparation of a carious cavity. When using a composite material with enamel adhesives, preparation is carried out traditionally: a right angle between the bottom and walls; in classes II and IV, an additional platform is required. It is necessary to bevel the edges of the enamel at an angle of 45° or more to increase the surface area of contact between the enamel and the composite. In class V - flame-shaped bevel. If composites with enamel-dentin systems of IV and V generations are used, traditional principles of preparation can be abandoned. The enamel bevel is carried out in cavities V and IV; Class III – for aesthetic reasons.

V stage. Medicinal treatment (alcohol, ether, hydrogen peroxide are not used) and drying.

Stage VI. Application of insulating and therapeutic pads (see section “Isolating therapeutic pads”).

VII stage. Pickling, washing, drying.

Solitare is a modification of the facing material Artglass “Heraeus kulze” and therefore can be classified as a group of materials based on polymer glass.

1) organic matrix: high molecular weight esters of methacrylic acid, achieving an amorphous highly wettable structure, similar to organic glass. Plexiglas is combined with a silane-treated inorganic filler;

2) inorganic filler;

a) polyglobular particles of silicon dioxide ranging in size from 2 to 20 microns;

b) fluoride glass, particle size – from 0.8 to 1 microns;

3) rheologically active silicic acid.

The total amount of inorganic filler is at least 90%.

Used with the IV generation “Solid Bond” adhesive system. Shrinkage during polymerization is 1.5–1.8%, the material is resistant to chewing loads, dissolution, polishes well, and is color stable.

Used according to a simplified method:

1) used with metal matrices and wooden wedges;

2) applied in layers parallel to the bottom, polymerized with light for 40 s directed perpendicular to the filling, the thickness of the layers is 2 mm or more (except for the first layer).

The presentation of Solitare took place in 1997. Clinical trials are currently underway. The results obtained within 6 months give hope that this material can serve as an alternative to amalgam and be used for filling the chewing group of teeth, along with fine hybrid composites.

8. Principles of biomimetic construction of teeth using restoration materials

A natural tooth is a translucent optical body consisting of two optically different tissues: more transparent and light enamel and less transparent (opaque - opaque) and dark dentin.

The ratio of enamel to dentin creates differences in the appearance of different parts of the tooth crown, such as:

1) the cervical part of the crown, where a thin plate of enamel is combined with a large mass of dentin;

2) the middle part of the crown, where the thickness of the enamel increases and the amount of dentin decreases significantly;

3) the edges of the crown, where a thin plate of dentin is combined with two plates of enamel.

The combination of enamel and dentin also creates differences in the appearance of different teeth in one person: light incisors, in which enamel is combined with a small amount of dentin; more yellow fangs – the enamel is combined with a large amount of dentin; darker molars – the amount of dentin increases even more compared to enamel.

Due to its translucency, the crown of the tooth exhibits color variability under different lighting conditions (cold blue light predominates in the morning, warm red light prevails in the evening; the lighting intensity changes). The range of variability of teeth depends on the individual transparency of the crown. Thus, more transparent teeth have greater variability, and less transparent teeth - vice versa.

Based on the degree of transparency, teeth can be divided into three conditional groups:

1) absolutely opaque “blind” teeth, when there is no transparent cutting edge, due to the peculiarities of the individual structure or abrasion - these are yellow teeth. The range of color changes of the vestibular surface is low and is revealed when the tooth is transilluminated from the oral side;

2) transparent teeth, when only the cutting edge is transparent. As a rule, these are teeth of yellow-gray shades; the range of color changes of the vestibular surface is not significant;

3) very transparent teeth, when the transparent cutting edge occupies 1/3 or 1/4 and the contact surfaces are also transparent.

9. Mechanism of adhesion of composites to enamel

Adhesion comes from lat. Adgesio "sticking".

Bond comes from the English. Bond "connection".

Adhesives and bonds are used to improve the micromechanical adhesion of composites to dental tissues, compensate for polymerization shrinkage, and reduce marginal permeability.

Enamel mainly consists of inorganic matter - 86%, a small amount of water - 12% and an organic component - 2% (by volume). Thanks to this composition, the enamel can be dried, so the hydrophobic organic component of the composite is the BIS-GMA monomer, which has good adhesion to the enamel. Thus, in the enamel area, hydrophobic viscous adhesives (bonds) are used, the main component of which is the BIS-GMA monomer.

Method for obtaining a bond between composites and enamel

Stage I– formation of a bevel at 45° or more. The bevel is necessary to increase the active adhesion surface of the enamel and composite.

Stage II– etching of enamel with acid. 30–40% orthophosphoric acid is used in the form of a liquid or gel, and the gel is preferable since it is clearly visible and does not spread. The etching period for enamel is from 15 s to 1 min. As a result of etching:

1) organic plaque is removed from the enamel;

2) micro-roughness of the enamel is formed due to the dissolution of enamel prisms to a depth of approximately 40 microns, which significantly increases the adhesion surface area of the composite and enamel. After applying the bond, its molecules penetrate into microspaces. The adhesive strength of the composite to etched enamel is 75% greater than that of unetched enamel;

3) etching allows you to reduce the marginal permeability at the enamel-composite interface.

Stage III– the use of enamel (hydrophobic) bonds based on an organic composite matrix (BIS-GMA monomer), which penetrate into the microspaces of etched enamel. And after polymerization, processes are formed that provide micromechanical adhesion of the enamel to the bond. The latter is chemically combined with the organic matrix of the composite.

Identification of the patient's teeth is carried out immediately after cleaning with a nylon brush and professional toothpaste (not fluoride-containing) in natural light, the surface of the teeth should be damp. The restoration result is assessed no earlier than 2 hours after completion of the work, preferably 1–7 days, then a decision is made on the need for correction. A properly completed restoration will appear darker and more transparent immediately after completion due to the drying of the enamel, which will become lighter and less transparent. After water absorption, the color and transparency of artificial and natural dental tissues match.

Stage IV– use of an adhesive system.

Stage V– filling.

Stage VI– final processing.

Treatment of enamel with fluoride preparations

Contraindications: allergic reactions to the components of the filling material, poor oral hygiene, the presence of an artificial heart rate stimulator.

10. Errors and complications when using composite materials, compomers, GIC

At the stage of cleaning the teeth and determining the color: before determining the color of the teeth and preparing the carious cavity, it is necessary to clean the tooth from plaque and remove the pellicle layer. For this, a nylon brush and fluoride-free paste are used, otherwise the color determination will be incorrect. It is also necessary to use standard rules for determining the color of teeth (shade scale, moistened tooth, natural light). In the case of aesthetic restorations, it is important to determine the individual tooth translucency.

Table No. 1.

Table No. 2.

Table No. 3.

Table No. 4.

Table No. 5.

Table No. 6.

Representatives of fine hybrid composites.

Table No. 7.

Glass ionomer cements.

1.1. Mineral cements

Mineral cements are one of the oldest groups of permanent filling materials. Highlight:

Zinc phosphate cements (ZPC)

Silicate cements (SC)

Silico-phosphate cements (SFC)

Features of the composition

These groups of mineral cements have a number of common features and a number of differences in their chemical structure. The release form of all mineral cements is powder and liquid. All cements in this group have almost the same liquid composition and is an aqueous solution of a mixture of ortho-, para- and meta-phosphoric acids with the addition of zinc, magnesium and aluminum phosphate. These cements differ in their powder composition.

CFC powder:

Zinc oxide – 70-90%

Magnesium oxide – 5-13%

Silicon oxide – 0.3-5%

Aluminum oxide – fractions of percent

The composition of the powder may include copper oxide (I or II), silver compounds (to give the cement bactericidal properties). When bismuth oxide is added to the composition of zinc-phosphate cement powder (up to 3%), the working time of plasticity increases and the resistance of the cement to the action of oral fluid increases.

SC powder:

Silicon oxide – 29-47%

Aluminum oxide - 15-35%

Calcium oxide – 0.3-14%

Fluorine compounds (calcium fluorides, aluminum fluorides, etc.) – 5-15%

Compounds of iron, cadmium, manganese, nickel, etc. can be introduced. in order to give the material the required shade.

Otherwise, the composition of SC is also called aluminosilicate glass.

SFC Powder:

It is a mixture of SC powder (60-95%) and CFC (40-5%).

Properties and areas of application of mineral cements:

CFC(“Unifas”, “Unifas-2”, “Visfat” (CFC with bismuth) (Medpolymer); “Vitscin”, “Bactericidal Foscin” (CFC with silver) (Rainbow R); “Adgesor” (Dental Spofa); “ DeTrey Zinc" (DeTrey/Dentsply); "Phosphacap" (Vivadent); "Phoscal" (Voco); "Harvard Kupfercement" (CFC with copper) (Harvard), etc.) has the following properties:

1.“+” properties:

A. Satisfactory hardness for cements

b. No shrinkage after hardening

V. CTE corresponding to that of enamel and dentin

d. Good thermal insulation properties

d. Low moisture absorption

e. Radiopacity

and. Adhesion to hard dental tissues, metal and plastic is satisfactory for cements.

2.“-“ properties:

A. Insufficient resistance to oral fluid

b. Insufficient resistance to fracture and abrasion

V. Poor aesthetics

d. Short-term irritating effect on the dental pulp due to high acidity during hardening of the material

CFCs may apply: as isolating pads (in case of deep caries, with preliminary application of a therapeutic pad); for fixation of orthopedic structures (crowns, inlays); for cementing intracanal pins; to fill the root canal before apical resection surgery; sometimes as a temporary filling material, if it is necessary to place a filling for a long time.

Currently, CFCs are increasingly being replaced by more modern filling materials.

SC(“Silicin-2”, “Alumodent” (Medpolymer); “Fritex” (Dental Spofa); “Silicap” (Vivadent)).

1. “+” properties:

A. Cheapness

b. Easy to use

V. Anti-caries effect due to fluorides included in the composition

d. Aesthetic properties satisfactory for cements

d. See paragraphs. b;c;d;d for CFC

2. “-“ properties:

A. Weak adhesion to hard tooth tissues

b. Insufficient resistance to oral fluid

V. Fragility

d. toxicity to the pulp due to the long-lasting acidity of the material during the structuring process (a filling made of SC necessarily requires isolation of the pulp with a lining)

d. SC - non-radiopaque

SC can be used to place permanent fillings in cavities of classes III – V according to Black.

LECTURE No. 11. Modern filling materials: classifications, requirements for permanent filling materials