|
Modern materials for dental fillings
16-09-2009
Excrete following groups of dental cements: zinc phosphate (phosphate cement, visfat-cement, unifas), bactericidal (phosphate cement with silver, dioksivisfat), zinc-ksidevgenolovye cements (kariosan), silicate (silitsin, silitsin-2, alyumodent) , silikofosfatnye (silidont, laktodont, infantid) polikarboksilatnye cements, cements GLASS.
Zinc phosphate cements. Produced powder and liquid in the kit. Components powder: 75-90% zinc oxide (ensuring adhesion), with the addition of silicon oxide (giving, hyaline, transparent, light), magnesium oxide (an increase of ductility and mechanical strength), calcium oxide (acceleration setting, viscosity), aluminum oxide (an increase of strength and hardness). Fluid – an aqueous solution of phosphoric acid.
Phosphate cement.
Powder yellow or light yellow color, is 90% zinc oxide, 60 / 0 magnesium oxide, 4% calcium oxide.
Liquid – 35% aqueous solution of phosphoric acid, with the addition of phosphate: zinc, aluminum, magnesium to reduce the rate of interaction between the powder and liquid.
Methods of mixing. On the smooth surface of glass separately applied powder and the liquid in the ratio of 4:1.
The powder is divided roughly into 4 parts, added sequentially to the liquid and carefully triturated. Properly kneaded mass is considered, if it is not reaching for a spatula when it is isolated and cut off, forming the teeth to 1 mm. If the masses have got a thick, add liquid can not, we must make it again. Maximum adhesive sealing of the test period, 4-8 minutes.
Positive properties: good adhesion, thermal expansion coefficient is close to the coefficient of thermal expansion of the tissues of the tooth, does not irritate the pulp, is impervious to acids and monomers permanent seal, has low thermal conductivity, radiopaque.
Negative Qualities: dissolves in the oral fluid, low mechanical strength, does not possess anti-inflammatory and antibacterial activity, has no aesthetic qualities.
Indications for use: as an insulating pads under permanent seal, for a permanent seal under artificial crown or for sealing primary teeth;
sealing of root canals according to indications, prosthetic fixation.
Unifas. Unified phosphate cement. Due to the matrix on the basis molibdataammoniya has good adhesion to the metal as well as to the tissues of the tooth, more durable and chemically resistant.
Visfat Cement (bismuth-cement). The powder has the same composition as that of phosphate cement, but with the addition of 3% bismuth oxide. Issued 3 shades: light yellow, golden yellow and dark yellow. Liquid – 37% aqueous solution of phosphoric acid. It has good adhesion, hardens faster, more durable and radiopaque, less soluble, has a bactericidal and bacteriostatic properties, but is able to change the color of dental hard tissues.
Maximum adhesive sealing test period 3-3,5 minutes.
Mixing technique is similar to phosphate-mixing cement.
Indications for use: as an insulating pads under permanent seal, for a permanent seal under artificial crown or for sealing primary teeth;
prosthetic fixation.
Microbicides. Phosphate cement with silver, Argil, uning.
Fostsem – phosphate cement with the addition of silver. It has bactericidal properties. Methods of preparation and application are similar phosphate cement, but can not be used as a shim under seal on the front of the teeth, as well as silver stain teeth tissues in gray color.
Dioksivisfat adding dioxidine. Cement also has bactericidal properties, mechanical strength, Malorastvorim, does not stain teeth tissues.
Silicate. Silitsin, Silitsin-2, Velatsin. Comes bundled powder-liquid. Components powder – silicon oxide (29-47%), aluminum oxide (15-35%), calcium (up to 14%), fluoride (15%), a small amount of salts of magnesium, iron, phosphorus. Issued 7 colors.
Positive properties: the color is close to the enamel, fluoride compounds attached antikarisogennye properties, reduce the solubility of enamel, reduce the possibility of secondary caries.
Disadvantages: toxic, so use on live teeth only with an insulating gasket, poor adhesion (no zinc oxide), low mechanical strength (brittleness and fragility), relatively high solubility in the oral cavity.
Methods of mixing. On the smooth surface of the glass causing 1 of the powder and 5-7 drops of liquid. The powder is gradually added to the liquid, knead a plastic spatula, as the metal changes color seal.
Indications for use: filling the front of teeth in the presence of cavities 3, 4, 5 classes on Blake.
Silikofosfatnye – a silicate cements, modified zinc phosphate cement.
Silidont, Veladont. Available in the complete powder-liquid. Powder – 80% powder silitsina and 20% phosphate cement. Liquid – solution of phosphoric acid.
Positive properties: good adhesion, mechanical strength and chemical resistance is higher than that silitsina.
Negative properties: toxic, not aesthetic (white is opaque), not solid enough and stands in comparison with modern filling materials.
Mixing technique is similar to silitsinu.
Indications: filling posterior teeth, 1,2, 5 classes on Blake.
Sealing phosphate, bactericide, silicate, silikofosfatnymi, polikarboksilatnym cements should be conducted in isolation of the tooth from saliva and thorough drying sealable cavity.
GLASS cements.
GLASS cement (cement polialkenovy) consists of typical dental cements components – powder and liquid solidified as a result of acid-base reaction.
Normally GLASS cements used aqueous solutions of polycarboxylic acids (polymers of alkene acids), for example, polyacrylic acid and their copolymers with itaconic or maleic acid. Carboxylic acid group of the polymer interacts with calcium ions and forms a solid polymer matrix. This same acid provides a chemical adhesion to enamel and dentin in calcium.
Produced chemical, light-curing, dual curing.
Because of the freeze drying of acid can be added directly to the powder, increasing the accuracy of dosing of liquid and powder. Liquid component of water-cement solidified GLASS consists of distilled water or tartaric acid. Powder component consists of calcium-aluminum-silicate glass with the inclusion of the crystallized saturated with calcium fluoride drops. Fluoride, after the application of seals, for a long time is allocated in the mouth, providing an organic anticarious protection in the marginal area of the seal.
Fixation of both main components takes place in 3 stages.
Acid releases of calcium ions of silicate glass and aluminum. Since calcium ions are released more quickly, they are the first to react with the acid. After wetting calcium bridges formed carboxylated polyacrylate acid gel, sensitive to moisture and drying. When you initially get wet increases the time of binding, decreased strength and hardness are observed loss of transparency, porosity and roughness of the surfaces, increased erosion of the seal. Because GLASS drying cement becomes opaque, cracks and not fully connected. Therefore need to be protected by varnish, bonding or matrices. Aluminum ions penetrate into the matrix after several hours, while forming a water-soluble calcium-aluminum-carboxylate gel.
The method of sintering can swim in the metal particles of glass. Applicable to this end, in most cases, silver is a shock absorber and increases the strength izrib and resistance to abrasion. This modification of the glass is kermettsementom (ceramic-metal-stekloinomerny cement).
The third component of glass-ionomer cements are light-and dual-curing, liquid components of which, except for acids, contain, for example, hydrophilic monomers (ridroksilmetakrilat – HEMA), Bis-GMA and fotouskoriteli. Because light copolymerization of methacrylate with troupes of polyacrylic acid formed covalent and ionic bonds that contribute to the solidification of the material.
The method of application. Before the fence powder thoroughly. Kneaded in a strict ratio of powder-liquid, of the firm – the manufacturer. After sampling the powder should be carefully and tightly close the lid of the bottle, as the powder is hygroscopic.
Should be the imposition of cement on a slightly damp surface is not over-dried, because the high concentration of ions facilitates the diffusion of fluid dentinal tubules out. In addition, of glass are hydrophilic, they absorb a small amount of fluid from the surface of dentin and dentinal tubules, which improves the adhesion. Therefore, immediately after making the seal material is covered with protective varnish (they are available in kit) to prevent the penetration of fluid from the oral cavity. Finishing seals spend 24 hours.
Positive properties:
chemical adhesion, which does not require acid etching;
biocompatibility with the tissues of the tooth;
absence of toxic effects on the pulp gradually secreted fluorine enters the tissues of the tooth and increases resistance to tooth demineralization (protivokariozny effect);
low polymerization shrinkage;
the coefficient of thermal expansion close to the coefficient of thermal expansion of dental tissues;
opaque.
Disadvantages: lack of mechanical strength, satisfactory aesthetic qualities.
Indications:
filling cavities in the main III and V classes, sealing of non-carious lesions of teeth (hypoplasia, wedge-shaped defects, erosion);
filling the cavities of deciduous teeth of all classes;
as insulating pads;
as a sealant;
Paving the restoration (the bulk of the cavity is filled with ionomer cement and the surface layer – composite materials); restore tooth crown under artificial crowns, inlays, crowns restore stump before removing the cast, fixation of prosthetic; root canal fillings.
| |
