Filling materials in stomatology
A special group is formed by composite materials designed to restore the integrity of hard tooth tissues.
Composite materials consist of two main components - filler and binder. As a filler, small granules of glass or ceramics are usually used.
Binder is a polymer and a monomer, the interaction of which( polymerization) produces a strong homogeneous mass that fills the entire free space between the filler granules. By weight, the filler content can range from 75 to 87%.
Depending on the type of polymerization, the composites can be:
- light curing
- chemical curing
- type "paste paste"
- type "powder-liquid"
- 1) Macro-filled. They have a high resistance to abrasion, but with time they quickly dye and darken. They are best used to repair defects on the less visible areas of the chewing teeth.
- 2) Microfilled. Finely dispersed filler provides high aesthetics, however this is achieved at the expense of abrasion resistance. Preference for such materials is given with cosmetic restorations on the front teeth.
- 3) Hybrid materials, the filler of which is a homogeneous mixture of coarse and fine particles.
- 1) Opakovye. They have minimal transparency and allow to simulate opaque dentin.
- 2) Enamel. This group is most diverse in color and is designed to perform the main part of the restoration.
- 3) Transparent. Located in the surface layer of the restoration, they mimic the natural transparency of the enamel of the tooth.
- 1) Dense materials, which have great strength and hydrophobicity. They are used to perform the main part of the seal.
- 2) Fluid, with increased plasticity and easily adjacent to moistened dentin. They are used in a small amount to apply the first layers directly to the tooth tissue, providing a reliable grip.
For better fixing of the seal, the hard tissues undergo special chemical treatment - etching. A gel containing about 35% phosphoric acid is applied to the walls of the cavity for 20-30 seconds. During this time there is a shallow destruction of the hard tissues of the tooth.
The walls of the cavity become rough and porous, they easily absorb a special liquid - a bond that is able to chemically bind to the tooth tissues.
Since the bond is a chemical relative to composite materials, it in turn is firmly connected with the seal, providing it with a strong fixation in the carious cavity.
A distinctive feature of the use of light-curing materials is associated with their low transparency. For complete polymerization, it is important to apply the material in small portions of a thickness of not more than 3 mm. Preference should be given to the exposure of the material through the walls of the tooth, which provides a directionality of the polymerization towards the tooth and increases the adhesion strength.
Upon completion of work, the finished restoration should be polished with various materials with decreasing abrasiveness. The final stage should be an additional exposure to a completely finished restoration.
The main advantages of modern composite materials:
- 1) Low toxicity. The concentration of the residual monomer that has not entered the polymerization process is very small.
- 2) Minor polymerization shrinkage. During polymerization, a reduction in the volume of the material inevitably occurs due to a decrease in the space between the connecting molecules. Light-curing materials shrink from 1.7 to 4.5%.
- 3) High strength.
- 4) Good polishability.
- 5) Continuous color fastness, etc.
The characteristics of radiation sources for polymerization are improved - ergonomic LED models with capacious and long-lasting batteries have appeared. In many models sensors are built in, allowing the doctor to regularly test the device to determine the power of the light flux.
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