The seals are of two types — temporary and permanent.
Temporary— Seals designed to remove through
Constant— Seals, which should stand for years and decades. Permanent fillings vary in composition.
Materials for the manufacture of seals:
- Seals metal — Different types of amalgam (metal alloy with mercury). The drawback is the presence of mercury harmful to the body. Amalgam also expanded after installation. Often there is a breakaway wall tooth adjacent to the seal, although this drawback today amalgam minimized. Amalgam fillings are used in the chewing teeth and in difficult situations, such as when subgingival defects. They are also often cast crowns, when appearance is important not seal.
- Glass ionomer cements have good marginal adaptation and cheap. Special supplements nourish the tooth fluoride ions and prevent the development of secondary caries. But such seals are fragile and easily erased.
- Cement seals (Powder + liquid). They also counteract the formation of "secondary caries", but short-lived
brittle material. because of
- Composites and Plastics Chemical rejection — An extensive group of sealers who came to the place of cement seals. Unlike composites of plastics is generally in the content of the filler (often a porcelain). Can be divided akrilsoderzhaschie composites, composites based on epoxy resins and light-curing composites. Akrilsoderzhaschie Composites— Very strong, "fracture", is very resistant to abrasion, but it is very toxic, and have a lot of pores formed by polymerization. By putting them on a healthy tooth, you can easily get the pulp (nerve inflammation). Also quite often develop secondary caries (including the teeth, which is adjacent to the seal). Composites based on epoxy resins— More durable to abrasion, but brittle. Of course, they are better acrylic resin is less toxic. However, after several years of such composites darken.
- Svetokompozity (Light-curing, they are also photopolymer, they also geliootverzhdaemye composites) — the most popular in our country, material for stopping teeth. This mixture of polymer and filler which hardens under the influence of the blue light emitted by the special lamp. They are beautiful, durable, hardened control allows the doctor to do a tooth for as long as necessary and without haste. Furthermore, they have extensive RGB color (can be reproduced in color and transparency in virtually all layers of the tooth), fine polishing (i.e., polished to shine seal is different from the enamel) and sufficient durability. Today we can say
five to seven yearsimpeccable service. Their main problem is the shrinkage and marginal adaptation. Therefore, they are not suitable for closing large defects and are not a substitute prosthetics.
Unfortunately, despite all the positive qualities of modern light-curing materials they have three major shortcomings:
- Shrinkage during polymerization (or svetootverdenii). This disadvantage is laid in the chemistry of these materials. At the moment when the seal begins to harden, it is reduced to the extent that Shrinkage occurs. The degree of shrinkage varies from 5% to 0.8%, this leads to the fact that the seal separates the walls of the tooth. However, devised several ways to combat this disadvantage, but they are not always effective, and sometimes technically feasible. And if the size of the seal is not great, it's not a problem, but if the seal is large, the risk of separation of the seal and caries beneath it grows with the size of the seal.
- The second problem is the continuation of the first, since Shrinkage leads toappearance of internal strains in the seal itself, break away from the thin walls.
- Lack of polymerization (or hardening) seals. The fact that the light-curing light hardens in the mouth seal (or polymerize) only
60-70%. Is suffering from the strength of the seal and its color stability. If any seal could simply be heated to 100 degrees for 15 minutes, then its strength increased to several times. This principle just lies in the technology of photocurable tabs from composite materials.
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