Composite or composites are filling materials used in dental practices. They are used to place fillings, secure crowns and root posts, and make ceramic improvements. The materials are mostly used in the anterior region. However, there are now substances with a higher filler content that can also be used for posterior teeth.
What is composite?
Composites consist of several high-tech composite materials. The main portion of about 80 percent is composed of ceramic, glass and quartz particles. Composite has almost completely replaced the amalgam filling that was once common, as amalgam is said to pose health risks due to its mercury content. Composites consist of several high-tech composite materials. The main part of about 80 percent is made up of ceramic, glass and quartz particles. Only 20 percent is made up of the actual plastic component. As a result, the filling material has gained in stability. In contrast to amalgam fillings, composite fillings are not stuffed, but applied and bonded in layers. Thanks to the nature of modern composites, they are able to withstand high mechanical stress and are highly resistant to abrasion. On average, a composite filling lasts at least seven years.
Shapes, types and kinds
The material that composites are made of is based on plastics that originate from an acrylic base. These include BisGMA, TEGMA, EGDMA, UDMA and methacrylate. They may also contain traces of acids, formaldehyde and glutaraldehyde. Particles of glass, quartz and ceramics serve as fillers. Silanes improve the coating with the plastics. There are three types of composites. The Conventional composites with large fillers, also called macrofillers. They are made of quartz, glass or ceramics with a size of one micrometer. There are also the microfiller composites with very fine microfillers. They consist of silicon dioxide with a size between 0.01 and 0.04 micrometers. As a third variant, there are the hybrid composites, which consist of both microfillers and macrofillers. These state-of-the-art composites contain between 85 and 90 percent macrofillers, with the remainder consisting of microfillers. This combination ensures increased packing density. There are further subdivisions among hybrid composites. There are hybrid composites with a medium filler of up to ten micrometers. Furthermore, there are fine particle hybrid composites with a filler size of up to five micrometers, then come the ultra-fine particle hybrid composites with a filler size of up to three micrometers, and finally the submicrometer hybrid composites with a filler size of up to less than one micrometer.
Structure and mode of operation
The first generation of composites was based on a combination of paste and liquid. This type of polymerization proved to be disadvantageous in several respects. For example, no layering was possible with this combination, the curing time could not be controlled, and the resins were not color stable. Therefore, light-curing composites are available today. The curing process is started with the polymerization lamp, which emits blue light. With this cold light source in a certain wavelength, a chemical process is stimulated that starts the curing process. A major advantage of the light-curing variant is the higher degree of curing as well as the significantly better color stability, which is particularly important in the anterior region. In addition, this allows the materials to be processed and modeled for as long as is required for the individual case. It is also possible to apply several layers. Only the targeted use of light triggers the final curing. If treatment with light-curing composites is not possible, which is often the case with opaque materials such as those used for partial and full crowns or ceramic inlays, dual-curing composites can be used. Only the marginal areas are cured with the polymerization lamp. Chemical polymerization is then used on the areas inaccessible to light.
Medical and health benefits
Fillings made from composites can be done within one visit without the help of a dental laboratory. Once the decay is removed by the dentist, the tooth is restored layer by layer. The various natural color shades make a lifelike reconstruction possible, so that after polishing, the filling is hardly, if at all, distinguishable from the actual tooth substance.The advantages over the earlier amalgam fillings are, in addition to the health benefits, better stabilization of the tooth and coloration. However, composite fillings are more costly than amalgam fillings because the composites have to be applied in several layers and hardened layer by layer. Compared to ceramic fillings, composite fillings have the advantage of being less expensive and less time-consuming, as impressions are required for ceramic fillings. The number of plastic fillings is increasing visibly, as amalgam fillings are considered to be harmful to health. In the meantime, however, a possible problematic effect of composites is also being discussed. There are assumptions about toxicity, mutagenicity, estrogenicity and allergies caused by the composites. However, apart from allergies, nothing of this kind has been proven in studies to date. The plastics BisGMA and UDMA are not mutagenic in their cell cultures, unlike TEGDMA, where mutagenicity has been demonstrated in cell cultures. However, it requires a very high concentration, which does not occur in dental fillings. Nor could an estrogenic effect be demonstrated. It is true that BisGMA contains bisphenol A, which has a pseudoestrogenic effect, but this has not yet been demonstrated in the oral environment.
