Direct composite restorations longevity
Direct resin composite restorations can be considered an example of successful biomaterial capable of replacing dental biological tissue, both for functionality as the aesthetics. These materials were used daily in restorative dentistry for many years and are recommended by the "preferred" for reconstructive treatment of the posterior teeth. However, compounds such as those used today are quite different from when they were introduced in conservative dentistry: his compositions have changed and improved a lot over time.
Initially, the composites could be subject to wear and tear, discoloration and high incidence of fracture. Besides, it was not uncommon to observe secondary caries and postoperative symptoms in teeth treated with resin composite. Some of the problems were resolved initially observed with increasing filler in the composite. By reducing the particle size, distribution and morphology optimizing and improving the surface treatment of the resins, it was possible to produce materials with improved mechanical capabilities, increased wear resistance, aesthetic simpler and better polishing.
The latest generation of compounds are nanopreenchidos or nano-hybrid, with internal fills composed of materials such as quartz, colloidal silica, silica crystals containing barium, strontium, zirconium and pre-polymerized resins.
Although the improvement of the filling components has had a major impact on the quality of the resin also is improved with time the composition of the resin matrix. Current composite resins are comprised of dimethacrylate monomers, especially bisphenol-A glycidyl methacrylate (BisGMA), bisphenol A-glycidyl methacrylate ethoxylated (BisEMA), triethyleneglycol dimethacrylate (TEGDMA) and / or urethane dimethacrylate (UDMA). The development of research in combination with various monomers or monomers alternative led to the development of compounds having a lower polymerization shrinkage, and a consequent lower stress.
These compounds associated with hydrophilic adhesive systems provided better adhesion of dentin, with consequent reduction of postoperative symptoms and increased adhesive strength of the restored tooth. More recently, the addition of acid groups within the monomer structure led to production of materials able to adhere to tooth structure autonomously.
Furthermore, by modifying the monomer mixture photo activated molecules have been developed with the bulk compounds, or resins with higher depth of cure. Despite the major technical improvements observed in the production of composites, these materials continue to show weakness as the longevity of restorations. Such problems - for example, training gaps, marginal discoloration, appearance of fractures or secondary caries - massively boosted further development of restorative materials and adhesives.
In general line, the research should be geared to developing solutions with better adhesion to dentin tissues, increased mechanical capabilities, ease of use and longer.
Source: Dentista Hoje, written by Ana R. Benetti and Ula Pellesen
Image takes from: http://www.dentistahoje.com.br/longevidade-das-restauracoes-diretas-de-resina-composta/