Abstract
GC everX PosteriorPresentation
Prof. PekkaVallittu, University of Turku, Institute of Dentistry and Turku Clinical Biomaterials Centre – TCBC, Turku, Finland,
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Replacement of damaged dental tissues is utilizing modern adhesive techniques, which have turned especially restorative and prosthetic dentistry to a new era. Fiber-reinforced composites (FRCs) have been utilized in a variety of technical and everyday applications since 1950s. Interestingly, begin of the use of FRCs in dental and medical fields has been slow, although there have been urgent needs for cost-effective mechanically and esthetic-cosmetically high quality materials. At the moment, the dental profession has one new exceptionally widely useable group of material – FRCs – to be used clinically.
The biggest demand for the industry in dental materials field has been finding material solutions to replace amalgam in large molar restorations to be used by direct techniques. Present composites made of particular fillers and resin matrix have not been able to solve problems related to fracture propagation through composite and isotropic polymerization contraction. Due to this, bulk fractures can occur. On the other hand, particulate fillers keep the composite isotropic in terms of many properties, including polymerization shrinkage. Shrinkage causes gaps between the restoration and the tooth, and predispose to secondary caries.
everX Posterior is a short fiber-reinforced composite, which is used to replace tissue largely damaged teeth, especially of dentine. Glass fibers of everX Posterior material simulate collagen fibers of dentine, and provide high toughness (5.1 MPa /m1/2) of the restoration-tooth system. The value of toughness exceeds the value of dentine, which is a collagen fiber-reinforced natural material. Length of the glass fibers has been optimized to provide high strength and toughness and to have good adaptation to the dimensions of posterior teeth. At the same fibers of everX Posterior also control and minimize polymerization shrinkage of the composite resin. everX Posterior is used as bilayered filling material, i.e. the outermost part of the filling, which simulates enamel, is made of high quality hybrid composite resin. Attachment of overlaying particulate composite to everX Posterior is ensured by fibers, which simulates attachment of enamel to dentine via collagen fiber decussation. This results in high load bearing capacity for the restored tooth.