Fracture resistance of teeth restored with Class II composite restorations.

Teeth with large mesio-occlusal-distal cavity preparations fracture more easily than intact teeth. An intracoronal restoration capable of increasing tooth fracture resistance is desired. This in vitro study compared the fracture resistance of maxillary premolars restored with enamel bonding and dentin bonding. The effects of the type of curing system (chemical or photochemical) and marginal preparation (beveled or not) were also evaluated. Premolars restored with large MOD composite resin restorations were approximately twice as strong as the unrestored prepared tooth. However, all restored teeth were no more than half as strong as the intact tooth. Dentin bonded restorations were not significantly stronger than enamel bonded restorations.