Effect of cyclical lateral forces on microleakage of cervical resin composite restorations

Abstract

The purpose of this in-vitro study was to compare the amount of microleakage occurring in cervical restorations in groups of extracted teeth restored with four different types of resin composite materials, representing four basic categories widely used by restorative dentists today. This comparison was made, both with and without the application of cyclic lateral forces. A testing instrument developed specifically to reproduce cyclic lateral forces was utilized. The amount of microleakage that occurred was compared, both with and without the application of the forces. Within the limitations of the study, we found that the packable and the hybrid resin composite material exhibited significantly more leakage than either the flowable or the microfilled resin composite. This was observed in both the fatigued and the non-fatigued specimens. This finding supported the theory that the lower modulus of elasticity of flowable and microfilled resin composites allows more flexure of the restoration during the flexure of the tooth, that results from its reciprocal movements. The non-fatigued specimens restored with flowable and microfilled resin composite material had less microleakage than did those restored with the hybrid resin composite material. The findings in the study supported the possibility that lower modulus of elasticity of the microfilled and flowable resin composite materials may have some beneficial effects in reducing the stress placed on the adhesive bond at the resin tooth interface during the polymerization phase.