Is it really not Necessary Retention and Resistance form of Cavity Preparation for Composite Restoration?

Abstract

The question arises, given the introduction of adhesive dentistry, whether the classic mechanical concepts of retention and resistance form for composite resin restorations continue to hold. This systematic review critically evaluates clinical, laboratory, and finite element analysis evidence regarding the influence of cavity preparation design on the long-term clinical success of direct composite restorations. A systematic search of the databases PubMed, Scopus, and Web of Science was conducted to identify the relevant studies for this review. Taken together, the available evidence indicates that, despite today’s adhesive systems affording excellent adhesion to the tooth, restorations placed without proper retention and resistance form fail significantly more often in high‑stress, multi‑surface, or high C‑factor cavities. In contrast, small Class I and Class III cavities with margins in enamel and non-carious cervical lesions without occlusal wear facets seem to be predictably restored, even with adhesive-only preparations, over the short to medium term. This is especially true for restorations placed in high C‑factor cavities, non-carious cervical lesions with occlusal wear facets, and severely compromised teeth. This evidence shows that retention and resistance forms are important factors in increasing the longevity of restorations, decreasing the risk of catastrophic fracture, and allowing the possibility of restoration repair. Adhesive systems should be considered supplements to mechanical retention and not replacements for it; however, the required amount of mechanical features is approached from a risk-stratified rather than an absolute approach.