Microtensile Bond Strength of Restorative Materials to Enamel and Dentin: A Narrative Review

The foundation of modern adhesive dentistry was laid by Buonocore’s introduction of the acid-etch technique in 1955 and Bowen’s development of composite resins in 1962. Today, adhesive restorative materials are widely used, offering reliable bonding to enamel. Achieving long-lasting adhesion to dentin is still challenging because of its variable structure and the presence of the smear layer. The constant evolution of adhesive systems introduces numerous products with varying compositions and clinical protocols, necessitating thorough performance evaluation. In vivo studies are limited by ethical and technical constraints, making in vitro bond strength tests a more practical alternative. While laboratory studies cannot fully replicate the oral environment, they allow for rapid, cost-effective comparisons. Various testing techniques – macroshear, macro push-out, macrotensile, microshear, micro push-out, and microtensile – are employed to assess adhesive performance, with outcomes influenced by specimen preparation, substrate variability, and environmental conditions such as thermocycling. Among these, microtensile bond strength (µTBS) has gained prominence due to its high sensitivity and ability to evaluate small bonding interfaces. It also facilitates the study of bonding behavior at different dentin depths and under localized conditions. However, translating laboratory findings into clinical success remains challenging. This review critically discusses the methodology, limitations, and clinical relevance of µTBS in adhesive dentistry.

Keywords: Adhesive systems; Enamel and dentin adhesion; Microtensile bond strength; Resin–dentin interface