Microleakage Evaluation of Expired and Non-expired Resin Composites and Bonding Agents: In Vitro Study

Aim: Although the shelf life is a key property of dental composites and bonding agents, these materials may often be used in simple procedures after expiration. In this study, the microleakage of two year expired and non-expired dental composites (Filtek Ultimate Universal A2 Enamel, 3M ESPE, USA, and Tetric N Ceram A2, Ivoclar Vivadent, Schaan, Liechtenstein) and a universal bonding system (Single Bond Universal, 3M ESPE, USA) was examined. Materials and Methods: In 40 freshly extracted human molars, two standardized Class II cavities (buccolingual and mesiodistal width of 3 mm and 4 mm, respectively) were prepared (80 cavity preparations). The teeth were thermocycled in distilled water for 1000 cycles in a 5°C to 55°C water bath. Next, the teeth and their apical foramens were coated with water resistant nail varnish, except for 1 mm around the restoration–tooth interface, and retained in a 1% methylene blue solution. After 24 h, the specimens were cut into two halves and analyzed using a stereomicroscope. Scanning electron microscopy images of two samples of the groups were obtained. Results: The Kruskal–Wallis test indicated no significant differences between the groups (P < .05). The occlusal median scores were not significant (P = .99). Moreover, the gingival median scores were not significant (P = .48). No difference was found between the occlusal and gingival values in any group (P > .05). Conclusion: These findings indicated that two-year-expired dental composites and bonding agent, which were maintained under proper conditions, do not have any significant difference in terms of the microleakage.