Comparative in Vitro Evaluation of Marginal Sealing in Class I Composite Restorations Using Fifth- and Seventh-Generation Adhesives

Abstract

Background: A major challenge in adhesive dentistry, often leading to restoration failure, is microleakage. This in vitro comparative study was designed to assess microleakage at the tooth–composite interface. The investigation aimed to compare the sealing efficacy of two commonly used adhesive systems. Methods: Standardized Class I cavities were prepared on 20 extracted human molars and randomly divided into two groups (n = 10 each). Group A was treated with a fifth-generation total-etch adhesive (OptiBond™ Solo Plus, Kerr Corporation, Orange, CA, USA), and Group B received a seventh-generation self-etch adhesive (Adhese® Universal VivaPen®, Ivoclar Vivadent AG, Schaan, Liechtenstein). All restorations were completed using Herculite XRV composite resin. Microleakage was evaluated using dye penetration analysis after immersion in 2% methylene blue for 10 days, followed by longitudinal sectioning and microscopic measurement at 500× magnification. Results: The fifth-generation adhesive group showed a mean microleakage of 0.2503 ± 0.1921 mm, while the seventh-generation group recorded 0.2484 ± 0.1764 mm. Statistical analysis using an independent t-test revealed no significant difference between the groups (p = 0.696). Conclusions: Both adhesive systems demonstrated comparable performance in minimizing microleakage under standardized conditions. Although the total-etch group exhibited slightly lower numerical values, the difference was not statistically significant. These findings suggest that both adhesive approaches can be clinically effective when applied appropriately.