Comparative Evaluation Of Surface Conditioning Methods On The Tensile Bond Strength Between Composite And Porcelain: An In Vitro Study

Abstract

Background: Ceramic restorations are preferred in dentistry for their esthetics, durability, and biocompatibility, but chipping and minor fractures are common. Repairing defective ceramics preserves tooth structure, reduces treatment time, and prolongs restoration longevity. Successful repair relies on strong adhesion between resin composite and porcelain, which can be enhanced through surface conditioning methods such as mechanical roughening, acid etching, salinization, or bond activators. This study aimed to compare the tensile bond strength (TBS) of resin composite to porcelain using different surface conditioning techniques. Methods: An in vitro comparative study was conducted on 48 standardized porcelain and composite blocks (30 mm × 3 mm × 3 mm), divided into three groups: Control (no conditioning), Silane-treated, and Porcelain Activator + Silane (PA+Silane). All specimens were bonded with dual-cure resin cement and stored in distilled water at 37 °C for 7 days. TBS was measured using a universal testing machine at 0.5 mm/min. Data were analyzed with independent t-tests and Tukey HSD post-hoc analysis (P < 0.05).  Results: TBS increased progressively across the groups: Control (8.24 MPa), Silane (9.50 MPa), and PA+Silane (11.01 MPa), with all differences statistically significant. SEM images showed minimal bonding in the Control group, moderate bonding with Silane, and the strongest, well-adapted interface with micro-retentive features in the PA+Silane group, indicating enhanced micromechanical and chemical adhesion. Conclusion: Combined phosphoric acid etching and silane treatment provides the strongest and most reliable bond between resin composite and porcelain. This approach offers an effective repair protocol that maximizes adhesion, durability, and clinical performance of ceramic restorations.