SCANNING ELECTRON MICROSCOPIC ANALYSIS OF THE BOND INTERFACE BETWEEN COMPOSITE AND PORCELAIN AFTER DIFFERENT SURFACE CONDITIONING TREATMENTS

Abstract

Background: Ceramic materials are widely used in fixed prosthodontics and esthetic restorations due to their durability, biocompatibility, and esthetic appeal. However, they are prone to chipping or fracture, often requiring repair. Intraoral composite resin repair is a conservative and cost-effective approach, but its success depends on strong adhesion achieved through micromechanical interlocking and chemical bonding, which can be enhanced by surface conditioning methods such as acid etching and silane application. This study evaluated the effects of different surface conditioning techniques on the bond interface between composite resin and porcelain using scanning electron microscopy (SEM). Methods: This cross-sectional in vitro study was conducted at BMU and BUET, Dhaka, from March 2024 to February 2025. Forty-eight porcelain discs (15 mm × 3 mm × 3 mm) were divided into three groups (n = 16): Group 1—no conditioning, Group 2—silane coupling agent, and Group 3—phosphoric acid etching plus silane. Composite resin was bonded to conditioned surfaces, stored in distilled water at 37°C for 24 hours, sectioned, polished, sputter-coated, and examined under SEM at ×1500 magnification. Bond line continuity, surface roughness, micromechanical interlocking, resin penetration, and overall bond quality were qualitatively analyzed. Results: SEM revealed clear differences among groups. Unconditioned samples showed a thin, irregular bond line with minimal micromechanical interlocking. Silane-treated samples exhibited improved chemical bonding and a more continuous interface, but limited mechanical retention. The combination of phosphoric acid and silane produced a roughened porcelain surface with intimate composite adaptation, well-defined micro-retentive features, and enhanced micromechanical and chemical bonding, yielding the highest bond quality. Conclusion: Phosphoric acid etching followed by silane application provides the strongest and most durable bond between porcelain and composite resin, making it the preferred method for intraoral repairs.