Microleakage in Class II Composite Restorations Bonded with Self-Etch, One-Step, One-Component Adhesive System: A CLSM Study

Objectives: The purpose of this study was to compare the effect of self-etch, one-step, one-component adhesive system to etch and rinse adhesive system on the microleakage of class II restorations located in dentin using confocal laser scanning microscope. Materials and Methods: 52 upper permanent premolar teeth were used and two class II cavities (3x1.5 mm) with gingival margins ended 1mm below CEJ were prepared and filled in each tooth. Two adhesive systems: self-etch, one-step, one-component adhesive system (G Bond, GC, Japan), etch and rinse adhesive system (Adper Single Bond 2, 3M ESPE, USA) and two composite materials: nanocomposite (Filtek Z350, 3M ESPE, USA), microhybrid composite (Filtek Z250, 3M ESPE, USA) were used and applied in this study according to the manufacturer's instructions. The 104 cavities were divided randomly into four groups (n = 26). Half of the groups were restored with Filtek Z350 (3M ESPE, USA) and the other half with Filtek Z250 (3M ESPE, USA). Furthermore, half of the groups were bonded with G Bond (GC, Japan) and the other half with Adper Single Bond 2 (3M ESPE, USA). The specimens were thermocycled between 5° to 55℃ with 30 second dwell time for 500 cycles. The samples were then immersed in 0.5% Rhodamine B dye for 10 hours and sectioned longitudinally. Dye penetration at the gingival margin was quantified in millimeters under confocal laser scanning microscopy (CLSM) at 10x magnification. Data were analyzed using Two-way ANOVA and results with P < 0.05 were considered statistically significant. Results: No significant difference (P > 0.05) in dye penetration was discovered between self-etch, one-step, one-component adhesive system (G Bond) and etch and rinse adhesive system (Adper Single Bond 2). Conclusion: Self-etch, one-step, one-component adhesive system shown efficacy in reducing class II gingival microleakage at least as good as those of etch and rinse adhesive systems.