Evaluation of Secondary Caries-free Restorations Bonded with Contemporary Adhesives

The mechanism of secondary caries has not been well clarified; therefore good resolution to prevent this wall-lesion has not been reported. Most failure in restored tooth and fixed partial dentures is still secondary caries. Leakage-free at the dentin-resin interface can be achieved when complete hybridization of resin into dentin is formed. The study hypothesis was that leakage-free restorations with impermeable barrier could resist lactic acid marginally leaked. Objective: To compare the dye penetration distance through leakage and normal tooth substrate of Class V restorations before and after artificial caries exposure. Methods: Class V cavities were prepared on axial surfaces of extracted human molars with occlusal margin in enamel, and cervical margin in cementum. All cavities were restored with resin composite using different resin adhesive systems: dry [Super-Bond C&B (Sup), Super-Bond D-Liner II Plus (SupP)], wet [All-Bond2 (All), Single-Bond2 (Sin)] and self-etch [AQ-Bond (AQ), Clearfil Protect Bond (Cle)]. Two subgroups of each treatment were immersed for 14 days at 37 °C either in artificial saliva or 0.1 mol lactic acid in buffer solution. After immersion in 0.5% basic fuschin dye for 24 h, the extent of dye penetration into enamel, cementum/dentin and tooth-resin interfaces were measured. Results: Leakage-free gingival margin was found in Groups: Sup, SupP and AQ for both before and after artificial caries exposure. The distance of dye penetration into adjacent tooth substrate was found significantly lower than leakage distance at tooth-resin interface of the other wet (All, Sin) and self-etch (Cle) groups. Conclusion: Lactic acid penetrated into leakage pathway and demineralized dentin further down to the pulp. Leakage-free interface with impermeable hybridized dentin can prevent wall lesion, thus long-lasting restorations without secondary caries formation is promising.