Morphological and microtensile bond strength evaluation of three adhesive systems to caries-affected human dentine with chemomechanical caries removal

Objectives

To evaluate the influence of chemomechanical caries removal on bond strengths of three adhesive systems to caries-affected human dentine.

Methods

45 extracted human third molars with occlusal moderate caries were used. One half of each cavity was prepared with chemomechanical method and the other half with bur as the control. Three adhesive systems, Prime&Bond NT (Dentsply, Germany) without any previous conditioning, an etch-and-rinse adhesive (One-Step, Bisco, USA) and a self-etching adhesive (Adper Prompt-L-Pop, 3M ESPE, USA), were applied. The compomer or resin crowns were, then, built up. The prepared specimens were sectioned for scanning electron microscopy (SEM) examination and microtensile bond strength (MTBS) testing. Data were analysed using two-way ANOVA with subsequent application of Student-Newman-Keuls test at p < 0.05.

Results

Opened dentinal tubules and less smear layer were visible by SEM after chemomechanical caries removal, whilst an obvious smear layer covering the dentine surface with occluded tubules was exhibited after bur excavation. Resin tags were seen only in specimens with chemomechanical excavation when Prime&Bond NT system was applied. Statistical analysis of the values of MTBS failed to show significant difference between caries removal methods. However, the values of MTBS for One-Step system achieved with two caries removal methods were both significant higher than other adhesive systems.

Conclusions

Chemomechanical caries removal did not influence the bond strengths of the adhesive systems used in this study to caries-affected human dentine. Highest bond strength was achieved with application of etch-and-rinse adhesive system.