Adhesion to Eroded/Abraded Enamel Using Two Etch-and-rinse Bonding Systems

Objective: This study aimed to assess the influence of two etch-and-rinse bonding systems on bond strength to enamel after regular cola-erosion associated or not with toothbrushing-abrasion challenges. Methods: Forty eight bovine enamel specimens (4x4mm²) were randomly assigned according to the erosive/abrasive challenges (n=16): AS- artificial saliva (control); RC- 5 minutes immersion in regular cola, 3x day during 5 days, and RC+T= RC + subsequent toothbrushing for 1 minute after each erosive cycle. Between the erosive and abrasive challenges and overnight, the specimens were immersed in artificial saliva. Following, all the specimens were washed. The specimens were bonded with Scothbondmulti-purpose (3-step conventional system-MP) or with Single Bond 2 (2-step conventional system-SB) and then, the resin build up with Filtek Z350. Specimens of approximately 1mm² were obtained from each block to be tested under microtensile bond strength (load 50N at 0.5mm/min). Data were statistically analyzed by two-way ANOVA and Bonferroni tests with á preset at 0.05. Results: Bond strength means (MPa) and standard deviations for SA, RC and RC+T were: MP= 19.09(5.41)/17.41(5.78)/15.02(3.55) and SB= 23.92(3.68)/17.98(5.63)/18.57(0.97). Dentin bonding system and challenge were both statistically significant factors; however no interaction between them was detected. For MP, no differences were found between the erosive/abrasive challenges and the control. For SB, differences on bond strength between SA and RC were significant. Conclusion: Bond strength to erosive/abraded enamel is material-dependent. The erosive challenge did not affect the bond strength when Scothbondmultipurpose was used; however, it had a negative effect in the case of Single Bond.