Effect of Saliva Contamination and Decontamination on Bovine Enamel Bond Strength of Four Self-etching Adhesives

OBJECTIVE: This study evaluated the effect of saliva contamination on the bovine enamel microtensile bond strengths (microTBS) of four self-etching adhesives. MATERIALS AND METHODS: The labial enamel surfaces of extracted non-carious bovine incisors were serially wet ground. The enamel surfaces were not contaminated (Group A), contaminated with saliva before/after priming (Groups B/C) or they were water-sprayed after salivary contamination occurred before/after priming (Groups D/E). Four self-etching adhesives and the corresponding resin composites from the same manufacturer (Clearfil SE Bond + Clearfil AP-X, Kuraray Co; Xeno III + Ceram X, Densply; Frog + Ice, SDI; FL Bond H + Beautifil II, Shofu Inc) were applied onto the enamel surfaces. The microTBS tests were performed with a micro tester (BISCO, Inc). The enamel surface was analyzed with AFM (Atomic Force Microscopy) before/after salivary contamination occurred or after the saliva-contaminated enamel was water-sprayed. The data were analyzed using one-way ANOVA, factorial design ANOVA and post hoc Tukey's HSD multiple comparisons. RESULTS: Salivary contamination significantly reduced the microTBS of all the adhesives in the current study (p < 0.001). Thorough water-spraying could significantly restore the microTBS of saliva-contaminated enamel to some degree (p < 0.05) or fully restore it for Clearfil SE Bond, but it could not remove some proteins adsorbed on the enamel surface. CONCLUSION: Hydrophilic self-etching adhesives are negatively influenced by salivary contamination. Thorough water-spraying could significantly improve the microTBS of the saliva-contaminated enamel. Proper isolation should be performed before and during application of the adhesives and during placement of the resin composite.