Effect of the Combined Use of Adhesive Systems and Oxalate-based and Fluoride-based Dentin Desensitizers on Bond Strength

Abstract

Introduction: The association of adhesive systems and desensitising agents could influence the values of the bond strength. That is because these desensitising agents cause the obliteration of the tubular holes and minimise the movement of the dentin fluids, promoted by environmental stimulus that tends to cause hydrolysis at the base of the hybrid layer over time. Aim: To evaluate the microtensile bond strength of total-etch (Single Bond II, SB, 3M ESPE, USA) and self-etch (Clearfil SE Bond, SE, Kuraray, Japan) adhesive systems in dentin conditioned after the application of oxalate-based and fluoride-based desensitising agents. Materials and Methods: Discs obtained from human molars were used, which had its occlusal enamel removed to expose flat surfaces of dentin. Six groups were formed, according to the materials used: G1 (control)- hybridization with SB; G2- desensitizer based on oxalate (BisBlock, BB) and SB; G3- desensitizer based on fluoride (Aqua Prep F, AF) and SB; G4 (control)- hybridization with SE; G5- BB and SE; G6- AF and SE. On these surfaces, blocks of composite resin Filtek Z350 of 5 mm high were prepared to obtain sticks of (1x1x10 mm). The samples were stored in deionized water at 37 degrees C for 24h and submitted to microtensile mechanical trial at 1mm/min speed till the fracture. The results were statistically analysed by one-way ANOVA followed by Tukey's post hoc test (p<0.05). Results: The mean values of bond strength of the studied groups in MPa (SD) were as follows: G2: 46.48 (4.02), G3: 44.87 (4.68), G5: 39.02 (4.72), G4: 36.95 (3.57), G1: 36.66 (3.42), G6: 32.71 (3.41) which did not show statistically significant differences (p>0.05). Regarding the fractures analysis, the mixed type prevailed. The fracture was on the base region of the hybrid layer for the total-etch adhesive system, and at the top of the hybrid layer for the self-etch system. Conclusion: There is no significant difference in bond strength between the combined use of desensitizers with total-etch and self-etch adhesive systems on human dentine.