Desempenho de sistemas adesivos autocondicionantes com diferentes pH

Abstract

The hybridization of dental hard tissues may be accomplished by both approaches, the etch rinse or the self-etching. The self-etching approach provides fewer steps and less sensitivity in clinical technique. The objective of this study was to analyze the microtensile bond strength (μTBS) immediately and after aging with thermocycling of adhesive systems in one step and two steps, considering the control group treated with conventional adhesive system. The occlusal surface of 24 third molars was removed, and then the root was cut to obtain a 5 mm thick disc, with the average dentin surface. The surfaces were standardized and distributed randomly into four groups according to the adhesive system tested on: G1-Single Bond 2, G2- Clearfil SE Bond, G3- Adper Easy One e G4- Clearfil TriS. About the treated surfaces were fabricated composite resin blocks, Filtek Z350 XT, blade A2 body. The samples were selected to produce sticks with approximately 1mm2 cross sectional area. Each group was divided again into two, namely: samples stored in deionized water and aged for 24 hours (1000 cycles). The specimens were submitted to microtensile testing and the values obtained were statistically analyzed by two-way ANOVA and the Tukey multiple comparison test (p <0.05). The classification of types of fracture was performed by SEM. The highest values were presented by groups: G1, G5, and G2, G6, with no statistical difference between them. The lowest values were performed by groups G4 and G8 presenting statistical difference in the groups treated with the conventional adhesive. From the analysis of the fractures were observed that fracture reduction type I (between hybrid layer and adhesive layer) of the groups submitted to microtensile testing after 24 hours compared to their counterparts submitted to aging by termocycling. It can be concluded that the best performance in microtensile test was made by conventional and self adhesive two steps. No association was found between the bond strength after 24 of aging.