Evaluation of microtensile bond strength and failure type analysis of two different types of universal dental adhesives. In vitro study

Background The aim of this research was to assess the microtensile bond strength of the recently released Beautibond Xtreme and investigate its impact on the hybrid layer compared to the Single Bond Universal. Methods Sixteen extracted teeth were collected and divided into 2 groups ( n = 8 ) according to the type of adhesive used, Single Bond Universal (3 M ESPE) and Beautibond Xtreme (Shofu). All teeth’s apical portions were embedded using auto-polymerizing acrylic resin (Imicryl, Konya, Turkey) in a silicone mold till the level of the cemento-enamel junction. The occlusal surfaces were flattened to the level of medium coronal dentin, leaving a residual thickness of about 2.5 mm. The two bonding agents were applied according to the manufacturer’s instructions. Following that, Shofu’s Beautifil II composite was used; each increment was 2 mm high. In order to create serial resin-dentin beams with an approximate area of 1 mm², the teeth were cut perpendicular to the bonding interface with water cooling. The microtensile bond strength test was done by a universal testing machine (5566 S, Instron, Canton, MA, USA) with a load applied at a crosshead speed of 0.5 mm/minute. The specimens were then examined using a scanning electron microscope (SEM) (QUANTA FEG250 Thermo Fisher Scientific, USA). Finally, the failure mode was determined. µTBS data was examined for normality using the Shapiro-Wilk and Kolmogorov-Smirnov tests. The statistical power of the study was set at 80%, statistical significance was set at P ≤ 0.05 with a 95% confidence level, and all tests were two-tailed. Results For the microtensile bond strength test, intergroup comparison revealed a statistically significant difference between 3 M and SHOFU ( P = 0.0121), while for the failure mode, there was no statistically significant difference between both groups in failure mode ( P = 0.2851). Conclusion Within the limitations of this study, 3 M showed higher µTBS than Beautibond Extreme. with no statistically significant difference observed in the overall failure mode following microtensile bond strength testing.