Evaluation of the accuracy of a modified microtensile test using micro-specimens

Abstract Purpose to evaluate the accuracy of a modified method of microtensile test (μTBS) through the performing of micro specimens (cross section 0.09 mm2) and to evaluate the interfacial integrity by confocal laser microscopy (CLSM). Material and methods two bond agents, Clearfil SE Bond and Scotchbond Multipurpose Plus were applied to flat dentin substrate of 32 human premolars and composite crowns were built up with Charisma Opal. The restored teeth were sectioned to produce beam-shaped specimens by diamond saw. For display in CLSM, 0.16 mg/ml of Rhodamine B was incorporated into adhesives thus forming two groups for each adhesive (n = 8) groups of teeth restored with adhesives stained and unstained. The presence of microporosities was recorded in CLSM before testing μTBS. The failure patterns were analyzed using SEM. Data of bond strength was submitted to two-way ANOVA. Results the results showed bond strength data with low rate of premature failure, high percentage of failures at the actual interface (90%) and low coefficient of variation. No significant difference were observed between the specimens mean values of stained and unstained adhesives (p > 0.05). The CLSM revealed detailed information of the adhesive interface, showing low percentage of microporosities for both bonding agents. Conclusion based on the results of different test parameters it can be inferred that the modified microtensile test performed with micro specimens, shown reliable and could be considered a valid method.