Microtensile and shear bond-strength methods - a comparative analysis

Objectives: Recently, Microtensile Bond Strength (uTBS)testing has become increasingly popular. In addition, there is significant amount of Shear Bond Strength (SBS)data currently available. The purpose of this study is to determine the correlation between SBS and uTBS test results with respect to trends and ranking. Specifically, establishment of a definitive relationship will enable researchers to correlate SBS and uTBS data. In this study, the dentin bond strength of several adhesives under shear and tensile conditions was determined. The bond strength results of each adhesive test were compared to determine significant differences. In addition, the results for each technique were compared using a linear regression analysis. Methods: Using extrated human teeth, Microtensile and Shear testing were performed using an Instron Testing Machine with 1mm/min crosshead speed. The data were analyzed by ANOVA, and Fisher's PLSD test. The Shear data was plotted against the Microtensile results and linear regression analysis was conducted to determine the correlation. Results: The overall values of testing and standard deviations for R-0971 (Dentsply), Clearfil SE (Kuraray), Brush&Bond (Parkell), Adper Prompt L-Pop (3MESPE), I-Bond (Kulzer) , were respectively: 45.1a ± 13.0, 44.4ab ± 9.9, 34.0bc ± 10.8, 29.3cd ± 13.4, 21.1d ± 7.9 for Microtensile; and were 27.4ab ± 4.4, 29.2a ± 4.0, 25.4ab ± 3.3, 8.4c ± 2.4, 9.1c ± 2.2 for Shear. Same superscript letters indicate p<0.05. The linear regression analysis indicates an 80% correlation between shear and microtensile bond strength values. Conclusions: The results of this study indicate that SBS and uTBS tests were able to detect similar statistically significant differences among the adhesives tested, despite the obvious differences in the absolute numbers generated using each test. Microtensile was capable of detecting smaller differences between adhesives. Overall the data exhibited a good correlation between shear and microtensile bond strength values. Supported by Dentsply.