Evaluation of microtensile and tensile bond strength tests determining effects of erbium, chromium: yttrium‑scandium‑gallium‑garnet laser pulse frequency on resin‑enamel bonding

Abstract

Objectives: The aim of the present study was to compare two different bond strength test methods (tensile and microtensile) in investing the influence of erbium, chromium: yttrium‑scandium‑gallium‑garnet (Er, Cr: YSGG) laser pulse frequency on resin‑enamel bonding.

Materials and Methods: One‑hundred and twenty‑five bovine incisors were used in the present study. Two test methods were used: Tensile bond strength (TBS; n = 20) and micro‑TBS (μTBS; n = 5). Those two groups were further split into three subgroups according to Er, Cr: YSGG laser frequency (20, 35, and 50 Hz). Following adhesive procedures, microhybrid composite was placed in a custom‑made bonding jig for TBS testing and incrementally for μTBS testing. TBS and μTBS tests were carried out using a universal testing machine and a microtensile tester, respectively.

Results: Analysis of TBS results showed that means were not significantly different. For μTBS, the Laser‑50 Hz group showed the highest bond strength (P < 0.05), and increasing frequency significantly increased bond strength (P < 0.05). Comparing the two tests, the μTBS results showed higher means and lower standard deviations.

Conclusion: It was demonstrated that increasing μTBS pulse frequency significantly improved immediate bond strength while TBS showed no significant effect. It can, therefore, be concluded that test method may play a significant role in determining optimum laser parameters for resin bonding.

Keywords: Bond strength, chromium: yttrium‑scandium‑gallium‑garnet laser, erbium, micro‑tensile, pulse frequency, tensile