Effects of ۸۱۰nm Diode Laser Irradiation on Flexural Strength of Dentin: An Invitro Study

Abstract INTRODUCTION: Thermal changes in laser assisted root canal therapy with the use of diode laser can predispose tooth structure to the fracture. This study evaluated the changes in flexural strength of dentin blocks after diode laser irradiations (۸۱۰ nm).METHODS: A total of ۶۰ dentinal blocks were prepared from freshly extracted teeth in three different thicknesses (۳۰۰, ۵۰۰ and ۱۰۰۰μm) and ۲۰ sections in each of these thicknesses were divided randomly to the test and control groups. Samples in the test groups were irradiated at ۲W power setting by scanning movement of ۲mm/s of diode laser, and the controls were stored in normal saline. The flexural strength of samples was evaluated by UTM (Universal Testing Machine). Data analysis was done with the SPSS Software ۱۱.۵.RESULTS: Samples of ۳۰۰μ had the lowest flexural strength (mean: ۷۱/۶۵ mpa) followed by ۵۰۰ (۱۱۶.۶۴ mpa) and ۱۰۰۰μ (۲۱۷.۵۶ mpa). Statistical analyses showed that after laser irradiation, the flextural strength in the samples of ۳۰۰μ was significantly lower than that in the other groups (۵۰۰μ, ۱۰۰۰μ) (P= ۰.۰۱۷).CONCLUSION: Within the limits of this study, diode laser irradiation in laser assisted root canal therapy has no significant effect on flexural strength of root dentinal walls with the thickness of more than ۵۰۰μ. Although in areas with critical dentinal width (≤۳۰۰μ), this setting can jeopardize root micromechanical properties and predispose tooth to the root fracture. Keywords: diode laser strength dentin