Low-Level Laser Action on Orthodontically Induced Root Resorption: Histological and Histomorphometric Evaluation

Abstract Introduction: Studies have been conducted to develop a means of preventing, controlling or reducing orthodontically induced root resorption. Phototherapy has demonstrated effectiveness as an anti-inlammatory and, considering the inlammatory origin of this pathology, this study evaluated the effects of laser on root resorption.Methods: The research was conducted among ۵۴ ۸۰-day-old male Wistar rats, with weights of ۲۸۰ ± ۴۰ g. Phototherapy consisted of a diode laser (Ga-Al-As), calibrated with a wavelength of ۸۰۸ nm, an output power of ۱۰۰ mW, ۲.۱ J or ۹۶ J of energy and area of ۰.۰۰۲۸ cm۲. The application was continuous, punctual and with contact. The left irst maxillary molar was moved by a super-elastic closed spring with a pre-calibrated and constant force of ۲۵ g. The specimens were irradiated every ۴۸ hours, totaling three or six times, depending on the group to which they belonged. Euthanasia was made in the ۷th or ۱۰th day after the onset of movement. The histological and histomorphometric examination was performed with sections of ۶ μm stained with hematoxylin and eosin (H&E).Results: Considering the dosimetry studied, when compared the subgroups with the same time of movement, ۷ or ۱۰ days, the low-level laser (LLL) has no statistically signiicant effect on the root resorption. As expected, differences were found between groups with different time of movement.Conclusion: Based on the result, this dosimetry does not seem to be clinically recommended to avoid or reduce inlammatory root resorption, but it also does not induce any root surface alteration. Keywords: Resorption Root Laser Therapy Tooth Movement Phototherapy