Low-level laser therapy stimulates bone metabolism and inhibits root resorption during tooth movement in a rodent model

• Published in: Journal of biophotonics Vol. 9; no. 11-12; pp. 1222 - 1235
• Main Authors: Suzuki, Selly Sayuri, Garcez, Aguinaldo Silva, Suzuki, Hideo, Ervolino, Edilson, Moon, Won, Ribeiro, Martha Simões
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 01.12.2016; WILEY‐VCH Verlag; Wiley Subscription Services, Inc
• Subjects: Animals; bone remodeling; Bone Remodeling - radiation effects; Bones; Displacement; Lasers; Low-Level Light Therapy; Male; microCT; Molar; near infrared laser; OPG; Orthodontics; Osteoclasts - radiation effects; RANK Ligand - metabolism; RANKL; Rats; Remodeling; Rodents; root resorption; Root Resorption - prevention & control; Root Resorption - radiotherapy; Roots; Scanning electron microscopy; Teeth; Therapy; Tooth Movement Techniques; TRAP; near infrared laser; RANKL; root resorption; OPG; bone remodeling; microCT; TRAP
• ISSN: 1864-063X; 1864-0648
• DOI: 10.1002/jbio.201600016

This study evaluated the biological effects of low‐level laser therapy (LLLT) on bone remodeling, tooth displacement and root resorption, occurred during the orthodontic tooth movement. Upper first molars of a total of sixty‐eight male rats were subjected to orthodontic tooth movement and euthanized on days 3, 6, 9, 14 and 21 days and divided as negative control, control and LLLT group. Tooth displacement and histomorphometric analysis were performed in all animals; scanning electron microscopy analysis was done on days 3, 6 and 9, as well as the immunohistochemistry analysis of RANKL/OPG and TRAP markers. Volumetric changes in alveolar bone were analyzed using MicroCT images on days 14 and 21. LLLT influenced bone resorption by increasing the number of TRAP‐positive osteoclasts and the RANKL expression at the compression side. This resulted in less alveolar bone and hyalinization areas on days 6, 9 and 14. LLLT also induced less bone volume and density, facilitating significant acceleration of tooth movement and potential reduction in root resorption besides stimulating bone formation at the tension side by enhancing OPG expression, increasing trabecular thickness and bone volume on day 21. Taken together, our results indicate that LLLT can stimulate bone remodeling reducing root resorption in a rat model. LLLT improves tooth movement via bone formation and bone resorption in a rat model. Orthodontic tooth movement is a complex biological process that induces periodontal tissue reactions of the supporting structures in response to biomechanical forces, leading to bone remodeling. Since tooth movement is based on a localized inflammatory effect, this study hypothesizes that low‐level laser therapy can accelerate metabolic changes, influence the bone resorption and formation processes, and consequently result in a faster tooth movement with less damage to root surface.