EFFECT OF LASER THERAPY ON ROOT REABORTIONS DURING ORTHODONTIC FORCE RELOADING

• Grant number: 25/01756-9
• Support Opportunities: Regular Research Grants
• Start date: September 01, 2025
• End date: August 31, 2027
• Field of knowledge: Health Sciences - Dentistry - Orthodontics
• Principal Investigator: Milton Santamaria Júnior
• Grantee: Milton Santamaria Júnior
• Host Institution: Instituto de Ciência e Tecnologia (ICT). Universidade Estadual Paulista (UNESP). Campus de São José dos Campos. São José dos Campos , SP, Brazil
• Associated researchers: Bruno Calsa

Abstract

Orthodontic movement occurs through a series of biochemical and molecular processes with alterations at cellular and tissue levels. Tooth movement within the alveolus occurs through bone remodeling mechanisms. Constant force activations - reloads - are important for movement, until the desired final position is reached. When the application of forces exceeds the capacity of the periodontal tissues to adapt to them, i.e. is excessive, undesirable damage can be caused to the surrounding bone tissue, as well as to the dental structures, the main one being inflammatory root resorption of orthodontic origin. Low-intensity lasers have been used to reduce the inflammatory process in various tissues. The aim of this study was to evaluate the effect of low-intensity laser during orthodontic force recharging on root resorption. The experimental protocol consisted of moving the left maxillary first molars of 40 Wistar rats, divided into four groups (n=10): Control Group (CG): Orthodontic movement for 21 days; Laser Therapy Group (GL): Orthodontic movement for 21 days and laser therapy every 48hrs; Orthodontic Recharge Group (GR): Orthodontic movement for 21 days, with reactivation of the device on the 10th day; and Orthodontic Recharge and Laser Therapy Group (GRL): Orthodontic movement for 21 days, with reactivation of the device on the 10th day and laser therapy every 48hrs. For the present project (protocol no. 10/2024), the samples of slides, microCT images and samples of bone and dental tissue already collected, referring to protocol no. 03/2022, approved by the Ethics Committee on the use of animals ICT- UNESP-SJC, will be used. Histomorphometric analyses will be carried out to quantify the hyaline area and root resorption (µm2); microCT analysis of tooth movement and bone tissue microstructure; quantification of collagen fibers in the periodontal ligament using second harmonic generation (SHG) microscopy; and transcript levels of the Ctsk, Nfkb, Il-1b, Il-6, Tnfa, Rankl and Dspp genes in alveolar bone and dental tissue. The results will be submitted to statistical analysis with a 5% significance level. This will allow us to assess potential periodontal changes and the presence of root resorption in tooth movement during orthodontic reloading in low-intensity laser therapy. (AU)