EFFECT OF LASER THERAPY ON ROOT REABORTIONS DURING ORTHODONTIC FORCE RELOADING - Stage I: Computed Microtomography and Histomorphometric Analysis

• Grant number: 25/19410-1
• Support Opportunities: Scholarships in Brazil - Master
• Start date: October 01, 2025
• End date: September 30, 2026
• Field of knowledge: Health Sciences - Dentistry - Orthodontics
• Principal Investigator: Milton Santamaria Júnior
• Grantee: Rebeka Bahia Rodrigues
• 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 research grant: 25/01756-9 - EFFECT OF LASER THERAPY ON ROOT REABORTIONS DURING ORTHODONTIC FORCE RELOADING, AP.R

Abstract

The objective of the first stage is microcomputed tomography (MicroCT) analysis, reconstruction of these, and analysis of bone microstructure, tooth movement, and root resorption in the distopalatine root area. In the second stage, we will analyze the histological slides, perform histomorphometry in the compression side region, where root resorption will be studied, and quantify the hyaline area in the periodontal ligament.In the first stage, after euthanasia, the maxillae were dissected and impregnated in 10% formalin for storage. The maxillae will be analyzed using microcomputed tomography (MicroCT) from the obtained sections and 3D image reconstruction. For bone microarchitecture analysis, the focus will be on the root bifurcation area of ¿¿the maxillary first molar. The longitudinal sections will assess bone percentage (BV/TV), total porosity, trabecular thickness (Tb.Th), trabecular number (Tb.N), and trabecular separation (Tb.Sp). To assess tooth movement, we will use a longitudinal section and measure the distance between the two closest reference points (a, b) identified on the crowns of the moved first molar (M1) and second molar (M2). Additionally, the shortest distance from the alveolar bone crest to the cementoenamel junction (CEJ) will be measured to analyze tooth inclination.To quantify root resorption, resorption lacunae will be analyzed in cross-sections every 50 slices along the root length, below the CEJ to the apical region. The number of resorption lacunae, the demineralization zone, the volume of each lacuna (in micrometers), and the percentage of resorbed tooth root relative to the original volume will be determined.In the second stage, after the microCT was completed, the same material was processed to prepare histological slides, allowing training in the use of the optical microscope and image acquisition. Analysis of the distopalatine root will be performed in cross-sections with a final magnification of 100x. The root area and the area of ¿¿tooth resorption (¿m²) will be determined; the division between the areas will determine the percentage (%) of root resorption. Similarly, the area of ¿¿the periodontal ligament and the hyaline area (¿m²) will be determined; the division between the areas will determine the percentage (%) of periodontal ligament hyalinization.