Effect of cigarette smoke inhalation on the rate of orthodontic dental injury

• Grant number: 24/00889-2
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date until: April 01, 2024
• End date until: March 31, 2025
• Field of knowledge: Health Sciences - Dentistry - Orthodontics
• Principal Investigator: Maria Bernadete Sasso Stuani
• Grantee: Gabriela de Moura Aguiar
• Host Institution: Faculdade de Odontologia de Ribeirão Preto (FORP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil

Abstract

Background: Currently, the habit of smoking is considered a global public health issue. It is known that the inhalation of cigarette smoke is capable of causing a series of alterations to systemic health, which impair the repair process of body tissues. There is still no scientific evidence that fully correlates this habit and its influences on orthodontic treatment, especially regarding changes in the alveolar bone microarchitecture during the process of tooth movement induced by orthodontic mechanics. Objective: this study aims to develop an "in vivo" evaluation of the effects of cigarette smoke inhalation on orthodontically induced tooth movement and the microarchitecture of the alveolar bone. Material and Methods: a total of 30 Wistar rats will be divided into 6 groups: negative control group (GCN - animals without induced tooth movement and without cigarette smoke), experimental group 1 (animals subjected to cigarette smoke for 30 days), experimental group 2 (animals with induced tooth movement for 7 days), experimental group 3 (animals with induced tooth movement for 14 days), experimental group 4 (animals subjected to cigarette smoke for 30 days before appliance assembly and with 7 days of induced tooth movement) and group 5 (animals subjected to cigarette smoke for 30 days before installing the device and with 14 days of induced tooth movement).The animals of each subgroup (n=5) will be sacrificed after 7 and 14 days of tooth movement. The acquisition of images of the anatomical parts of the jaws will be performed using the VTOMEX/m microtomograph, being analyzed in the CT-Analyser software. Changes caused by tooth displacement will be evaluated using superimposed three-dimensional micro-cT images, while the alveolar bone microarchitecture will be evaluated in terms of bone mineral content, bone volume, bone mineral density, tissue volume, total sample volume, thickness trabeculae, separation of trabeculae and number of trabeculae per millimeter of the sample. The presence of root resorption will be evaluated by detecting the presence of resorption gaps in mesial and distal buccal roots of the maxillary first molars, which volume will be duly calculated. The results will be grouped according to different study groups and experimental periods, and subsequently submitted to the Shapiro-Wilk and Levene tests. If normal and homogeneous distribution of the variables is verified, the ANOVA test will be applied, followed by Tukey's. Otherwise, the Kruskal-Wallis and Mann-Whitney non-parametric tests will be used, considering a significance level of 0.05.