Influence of Dentoalveolar Trauma and Orthodontic Forces on Dentin Pulp Complex: A Experimental Study in Rats

Abstract

Aims: The present study aims to analyze the amount of tooth movement and pulp conditions in teeth with dentoalveolar trauma history (extrusive luxation), when three types of orthodontic forces are applied. Study Design: Experimental research. Methodology: Wistar rats (n = 48) were divided into 8 groups (n = 6), having as variables the three different types of orthodontic forces: continuous (CF), interrupted continuous (ICF) and intermittent (IF), the presence or absence of trauma (PT or AT) and the presence or not orthodontic movement (WM or WOM). The groups were arranged as follows: ATCF, ATICF, ATIF, PTCF, PTICF, PTIF, PTWM and ATWOM (control group). Extrusive dislocation (ED) of the healthy upper right first molar was performed and after 15 days for periodontal reestablishment, the orthodontic springs were installed as devices to promote induced tooth movement and on the 14th day after the first activation, the amount of tooth movement was measured, and euthanasia of the animals was performed for mounting the histological slides and histomorphometric evaluation. The variables were performed using the parametric analysis of variance (ANOVA) with Tukey’s post-test and Kruskal-Wallis test with Dunn’s post-test, depending on the characteristic of each variable. Differences were considered statistically significant at the 5% level (p<0.05). The variables analyzed were divided into 4 major groups: cellularity pattern, dystrophic alterations, hemodynamic alterations and dentin alterations. The data obtained were statistically examined by an appropriate test according to the characteristics of each variable. Results: The results showed that there was a statistically significant difference in tooth movement for CF and ICF forces compared with IF (p <0.05). There was a lower amount of inflammatory infiltrate in the control group compared with others. The CF showed a higher resorption area. Conclusion: Pulpal changes are more frequent in relation to hemodynamic alterations, followed by dentin alterations, cellularity alterations, and lastly, dystrophic alterations, but without difference among the groups.