Induced Orthodontic Movement in Obese Rats: A Microtomographic Analysis

Objectives: To evaluate induced mesial molar tooth movement (ITM) in obesity-induced Wistar rats using microtomographic analysis.
Methods: Twenty rats of approximately 125g were randomly assigned into 4 groups: Group I, non-obese rats submitted to ITM for 7 days; Group II, obesity-induced rats submitted to ITM for 7 days; Group III, non-obese rats submitted to ITM for 14 days; Group IV, obesity-induced rats submitted to ITM for 14 days. Obesity was induced by supplying a high-fat diet for eight weeks. ITM aimed the mesial movement of the left maxillary first molar using a nickel-titanium closed coil spring. Samples were scanned by a cone-beam micro-CT system Skyscan 1172 and BMP images were reconstructed by the NRecon software. Twenty-one linear, angular and volume measures assessing molar position and surrounding bone characteristics were performed using Data Viewer, Avizo and CT-Analyzer software.
Results: Different animal weights between groups were reported since week one (p=0.002 and p≤0.001). Obese animals showed higher rates of ITM after 7 days than non-obese animals (p=0.081). This difference became more evident after 14 days (p≤0.001). Bone surface density at the compression site showed reduced values in obese animals submitted to ITM of 7 (p=0.027) and 14 days (p=0.050). After 7 days of ITM, obese animals presented a reduced number of trabecula (p=0.002), increased trabecular separation (p≤0.001) and higher total porosity (p=0.027) at the compression site. However, after 14 days, trabecular number, trabecular separation, and porosity, and after 7 and 14 days, bone volume, percentage of bone volume, disto-buccal root volume and angular measurements were similar between obese and non-obese animals (p>0.05).
Conclusions: Obese animals showed different responses in molar position and morphological surrounding bone to induced tooth movement through a micro-CT analysis.