Induced Orthodontic Movement In Obese Rats: A Preliminary Histoenzymological Study

Objectives: The aim of this study was to evaluate induced tooth movement (ITM) in obese Wistar rats using tartrate-resistant acid phosphatase (TRAP) histoenzymologic analysis.
Methods: Twenty-four hemi-maxillas from twelve rats were analyzed. The animals of approximately 125g were randomly assigned into 4 groups: Group I – rats with one hemi-maxilla submitted to ITM for 7 days; Group II – obesity-induced rats and with one hemi-maxilla submitted to ITM for 7 days; Group III – rats with one hemi-maxilla submitted to ITM for 14 days; Group IV – obesity-induced rats with one hemi-maxilla submitted to ITM for 14 days. The contralateral hemi-maxilla of each rat was used as a control. Obesity was induced by suppling a high-fat diet (HFD) for eight weeks. Increase in weight was tested weighing the animals weekly. The ITM was performed according to the group distribution following a standardized protocol: mesial movement of the left maxillary first molar using a nickel titanium closed coil spring and a 0.20 mm orthodontic ligature attached to the incisors (anchorage teeth). After ITM the animals were euthanized. The hemi-maxillas were submitted to chemical and biological processing for histoenzymological examination aiming the analysis of positive osteoclasts on radicular and peri-radicular regions in sections stained with TRAP under conventional microscopy.
Results: Even though that after 7 and 14 days, the hemi-maxillas with ITM compared with the control groups presented moderate to severe increased tartrate-resistant acid phosphatase positive osteoclast activity, no difference could be observed between obese and normal weight rats. At 14 days of ITM, a reparatory phase was observed with a reduced number of osteoclasts in both groups.
Conclusions: Different response was observed on hemi-maxillas submitted to ITM when compared to the control ones regardless of the presence of obesity on Wistar rats.