Orthodontic tooth movement in the prednisolone-treated rat

Adverse effects of corticosteroids on bone metabolism raise concerns as to whether steroid treatment may influence orthodontic movement. This study ex amined the effect of prednisolone on orthodontic movement using an establis hed rat model. The corticosteroid treated group (N = 6) was administered pr ednisolone (1 mg/kg) daily, for a 12-day induction period; the control grou p (N = 6) received equivalent volumes of saline. On day 12, an orthodontic appliance was placed which exerted 30 g of mesial force to the maxillary fi rst molar. Animals were sacrificed on day 24 and tooth movement was measure d. Sagittal sections of the molars were stained with haematoxylin and eosin , and for tartrate-resistant acid phosphatase (TRAP) activity. While there were no significant differences in the magnitude of tooth movement between the 2 groups, steroid-treated rats displayed significantly less root resorp tion on the compression side and fewer TRAP-positive cells within the PDL s pace on the same side. This suggests steroid treatment suppressed elastic a ctivity.