BIOMETRIC-ANALYSIS OF TOOTH MIGRATION AFTER APPROXIMAL CONTACT REMOVAL IN THE RAT

Nineteen 8-week-old female Sprague-Dawley rats were used to observe ma croscopically the direction of tooth movements following removal of ap proximal contacts. In 10 rats, under anaesthesia, approximal contact b etween the second and third right maxillary molars (M2-M3) was removed by grinding. These animals and a control group of nine rats were hous ed with normal diet and water nd libitum for 7 weeks. After killing, t he skulls of all animals wre removed, dried, and fixed in a standardiz ed position on a Horsley-Clarke type stereotaxic frame. Using a microm anipulator graduated to 1/100 mm and mobile in three orthogonal direct ions, distances between the teeth (M1 or M3) and some bone structures that served as landmarks were measured. These measurements showed the direction of tooth movements in the experimental approximal space. Aft er statistical analysis of the data, the results showed that the appro ximal space between M2 and M3 was closed by both a distal drift of M1- M2 and a mesial migration of M3. It was concluded that, in the rat, a mesial drift exists that can be induced by the loss of approximal cont act. This movement is distinct from the distal physiological dental mi gration classically described in histological studies.