[The importance of the center of resistance for the biology of tooth movement].

The tooth movement of loaded premolars was investigated in four two-years-old beagle dogs under general anesthesia. Two supragingival registrations were performed to calculate the center of rotation in order to estimate the amount of tipping. Loads of 5 to 20 N were applied for two to four seconds. The amount of tipping was found to be load- and time-dependent. The discrepancy between these findings and the models of analytical mechanics were explained by bone bending in our experiments. Biology and localization of periodontal remodelling is supposed to be dependent on load magnitude, load duration and physical properties of all periodontal tissues including bone.