[Alveolar bone remodelling following orthodontic tooth movement in aged rats. An animal experimental study].

Orthodontic tooth movement of upper first molars was performed in twelve aged (500 days old) rats. It was demonstrated by histomorphologic findings as well as by vital polychrome staining that the remodelling process of the periodontal tissues in the aged animals was qualitatively similar to that in younger ones. The first molar in all animals was tipped mesially, while its mesial root was intruded. According to the vital polychrome staining the bone formation rate at the mesio-apical bone surface of the mesial root was determined as 7-8 microns per day. After 14 days comprehensive root resorption in the pressure zone distal of the bifurcation was found.