| Abstract: | When tetracycline antibiotics are administered either orally or by injection they bind at the forming mineral front of the dentine and become incorporated into teeth as a permanent label. In this study, oxytetracycline was used as a label in order to investigate the growth of root dentine in macaques. There are no good data available in the literature for daily rates of root dentine formation over a prolonged period of time in either humans or macaques. Records of ten doses of oxytetracycline administered orally at irregular intervals (but at the same time of day) over a period of 10 months to a young rhesus macaque monkey (Macaca mulatta) were used to calculate the rate of dentine formation in tooth roots. Rates of dentine formation in the first portion of third permanent molar root formation, and in the apical portion of permanent canine and premolar root formation, were consistently between 3 μm and 4 μm per day. There was no evidence in this study of a gradual decrease in daily dentine formation rate from the crown to the root, or along the length of a dentine tubule through the bulk of the dentine, as has been implied previously. With the exception of faster rates recorded in cusps or slower rates recorded at the very beginning or very end of primary dentine secretion in other studies, the results of the present study suggest a consistent rate of dentine formation in permanent macaque teeth. What data there are for human dentine formation rates suggests that it is likely this finding can be extended to human dentine as well. |
