[Studies on factors causing tooth resorption. 2. Dose-response effects of indomethacin on resorption of deciduous...

The aim of the present study was to confirm whether prostaglandin (PGs) had any connection with physiological root resorption. 16 young rabbits aged 7 days which had been in utero for 32 days were used and were divided into 4 groups. The control group was injected with normal saline solution, and the experimental groups were injected with indomethacin, a specific inhibitor of PGs synthetase, in doses of 0.1 mg/kg, 1.0 mg/kg, 10.0 mg/kg every 12 hours for 5 days, respectively. All animals were sacricfied at 11 days postnatal. Their maxillary deciduous incisors were embedded in paraffin and sectioned serially in 7 mus thickness. The number of odontoclasts appearing on the root surface were counted, and the volume of the maxillary deciduous incisor was measured. The results were as follows: 1. The readings of the odontoclasts appearing in the control group was 260.3 +/- 60.1, and those of the experimental groups injected with 0.1 mg/kg, 1.0 mg/kg, 10.0 mg/kg indomethacin were 249.0 +/- 32.2, 199.5 +/- 15.1 (P less than 0.05 one sided test) and 163.8 +/- 40.0 (P less than 0.01), respectively. The number of odontoclasts was reduced linearly as the logarithmic dose of indomethacin increased. 2. As far as the volumes of the maxillary deciduous incisors were concerned, that of the group with 10.0 mg/kg was significantly greater than that of the group with 0.1 mg/kg (P less than 0.05). In comparison with the control and the experimental group, the volume of the 10.0 mg/kg group was greater than the others, but statistical differences were not found.