[Studies on factors causing tooth resorption. 1. Role of prostaglandins as a chemical mediator on resorption of deciduous teeth in rabbits].

The aim of this study was to investigate the effects in the administration of indomethacin which is a specific inhibitor of prostaglandins (PGs) in order to understand the role of PGs in physiologic root resorption. For this study, 24 young rabbits aged 7 days which had been in utero for 31-32 days were used. The experimental group (N = 12) was injected with 5.0 mg/kg indomethacin every 12 h, and the control group (N = 12) was injected with normal saline solution every 12 h. 4 animals of each group were sacrificed at the 9th, 11th and 13th day, respectively. Their maxillary deciduous incisors embedded in paraffin were sectioned serially 7 mus in thickness. From each sample was counted the number of odontoclasts appearing on the root surface and measured the volume of the root in the maxillary deciduous incisor. The results were as follows: 1. The appearance of odontoclasts increased in a day-related manner from 9 days to 13 days on the resorption of maxillary deciduous teeth in the control and experimental rabbits. 2. The number of odontoclasts was significantly decreased by the administration of indomethacin (9 days P less than 0.05, 11 and 13 days P less than 0.01). 3. The amount of the root resorption was significantly inhibited by the administration of indomethacin at 9 days which was the initial stage of root resorption in the maxillary deciduous incisors, and then the effect of inhibition rapidly disappeared. These results strongly suggest that PGs can possibly act as a chemical mediator of odontoclastic root resorption occurred during tooth exchange.