Influence of indomethacin on bone turnover related to orthodontic tooth movement in miniature pigs.

The purpose was to evaluate the influence of a prostaglandin inhibitor, indomethacin, on the tissue reaction related to orthodontic tooth movement. Sixteen miniature pigs were chosen for the study, eight of which received indomethacin perorally every day of the 39-day observation period. Sentalloy expansion springs (GAC, Central Islip, N.Y.) delivering 100 cN were inserted on a segmented arch between the central lower incisors. Intravital labeling with tetracycline was used for the evaluation of the rate of bone formation. After the pigs were killed, the bone turnover was evaluated on undecalcified methacrylate embedded sections and on microradiographs. The histomorphometric analysis of bone turnover revealed that the relative extent of resorption surfaces was decreased significantly in the indomethacin treated animals. Formation surfaces were also decreased although not significantly. The bone turnover, but not the mineralization rate, was influenced. The results corroborate the recommendation that prostaglandin inhibitors should be avoided during orthodontic treatments.