INHIBITION OF TOOTH ERUPTION IN THE RAT BY A BISPHOSPHONATE

Studies of osteopetrotic rodents suggest that localized alveolar bone resorption must occur if the tooth is to erupt. To test this hypothesi s directly, we injected postnatal rats with pamidronate, a bisphosphon ate that reduces bone resorption by osteoclasts. The results of these experiments demonstrate that this bisphosphonate inhibits the time of tooth eruption of both rat molars and incisors. Pamidronate does not i nhibit the gene expression of the putative tooth eruption molecules, c olony-stimulating factor-1 and c-fas, both of which are expressed in t he dental follicle, the tissue that is required for eruption to occur. Pamidronate does increase the size of the osteoclasts, including an i ncrease in the number of nuclei, suggesting that the precursor mononuc lear cells can still fuse to form osteoclasts despite the reduced abil ity of the osteoclasts to resorb bone. Thus, we report the discovery o f an agent that inhibits tooth eruption and also show that tooth erupt ion requires alveolar bone resorption.