Tooth eruption: the regulation of a localized, bilaterally symmetrical metabolic event in alveolar bone.

Tooth eruption is a complicated process by which developing teeth are moved within the jaws to their functional position. The usual model chosen to study this process, the erupted rodent incisor, differs both structurally and functionally from the human dentition and conclusions drawn from these studies are not directly applicable to tooth eruption in human beings. We have studied the eruption of developing permanent premolars in dogs and present evidence by scanning electron microscopy for regional differences in metabolic activities on bone surfaces of the crypt during eruption. We review evidence that these polarization of alveolar bone metabolism are cell-mediated, dependent upon the dental follicle, independent of root formation or the tooth itself and that tooth eruption depends on coordination of these activities by the dental follicle. We conclude that tooth eruption is a localized, bilaterally symmetrical event in alveolar bone and that this is an excellent model system in which to study the regulation of alveolar bone metabolism.