Research progress in studies on tooth development based on diphyodont mammals

Abstract

For decades, the molecular and cellular mechanisms that govern tooth development have been extensively investigated. However, most of the studies are based on mice, whose teeth are quite different from human teeth in morphological and developmental aspects. Mice are not the ideal model for understanding the development of permanent teeth as they have only one set of dentition. Thus, using of diphyodont mammals is a better model to study the deciduous and permanent tooth development and to understand the process of tooth replacement. Several diphyodont mammal models have been established including minipig, ferret, house shrew and rabbit. Studies based on the diphyodont mammals have characterized the morphological changes involved in tooth replacement and molecular mechanisms of tooth replacement. However, few developmental stages were studied on ferret due to the presence of seasonal estrus and the difficulty to obtain ferret embryos at the correct stage. The house shrew is limited as a model because their deciduous tooth germs become vestigial in the embryonic period. The main disadvantage of the rabbit is an incomplete dentition with the lack of canines. Compared to the above mentioned animal models, the miniature pig has proven to be a valuable animal model for diphyodont development due to its dentition similarities, including the morphology, number and size of teeth, to human's, and particularly its heterodont dentition consisting of incisors, canines, premolars and molars. The present article reviews the current knowledge on the development of the primary and successional teeth in minipig modle and briefly summarizes the studies based on other diphyodont mammal models.