Supernumerary teeth in anthropoid primates and models of tooth development.

Supernumerary teeth are usually regarded as de-novo structures that result from abnormal development by the splitting of a tooth germ. The notions of abnormal and de novo appear to be applicable in only one instance, the morphological dental twin. All other types of supernumerary deciduous teeth can be explained by either a progress zone or an interstitial budding model of tooth differentiation. The development of extra structures as well as the loss of normally-present teeth can be explained by differences in potential within the context of normal development.