During the last half of the 20^th century, tooth autotransplantation and dental implant procedures improved significantly. Using the foundations of experimental embryology, developmental and molecular biology, and the principles of biomimetics, tooth regeneration is becoming a realistic possibility. The development of teeth is regulated by inductive interactions between epithelial and mesenchymal cells, and is under genetic control. The number of teeth is usually strictly determined. Recently, rudimentary incisors were found to survive and erupt as supernumerary teeth as a result of USAG-1 abrogation. If we extrapolate our research findings to humans, they support the suggestion that a “third dentition” of one more sets of teeth can occur in addition to the permanent dentition. In this context, stimulation of the formation of a third dentition might be a novel approach in order to achieve biological tooth replacement. We present an overview of the collective knowledge of tooth developmental biology, especially regarding the control of the number of teeth in a mouse model.