The document discusses the phases of tooth eruption and theories of tooth eruption. It describes three phases of tooth eruption: 1) the preeruptive phase where the tooth germ moves within the jaw bone, 2) the eruptive or prefunctional phase where the root forms and the tooth emerges into the mouth, and 3) the functional or post-eruptive phase where the tooth reaches the bite and the roots continue to develop. Several theories for the mechanism of tooth eruption are mentioned, including the roles of vascularity, pressure changes, root formation, bone remodeling, the dental follicle, and the periodontal ligament.