This document discusses tooth eruption patterns and calcification. It describes the pre-eruptive, eruptive, and post-eruptive phases of tooth development and eruption. The eruptive phase involves root formation, movement within the bone, penetration of the gums, and occlusal contact. Primary teeth typically erupt between ages 2-6 years, mixed dentition from 6-12 years, and permanent dentition after age 12. Theories on the mechanisms of eruption include root formation, bone remodeling directed by the dental follicle, and traction from the periodontal ligament. Compensatory movements after eruption accommodate jaw and tooth surface growth.