This course provides an in-depth examination of biologic and clinical factors influencing treatment stability and long-term outcomes in orthodontics. Topics include the biology of tooth movement, mechanisms of root resorption, tooth eruption patterns, and the role of functional influences in the development and management of malocclusions and temporomandibular disorders (TMD). Through lectures, seminars, and case-based discussions, students will gain the knowledge and diagnostic skills necessary to evaluate TMD, understand force dynamics, and apply evidence-based principles to enhance treatment stability and retention.