Harris, AngelaWalton, Leeren2022-01-262024-11-112022-01-262024-11-112021https://hdl.handle.net/10566/19517Magister Chirurgiae Dentium - MChDThe stable position of the mandibular incisors, and the extent to which their spatial position may be changed in the sagittal plane, represents a key point in determining orthodontic treatment goals and objectives. According to the equilibrium theory, the mandibular incisors lie in a narrow zone of stability that is governed by pressure from the lips, cheek, tongue and periodontium. Proclining the mandibular incisors more than 2 mm leads to instability because of an increase in lip pressure. The magnitude of incisor proclination therefore determines aesthetics, stability and function.enClass II division 1Lower incisor positionPassive self-ligating systemPremolar extractionsLower incisor proclinationUniversity of Western Cape