Change in lip contour with maxillary incisor retraction.

Cephalometric analysis of the influence of hard tissue changes on lip contour in 41 cases showed the following effects. Patients with large palatal tilt angles showed larger changes in the nasolabial angle with incisor retraction. Nasolabial angle is increased with uprighting (lingual tipping) of the incisors. Horizontal movement of the incisor edge has an unpredictable relationship with change in the nasolabial angle. A ratio of 1:3.8 was found between lip retraction and incisor retraction.