Changes in nasolabial angle related to maxillary incisor retraction.

Changes in the nasolabial angle of the soft-tissue profile were assessed quantitatively in a serial cephalometric study of fifty treated subjects and forty-three untreated subjects, all of whom had Class II, Division 1 malocclusions. Correlations, simple and multiple regression analyses, and multifactorial analysis of variance were used to examine the changes in the nasolabial angle owing to incisor superius retraction and associated skeletal displacements. There were no significant changes in nasolabial angle because of growth. However, the greater the maxillary incisor retraction, the greater was the increase in nasolabial angle. Increase in the nasolabial angle showed a significant correlation with treatment-related increase in the vertical dimension of the lower face. The soft-tissue profile followed closely the underlying skeletal framework. Extraction and nonextraction treatment procedures did not show significant differences in the changes of the nasolabial angle. Results permit prediction of the changes in nasolabial angle owing to incisor superius retraction in orthodontic treatment.