Profile changes associated with maxillary incisor retraction in the postadolescent orthodontic patient.

Maxillary incisor retraction and associated upper lip changes were studied in 30 male and 30 female postadolescent orthodontic patients to determine if a statistically significant correlation and ratio existed between maxillary incisor and lip retraction, dependent on thickness, strain, and length of the upper lip. This analysis attempted to eliminate the effects of growth and gender. Statistically significant correlations were found in both male and female patients who had thin, highly strained lips. Although a ratio for predictive purposes was determined for each of these groups, their absolute value is questionable because no apparent pattern exists between them. Furthermore, as lip thickness increased and lip strain decreased, correlation coefficients fell to nonsignificance, making it more difficult to predict upper lip change resulting from maxillary incisor retraction in these individuals.