Effect Of Chin Position On Lip Positions Of Esthetic Chinese Facial Profile

Objective: The purpose of this study was to assess the most-favored or mostwell-balanced profile from a series of facial silhouettes with varying anteroposterior lip positions by a group of raters. And to determine the influence of chin prominence on preferred lip positions in profile by changing chin position.Methods: 1 .The first part is the assessment of anteroposterior lip positions of themost-favored Chinese profile. Average male and female profiles were constructed from the profiles of a young Chinese man and a woman who have typical Chinese facial profiles. The lips in each average profile were protruded or retruded in 1-mm increments, and 9 silhouettes were arranged with the average profile in the center. Eighty-six orthodontists and 90 adult patients were asked to select the 3 most-favored, well-balanced profiles for each sex.2.The second part is the effect of chin position on preferred lip positions in Chinese profile. The average profiles were constructed as the first part did. Changes in facial convexity were established by altering the antero-posterior chin position by protruding or retruding the chin in increments of 5°and 10°from the average profiles. The lips were then protruded or retruded in 1-mm increments from the average profile and 9 silhouettes were arranged respectively. One hundred and eighty college students were asked to rate the top three most favored, well-balanced profiles.3. SPSS13.0 software was used to compare the differences in the scores between the top three most favored profiles and the other profiles.Results: 1.The results of the first part were that both the orthodontists and the patients preferred a profile with slightly retruded lips. The straight male profile and a slightly straight female profile were the best. The preferences for facial profile esthetics were different between orthodontists and patients.2.The results of the second part were that slightly retruded lip positions were preferred for the average profile; The raters tended to prefer more retruded lip positions as the facial convexity decreased and more protruded lip positions as the facial convexity increased.Conclusions: 1. These findings suggest that Chinese orthodontists and patientsprefer a retruded profile. There is a difference between the most-favored male and female profile.2.Raters tended to prefer a more retruded lip position as the facial convexity decreased for both males and females.3.Raters tended to prefer a slightly more protruded lip position compared with chin protrusion cases as the facial convexity increased.4.The chin position does significantly impact preferred lip position and different esthetic standards should be applied to the various profiles encountered in clinical practice. The results might be helpful in decisions between extraction and nonextraction treatment in borderline cases.