[Influence of chin prominence on anterior-posterior lip positions of facial profile].
OBJECTIVE
To determine the influence of chin prominence on preferred lip position in profile.


METHODS
The average profile was constructed from the profile of a young Chinese man who has typical Chinese facial profile. Changes in chin position were established by altering the antero-posterior position by protruding or retruding the chin in increments of 5 degrees and 10 degrees from the average profile. The lips were then protruded or retruded in 1mm 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.SPSS13.0 software package was used to compare the differences in the scores between the top three most favored profiles and the other profiles.


RESULTS
Slightly retruded lip positions were preferred for the average profile.The scores in top three profiles were significantly larger than the other profiles(P<0.05);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
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.
Su
Ying-ying
YY
Department of Orthodontics,Shandong University, Jinan 250012, China. laodiaosyy@yahoo.com.cn
Wang
Chun-ling
CL
Liu
Dong-xu
DX
Dong
Ren-ping
RP
Li
Hong
H
D044466:Asian People; D002680:Chin / Q000033:anatomy & histology*; D004955:Esthetics, Dental; D005145:Face; D006801:Humans; D008046:Lip; D008297:Male; D008313:Malocclusion, Angle Class III