title: Analysis of dynamic smile and upper lip curvature in young Chinese.
abstract: During smile evaluation and anterior esthetic construction, the anatomic and racial variations should be considered in order to achieve better matching results. The aims of this study were to validate an objective method for recording spontaneous smile process and to categorize the smile and upper lip curvature of Chinese Han-nationality youth. One hundred and eighty-eight Chinese Han-nationality youths (88 males and 100 females) ranged from 20 to 35 years of age were selected. Spontaneous smiles were elicited by watching comical movies and the dynamics of the spontaneous smile were captured continuously with a digital video camera. All subjects' smiles were categorized into three types: commissure, cuspid and gummy smile based on video editing software and final images. Subjects' upper lip curvatures were also measured and divided into three groups: upward, straight and downward. Reliability analysis was conducted to obtain intra-rater reliabilities on twice measurements. The Pearson Chi-square test was used to compare differences for each parameters (α=0.05). In smile classification, 60.6% commissure smile, 33.5% cuspid smile and 5.9% gummy smile were obtained. In upper lip measurement, 26.1% upward, 39.9% straight and 34.0% downward upper lip curvature were determined. The commissure smile group showed statistically significant higher percentage of straight (46.5%) and upward (40.4%) in upper lip curvatures (P<0.05), while cuspid smile group (65.1%) and gummy smile group (72.7%) showed statistically significant higher frequency in downward upper lip curvature (P<0.05). It is evident that differences in upper lip curvature and smile classification exist based on race, when comparing Chinese subjects with those of Caucasian descent, and gender.
authors.affiliation: Department of Periodontology, Peking University School & Hospital of Stomatology, Beijing, China.
authors.forename: Ling-Zhi
authors.initials: LZ
authors.lastname: Liang
authors.forename: Wen-Jie
authors.initials: WJ
authors.lastname: Hu
authors.forename: Yan-Ling
authors.initials: YL
authors.lastname: Zhang
authors.forename: Kwok-Hung
authors.initials: KH
authors.lastname: Chung
mesh_terms: D000328:Adult; D002508:Cephalometry / Q000379:methods; D002681:China / Q000208:ethnology; D003481:Cuspid / Q000033:anatomy & histology; D005006:Ethnicity; D005260:Female; D005881:Gingiva / Q000033:anatomy & histology; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008046:Lip / Q000033:anatomy & histology*; D008297:Male; D012904:Smiling; D014741:Video Recording / Q000379:methods; D055815:Young Adult
references.citation: Am J Orthod Dentofacial Orthop. 2007 Mar;131(3):301.e1-8
references.pmid: 17346578
references.citation: Am J Orthod Dentofacial Orthop. 2003 Jul;124(1):4-12
references.pmid: 12867893
references.citation: Orthod Craniofac Res. 2007 Feb;10(1):15-21
references.pmid: 17284243
references.citation: Am J Orthod Dentofacial Orthop. 2009 Sep;136(3):310.e1-10; discussion 310-1
references.pmid: 19732654
references.citation: Acta Odontol Scand. 2008 Aug;66(4):207-13
references.pmid: 18622829
references.citation: Br J Plast Surg. 2005 Mar;58(2):183-95
references.pmid: 15710113
references.citation: Am J Orthod. 1970 Feb;57(2):132-44
references.pmid: 5263359
references.citation: J Plast Reconstr Aesthet Surg. 2010 Jan;63(1):65-72
references.pmid: 19097956
references.citation: Am J Orthod Dentofacial Orthop. 1992 Jun;101(6):519-24
references.pmid: 1598892
references.citation: Angle Orthod. 1992 Summer;62(2):91-100; discussion 101-2
references.pmid: 1626754
references.citation: Am J Orthod. 1977 Oct;72(4):359-72
references.pmid: 269665
references.citation: Plast Reconstr Surg. 2005 Mar;115(3):696-704
references.pmid: 15731666
references.citation: J Prosthet Dent. 1984 Jan;51(1):24-8
references.pmid: 6583388
references.citation: Cleft Palate Craniofac J. 2000 Jan;37(1):48-54
references.pmid: 10670889
references.citation: J Prosthet Dent. 1992 Nov;68(5):839-50
references.pmid: 1432812
references.citation: Clin Oral Implants Res. 2004 Oct;15(5):616-24
references.pmid: 15355405
references.citation: Semin Orthod. 1995 Jun;1(2):105-26
references.pmid: 8935049
references.citation: Aesthetic Plast Surg. 1997 Jul-Aug;21(4):265-9
references.pmid: 9263550
references.citation: Int J Prosthodont. 1999 Jan-Feb;12(1):9-19
references.pmid: 10196823
references.citation: Ann Plast Surg. 2005 Apr;54(4):379-83
references.pmid: 15785276
references.citation: Int J Prosthodont. 2002 May-Jun;15(3):283-8
references.pmid: 12066492
references.citation: Angle Orthod. 2006 Jul;76(4):557-63
references.pmid: 16808559
references.citation: J Prosthet Dent. 1978 Feb;39(2):128-34
references.pmid: 271728
references.citation: Int J Prosthodont. 2011 Jan-Feb;24(1):64-70
references.pmid: 21210007
references.citation: Angle Orthod. 1980 Oct;50(4):301-11
references.pmid: 6935981
references.citation: Int J Prosthodont. 2002 May-Jun;15(3):273-82
references.pmid: 12066491
references.citation: Am J Orthod Dentofacial Orthop. 2005 Feb;127(2):208-13; quiz 261
references.pmid: 15750540
references.citation: Plast Reconstr Surg. 1974 Apr;53(4):384-7
references.pmid: 4815693
references.citation: Biometrics. 1977 Mar;33(1):159-74
references.pmid: 843571
references.citation: J Prosthet Dent. 1992 Apr;67(4):502-8
references.pmid: 1507134