title: Upper lip changes and gingival exposure on smiling: vertical dimension analysis.
abstract: BACKGROUND
  Our objectives were to evaluate and quantify upper lip soft-tissue changes in the vertical dimensions both at rest and at maximum smile, and to examine the correlation between upper labial vestibular attachment height and maxillary gingival exposure on smiling.
  
  
  METHODS
  Seventy-two volunteers (36 men, 36 women) aged 20 to 40 (mean, 30.49 years) were recruited for this study. For each subject, 9 measurements of upper lip position and maxillary incisor crown height at rest and in maximum smile were recorded.
  
  
  RESULTS
  A statistically significant sexual dimorphism was apparent in most of the measured variables. Relaxed external upper lip length was 3.1 mm shorter in the women than in the men. The mean maxillary central incisor display at rest was 1.78 mm greater in the women than in the men. A high smile line was 2.5 times more prevalent in the women. The upper lip was shortened by 30% in subjects with a high smile line compared with 23% in subjects with a low smile line.
  
  
  CONCLUSIONS
  The following findings were observed in subjects with a high smile pattern: (1) short upper lip length, (2) low smiling/resting upper lip length ratio, (3) inferior attachment of the upper labial vestibule, and (4) prominent upper lip vermilion.
authors.affiliation: Department of Oral and Maxillofacial Surgery, Rabin Medical Center, Beilinson Campus, Petach Tikva, Israel. hagaimi@gmail.com
authors.forename: Hagai
authors.initials: H
authors.lastname: Miron
authors.forename: Shlomo
authors.initials: S
authors.lastname: Calderon
authors.forename: Dror
authors.initials: D
authors.lastname: Allon
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D005260:Female; D005881:Gingiva / Q000033:anatomy & histology*; D006801:Humans; D007180:Incisor / Q000033:anatomy & histology; D008046:Lip / Q000033:anatomy & histology*; D008297:Male; D012727:Sex Characteristics; D012904:Smiling; D018709:Statistics, Nonparametric; D019228:Tooth Crown / Q000033:anatomy & histology; D014716:Vertical Dimension; D055815:Young Adult