title: Nasolabial angle at rest and upon smiling.
abstract: OBJECTIVE
  The objectives of this study were 1) to determine the mean and SD of the nasolabial angle (NLA) and the linear measure pronasale (Prn)-A' at rest and upon smiling and 2) to determine the difference between smile and rest in participants with normal occlusion and facial harmony.
  
  
  METHODS
  The sample consisted of 40 white Brazilian participants (20 of each gender) aged 20 to 30 years and with normal occlusion, a pleasant profile, and facial harmony. The measures NLA and Prn-A' were analyzed in profile photographs at rest and during smile, with a millimeter ruler in front of the profile during use of the Dolphin software. The statistical analysis included dependent t tests to compare the rest and smiling variables.
  
  
  RESULTS
  The mean of the NLA at rest was 104.93°; it was 110.67° during smile; and the difference between them was statistically significant, with a mean of 5.74°. The mean of the linear variable Prn-A' at rest was 23.25 mm, whereas during smile it was 24.04 mm, and the difference between them was statistically significant, with a mean of 0.79 mm.
  
  
  CONCLUSIONS
  The variability in the NLA and Prn-A' at rest and upon smiling was found to be significant in a normal sample, and it should be considered as a diagnostic tool in the treatment planning for sagittal dentoskeletal deformities.
authors.affiliation: Orthodontic Graduate Student, Department of Orthodontics, Bauru Dental School, University of São Paulo, Bauru, Brazil.
authors.forename: Daniel Salvatore
authors.initials: DS
authors.lastname: de Freitas
authors.affiliation: Professor, Department of Orthodontics, Bauru Dental School, University of São Paulo, Bauru, Brazil.
authors.forename: Marcos Roberto
authors.initials: MR
authors.lastname: de Freitas
authors.affiliation: Professor, Department of Orthodontics, Bauru Dental School, University of São Paulo, Bauru, Brazil.
authors.forename: Guilherme
authors.initials: G
authors.lastname: Janson
authors.affiliation: Professor, Department of Orthodontics, Ingá Dental School, Maringá, Brazil. Electronic address: kmsf@uol.com.br.
authors.forename: Karina Maria Salvatore
authors.initials: KM
authors.lastname: de Freitas
authors.affiliation: Stomatology Graduate Student, Bauru Dental School, University of São Paulo, Bauru, Brazil.
authors.forename: Camila Lopes
authors.initials: CL
authors.lastname: Cardoso
mesh_terms: D000328:Adult; D005149:Facial Expression; D005260:Female; D006801:Humans; D008297:Male; D060052:Nasolabial Fold / Q000502:physiology*; D012904:Smiling; D055815:Young Adult