title: Maximum occlusal force and medial mandibular flexure in relation to vertical facial pattern: a cross-sectional study.
abstract: BACKGROUND
  Vertical facial pattern may be related to the direction of pull of the masticatory muscles, yet its effect on occlusal force and elastic deformation of the mandible still is unclear. This study tested whether the variation in vertical facial pattern is related to the variation in maximum occlusal force (MOF) and medial mandibular flexure (MMF) in 51 fully-dentate adults.
  
  
  METHODS
  Data from cephalometric analysis according to the method of Ricketts were used to divide the subjects into three groups: Dolichofacial (n = 6), Mesofacial (n = 10) and Brachyfacial (n = 35). Bilateral MOF was measured using a cross-arch force transducer placed in the first molar region. For MMF, impressions of the mandibular occlusal surface were made in rest (R) and in maximum opening (O) positions. The impressions were scanned, and reference points were selected on the occlusal surface of the contralateral first molars. MMF was calculated by subtracting the intermolar distance in O from the intermolar distance in R. Data were analysed by ANCOVA (fixed factors: facial pattern, sex; covariate: body mass index (BMI); alpha = 0.05).
  
  
  RESULTS
  No significant difference of MOF or MMF was found among the three facial patterns (P = 0.62 and P = 0.72, respectively). BMI was not a significant covariate for MOF or MMF (P > 0.05). Sex was a significant factor only for MOF (P = 0.007); males had higher MOF values than females.
  
  
  CONCLUSIONS
  These results suggest that MOF and MMF did not vary as a function of vertical facial pattern in this Brazilian sample.
authors.affiliation: Department of Prosthodontics, Pontifical Catholic University of Rio Grande do Sul, Porto Alegre, RS, Brazil. rshinkai@pucrs.br
authors.forename: Rosemary S
authors.initials: RS
authors.lastname: Shinkai
authors.forename: Fabio L
authors.initials: FL
authors.lastname: Lazzari
authors.forename: Simone A
authors.initials: SA
authors.lastname: Canabarro
authors.forename: Márcia
authors.initials: M
authors.lastname: Gomes
authors.forename: Márcio L
authors.initials: ML
authors.lastname: Grossi
authors.forename: Luciana M
authors.initials: LM
authors.lastname: Hirakata
authors.forename: Eduardo G
authors.initials: EG
authors.lastname: Mota
mesh_terms: D000328:Adult; D001732:Bite Force; D002508:Cephalometry; D003430:Cross-Sectional Studies; D005145:Face / Q000033:anatomy & histology* / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008334:Mandible / Q000502:physiology*; D008410:Masticatory Muscles / Q000502:physiology*; D008875:Middle Aged; D012016:Reference Values; D055815:Young Adult