title: The inadequacy of the Y-axis of growth (SNGn) for the vertical pattern assessment in patients with sagittal discrepancies.
abstract: OBJECTIVE
  The aim of this cephalometric study was to evaluate the influence of the sagittal skeletal pattern on the 'Y-axis of growth' measurement in patients with different malocclusions.
  
  
  METHODS
  Lateral head films from 59 patients (mean age 16y 7m, ranging from 11 to 25 years) were selected after a subjective analysis of 1630 cases. Sample was grouped as follows: Group 1 - class I facial pattern; group 2 - class II facial pattern; and Group 3 - class III facial pattern. Two angular measurements, SNGoGn and SNGn, were taken in order to determine skeletal vertical facial pattern. A logistic regression with errors distributed according to a binomial distribution was used to test the influence of the sagittal relationship (Class I, II, III facial patterns) on vertical diagnostic measurement congruence (SNGoGn and SNGn).
  
  
  RESULTS
  RESULTS show that the probability of congruence between the patterns SNGn and SNGoGn was relatively high (70%) for group 1, but for groups II (46%) and III (37%) this congruence was relatively low.
  
  
  CONCLUSIONS
  The use of SNGn appears to be inappropriate to determine the vertical facial skeletal pattern of patients, due to Gn point shifting throughout sagittal discrepancies. Clinical Significance: Facial pattern determined by SNGn must be considered carefully, especially when severe sagittal discrepancies are present.
authors.affiliation: Associate Professor, Department of Dentistry, Federal University of Sergipe, UFS Sergipe, Brazil.
authors.forename: Luiz Renato
authors.initials: LR
authors.lastname: Paranhos
authors.affiliation: Student, Department of Orthodontics, Methodist University of Säo Paulo, Brazil.
authors.forename: Tiago Monteiro
authors.initials: TM
authors.lastname: Brando
authors.affiliation: Student, Department of Public Health, Piracicaba Dental School Unicamp, Säo Paulo, Brazil.
authors.forename: Armando K
authors.initials: AK
authors.lastname: Kaieda
authors.affiliation: Associate Professor, Department of Orthodontics, Maringá University Center, PR Brazil.
authors.forename: Adilson Luiz
authors.initials: AL
authors.lastname: Ramos
authors.affiliation: Associate Professor, Department of Division of Orthodontics, University of Sao Paulo City, UNICID, Säo Paulo, Brazil.
authors.forename: Fernando César
authors.initials: FC
authors.lastname: Torres
mesh_terms: D000293:Adolescent; D000328:Adult; D059925:Anatomic Landmarks / Q000473:pathology / Q000503:physiopathology; D002508:Cephalometry / Q000379:methods*; D002648:Child; D005147:Facial Bones / Q000254:growth & development* / Q000473:pathology; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008046:Lip / Q000473:pathology; D008297:Male; D008310:Malocclusion / Q000473:pathology / Q000503:physiopathology*; D008311:Malocclusion, Angle Class I / Q000473:pathology / Q000503:physiopathology; D008312:Malocclusion, Angle Class II / Q000473:pathology / Q000503:physiopathology; D008313:Malocclusion, Angle Class III / Q000473:pathology / Q000503:physiopathology; D008334:Mandible / Q000254:growth & development / Q000473:pathology; D009295:Nasal Bone / Q000254:growth & development / Q000473:pathology; D009666:Nose / Q000473:pathology; D010781:Photography / Q000379:methods; D012658:Sella Turcica / Q000254:growth & development / Q000473:pathology; D014716:Vertical Dimension; D055815:Young Adult