The Journal of Contemporary Dental Practice

Register      Login



Volume / Issue

Online First

Related articles

VOLUME 15 , ISSUE 2 ( March-April, 2014 ) > List of Articles


The Inadequacy of the Y-axis of Growth (SNGn) for the Vertical Pattern Assessment in Patients with Sagittal Discrepancies

Luiz Renato Paranhos, Fernando César Torres, Tiago Monteiro Brando, Armando K Kaieda, Adilson Luiz Ramos

Citation Information : Paranhos LR, Torres FC, Brando TM, Kaieda AK, Ramos AL. The Inadequacy of the Y-axis of Growth (SNGn) for the Vertical Pattern Assessment in Patients with Sagittal Discrepancies. J Contemp Dent Pract 2014; 15 (2):169-173.

DOI: 10.5005/jp-journals-10024-1509

Published Online: 01-10-2014

Copyright Statement:  Copyright © 2014; The Author(s).



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.

Materials and 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 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.


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.

How to cite this article

Paranhos LR, Brando TM, Kaieda AK, Ramos AL, Torres FC. The Inadequacy of the Y-axis of Growth (Sng n) for the Vertical Pattern Assessment in Patients with Sagittal Discrepancies. J Contemp Dent Pract 2014;15(2): 169-173.

PDF Share
  1. Variations in facial relationships; their significance in treatment and prognosis. Am J Orthod 1948;34:812-840.
  2. Was the development of the diagnostic facial triangle as an accurate analysis based on fact or fancy? Angle Orthod 1962;48:823-840.
  3. Aparatologia del arco de canto com alambres delgados: técnica y tratamiento. Buenos Aires: Mundi; 1975;1:p. 1263.
  4. Roth RH, Chaconas SJ, Schulhof RJ, Engel GA. Orthodontic diagnosis and planning: their roles in preventive and rehabilitative dentistry. 1st ed. Denver: Rocky Mountain Orthodontics 1982;1:p.472.
  5. Diagnóstico en Ortodoncia. 1st ed. Maringá: Dental Press 2005;1:p.538.
  6. The relation of maxillary structures to cranium in malocclusion and in normal oclusion. Angle Orthod 1952;22:142-145.
  7. Cephalometric analysis of dentofacial normals. Am J Orthod 1980;78:404-420.
  8. Cephalometrics in clinical practice. Angle Orthod 1959;29:8-29.
  9. Spontaneous facial growth in pattern II: a longitudinal cephalometric study. Dental Press Ortodon Ortop Facial 2009;14:40-60.
  10. Modern applied statistics with S. Springer: Frankfurt; 4th ed. 2010;1:p.497.
  11. Data analysis using regression and multilevel/hierarchical models. 1st ed.: Cambridge University Press 2007.
  12. Classification of malocclusion. Dent Cosmos 1899;41:248-264, 350-357.
  13. A new X-ray technique and its application to Orthodontics. Angle Orthod 1931;1:45-66.
  14. Planning treatment on the basis of the facial pattern and an estimate of its growth. Am J Orthod 1957;27:14-37.
  15. Correlation of different cephalometric measurements to define facial type. Int J Orthod Milwaukee 2012;23:31-37
  16. Longitudinal changes in three normal facial types. Am J Orthod 1985;88:466-502.
  17. Cranial base development: a follow-up X-ray study of the individual variation in growth occurring between the ages of 12 and 20 years and its relation to brain case and face development. Am J Orthod 1955;41:198-225.
  18. The face of the normal child. Angle Orthod 1937;7:183-208.
  19. The Frankfort-mandibular plane angle in orthodontic diagnosis, classification, treatment planning and prognosis. Am J Orthod Oral Surv 1946;32:175-230.
  20. Cephalometrics for you and me. Am J Orthod 1953;39:729-755.
  21. The role of mandibular plane inclination in orthodontic diagnosis. Angle Orthod 1975;45:273-281.
  22. Skeletal Class II patterns in the primary dentition. Am J Orthod Dentofacial Orthop 2002;121:596-601.
  23. Vertical growth versus anteroposterior growth as related to function and treatment. Angle Orthod 1964;34: 75-93.
PDF Share
PDF Share

© Jaypee Brothers Medical Publishers (P) LTD.