Comparative study of linear and angular measures of the cranial base in skeletal Class I and III malocclusion

  • Olga Patricia Dias de Almeida Berger Pontifical Catholic University of Rio Grande do Sul
  • Ernani Menezes Marchioro Pontifical Catholic University of Rio Grande do Sul
  • Suzana Maria Deon Rizzato Pontifical Catholic University of Rio Grande do Sul
  • Eduardo Martinelli Santayana de Lima Pontifical Catholic University of Rio Grande do Sul
Keywords: Cranial base, cephalometry, Class III malocclusion

Abstract

Purpose: To evaluate the effect of flexion and linear measures of the cranial base on the anteroposterior position of the jaws in skeletal Class III malocclusion compared with skeletal Class I. Methods: One hundred-twenty lateral radiographs were divided in two groups: Group 1 - 60 radiographs of individuals with a Class I skeletal pattern; and Group 2 - 60 radiographs of individuals with a skeletal Class III pattern. The radiographs were of adult Caucasian individuals with no previous orthodontic treatment. Data were analyzed by using ANOVA. Results: There were significant differences in the cranial base angle (NSBa) and anterior cranial base length (S-N) between the two groups. Group 2 had the lowest values for NSBa and S-N. The analysis of cranial base complementary angles (NSGn and BaSGn) revealed a significant statistical difference in NSGn: Group 2 had lower NSGn values, which indicates a more anterior position of the gnathion. Variations of the cranial base angle and the Y axis were inversely correlated with variations of SNA and SNB angles, and the differences were statistically significant for the two groups. Conclusion: This study supports previous findings that the cranial base flexion contributes to skeletal configuration in Class III skeletal patterns. Therefore, the cranial base should be evaluated for growth predictions and Class III diagnosis. The effect of the cranial base on the positioning of the jaws should be further assessed.
base do crânio: medidas lineares e angulares
Published
2011-03-01
Section
Original Article