Abstract

Objective: The aim of this study was to compare three methods of gonial angle formation on cephalogram with the method on orthopantomogram, amongst three vertical facial groups.
Study Design: Cross-sectional comparative study
Place and Duration of Study: Department of Orthodontics, Ziauddin College of dentistry, Ziauddin university hospital, Clifton campus, Karachi, from March to October 2017.
Methodology: A total of 178 panoramic and cephalometric radiographs of patients ranging from age 12-39 were used in this study. The patients were divided into three groups according to their vertical skeletal pattern namely hyperdivergent, normodivergent and hypodivergent. Gonial angle was constructed by three methods defined by Tweed’s, Steiner’s and Down’s on the cephalogram and was then compared to the method of gonial angle determination on an OPG. Repeated measure ANOVA with Bonferroni correction was used for comparison amongst three vertical facial groups.
Results: Statistically significant difference after Bonferroni correction (i.e; P≥0.05), amongst three vertical groups was found for the three methods of gonial angle determination on a latral cephalogram compared to that on an Orthopantomogram.
Conclusion: The value of gonial angle determination on an Orthopantomogram was found to be different when compared with the three methods (Tweed’s, Steiner’s and down’s) of gonial angle determination on lateral cephalogram. Thus, orthopantomogram cannot be used as an alternative for gonial angle determination in orthodontic patients in various vertical facial

Key words: Gonial Angle, Lateral Cephalogram, Orthopantomogram, Vertical facial group