Comparative Evaluation of the External Gonial Angle in Adults Patients with Class I Malocclusion from Panoramic Radiographs and Lateral Cephalograms

Introduction: One of the most important measurements required for Orthodontic treatment and Orthognathic surgery is gonial angle. It is difficult to determine the accurate measurement of each gonial angle on cephalometric radiographs because of superimposition of the left and right angles. Objectives: the aim of the present study was to evaluate external gonial angle using orthopantomogram and comparing it with lateral cephalogram in skeletal class I malocclusion. Materials and Methods: From 14 to 29-year adult patients, a total of 100 panoramic and cephalometric radiographs were obtained and the gonial angle was determined by the tangent of the inferior border of the mandible and the most distal aspect of the ascending ramus and the condyleon both panoramic and cephalometric radiographs. To mark and measure the angles and other parameters, cephalometric protractor and calipers were used. Results: The mean gonial angle was 123.30 ± 6.04o and 120.13o ± 5.770 degrees on cephalometric and panoramic and radiographs, respectively. There was no significant difference between the values of gonial angles determined by lateral cephalogram and panoramic radiography (P=0.995). Conclusion: The value of the gonial angle measured on panoramic radiography was the same as that measured on the routinely used cephalometric radiography.