Accuracy of panoramic radiographs and lateral cephalograms in determination of external gonial angle of adult patients with class I skeletal pattern

Abstract

Introduction: In dentistry worldwide, for planning Orthodontic treatment and Orthognathic surgery, the measurement of Gonial angle is incredibly important. In cephalometric radiographs, the influence of underlying anatomical superimposition makes it troublesome to measure the gonial angle precisely. Orthopantomogram (OPG) could be an accurate alternative investigating source to measure right and left gonial (mandibular) angle precisely. Hence the objective of the present study was to determine the accuracy of panoramic radiographs and lateral cephalograms in determination of external gonial angle of adult patients with class I malocclusion.

Material and Methods: 273 OPG and 273 lateral cephalograms of skeletal class 1 patients aged 13 to 23-year, having class I malocclusion were traced for the gonial angle. The comparative analysis was done using Pearson’s correlation coefficient and paired t-test.
Results: On lateral cephalogram and OPG, Gonial angle was measured to be 123.85 ± 7.564 and 123.77 ± 7.452 degrees respectively. The difference of measurement obtained from lateral cephalogram and OPG was insignificant, and there were insignificant results found among the values of gonial angle measured on Right and Left side of the mandible individually on same OPG.

Conclusions: Measuring the gonial angle on both OPG and Lateral cephalogram has insignificant difference, hence enabling the use of an OPG radiograph as an alternative x ray for determining gonial angle precisely. Moreover, gonial angles of the right and left sides of the mandible can be measured individually on an OPG radiograph and is not influenced by underlying superimposed anatomical structures as in a lateral cephalogram.