Reliability of Construction of Gonial Angle in Mixed Indian Population: OPG or Lateral Cephalogram – A Pilot Study

Abstract

Diagnosis, formulation, and execution of treatment plan are the steps involved in successful management of malocclusions. Diagnosis defines the problem and lays the foundation for the treatment objectives. Treatment plan is execution of the treatment objectives. Proper determination and treatment planning are dependent on information obtained from clinical examination, study models, and the applicable radiographs. Lateral cephalograms and Orthopantomograms (OPG) are important radiographic tools for treatment planning and are regularly used for orthodontic patients. OPGs may be utilized for assessing the supporting bone, screening for cysts, neoplasms, ankylosed teeth, eruption path of teeth and asymmetry of mandible and supernumerary or missing teeth [1,2]. The angle formed by the junction of the posterior and lower borders of the mandible is called the gonial angle. The radiographic gonial angle measurements aid in ascertaining growth patterns of facial skeleton, mandibular rotation, facial asymmetry, age estimation in forensic odontology, decisions on extractions in Class II and orthognathic surgery in Class III skeletal base [3-6]. Lateral cephalograms are usually used for measuring this angle. However, superimposed images on a lateral cephalogram adversely affect reliability of measurements of the gonial angle and are of utmost importance while planning orthognathic surgery [7]. The right and left gonial angles can be measured individually without superimposition in an OPG; hence the measurement may be more accurate than lateral cephalometry [2].