Evaluation of the Precision of Panoramic Radiography in Dimensional Measurements and Mandibular Steepness in Relation to Lateral Cephalomerty

Introduction: Lateral cephalometry is mostly used when cephalometric measurements are made from radiographs. However, because of the superimposed images appearing on the lateral cephalograms, reliable measuring of the individual angles (for example Gonial angle) becomes very difficult. How reliable the cephalometric measurements are when determined from an orthopantomogram is the purpose of this study. Materials & Methods: In the first stage of this descriptive analytical study, five different measurements (Gonial angle, FMA, Condyle height, Ramus height and Body length of the mandible) were studied on two dry skulls. The same measurements were made on the panoramic images of these dry skulls and then compared with these measurements in lateral cephalometirc radiography. In the second stage of this study, the same measurements were studied on the panoramic and lateral cephalometry of 101 subjects (52 females and 49 males, mean age of 16). Then the measurements were compared in different growth patterns. For data analysis, the pearson correlation coefficient was used. Results: In comparison of actual measurements obtained from dry skulls and panoramic radiographic measurements, it was revealed that all the five measurements (except length of the body of the mandible) in panoramic radiographs were close to actual degrees in dry skulls. Correlation tests showed the hightest correlation between panoramic and cephalometric radiographs in gonial angle (r=0.89, P<0.001) whereas the least correlation was seen in the length of mandibular body. In different growth patterns, it was seen that gonial angle and ramus height showed the highest correlation between the two radiographs. Conclusion: The ability to determine growth direction from the orthopantomogram will be useful because majority of dentists request an OPG for patients during routine dental examination. Key words: Panoramic radiography, Gonial angle, Mandibular steepness.