Comparison of Panoramic Radiography and Lateral Cephalometry for Angular Measurements in Different Skeletal Classes

Objectives: This study evaluated the reliability of panoramic radiography in comparison with lateral cephalometry for angular measurements in different skeletal classes. Materials and Methods: In this retrospective study, the gonial angle, the angle formed between the palatal plane and the Frankfort plane (palatal plane inclination), and the angle formed between the incisal edge of the upper incisor and the Frankfort plane (upper incisor vertical index) were measured on panoramic and lateral cephalometric radiographs of 278 patients in three skeletal classes. Intraclass correlation coefficient (ICC) was calculated to compare panoramic and lateral cephalometric radiographs. Paired t-test was used for comparison of the right- and left-side angles on panoramic radiographs. Results: The ICCs were 0.941, 0.927, and 0.954 for the gonial angle, 0.650, 0.605, and 0.320 for the palatal plane inclination, and 0.812, 0.810, and 0.758 for the maxillary incisor vertical index in skeletal Class I, II and III patients, respectively. The ICCs were all statistically significant (P<0.05) except for the palatal plane inclination in Class III patients (P>0.05). There was a significant difference in the gonial angle of Class II patients between the right and left sides (P<0.05). The upper incisor vertical index in the right and left sides showed significant differences in all three skeletal classes (P<0.05). The difference between the right and left sides in other angles and skeletal classes was not statistically significant (P>0.05). Conclusion: Skeletal class does not affect the reliability of panoramic radiographs for angular measurements, except for the palatal plane inclination in Class III patients.