Reliability of Two Techniques for Measuring Condylar Asymmetry with X-Rays

Among structural alterations that can be a risk factor for temporomandibular joint disorder (TMD) is condylar asymmetry. In order to measure the condylar asymmetry index in panoramic x-rays quantitatively, two methods have been proposed: those of Habets and Kjellberg. The aim of this study was to determine whether the x-ray method of measuring condylar asymmetries in orthopantomographies presents a minor tendency to error due to slight displacements of the head in the horizontal plane. 30 patients between 18 and 25 years of age were assessed. Each of them underwent three panoramic x-rays in three different positions: orthoradial, and at 5 degrees and 10 degrees horizontal angles. Then the Habets and Kjellberg measurements were taken. Habets' technique did not show any statistically significant differences in the x-rays at 5 degrees and 10 degrees horizontal angles compared to the 0 degrees angle. However, Kjellberg's technique showed statistically significant differences only at the 10 degrees angle compared to the 0 degrees angle. The 10 degrees changes produced linear and ratio variations, but the indices did not vary. It was concluded that both methods provide acceptable clinical information within the limitations of these techniques to obtain data on condylar symmetries or asymmetries of the mandibular body or ramus.