A reliability comparison of submentovertex and zonographic methods of horizontal condylar angle estimation

The objectives of this retrospective clinical study were, first, to compare submentovertex radiography and zonographic temporomandibular joint orientation programs that use the Scanora imaging system with respect to the reproducibility with which the angulation of the horizontal condylar axis may be determined and, second, to assess the level of agreement between the 2 methods.

Submentovertex radiographs and zonographic projections of 16 joints (8 patients) were evaluated. Two raters independently determined the horizontal angulation of each condyle 3 times using each method. Horizontal condylar angle measurements differing by no more than 5 degrees were considered to be in agreement. Statistical analyses were performed with a repeated-measures analysis of variance, sign tests, and Wilcoxon signed rank test.

No significant difference was found in the 3 measurements between the 2 raters (P = .9122) or between the raters adjusted for method (P = .5093). A significant difference was found between methods (P = .0001). Intrarater agreement values were 81% and 88% for the submentovertex method and 75% for each rater for the zonographic method. Interrater agreement was 94% for each method. Intermethod agreement was 50% for one rater and 81% for the other.

The submentovertex and zonographic methods of determining the horizontal condylar angulation demonstrated consistency and reliability both within and between the raters. However, the zonographic method did not agree with the submentovertex method. This findings does not imply that the zonographic is not a clinically acceptable technique for the determination of the horizontal condylar angulation when subsequent tomographic projections are made on the same unit with the same head-positioning device.