Analysis of condylar position change on digitally subtracted Orthophos P-4 and Sectograph zonogram images

The purpose of this study was to compare the accuracy of two single-image techniques that provide parasagittal views of the temporomandibular joint. Orthophos program 4 and Sectograph zonographic techniques were evaluated using digital subtraction to measure 1-, 2-, and 3-mm shifts of condylar position in horizontal or vertical planes. Precise repositioning of a human skull was facilitated by laser alignment beams. Statistically significant differences between radiographic techniques reflected the tendency for overestimating of shifts with program 4 and underestimation with zonographic techniques. Pooled mean difference values were 0.12 mm for program 4 images of -0.17 mm for zonograms. Program 4 images and zonograms produced with precise repositioning of anatomy approached the accuracy of tomograms and may prove useful for evaluating parasagittal alterations in condylar position in pretreatment and posttreatment radiographs.