Influence of changing position around the sagittal plane on magnification of panoramic image in different areas of jaws relative to the normal position

Many factors may cause distortion of panoramic radiographs, of which patient’s head position can be mentioned. The aim of this study was to determine the effect of changing the head position in sagittal plane on magnification in different zones of the jaws and to compare it with the normal position. In this in vitro descriptive-analytical and cross-sectional study seven human dry mandibles were used. The skulls were marked in different dental areas at specific horizontal and vertical distances by radiopaque markers. Panoramic radiographs were taken from each skull tilted and rotated 1‒2, 2‒4 and 4‒6 degrees to left. Magnification in each area was calculated. Data were analyzed with SPSS 18, using t-test and ICC (α ≤ 0.05). The results suggested that changing the position of head in the sagittal plane resulted in greatest changes in the horizontal dimension. The majority of statistically significant changes were observed in values higher than 4 degrees in the third to sixth left mandibular teeth (p values of 0.044, 0.005, 0.044 and 0.006, respectively). Changes in the second premolar and first molar were observed in lower degrees (higher than 2 degree). During tilting and rotation of skulls, the maximum changes were observed in horizontal plane from maxillary lateral incisors to second molars (with p values of 0.013, 0.026, 0.011, 0.016, 0.007 and 0.012, respectively) and in the mandibular lateral incisors to the first molars (with p values of 0.033, 0.002, 0.026, 0.017 and 0.052, respectively). Significant changes were observed in rotations higher than 2 degrees on the left side. Changing head position (rotation and tilting) to a maximum of 6 degrees around the sagittal plane will cause statistically significant changes in horizontal dimensions, but these changes are clinically negligible.