Area-dependent enlargement ratios of panoramic tomography on orthograde patient positioning and its significance for implant dentistry.

The aim of this work was to study the behavior of vertical and horizontal enlargement ratios in panoramic tomography in various implant regions of the maxilla and the mandible. A method is presented that admits determination of regional enlargement ratios as a function of the implant region. Clearly defined characteristics of the implant body (Frialit-2 implants) are used as reference points. The vertical enlargement ratio varied between 1.21 and 1.29 on optimal orthograde adjusted tomographs, depending on the measured area. The horizontal enlargement ratio at the coronal end of the implant varied between 1.15 and 1.35. As it is below the vertical value in the lateral tooth area, this contributes to the distortion of the implant structures depicted. The horizontal enlargement at the apical end of the implant varies between 1.12 and 1.44. The difference in horizontal enlargement ratios also causes a distortion of the implant structures shown on the panoramic tomograph. Based on this study scenario, panoramic tomography may be well suited to preimplant diagnosis, particularly in the vertical dimension. With regard to transparent templates designed for implant placement, an enlargement of 1.3 in the perpendicular line and 1.35 in the horizontal line is proposed.