抄録
Presurgical imaging diagnosis is important to obtain a more accurate prediction of the outcome of implant treatment.
Cross-sectional jaw images in the bucco-lingual direction can usually be obtained by computed tomography (CT), or conventional X-ray tomography. However, it is considered that the measurement accuracy of conventional tomograms is affected by the angle of the tomographic objective plane and the mandibular shape. This study was performed to clarify the change in mandibular shape by shifting the angles of tomographic objective planes.
Cross-sectional tomographic images were obtained on the bilateral central incisor, first premolar, and first molar regions of 10 dried mandibles, using a panoramic machine with a tomographic function (AZ 3000 DLP, Asahi Roentgen Ind. Co., Japan). The angles of tomographic objective planes were shifted horizontally within a range of ±20 degrees, at intervals of 5 degrees, from the tomographic objective plane which was automatically determined. We measured the width between the surface of the buccal and lingual cortical bone.
The optimal tomographic objective plane was defined as the plane representing the thinnest buccolingual width.
The results were as follows.
The means of bucco-lingual widths in the optimal planes were 9.3 mm, 9.7 mm, and 11.2 mm, in the incisor, premolar, and molar regions, respectively. The angle from the optimal plane, which permitted magnification within 0.5 mm in bucco-lingual width, was from -12.3 degrees to＋11.4 degrees in the incisor region. In the molar region, it was from -12.1 degrees to＋9.8 degrees, while it could not be determined, because of the limit of the machine's movement, in the premolar region.
In conclusion, the change in mandibular shape by shifting the angles of tomographic objective planes was clarified.
