The Role of Objective Plane Angulation on the Mandibular Image Using Cross-Sectional Tomography
Cross-sectional jaw images in the buccolingual direction obtained by conventional or computerized tomography are used in the image diagnosis of dental implant treatment. This study was performed to clarify the subjective image quality of the mandibular depiction by shifting the angles of the tomographic objective plane. A panoramic machine with a linear tomographic function was used to obtain cross-sectional tomographic images on bilateral first molar regions of 10 dried human mandibles. The angles of tomographic objective planes were shifted horizontally within a range of ±20° at intervals of 5° from the tomographic objective plane, which was automatically determined. The image qualities of 4 anatomical structures—alveolar crest, buccal and lingual cortical bone, and mandibular canal—were subjectively scored on a 5-point scale method. As a result, the permitted tomographic objective angles were from −1.7° to 2.5°, a range of 4.2° for all 4 anatomical structures. When this result was compared with a previous geometric result, the permitted range of the angles was quite narrow. The tomographic objective angles should be manually set in accordance with an optimal tomographic plane for individual patients by using the positioning technique in linear tomography.Abstract
Tomographic objective plane. The bold line shows a tomographic objective plane set automatically by a machine
Cross-sectional tomographic images. Tomographic objective planes were shifted horizontally within a range of ±20 degrees at intervals of 5° from the tomographic objective plane, which was automatically determined. (A) Tomographic objective plane set automatically. (B) Optimal tomographic objective plane (0°)
and 4. Figure 3. Schematic drawing of measurements for mandibular width and the 4 anatomical structures (alveolar crest, buccal and lingual cortical bone, and mandibular canal) in the cross-sectional image. Figure 4. Results of a mandibular depiction from cross-sectional images. 0° in x-axis of the graph indicates the optimal tomographic plane
Contributor Notes
Munetaka Naitoh, DDS, PhD, is an associate professor in the Department of Oral and Maxillofacial Radiology, School of Dentistry, Aichi-Gakuin University, and chief of Oral Implant Clinic, Dental Hospital, Aichi-Gakuin University, 2-11, Suemori-Dori, Chikusa-Ku, Nagoya 464-8651, Japan (mune@dpc.aichi-gakuin.ac.jp). Address correspondence to Dr Naitoh.
Akitoshi Katsumata, DDS, PhD, is an associate professor in the Department of Oral Radiology, Asahi University School of Dentistry, Mizuho, Japan.
Yukinobu Kubota, DDS, and Hisashi Hayashi, DDS, are researchers in the Department of Oral and Maxillofacial Radiology, School of Dentistry, Aichi-Gakuin University, Nagoya, Japan.
Shinji Okumura, RT, is a radiologic technician in the Division of Radiology, Dental Hospital, Aichi-Gakuin University, Nagoya, Japan.
Hisashi Hayashi, DDS, is a researcher in the Department of Oral and Maxillofacial Radiology, School of Dentistry, Aichi-Gakuin University, Nagoya, Japan.
Eiichiro Ariji, DDS, PhD, is a professor and chairman in the Department of Oral and Maxillofacial Radiology, School of Dentistry, Aichi-Gakuin University, Nagoya, Japan.