TI : The Medial Sigmoid Depression: Its Anatomic and Radiographic Considerations
AU : Kang BC
AD : Department of Oral Radiology . School of Dentistry, Chonnam National University
SO : JKAOMFR. 1991;21(1):7-18
ISSN : 1225-049X
PY : 1990
LA : English
CP : KOREA
AB : A foramen-like radiolucency was occasionally observed on a panoramic radiographs in the upper ramus just below and anterior to the mandibular sigmoid notch. The medial sigmoid depression is an anatomic radiolucency which can be observed on a number of panoramic radiographs in the upper ramus just below and anterior to the mandibular sigmoid notch. The radiolucent shadow was first reported by Langlais et al. (1983) The anatomic significance of this depression on the mandible is not determined. Though it can be observed at the age of three, whether the origin of the depression is congenital or developmental is a problem to be solved. There was a difference in incidence between mandibular specimen's radiographs and the patient's radiographs. The difference may be due to the following considerations: The radiolucent airway shadow, pterygoid plate, soft palate are superimposed the sigmoid notch region. And there are soft tissues and other anatomies which are superimposed the sigmoid notch region. Seventy-eight mandibles (of dry skulls) were examined. The observable incidence, location, and size of the depression were recorded. Some of the representative specimens were photographed. The specimens were radiographed with Veraview panoramic machine (J. Morita Co.). The observable incidence of the medial sigmoid depression was compared with the radiographic incidence.
The results are as follows:
1. The observable incidence of th medial sigmoid depression was 62% (28% unilateral, 33% bilateral).
2. The radiographic incidence of the medial sigmoid depression was 33% (14% unilateral, 19% bilateral).
3. The center of the medial sigmoid depression was located 6.0mm below and 3.8mm anterior to the sigmoid notch (on the skulls).
4. The mean size of the medial sigmoid depression was 7.8mm in vertical and 8.3mm in horizontal length.
5. The radiographic incidence of the depression in dental patient was 24% (18% unilateral, 7% bilateral).