THE BULLETIN OF TOKYO DENTAL COLLEGE

Vol. 48 No. 4      November 2008

ISSN: 0040-8891      UBIC: 66

Abstract

The objective of the present study was to investigate frontal morphological asymmetry in the mandibular molar region in terms of tooth axis and skeletal structures using vertical MPR sections in jaw deformity accompanied by facial asymmetry. Subjects consisted of 15 patients with jaw deformity accompanied by facial asymmetry aged 17.4 years lo 37.8 years. There were four men and eleven women. Based on X-ray computed omography (CT) scans, DICOM viewer software was used to prepare multiplanar reconstruction (MPR) sections. The mandible was then positioned on a reference plane based on the menton and left right gonions, and a vertical MPR section passing through the mesial root of the first mandibular molar was prepared. The following easurements were made on both the shifted and non-shifted sides: maximum buccolingual width of the mandibular body; height of the mandibular body; inclination angle of the mandibular body; degree of buccal protrusion of the mandibular body; and inclination angle of the buccolingual tooth axis of the first molar. Furthermore, degree of median deviation in the menton was measured using frontal cephalograms. Differences in morphological parameters between the shifted and non- shifted sides were assessed. Furthermore, the relationship between median deviation and asymmetry were statistically analyzed. There was no significant asymmetry in the maximum buccolingual width of the mandibular body, the height of the mandibular body or he degree of buccal protrusion of the mandibular body. However, when compared to the shifted side, the inclination angle of he buccolingual tooth axis of the first molar for the non-shifted side was significantly reater. There was a relatively strong correlation between median deviation and inclination angle of the mandibular body. The above findings clarified that, in orthognathic surgery for jaw deformity accompanied by facial symmetry, actively improving asymmetry in the buccolingual inclination of the tooth axis of the molar region during presurgical orthodontic treatment is important in achieving favorable post-treatment occlusal stability nd facial symmetry. Key words: Jaw deformity-Facial asymmetry-X-ray CT -Mandibular vertical section - Bucco-lingual inclination.

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