An intramedullar pin inserted from the base of the mandible is used for open reduction of fractures of the mandibular condylar process. However, as this procedure requires that the pin or screw is inserted into the mandibular ramus, there is a risk of injuring the mandibular canal during insertion. In this study, we evaluated the possibility of mandibular canal injury during insertion of an intramedullar pin in Japanese dry skulls.
The results were as follows. 1. Between 10.8% and 29.7% of the skulls had the risk of mandibular canal injury during pin insertion, and the risk of injury was higher (16.7% to 58.3%) in the presence of an edentulous mandible.
2. When the morphologic characteristics of mandibles with the risk of mandibular canal injury were compared with those of mandibles without such a risk, there were significant differences in the angle of the condylar neck, the angle of the posterior border of the condylar neck, or the angle of the posterior border of the mandibular ramus to the mandibular plane.
3. The shorter the distance between the mandibular canal and the posterior border of mandible or the mandibular angle, the higher was the risk of the mandibular canal injury.
The larger the angle between the mandibular condylar neck and the mandibular plane or between the posterior border of the mandible and the mandibular plane, the higher was the risk of mandibular canal injury.
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