Abstract
Factors involved in the mechanism of mandibular fracture were studied using dentate human air-dried skulls with mandibles by measuring the acceleration of impact with a threeaxial acceleration convertor and the impact-produced strain with monoaxial strain gauges.
The following results were obtained:
1) Application of impact onto the medial region of the mentum suggested a high probability of mandibular fracture to occur at the mandibular neck when the mouth was occluded, and intracapsular fracture of the temporomandibular joint to occur by compression of the condylar process when the mouth was open.
2) Application of impact in the direction of the mentum to the mandibular head suggested a high probability of mandibular head fracture to occur by bidirectional (mediolateral and anterior) buckling of the mandibular head when the mouth was occluded, and mandibular neck fracture to occur by transverse buckling mediolaterally to the neck when the mouth was open.
3) Application of impact onto the mandibular body suggested a high probability of fracture to occur at the site of impact application by buckling, and fracture of the mandibular head to occur by mediolateral buckling of the head, regardless of whether the mouth was occluded, open or rigidly fixed. The probability of mandibular head fracture by crushing was considered to be low when the mouth was occluded or open.
4) Application of impact onto the mandibular angle suggested a high probability of mandibular fracture to occur at the wisdom tooth by bending, regardless of whether the mouth was open, occluded or rigidly fixed.
5) Application of impact in the direction of the mandibular angle to the mandibular head suggested a high probability of mandibular neck fracture, regardless of whether the mouth was open, occluded or rigidly fixed. Fracture of the mandibular head by compression was considered to be less likely when the mouth was open than when the mouth was occluded or rigidly fixed.
