Tadahiko Kawai

Norio Takeuchi

Kiyomasa Nakagawa

Etsuhide Yamamoto

The quantitatively and objectively present invention provides an apparatus for evaluating the contact pressure distribution in a temporomandibular joint. Specifically, the mandible and cranium are converted to two-dimensional rigid body element models by use of positional data of their contact line acquired from an image input device to compose a rigid body spring model, where only vertical springs resisting in vertical direction to the contact line are assumed in temporomandibular joint portion and vertical springs resisting in vertical direction as well as shear spring resisting in the direction parallel to the contact line are assumed in the teeth portion. An external force converted from an assumed elevation myodynamia is exerted on this model, and based on the theory of a rigid body spring model, stresses at each of the springs are calculated to represent contact pressures due to reaction forces against the external force mentioned above. At the time when these contradictory stresses of the negative stresses at the vertical springs of temporomandibular joint portion and the stress at the shear spring of teeth portion are both decreased to approximately 0 during repetition of the calculation steps the stress at each vertical spring of the temporomandibular joint portion is calculated and displayed of its distribution.

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Kanazawa, Japan

Etsuhide Yamamoto