In recent years, the number of patients with mandibular defects is increasing, and the orthognathic surgery of mandible has become a common treatment for re-establishing functional and aesthetic anatomy by repositioning displaced skeletal elements. To decrease a heavy burden and high risk of the surgery falling on the patients and clinicians, the present authors have developed a mechanical support system for orthognathic surgery. An easy, quick and patient-specific mesh generation including the periodontal ligament is essential. First, a mandible template was obtained manually, which requests the small number of elements. It is composed of 7 different materials and could reproduce the original shape of each material pretty well with a reduced number of elements. Next the template of around 6600 nodes is mapped by a simple formula in a moment of time to fit the patient's mandible polygonal image obtained from an individual CT image. The calculation with the resulted patient-specific mesh by a 3D FEM code is also performed successfully.