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.

Keywords

FEM, Patient Specific Model, Mandible, Tooth, Periodontal Ligament

Paper information

Yoshihiro TAKAO, Junpei TAKAHASHI, Masahiko TERAJIMA, Wen-Xue WANG and Akihiko NAKASHIMA, “An Easy and Quick Formulation of Patient-Specific 3D-FEM Dentate Mandible Model with Periodontal Ligament for Mechanical Analysis”, Journal of Biomechanical Science and Engineering, Vol. 4, No. 4 (2009), pp.550-561 . doi:10.1299/jbse.4.550

In the present study, peri-implant tissue alteration was studied histologically, and then differences in the gene expression pattern of certain proteins were analyzed using cDNA microarray analysis, under the influence of static lateral load. Beagle dogs were divided into two groups: control and load. Three months after the extraction of mandibular premolars, two implants were placed in each side of the mandible. Each group was further divided into subgroups for loading times of 1, 7 and 14 days. Immediately after the implant installation, a loading device was adhered between the abutments of neighboring implants. Afterward, the expansion screw of the load group was activated by 360-degree rotation, resulting in 0.7 mm horizontal expansion. After sacrificing the dogs, peri-implant tissue was collected, then microarray analysis for the detection of gene expression was performed, as well as histology. Histology indicated that the peri-implant tissue broke down under the influence of the load. Microarray analysis demonstrated the presence of load-sensitive gene expression even after 1 day. Differences in gene expression patterns in concert with static lateral load were demonstrated, even at an early stage post-operation. Further study may help in the diagnosis of pathological overload.

Keywords

Mechanical Stress, Static Load, Microarray Analysis, Dental Implant, Dental Implant Failure

Paper information

Yasuko MORIYAMA, Yasunori AYUKAWA, Kenichi KABEMURA, Yasuyuki MATSUSHITA, Masafumi KIHARA, Yoshihiro TSUKIYAMA, Mitsugu TODO, Yoshihiro TAKAO and Kiyoshi KOYANO, “The Alternation of Peri-Implant Bone Response Exposed to Static Lateral Load”, Journal of Biomechanical Science and Engineering, Vol. 4, No. 3 (2009), pp.326-335 . doi:10.1299/jbse.4.326