|Budget Amount *help
¥2,100,000 (Direct Cost : ¥2,100,000)
Fiscal Year 1994 : ¥800,000 (Direct Cost : ¥800,000)
Fiscal Year 1993 : ¥1,300,000 (Direct Cost : ¥1,300,000)
It is believed that the maxillofacial tissue has adaptive property in response to occlusion and mastication. It is thought that this adaptive property accelerates bone remodeling, causing skeletal malocclusion and aggravates the condition.
this study attempts to look into the adaptive property of the maxillofacial tissue by modifying occlusion via intrusion of the upper molars.
The initial plan was designed to use Miniature pig G.However, the plan was modified to use Yucatan micro pig, as a result of difficulty in obtaining the earlier. In 1993, the retention device and head stabilizing device were made to take the cephalogram of the normal group as the standard. The reliability was confirmed. With regards to the optical microscope study, The original intent was to analyze the spheno-occipital synchondrosis, vomer, temporomandibular joint, and masticatory muscles. However, due to the limited number of specimen and other practical difficulties, the temporomandibular joint was chosen since the change is most prominent here. Two groups of 15 weeks old and 33 weeks old specimens were chosen. In 1994, experiment was carried out for the study group also. Bite plate was inserted in the molar region of the 15 weeks group to extrude the molar, which resulted in open bite or mandibular protrusion. This was confirmed intraorally. Cephalograms and decalcified specimen were made for the 33 weeks group. Cephalometric comparisons revealed slight discrepancies in the angles of the anterior cranial floor and the posterior cranial floor, and also in the mandibular angles. Depending on the individual, some showed open bite tendency and others showed mandibular protrusion and the reasons for this phenomenon was not clear. Also, the skull and maxilla showed virtually no noticable differences. The decalcified specimens showed thickness difference of the condylar cartilage in the temporomandibular joint.