Effect of occlusion on mechanical stress of the TMJ

Research Project

Project/Area Number	13672020
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Single-year Grants
Section	一般
Research Field	補綴理工系歯学
Research Institution	TOHOKU UNIVERSITY
Principal Investigator	HATTORI Yoshinori Graduate School of Dentistry, Assistant Professor, 大学院・歯学研究科, 助手 (40238035)
Co-Investigator(Kenkyū-buntansha)	TAKATSU Masaki Dental Hospital, Assistant Professor, 歯学部附属病院, 助手 (50343033) SATOH Chiaki Graduate School of Dentistry, Assistant Professor, 大学院・歯学研究科, 助手 (50312591)
Project Period (FY)	2001 – 2002
Project Status	Completed (Fiscal Year 2002)
Budget Amount *help	¥3,300,000 (Direct Cost: ¥3,300,000) Fiscal Year 2002: ¥1,800,000 (Direct Cost: ¥1,800,000) Fiscal Year 2001: ¥1,500,000 (Direct Cost: ¥1,500,000)
Keywords	bite force / temporomandibular joint / mechanical stress / finite element model / simulation / 顎関節症 / バイオメカニクス / 顎関節負荷 / 咀嚼筋収縮力 / 三次元有限要素モデル / 咬合
Research Abstract	To determine whether the changes of occlusion due to the loss of the posterior teeth cause functional overloading of the teeth and the temporomandibular joints, which has been implicated in periodontal diseases and temporomandibular disorders, we investigated the influences of SDA (shortened dental arch) on occlusal and joint loads. Bite forces and masticatory muscles' electromyograms were recorded in five dentate subjects who clenched maximally on intra-oral appliances creating symmetrical SDAs experimentally. Muscular forces estimated from the recorded electromyograms were fed into a finite element jaw model calculating bite forces and joint loads. Comparison between the measured and the calculated bite forces assured that the joint loads were representative. The bite force on each tooth increased with missing molar occlusions while joint loads decreased. The bite force per root surface area was always greatest on the most posterior tooth, and these values were most constant. The findings provide no evidence suggesting that SDA causes overloading of the joints and the teeth