Does the change in masticatory environment in the growing period cause osteoarthrosis of TMJ?

• Project/Area Number: 25862026
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Orthodontics/Pediatric dentistry
• Research Institution: Yokohama City University
• Principal Investigator: FUJITA Koichi 横浜市立大学, 附属市民総合医療センター, 助教 (30451909)
• Project Period (FY): 2013-04-01 – 2016-03-31
• Project Status: Completed (Fiscal Year 2015)
• Budget Amount: ¥2,600,000 (Direct Cost: ¥2,000,000、Indirect Cost: ¥600,000); Fiscal Year 2014: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000); Fiscal Year 2013: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
• Keywords: 変形性顎関節症 / 咀嚼環境変化 / 顎関節機械受容器 / 成長期 / 咀嚼環境 / 顎関節受容器 / 開口反射 / 大脳皮質一次運動野

Outline of Final Research Achievements

The present study was conducted to reveal the effects of changes in the orofacial environment (e.g., liquid diet, increased occlusal vertical dimension (iOVD), and nasal obstruction) on the orofacial sensorimotor system (e.g., temporomandibular joint (TMJ) mechanoreceptors, jaw-opening reflex (JOR) and face primary motor cortex (face-M1)) in rats. Alterations in mastication due to liquid diet significantly increased the TMJ mechanoreceptor sensitivity. It was clarified that the adaptation of the JOR and the motor representation within face-M1 after iOVD is long time-dependent. Nasal obstruction affected the orofacial functions by delaying the JOR response and increasing the contraction force of the tongue-protruding muscles. These findings suggest changes in the orofacial environment may affect the masticatory function, which may influence the shape and development of the TMJ in growing rats.

Research Products

• [Journal Article] Effect of unilateral nasal obstruction on tongue protrusion forces in growing rats (2015)
  • Author(s): Karin Harumi Uchima Koecklin, Chiho Kato, Yukiha Funaki, Maya Hiranuma, Takayoshi Ishida, Koichi Fujita, Tadachika Yabushita, Satoshi Kokai, Takashi Ono
  • Journal Title: Journal of Applied Physiology Volume: 118 Issue: 9 Pages: 1128-1135
  • DOI: 10.1152/japplphysiol.01152.2014
  • Peer Reviewed / Open Access / Acknowledgement Compliant
• [Presentation] 成獣ラットにおける開口反射は咬合高径増加に対して長期的に順応する (2015)
  • Author(s): 1.牧口実央、舟木幸葉、沖原秀政、加藤千帆、石田宝義、藤田紘一、藪下忠親、小海暁、小野卓史
  • Organizer: 第74回日本矯正歯科学会学術大会
  • Place of Presentation: 福岡国際会議場・マリンメッセ（福岡）
  • Year and Date: 2015-11-18
• [Presentation] 成長期ラットにおける大脳皮質一次運動野顎顔面領域の機能局在の発達 (2015)
  • Author(s): 2.阿部泰典、加藤千帆、舟木幸葉、沖原秀政、藤田紘一、石田宝義、藪下忠親、小海暁、小野卓史
  • Organizer: 第74回日本矯正歯科学会学術大会
  • Place of Presentation: 福岡国際会議場・マリンメッセ（福岡）
  • Year and Date: 2015-11-18
• [Presentation] Increase in force and changes in the contractile characteristics of the tongue-protruding muscles after nasal obstruction in growing rats. (2015)
  • Author(s): 3.Karin Harumi Uchima Koecklin, Chiho Kato, Yukiha Funaki, Maya Hiranuma, Takayoshi Ishida, Koichi Fujita, Tadachika Yabushita, Satoshi Kokai, Takashi Ono.
  • Organizer: 8th International Orthodontic Congress
  • Place of Presentation: London（UK）
  • Year and Date: 2015-09-27