Okano N, Baba K, Ohyama T
Removable Prosthodontics, Tokyo Medical and Dental University, Tokyo, Japan.
J Oral Rehabil. 2005 Oct;32(10):714-9. doi: 10.1111/j.1365-2842.2005.01501.x.
As cited in literatures, canine protected occlusion has a potential to reduce clenching induced temporomandibular joint loadings. However, these previous studies did not perform a control of the clenching level which differed with the depending occlusal conditions. This result may be due largely to an associated reduced jaw closing muscle activity. The present study has investigated clenching induced condylar displacements with controlled clenching level. Twenty healthy human subjects (15 males and five females with an average age of 26.5 years) volunteered to participate in this study. Metallic occlusal overlays were fabricated for the lower working side canine and overlaid to the second molar and the non-working side second molar in order to simulate a canine protected occlusion, group function occlusion and bilateral balanced occlusion. Electromyographic (EMG) activity from the bilateral masseter, anterior temporalis, and posterior temporalis was recorded. These signals were rectified, summarized, and presented to each subject using an oscilloscope screen. Using this visual feedback, subjects were asked to perform clenching tasks at a 50% level of maximal voluntary contraction exerted with simulated group function occlusion and three-dimensional condylar displacements were recorded. An experimental occlusal pattern that shows statistically significant affects on condylar displacements (anova: P<0.001) was found. When compared with the simulated canine protected occlusion, the simulated group function occlusion caused smaller working side condylar displacement and the simulated bilateral balanced occlusion caused significantly smaller non-working side and working side condylar displacements. These results suggest that the increased working side tooth contacts have a potential to reduce working side joint loadings, and a balancing side contact has a potential to reduce non-working side joint loadings, under the laboratory condition where the clenching level is controlled.
如文献中所引用的，犬牙保护咬合有可能降低紧咬引起的颞下颌关节负荷。然而，这些先前的研究没有对紧咬水平进行控制，而紧咬水平会因不同的咬合条件而有所不同。这一结果可能主要归因于相关的咬肌活动减少。本研究在控制紧咬水平的情况下，研究了紧咬引起的髁突位移。20名健康的人类受试者（15名男性和5名女性，平均年龄26.5岁）自愿参与本研究。为下颌工作侧犬牙制作金属咬合面，并覆盖到第二磨牙和非工作侧第二磨牙上，以模拟犬牙保护咬合、组牙功能咬合和双侧平衡咬合。记录双侧咬肌、颞肌前束和颞肌后束的肌电图（EMG）活动。这些信号经过整流、汇总，并通过示波器屏幕呈现给每个受试者。利用这种视觉反馈，要求受试者在模拟组牙功能咬合时以最大自主收缩的50%水平进行紧咬任务，并记录三维髁突位移。发现了一种对髁突位移有统计学显著影响的实验性咬合模式（方差分析：P<0.001）。与模拟犬牙保护咬合相比，模拟组牙功能咬合导致工作侧髁突位移较小，模拟双侧平衡咬合导致非工作侧和工作侧髁突位移显著较小。这些结果表明，在控制紧咬水平的实验室条件下，工作侧牙齿接触增加有可能降低工作侧关节负荷，平衡侧接触有可能降低非工作侧关节负荷。
