Yamaguchi S, Okada C, Watanabe Y, Watanabe M, Hattori Y
Division of Aging and Geriatric Dentistry, Tohoku University Graduate School of Dentistry, Sendai, Japan.
Department of Health Services Management, Faculty of Health Sciences, Tohoku Fukushi University, Sendai, Japan.
J Oral Rehabil. 2018 Jan;45(1):9-16. doi: 10.1111/joor.12583. Epub 2017 Nov 15.
In a previous study, we used muscle functional magnetic resonance imaging to show that the anterior movement of the occlusal point increased the activity of the superior head of the ipsilateral lateral pterygoid muscle (ipsilateral SHLP) during unilateral single-tooth clenching. The purpose of this study was to verify the hypothesis that the increased activity of the ipsilateral SHLP described above serves to antagonise the occlusal force acting on the condyle. In total, 9 healthy volunteers were requested to perform left unilateral clenching at the first molar or first premolar region for 1 minute at 20% or 40% maximum voluntary clenching force. Changes in the mean proton transverse relaxation time (∆T2) were examined from the magnetic resonance images obtained before and after each clenching act as an index of the activity in all masticatory muscles. Correlation analyses of the mean ΔT2 for each volume of interest were performed with the first molar or premolar clenches to analyse the correlation between the activities in each muscle. A statistically significant correlation was exhibited between the ipsilateral temporal and ipsilateral SHLP (r = .651, P = .003) during first premolar clenching. However, no significant correlations were observed in the ipsilateral SHLP during first molar clenching. The results of this study suggest that the ipsilateral SHLP may contribute to the pulling of the mandibular condyle forward against the occlusal force generated by the ipsilateral temporal muscle.
在之前的一项研究中，我们使用肌肉功能磁共振成像显示，在单侧单牙咬紧期间，咬合点向前移动会增加同侧翼外肌上头（同侧SHLP）的活动。本研究的目的是验证上述同侧SHLP活动增加有助于对抗作用于髁突的咬合力这一假设。总共9名健康志愿者被要求在第一磨牙或第一前磨牙区域以最大自主咬合力的20%或40%进行左侧单侧咬紧1分钟。从每次咬紧前后获得的磁共振图像中检查平均质子横向弛豫时间（∆T2）的变化，作为所有咀嚼肌活动的指标。对每个感兴趣体积的平均∆T2与第一磨牙或前磨牙咬紧进行相关性分析，以分析各肌肉活动之间的相关性。在第一前磨牙咬紧期间，同侧颞肌和同侧SHLP之间表现出统计学上的显著相关性（r = 0.651，P = 0.003）。然而，在第一磨牙咬紧期间，同侧SHLP未观察到显著相关性。本研究结果表明，同侧SHLP可能有助于下颌髁突对抗同侧颞肌产生的咬合力向前拉动。
