Takada Jun-Ichi, Miyamoto Jun J, Sato Chiemi, Dei Ayano, Moriyama Keiji
Maxillofacial Orthognathics, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, Japan.
Eur J Orthod. 2018 May 25;40(3):304-311. doi: 10.1093/ejo/cjx061.
BACKGROUND/OBJECTIVES: The peri-oral muscles-including orbicularis oris-are critical in maintaining equilibrium in tooth position. Lip incompetence (LI) can thus be a factor in malocclusion. We therefore aimed to validate a technique to evaluate not only muscle activity via electromyography (EMG) but also muscle endurance and fatigue via blood flow (BF) for LI.
SUBJECTS/METHODS: Subjects were classified into increased muscle tension/lip incompetent (experimental) and normal muscle tension/lip competent (control) groups. Each subject then exerted force on a custom-made traction plate connected to a tension gauge. Using laser speckle imaging and electromyographic measurements, we characterized muscle activity and corresponding BF rates in these subjects in various states of resting, loading, and recovery.
Results showed a significant difference between the experimental and control groups, notably in the rate of change in BF to the inferior orbicularis oris muscle under conditions of increasing load (graded exertion). Furthermore, the data suggested that the muscles in the control group undergo a more prolonged (and therefore presumably more complete) recovery than muscles in the experimental group. These factors of reduced BF and short recovery may combine to accelerate muscle fatigue and produce LI.
The sample used here was controlled for malocclusion (including open bite) to eliminate this type of confounding effect.
CONCLUSIONS/IMPLICATIONS: From these findings, we conclude that reduced BF and inadequate recovery in the orbicularis oris muscles may be more significant than EMG activity in the assessment of LI.
背景/目的：包括口轮匝肌在内的口周肌肉对于维持牙齿位置的平衡至关重要。因此，唇功能不全（LI）可能是错牙合畸形的一个因素。我们的目的是验证一种技术，该技术不仅可以通过肌电图（EMG）评估肌肉活动，还可以通过血流（BF）评估LI患者的肌肉耐力和疲劳情况。
受试者/方法：将受试者分为肌肉张力增加/唇功能不全（实验组）和肌肉张力正常/唇功能正常（对照组）两组。然后，让每个受试者对连接到张力计的定制牵引板施加力。通过激光散斑成像和肌电图测量，我们对这些受试者在休息、加载和恢复的各种状态下的肌肉活动和相应的BF率进行了表征。
结果显示实验组和对照组之间存在显著差异，特别是在负荷增加（分级用力）条件下，口轮匝肌下部的BF变化率。此外，数据表明，与实验组的肌肉相比，对照组的肌肉恢复时间更长（因此可能更完全）。BF降低和恢复时间短这些因素可能共同作用，加速肌肉疲劳并导致LI。
这里使用的样本对包括开牙合在内的错牙合畸形进行了控制，以消除这种混杂效应。
结论/启示：从这些发现中，我们得出结论，在评估LI时，口轮匝肌的BF降低和恢复不足可能比EMG活动更重要。
