覚醒時の咬筋活動と顎関節症関連症状の関係

Relationship between masseter muscle activity during wakefulness and temporomandibular disorder-related symptoms.

抄録

背景:

覚醒時の咬筋活動は、顎関節症（TMD）関連症状、心理社会的状態、疼痛関連障害と関連する可能性があるが、この関係は不明である。

BACKGROUND: Masseter muscle activity during wakefulness may be associated with temporomandibular disorder (TMD)-related symptoms, psychosocial status and pain-related disability; however, this relationship is unclear.

目的:

本研究は、覚醒時の咬筋筋電図（EMG）バースト／持続時間と顎関節症関連症状、心理社会的状態、疼痛関連障害との関連を明らかにすることを目的とした。

OBJECTIVES: This study aimed to determine the relationship between masseter muscle electromyography (EMG) burst/duration during wakefulness and TMD-related symptoms, psychosocial status and pain-related disability.

方法:

60名の参加者を対象に、データロガー型超小型筋電図システムを用いて覚醒時の咬筋活動を評価し、顎関節症の診断基準（DC/TMD）のI軸とII軸を通して顎関節症関連症状、心理社会的状態、疼痛関連障害を評価した。0.25秒以上2.0秒未満の筋電バーストと2.0秒以上の筋電バーストをそれぞれ相性バーストと強直バーストに分類した。

METHODS: Sixty participants were assessed masseter muscle activity during wakefulness using a data-logger-type ultraminiature EMG system and TMD-related symptoms, psychosocial status and pain-related disability through Axis I and II of the diagnostic criteria for TMD (DC/TMD). EMG bursts lasting longer than 0.25 s but less than 2.0 s and those lasting longer than 2.0 s were classified as phasic and tonic bursts, respectively.

結果:

I軸のDC/TMD検査票で評価したところ、側頭筋および咬筋の触診関連痛を有する参加者は、覚醒中の咬筋のバースト回数（回数/h）が多く（それぞれp=.035およびp=.009）、持続時間（時間/h）が長かった（それぞれp=.013およびp=.004）。咬筋の触診関連痛を有する参加者は、Axis IIを用いた覚醒時の口腔行動スコアが高く（p=.001）、これは覚醒時の咬筋の緊張性バースト活動の回数と持続時間に影響した（それぞれp=.011とp=.007）。

RESULTS: Participants with palpation-related pain in the temporalis and masseter muscles, as assessed through the DC/TMD examination form in Axis I, had more bursts (number/h) (p = .035 and p = .009, respectively) and longer duration (time/h) (p = .013 and p = .004, respectively) of tonic bursts of the masseter muscle during wakefulness. Participants with palpation-related pain in the masseter muscles had higher oral behaviour scores during wakefulness using Axis II (p = .001), which affected the number and duration of tonic bursts of the masseter muscle activity during wakefulness (p = .011 and p = .007, respectively).

結論:

トニックバーストは主に食いしばりを反映するため、触診で咬筋に痛みのある人は、食いしばりの頻度が高く、持続時間が長い可能性があり、また覚醒中の口腔行動の頻度も高い可能性がある。

CONCLUSION: As tonic bursts mainly reflect clenching, individuals with pain in the masseter muscles by palpation may have a high frequency and longer duration of clenching, as well as a high frequency of oral behaviours during wakefulness.