Exploring the relationship between muscle activity, jaw behaviour and pain

Area of Science:

• Biomedical Engineering
• Pain Management
• Musculoskeletal Research

Background:

• Muscle overload is a known factor in musculoskeletal pain, but real-time assessment of behavioral and physiological markers is difficult.
• Awake bruxism and its link to temporomandibular disorder (TMD) pain require further investigation using objective measures.

Purpose of the Study:

• To explore the relationship between self-reported awake bruxism (via EMA) and jaw muscle activity (via sEMG).
• To differentiate between individuals with and without TMD pain regarding these measures.
• To assess the combined utility of EMA and sEMG for evaluating musculoskeletal overload.

Main Methods:

• Seventy participants (31% reporting pain) underwent a 3-day EMA using a smartphone app, with sEMG data collected on day 1.
• Muscle overload was defined as activity exceeding 20% of maximum voluntary contraction (MVC).
• Analysis focused on overload duration, area under the curve (AUC), and intensity levels.

Main Results:

• A strong correlation was found between EMA-reported bruxism and sEMG overload duration (ρ=0.62).
• AUC correlated with EMA only in the TMD group.
• TMD patients showed shorter high-intensity bursts but prolonged low-intensity muscle activity compared to controls.
• Higher bruxism behavior and stress were reported by women and those with pain.

Conclusions:

• The combination of EMA and sEMG offers a valid method for assessing musculoskeletal overload, integrating perceptual and physiological data.
• EMA can identify pain-related risk behaviors, aiding in the development of tailored, patient-centered pain management strategies for TMD.