Related Experiment Video
Updated: Apr 15, 2026
Temporomandibular Joint Pain Measurement by Bite Force and Von Frey Filament Assays in Mice
Published on: September 13, 2024
A pilot study of ambulatory masticatory muscle activities in temporomandibular joint disorders diagnostic groups
L R Iwasaki1, Y M Gonzalez, H Liu
1Departments of Orthodontics & Dentofacial Orthopedics and Oral & Craniofacial Sciences, School of Dentistry, University of Missouri-Kansas City, Kansas City, MO, USA.
Objective:
To determine differences in masticatory muscle usage between temporomandibular joint disorders diagnostic groups.
Setting And Sample Population:
Seventy-one informed and consented subjects (27 men; 44 women) participated at the University at Buffalo.
Material And Methods:
Research diagnostic criteria and imaging data were used to categorize subjects according to the presence/absence +/- of TMJ disc placement (DD) and chronic pain (P) (+DD+P, n=18; +DD-P, n=14; -DD-P, n=39). Electromyographic (EMG)/bite-force calibrations determined subject-specific masseter and temporalis muscle activities per 20 N bite-force (T20N , μV). Over 3 days and nights, subjects collected EMG recordings. Duty factors (DFs, % of recording time) were determined based on threshold intervals (5-9, 10-24, 25-49, 50-79, ≥80% T20N ). anova and Tukey-Kramer post hoc tests identified 1) diagnostic group differences in T20N and 2) the effects of diagnostic group, gender, time and interval on muscle DFs.
Results:
Mean (±SE) temporalis T20N in +DD+P subjects was significantly higher (71.4±8.8 μV) than masseter T20N in these subjects (19.6±8.8 μV; p=0.001) and in -DD-P subjects (25.3±6.0 μV, p=0.0007). Masseter DFs at 5-9% T20N were significantly higher in +DD-P women (3.48%) than +DD-P men (0.85%) and women and men in both other diagnostic groups (all p<0.03), and in +DD+P women (2.00%) compared to -DD-P men (0.83%; p=0.029). Night-time DFs at 5-9% T20N in +DD-P women (1.97%) were significantly higher than in -DD-P men (0.47%) and women (0.24%; all p<0.01).
Conclusions:
Between-group differences were found in masticatory muscle activities in both laboratory and natural environmental settings.
