Effect of experimental anterior temporalis muscle pain on jaw movements

Abstract

To test the hypotheses that experimental noxious stimulation of the anterior temporalis muscle results in significant decreases in jaw movement amplitude and velocity, and there are significant correlations between scores of mood or pain-related cognitions and amplitude and velocity. The jaw movements of 14 asymptomatic participants were recorded during standardised open/close jaw movements and free and standardised chewing tasks. Tonic infusion of hypertonic saline into the right anterior temporalis muscle maintained pain intensity between 40 and 60 mm on a 100-mm visual analogue scale. Tasks were performed in a single session in the following sequence: baseline condition, test 1 condition (during hypertonic or isotonic saline infusion), test 2 condition (during saline infusion) (10-min rest between conditions). Participants completed the Depression, Anxiety and Stress Scale (DASS-21) and the Pain Catastrophizing Scale (PCS). Amplitude and velocity of opening and closing were compared between conditions with a repeated-measures analysis of variance (anova), and Spearman's rank correlation coefficient explored correlations; statistical significance: P < 0·05. For any of the three tasks, there were no significant differences in kinematic variables between any condition and no significant correlations between DASS-21 or PCS scores and kinematic variables during hypertonic saline infusion. The absence of a significant reduction in velocity or amplitude of open/close or chewing jaw movements during experimental temporalis muscle pain is not consistent with the Pain Adaptation Model proposing decreases in kinematic measures in pain. The lack of significant correlations between psychological variables and measures of jaw movement may reflect the low scores reported by our study sample.

Reorganization of motor unit activity at different sites within the human masseter muscle during experimental masseter pain

“…The PCS scores ranged from 0 to 33 with a mean total score of 9.5 (9.0; mean scores for rumination: 4.2, helplessness: 3.6, and magnification: 1.7). The low DASS-21 scores and the mostly low PCS scores are consistent with previous reports of these scale scores in young, healthy participants (25,26). Given that these scores were consistently low, no correlations were made with the SMU occurrence data.…”

Experimental noxious stimulation of the right masseter muscle does not affect bilateral masseter and temporalis muscle activity and force parameters during standardised isometric biting tasks

“…Experimental noxious stimulation of the right masseter muscle did not significantly affect force rates (Tables and ) or force levels (Table ) during the jaw closing isometric tasks across the blocks. These findings are consistent with previous data demonstrating the ability to maintain constant force during experimental muscle pain both in the spinal system and the trigeminal system . The present findings show that whatever neuroplastic changes are occurring in the brain regions driving these tasks during the experimental noxious masseter muscle stimulation, the resultant muscle activity is sufficient to allow the individuals to generate force at 2 steady force levels and at 2 rates of force application.…”

A New Tridimensional Insight into Geometric and Kinematic Characteristics of Masticatory Cycles in Participants with Normal Occlusion

“…Several studies have evaluated the speed of the movements of the masticatory cycles [ 15 , 17 – 20 , 28 – 30 ]. However, there is still no agreement in reported values, from 36 (± 10.1) mm/s average speed [ 20 ] up to 147 mm/s peak speed [ 30 ] in patients with healthy teeth.…”

“…Several studies have evaluated the speed of the movements of the masticatory cycles [ 15 , 17 – 20 , 28 – 30 ]. However, there is still no agreement in reported values, from 36 (± 10.1) mm/s average speed [ 20 ] up to 147 mm/s peak speed [ 30 ] in patients with healthy teeth. Most of the studies chose a peak speed [ 17 – 19 , 30 , 31 ] as a base parameter of the speed of masticatory movement, reporting approximate values between 100 and 160 mm/s.…”

“…Previous studies evaluated the geometric characteristics of the masticatory cycles related to the speed of these movements [ 15 , 17 – 20 ] in various clinical situations using different methods of recording and analysis. This fact reveals the importance of a valid quantitative analysis of masticatory movements, which is crucial for dental practice, because it eliminates subjectivity in understanding changes/improvements obtained with clinical interventions [ 15 ].…”