RT  - Journal of Oral & Facial Pain and Headache
ID  - 10.11607/ofph.1210
T1  - Effect of Experimental Tooth Clenching on the  Release of 𝛃-Endorphin
A1  - Andreas Dawson
A1  - Lennart Ljunggren
A1  - Malin Ernberg
A1  - Peter Svensson
A1  - Thomas List
K1  - beta-endorphin; bruxism; masseter muscle; temporomandibular joint disorders
YR  - 2014
SP  - 159
AB  - <p><b>Aims:</b> To investigate the association between experimental tooth clenching and the release of β-endorphin in patients with myofascial temporomandibular disorders (M-TMD) and healthy subjects. <b>Methods:</b> Fifteen M-TMD patients and 15 healthy subjects were included and assigned an experimental tooth-clenching task. Venous blood was collected and pain intensity was noted on a visual analog scale. The masseter pressure pain threshold (PPT) was assessed 2 hours before the clenching task and immediately after. A mixed-model analysis of variance was used for statistical analyses. <b>Results:</b> Significant main effects for time and group were observed for pain intensity and PPT, with significantly lower mean values of pain intensity (<i>P</i> &lt; .001) and PPT (<i>P</i> &lt; .01) after the clenching task compared with baseline. M-TMD patients had significantly higher pain intensity (<i>P</i> &lt; .001) and significantly lower PPT (<i>P</i> &lt; .05) than healthy subjects. No significant time or group effects were observed for the level of β-endorphin. Neither pain intensity nor PPT correlated significantly with β-endorphin levels. <b>Conclusion: </b>This experimental tooth-clenching task was not associated with significant alterations in β-endorphin levels over time, but with mechanical hyperalgesia and low to moderate levels of pain in healthy subjects and M-TMD patients, respectively. More research is required to understand the role of the β-endorphinergic system in the etiology of M-TMD. </p>