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Journal of Oral & Facial Pain and Headache



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J Orofac Pain 28 (2014), No. 2     9. May 2014
J Orofac Pain 28 (2014), No. 2  (09.05.2014)

Page 159-164

Effect of Experimental Tooth Clenching on the Release of β-Endorphin
Dawson, Andreas / Ljunggren, Lennart / Ernberg, Malin / Svensson, Peter / List, Thomas
Aims: 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.
Methods: 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.
Results: Significant main effects for time and group were observed for pain intensity and PPT, with significantly lower mean values of pain intensity (P < .001) and PPT (P < .01) after the clenching task compared with baseline. M-TMD patients had significantly higher pain intensity (P < .001) and significantly lower PPT (P < .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.
Conclusion: 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.

Keywords: beta-endorphin, bruxism, masseter muscle, temporomandibular joint disorders