Effects of Experimental Tooth Clenching on Pain and Intramuscular Release of 5-HT and Glutamate in Patients With Myofascial TMD. Issue 8 (August 2015)

• Record Type: Journal Article
• Authors: Dawson, Andreas; Ghafouri, Bijar; Gerdle, Björn; List, Thomas; Svensson, Peter; Ernberg, Malin
• Is Part Of: Clinical journal of pain. Volume 31:Issue 8(2015)
• Publication Date: 2015-08
• Subjects: Pain -- Periodicals; Pain -- Treatment -- Periodicals; Analgesia -- Periodicals; 616.047205
• DOI: 10.1097/AJP.0000000000000154
• Languages: English
• ISSNs: 0749-8047

Abstract

<abstract> <title> <x xml:space="preserve">Abstract</x> </title> <sec> <title>Objectives:</title> <p>It has been suggested that tooth clenching may be associated with local metabolic changes, and is a risk factor for myofascial temporomandibular disorders (M-TMD). This study investigated the effects of experimental tooth clenching on the levels of 5-HT, glutamate, pyruvate, and lactate, as well as on blood flow and pain intensity, in the masseter muscles of M-TMD patients.</p> </sec> <sec> <title>Methods:</title> <p>Fifteen patients with M-TMD and 15 pain-free controls participated. Intramuscular microdialysis was performed to collect 5-HT, glutamate, pyruvate, and lactate and to assess blood flow. Two hours after the insertion of a microdialysis catheter, participants performed a 20-minute repetitive tooth clenching task (50% of maximal voluntary contraction). Pain intensity was measured throughout.</p> </sec> <sec> <title>Results:</title> <p>A significant effect of group (<italic>P</italic><0.01), but not of time, was observed on 5-HT levels and blood flow. No significant effects of time or group occurred on glutamate, pyruvate, or lactate levels. Time and group had significant main effects on pain intensity (<italic>P</italic><0.05 and <0.001). No significant correlations were identified between: (1) 5-HT, glutamate, and pain intensity; or between (2) pyruvate, lactate, and blood flow.</p> </sec> <sec> <title>Discussion:</title> <p>This experimental tooth clenching model increased jaw muscle pain levels in M-TMD patients and evoked low levels of jaw muscle pain in controls. M-TMD patients had significantly higher levels of 5-HT than controls and significantly lower blood flow. These 2 factors may facilitate the release of other algesic substances that may cause pain.</p> </sec> </abstract>