Orofacial muscle pain – a translational approach to study mechanisms and treatment outcome
||Malin Ernberg, Karolinska Institutet, Stockholm, Sweden; Peter Svensson, Aarhus University, Aarhus, Denmark; Björn Gerdle, Faculty of Health Science, Linköping, Sweden; Britt Larsson, University Hospital, Linköping University, Linköping, Sweden; Sofia Lo
||Swedish Dental Council
||2009-08-01 -- 2013-01-01
||Faculty of Odontology
Numerous epidemiological studies report higher frequencies of pain disorders, including myofascial TMD, in women than in men. Studies have reported that stress-induced bruxism increases the risk of myofascial TMD 5-fold. Female TMD patients were found to have markedly increased daytime cortisol levels and significantly higher cortisol responses to experimental stress than a control group. Increased levels of 5-HT in patients with chronic myalgia compared to healthy subjects has been reported, as have higher cortisol levels in women who take oral contraceptives compared with women who do not. This latter finding indicates that sex steroid hormones interact with cortisol release, which was reported to interact with central release of 5-HT.
Pain models that mimic the pain condition are essential for broadening knowledge of clinical pain. Jaw muscle overload due to tooth clenching, for example, is believed to cause pain by the release of inflammatory mediators. Static contractions are considered more harmful than dynamic contractions.
The pathophysiology of myofascial TMD is largely unknown; suggested treatments are mainly symptomatic. Treatment regimes include, for example, pharmacological treatment, occlusal appliances, physiotherapy, and cognitive behavioral therapy (CBT). Use of CBT is widespread in pain clinics, and CBT has been incorporated in overall management of a variety of chronic pain conditions. Studies and systematic reviews have found that CBT is efficacious in the treatment of TMD, which indicates that psychological distress is also involved in the etiology of myofascial TMD.
The hypothesis is that tooth clenching facilitate the peripheral release of 5-HT and contributes to the development and maintenance of myofascial TMD and that this is influenced by estrogen and cortisol levels. If so, management strategies for myofascial TMD that aim to decrease intramuscular 5-HT levels and restore blood flow would reduce pain and dysfunction.
The overall aim is to gain better understanding of the pathophysiology underlying myofascial TMD to improve diagnostics and establish more rational management. Using a translational approach, the project will combine basic neurobiology with clinical trials that have a special emphasis on the involvement of serotonergic and cortisol-dependent mechanisms in relation to gender.
Publikationer inom projektet
1a) Investigate release of 5-HT in the masseter muscle in healthy females and healthy males and, if a correlation exists, between released 5-HT levels and cortisol and estrogen levels.
1b) Assess 5-HT release and microcirculation in the masseter muscle after tooth-clenching exercises in myofascial TMD patients compared to healthy age- and gender-matched subjects (controls).
2) Analyze differences in pain-related variables, levels of psychological stress, and cortisol and 5-HT levels between healthy subjects with experimental tooth-clenching induced myalgia and myofascial TMD patients.
3) Investigate the relation between tooth-clenching forces and development of masseter muscle pain and vibrotactile sensitivity.
4) Assess CBTs’ influence on pain-related variables and psychological stress, blood 5-HT, cortisol levels, and tooth-clenching activity in myofascial TMD patients compared to myofascial TMD patients receiving brief information.