Evaluation of genetic risk related to catechol-O-methyltransferase (COMT) and ß2-adrenergic receptor (ADRB2) activity in different diagnostic subgroups of temporomandibular disorder in Brazilian patients.

The aim of this study was to evaluate the possible association between polymorphisms in the catechol-O-methyltransferase (COMT) and ß2-adrenergic receptor (ADRB2) genes and muscular temporomandibular disorders (TMD). This was a case-control study. Individuals were evaluated using the Research Diagnostic Criteria for Temporomandibular Disorders and were divided into three groups: unaffected (no TMD) (n=154); exclusively muscular TMD (n=49); exclusively articular TMD (n=49). Genomic DNA was obtained from saliva samples, and single nucleotide polymorphisms in the COMT (rs165774, rs6269, rs9332377) and ADRB2 (rs2053044, rs1042713, rs1042714) genes were investigated. The TT genotype for the COMT rs9332377 gene was highly associated with the presence of muscular TMD (P= 0.03). With respect to the ADRB2 gene, the non-polymorphic AA genotype in the rs1042713 region was more prevalent in the articular TMD group than in the muscular TMD group (P= 0.05). This study supports the hypothesis that alterations in the COMT and ADRB2 genes influence the muscular pathophysiology.

Association between temporomandibular disorders and pain in other regions of the body.

The pain from temporomandibular disorder (TMD) is often associated with physical symptoms of other chronic pain disorders and comorbidities, such as generalised muscle and joint pain. However, this association is not widely studied. To evaluate the prevalence of comorbid pain in joints, specifically in the knees, hips, ankles, shoulders, wrists and elbows, in individuals with and without TMD. We evaluated 337 patients from a public hospital in the city of Rio de Janeiro, Brazil. The Research Diagnostic Criteria for TMD questionnaire were used for the diagnosis of TMD. To assess the presence of other joint pain, the patients were asked to answer questions considering: the presence of pain in the knee, hip, ankle, shoulder, wrist and elbow joints and time duration of pain. Individuals with TMD are 5·5 times more likely to present with other joint pain compared with those without the disorder. TMD muscle disorders were most associated with a higher number of pain at the other locations. There was a significant association between the presence of pain at the other locations, muscle (P < 0·001) and joint disorders (P = <0·001), as well as age advance, in TMD participants, showed to be a covariate factor for pain at the other locations. Individuals with TMD showed a high prevalence of pain in other joints of the body when compared with individuals without the disorder, and knee pain was the most prevalent pain complaint.

Evaluation of temporomandibular joint disc displacement as a risk factor for osteoarthrosis.

Temporomandibular joint (TMJ) disc displacement is a clinical sign often found in patients with temporomandibular disorders (TMDs) and associated with TMJ osteoarthrosis. Osteoarthrosis is a degenerative joint disease that may be associated with pain and functional disability. The aim of this study was to evaluate the odds ratio (OR) of joints with disc displacement presenting osteoarthrosis via magnetic resonance imaging (MRI) analysis. In total, 224 TMJ images from patients with signs and symptoms of a TMD were evaluated. The OR, a measure of association, was used to calculate the likelihood of TMJ disc displacement (with or without reduction) with osteoarthrosis. Joints with anterior disc displacement with reduction (ADDwR) and anterior disc displacement without reduction (ADDwoR) were 2.73- and 8.25-times, respectively, more likely to have osteoarthrosis. A nine-times greater likelihood of osteophyte occurrence was observed in cases of ADDwoR, whereas a lower OR for their occurrence (OR 2.96) was observed in cases of ADDwR. The significant OR of joints with disc displacement presenting osteoarthrosis, particularly in cases of ADDwoR, emphasizes the importance of accurate assessment of changes in disc position, which may be associated with other painful and functional disorders of the TMJ.

Correlation between the levels of non-specific physical symptoms and pressure pain thresholds measured by algometry in patients with temporomandibular disorders.

Recent studies showed that patients with chronic TMD pain also feature increased sensitivity in other craniofacial regions, and even in remote peripheral areas, suggesting that nociceptive processing is centrally facilitated in this patient population. The aim of this study was to investigate the existence of a negative correlation between the levels of non-specific physical symptoms and pressure pain thresholds measured by algometry at sites distant from the chief complaint of oro-facial pain in patients with TMD. A total of 20 female patients were evaluated comprising 11 patients diagnosed with myofascial pain (Group I of RDC/TMD) and 9 patients with arthralgia (Group III of RDC/TMD), with both reporting chronic TMD pain for at least 3 months. Patients were tested by the pressure algometry technique, and, in the same visit, clinical diagnosis and levels of non-specific physical symptoms, including pain-related issues or not, were obtained. The raw scores were then standardised into a T-score. The possible correlation between the dependent variable levels of non-specific physical symptoms and pressure pain thresholds measured by algometry at sites distant from the chief complaint of oro-facial pain was assessed with Spearman's correlation coefficient. Results were considered statistically significant, which stood a lower than 5% probability of occurring by chance (P < 0·05). A statistically significant (P = 0·02) negative correlation (-0·51) was found to exist between the levels of non-specific physical symptoms, only if including issues involving pain-related symptoms, and experimental pressure pain thresholds in patients with painful TMD.

Depression levels in chronic orofacial pain patients: a pilot study.

The assessment of depressive behaviour in chronic pain patients is especially important, because depression is commonly associated with chronic pain. The aim of this pilot study was to compare depression levels between patients with head and neck cancer pain and temporomandibular disorders (TMD), and to determine whether there is an association between depression levels and chronic pain severity. This study was an observational and sectional study and the sample consisted of 40 patients, uniformly divided into those with chronic orofacial pain related to cancer and those with painful TMD classified with research diagnostic criteria for temporomandibular disorders (RDC/TMD) axis I. Depression levels, pain intensity and severity were assessed with RDC/TMD axis II. The study demonstrated statistically significant differences in depression levels present in the head and neck cancer pain group and the painful TMD group, with the occurrence of a moderate statistically significant correlation between depression levels and chronic pain severity.