Temporomandibular Disorders Group Research Articles

Oral splints for temporomandibular disorder or bruxism: a systematic review

Objectives To evaluate the clinical-effectiveness of oral splints for patients with TMD or bruxism for the primary outcomes: pain (TMD) and tooth wear (bruxism).Data sources Four databases including MEDLINE and EMBASE were searched from inception until 1 October 2018.Data selection and extraction Randomised controlled trials comparing all types of splints versus no/minimal treatment for patients with TMD or bruxism were eligible. Standard Cochrane review methods were used. Standardised mean differences (SMD) were pooled for the primary outcome of pain, using random effects models in TMD patients.Data synthesis Thirty-seven trials were included and the evidence identified was of very low certainty using GRADE assessments. When all subtypes of TMD were pooled into one global TMD group, there was no evidence that splints reduced pain: SMD (up to 3 months) -0.18 (95% CI -0.42 to 0.06); 13 trials, 1,076 participants. There was no evidence that any other outcomes improved when using splints. There was no evidence of adverse events associated with splints, but reporting was poor regarding this outcome. No trials measured tooth wear in patients with bruxism. There was a large variation in diagnostic criteria, splint types and outcome measures used and reported. Sensitivity analyses based on these factors did not indicate a reduction in pain.Conclusions The very low-certainty evidence identified did not demonstrate that splints reduced pain in TMD as a group of conditions. There is insufficient evidence to determine whether splints reduce tooth wear in patients with bruxism.

Removable prostheses improve OHRQL and satisfaction of elderly people with rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune disease that affects joint tissues and causes severe physical and functional impairments on quality of life due to muscular and articular pain. The involvement of temporomandibular joint in RA interferes with mouth opening and masticatory process. However, no studies addressed the impact of RA on oral health-related quality of life (OHRQoL) and satisfaction with prostheses use in elderly people. Aim: This study assessed the impact of oral rehabilitation with conventional dentures on the OHRQoL and prostheses satisfaction in elderly patients with RA, associated or not with temporomandibular disorder (TMD). Methods: Forty-five elderly were enrolled and divided into three groups: (1) RA and TMD (n=15, experimental), (2) RA without TMD (n=15, experimental), and (3) without RA and without TMD (n=15, control). The OHRQoL and the prostheses satisfaction were evaluated before and after new oral rehabilitation with partial and/or complete dentures. The OHRQoL and prosthesis satisfaction were assessed and verified through OHIP-14 questionnaire and visual analogue scale, respectively. Results: TMD group exhibited the worst mean values (P<0.05) for all OHIP-14 domains before insertion of new dentures. Group 2 showed worst means (P<0.05) compared to controls for functional limitation and physical pain domains of the OHIP-14, but not in the general score. Patients showed better outcomes of satisfaction with prostheses use only after the new rehabilitation. Conclusion: The use of new and well-fitted dentures improves all domains of OHRQoL in patients with RA and TMD and all groups were satisfied with prostheses use after the new rehabilitation with conventional dentures.

Sleep Disorders in Patients with Temporomandibular Disorders (TMD) in an Adult Population-Based Cross-Sectional Survey in Southern Brazil.

To verify the prevalence of sleep disorders in temporomandibular disorders (TMD) subjects in a Brazilian population-based, cross-sectional survey (N = 1,643). Patients were assessed with the Research Diagnostic Criteria for TMD (RDC/TMD) Axes I and II and the Sleep Assessment Questionnaire. Student t test and Pearson chi-square test were used for continuous and categorical data analyses, respectively. TMD subjects had significantly worse sleep disorders than controls (Graded Chronic Pain Severity categories I through IV vs 0, respectively) in RDC/TMD Axis II variables. Sleep disorders were also worse in the Axis I TMD groups (myofascial pain and arthralgia/osteoarthritis/osteoarthrosis), with the exception of disc displacements. TMD subjects had worse sleep disorders, mainly in Axis I TMD groups, with higher pain/disability levels.

Frequency distribution of temporomandibular disorders according to occlusal factors: A cross-sectional study

Temporomandibular disorder (TMD) is a common condition affecting the temporomandibular joint and causes pain and discomfort. However, the role of factors contributing to this problem is still controversial. The purpose of this cross-sectional study was to determine the correlation of occlusal factors and parafunctional habits with TMD and The determination of TMD prevalence among patients referring to Isfahan Dental School in 2017. In this cross-sectional study, A total of 200 patients between 20 and 50 years were examined and questioned based on the Research Diagnostic Criteria for Temporomandibular Disorders assessment instrument. The association of occlusal factors (dental relationship, lateral occlusal scheme, horizontal differences between centric occlusion and Maximum intercuspation (MI), difference between MI and mandibular resting position) and parafunctional habits (bruxism/clenching and habits) with TMD was analyzed using Chi-square tests and independent sample t-test (α = 0.05). Binomial logistic regression analysis was performed with respect to confounding variables. The prevalence of TMD in the studied sample was 58.9%. Only bruxism showed a significant difference between TMD and non-TMD groups (P < 0.05). Other parafunctional and occlusal factors did not act as influential factors for TMD. Parafunction may play an important role in the initiation of TMD, although other habits and occlusal factors are considered as noninfluential factors. However, larger sample size and multicenter sampling are recommended for the future studies.

Salivary cortisol could be a promising tool in the diagnosis of temporomandibular disorders associated with psychological factors

Background: Biopsychosocial models emphasize the multifactorial nature of temporomandibular disorders (TMDs). The role of cognitive, social, and biological factors in the etiology of TMDs has been reported. Aim: To test the salivary cortisol levels in young adults with the temporomandibular joint disorder and having positive depression level and with TMD but with negative depression level and compared with the control group. The correlation between cortisol levels and depression levels according to axis-II of Research Diagnostic Criteria (RDC) was assessed. Settings and Design: The study was a randomized, prospective, and double-blinded study. Materials and Method: The total sample comprised 60 subjects. The study comprised 20 subjects with TMD and depression, 20 subjects with TMDs and without depression, and 20 subjects were taken as the control group. To measure these variables, research diagnostic criteria (RDC/TMJ) were used for the study. Salivary cortisol levels were determined by Enzyme-linked immunosorbent assay (ELISA). Statistical Analysis: A paired t-test, ANOVA, and linear multi regression tests applied to compare the TMD groups with the control group. Results: The results showed that there was a positive correlation between morning and evening salivary cortisol levels in all the groups and the correlation coefficient was 0.729. There was a significantly higher value of salivary cortisol in TMD patients with depression than TMD patients without depression and the control group. Conclusion: Salivary cortisol could be a promising tool in identifying underlying psychological factors that could be associated with TMD.

A novel mobile application to determine mandibular and tongue laterality discrimination in women with chronic temporomandibular disorder.

Background Chronic pain from temporomandibular disorders (TMDs) is caused by a somatosensory disturbance due to sustained activation of central nervous system nociceptive pathways, which can induce changes in neuroplasticity in the thalamus, basal ganglia and limbic system, as well as disturbances in the somatosensory, prefrontal and orbitofrontal cortex and cognitive impairment. The main objective of this study was to determine the discrimination capacity of mandibular and tongue laterality between women with chronic TMDs and asymptomatic women. Material and Methods This descriptive-comparative study examined 2 groups with a total of 30 women. All participants were between the ages of 23 and 66 years and were assigned to the chronic TMD group or the asymptomatic group according to the inclusion criteria. We employed a mobile application developed specifically for this study to measure the accuracy and reaction time (RT) of mandibular and tongue laterality discrimination. Results The chronic TMD group had a lower success rate in laterality discrimination (mean mandibular accuracy of 40% and mean tongue accuracy of 67%) than the asymptomatic group (mean mandibular accuracy of 61% and mean tongue accuracy of 90%). These results showed statistically significant differences between the groups for mandibular laterality discrimination (d, 1.14; p<0.01) and tongue laterality discrimination (d, 0.79; p=0.03). The asymptomatic group had faster RTs than the chronic TMD group. The data revealed statistically significant differences for the right mandibular RT (d, 0.89; p=0.02) and right tongue RT (d, 0.83; p=0.03). However, there were no significant differences for left mandibular and left tongue RT. Conclusions We found that the women with chronic TMDs had a lower success rate and slower RTs in the discrimination of mandibular laterality when compared with the asymptomatic women. Key words:Mobile application, tongue, chronic temporomandibular disorder, pain, lateral discrimination, cortical representation, reaction time.

Infrared thermography assessment of patients with temporomandibular disorders.

To assess patients with and without temporomandibular disorders (TMD) infrared thermography according to the differences in thermal radiance using quantitative sensitivity and specificity tests; and to evaluate the thermal asymmetry and the correlation of the thermal intensity with the intensity of pain upon palpation. This cross-sectional study performed a quantitative evaluation of clinical and thermographic examinations. The volunteers were evaluated for the presence of TMD using RDC/TMD (Diagnostic Research Criteria for Temporomandibular Disorders), and were divided into two groups: TMD group (n = 45); control group (n = 41), composed of volunteers without TMD, according to the Fonseca Anamnestic Index. The images were assessed for selected regions of interest for the masseter, anterior temporal and TMJ muscles. The mean values ​​of the areas of both groups were compared under the receiver operating characteristic curve. Spearman correlation analysis (non-parametric data) between pain level and mean temperature, by region, and the Pearson's χ2 test was used to verify the association between the presence of temperature and pain asymmetry. The level of significance was set at p < 0.05. Both Groups, with and without TMD, presented with absolute and non-dimensional mean temperature without statistical differences (p>0.05). When correlating temperature with intensity of pain upon palpation, a negative correlation was observed for the masseter muscle. Infrared Thermography resulted in low area under the curve, making it difficult to differentiate TMD via thermographic analysis. The intensity of pain upon palpation in patients with TMD may be accompanied by a decrease in local temperature.

Comorbidity of TMD and malocclusion

Aim: to evaluate the synergic impact of muscular TMD and malocclusion on quality of life, masticatory capacity and emotional features of young adults. Methods: this cross-sectional study comprised 4 groups (n= 15): G1, individuals without TMD or malocclusion; G2, with TMD and malocclusion; G3, with TMD and without malocclusion, and G4, without TMD and with malocclusion. Muscular TMD was diagnosed by RCD/TMD. Data included quality of life (OHIP-14), masticatory capacity test (X50), emotional stress (PSS-14), depression (MDI), pain intensity and salivary cortisol. Comparative statistical analysis included One-way ANOVA and Tukey post hoc test (X50, stress and cortisol) and GENMOD followed by Wald test (OHIP-14 and pain data). Fisher's and Pearson's association analysis were carried out. Results: Comorbidity of muscular TMD and malocclusion leads to significant lower masticatory capacity (p&lt;0.05). TMD groups independently of the occlusal condition had considerably lower OHIP-14 scores and higher stress levels (self-perceived and hormonal) (p&lt;0.05). There was no statistically significant difference of emotional depression among groups. A significant positive correlation was observed among quality of life, stress and pain perception. Conclusion: muscular TMD in the overlap of malocclusion potentializes their negative effect on masticatory capacity. In addition, the hindering effect of the comorbidity is variable, however, TMD has a greater negative impact on quality of life and stress, whilst malocclusion on mastication.

Serum Analysis in Patients with Temporomandibular Disorders: A Controlled Cross-Sectional Study in Norway.

Temporomandibular disorder (TMD) is characterized by pain and dysfunction in the temporomandibular join (TMJ) and the masticatory apparatus. Associations with autoimmune diseases, inflammatory conditions, and nutrition deficiencies have been reported in previous studies of TMD patients. To evaluate essential proteins, hormones, electrolytes, and vitamins in serum from TMD patients, a standard blood sample analysis was performed in 60 TMD patients and 60 healthy controls matched for age and gender, retrieving 19 different analyses. We found that TMD patients had significantly higher values of hemoglobin (p=0.036), cobalamin (p=0.023), albumin (p=0.005), parathyroid hormone (PTH) (p=0.038), and vitamin D (p=0.005), and significantly lower values of creatinine (p=0.006) and potassium (p=0.011), compared to controls. In the TMD group, most of the determinants had a wider range, and several subjects, compared to the control group, had values outside the normal reference area. However, most of the TMD patients and controls had values within normal biological range. Our findings could not associate any severe systemic disease, malnutrition, or systemic inflammation with the TMD. Results from our study suggest that serum analyses should neither be used as a biomarker of TMD nor a diagnostic tool for an individual subject with TMD.

Cone-Beam Computed Tomographic Evaluation of Styloid Process in Patients With Temporomandibular Disorders and Asymptomatic Individuals.

Elongated styloid processes (ESP) may show clinical symptoms that are readily confused with symptoms associated with temporomandibular disorders (TMDs). The purpose of study was to compare the prevalance and characteristics of ESP in patients with TMD and asymptomatic individuals are examined by cone beam computed tomography. Angulations and length of the styloid process (SP) were evaluated in CBCT images of 100 patients with TMD symptoms and 100 control patients, retrospectively. Differences between the patient and control groups were assessed by analysis independent sample t test. Pearson correlation test was used to evaluate between length and angulation of SP relationship. The mean length of SP in the TMD group was 38.19 ± 8.6 mm for the right and 38.99 ± 8.1 mm for the right side. The mean length of SP in the control group was 36.80 ± 6.3 for the right side and 36.18 ± 6.5 mm for the left side. The mean anterior angulation of the SP in the TMD group was 22.08 ± 5.5 degree in the TMD group and 23.97 ± 4.1 degree in the control group. The mean medial angulation of the SP in the TMD group was 30.57 ± 4.9 degree and 29.89 ± 4.4 degree in the control group. There was no significant difference in length and angle between the groups (P > 0.05). No correlation was found in terms of length and angulations of SP between TMD and control groups.

Mobility of the upper cervical spine and muscle performance of the deep flexors in women with temporomandibular disorders.

Cervical spine disorders are frequently associated with temporomandibular disorders (TMDs). Although headache is common in TMD, few studies have considered headache regarding the functional performance of the cervical spine in TMD. To evaluate TMD subjects with and without self-reported headache, assess the active and passive range of motion (ROM) of the upper cervical spine (C1-C2) and performance of the deep cervical flexors, and evaluate the correlation of these outcomes with neck disability and temporomandibular pain. In this cross-sectional study, we assessed 57 women (40 with TMDs and 17 without TMDs [controls]). The TMD group was divided into 25 and 15 patients with and without self-reported headache, respectively. We assessed the active and passive upper cervical ROMs using the flexion-rotation test (FRT) and muscle performance using the craniocervical flexion test (CCFT). The neck disability index questionnaire and visual analog scale were used to assess self-reported neck disability and temporomandibular pain, respectively. Compared to controls, all TMD subjects showed reduced cervical mobility on flexion/extension movements, reduced FRT findings and worse performance in CCFT (P<.05 all). Additionally, the CCFT and FRT findings were correlated with temporomandibular pain (r=.4 and .5, respectively) and neck disability (r=.3 and .4, respectively). Women with TMDs, regardless of self-reported headaches, showed limited flexion/extension ROM, limited upper cervical spine (C1-C2) mobility and poor deep cervical flexor performance. Neck disability and temporomandibular pain showed a moderate correlation with the functional test findings, that is FRT and CCFT, in subjects with TMDs.

Characteristics of Grouped Discharge Waveforms Observed in Long-term Masseter Muscle Electromyographic Recording: A Preliminary Study.

We investigated the characteristics of grouped discharge (GD) waveforms obtained from long-term masseter electromyogram (EMG) recording in 6 female temporomandibular disorder (TMD) patients with myofascial pain and 6 healthy females. The EMG measurement was performed from the morning of the experiment day until the subject woke up the next day. We observed a significantly larger number of GD waveforms in the TMD group compared to the control group (p=0.002). Our results indicate that the existence of GD waveforms in masseter EMGs might be a predictor of future TMD with myofascial pain.

Evaluation of genetic risk related to catechol-O-methyltransferase (COMT) and β2-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 β2-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.

Dopamine receptor D2 and ankyrin repeat domain containing one in temporomandibular disorder of adolescents.

Temporomandibular disorder (TMD) is a multifactorial condition that combines environmental and genetic factors and its prevalence increases during adolescence. To investigate the association between TMD and genetic polymorphisms in the DRD2 and ANKK1 in a population of Brazilian adolescents. The TMD group included adolescents diagnosed with any of the following TMD subgroups according to the RDC/TMD criteria: myofascial pain, arthralgia and disc displacement and painful TMD. Genomic DNA for molecular analysis was extracted from buccal cells, and genetic polymorphism rs6275 in DRD2 and rs1800497 in ANKK1 were genotyped by real-time polymerase chain reactions using the TaqMan assay. Data were analysed using the Epi Info 3.5.7 and Stata software, with significance level of 0.05. Two hundred fifty-one individuals were included in this study, 148 subjects presented TMD. For disc displacement, the genetic polymorphisms rs6275 was associated in a recessive model (P=0.04), whereas the rs6276 and rs1800497 presented only a borderline association in a recessive and dominant models, respectively (P=0.07 and P=0.06). The genetic polymorphism rs6275 in DRD2 was associated with disc displacement in Brazilian adolescents.

Depression and Somatization in Patients with Temporomandibular Disorders in a Population-Based Cross-Sectional Study in Southern Brazil

To assess the prevalence of depression and somatization in patients with temporomandibular disorders (TMD) in a Brazilian population-based cross-sectional survey. A total of 1,643 subjects were assessed for TMD using the Research Diagnostic Criteria for Temporomandibular Disorders Axes I and II and were assessed for depression and somatization using the Graded Chronic Pain Scale. The data were cross-tabulated for comparison between TMD subjects and controls. TMD subjects had significantly worse depression and somatization levels than controls in the RDC/TMD Axis II. The levels were also worse in most Axis I TMD groups (muscle disorders and arthralgia/osteoarthritis/osteoarthrosis). TMD subjects had worse depression and somatization, particularly in diagnostic groups with higher pain/disability levels.

Reliability in Mandibular Movement Evaluation Using Photogrammetry in Patients With Temporomandibular Disorders

ObjectiveThe purpose of this study was to propose a quantitative evaluation for mandibular opening–closing movement asymmetries and to verify the intraexaminer and interexaminer reliability using photogrammetry in individuals with and without myogenic temporomandibular disorders. MethodsForty-nine female participants between ages 18 and 40 were enrolled in this study. They were assigned to 2 different groups: a temporomandibular disorder group, (n = 25; 28.1 ± 3.6 years) and an asymptomatic group (n = 24; 25.6 ± 5.1 years). Data were collected through photogrammetry using Corel Draw X3 software (Corel Corp, Ottawa, Ontario, Canada) for angle measurements. Reliability analysis was done on the total sample, and the photographs were obtained by a singular examiner on 2 occasions (intraexaminer) 1 month apart and from measurement made by another examiner (interexaminer) on different days. The intraclass correlation coefficient (ICC) was applied with a significance level of 5%. ResultsThe photogrammetry had excellent intrarater and inter-rater reliability for the evaluation of opening and closing movements of the jaw (intrarater: opening ICC = 0.99; closing ICC = 0.98; inter-rater: opening ICC = 0.89 and closing ICC = 0.82). Photogrammetry also demonstrated excellent intra- and inter-rater reliability in the evaluation of head posture (intra-rater: head deviation ICC = 0.96; head position ICC = 0.75; inter-rater: head deviation ICC = 0.98; head position ICC = 0.98). ConclusionUnder these experimental conditions, most angular values presented excellent intra- and interexaminer reliability.

Posturographic changes in university students with temporomandibular dysfunction

Introduction: Temporomandibular dysfunction (TMD) is a problem which is increasing in general population. It is considered a multifactorial problem, which can become from biomechanical, neuromuscular, biopsychosocial or neurobiological factors. It is associated with risk of occlusion, parafunction, stress, trauma and hypermobility. The treatment of this pathology is based on teamwork, where Physiotherapy has a significant role (1). In recent years, the relationship between TMD and posturographic changes has been studied. Despite numerous studies have been published it is not clear yet if postural imbalances are etiological or perpetuating agents of TMD. Evidence from most of the studies shows that muscle and postural disorders are more frequent in patients with TMD and seem to be a correlation between the type of occlusion, the existence of signs and symptoms of dysfunction and postural imbalance (2). The general objective of this study was to observe if there is a relationship between the level of TMD and posturographic changes in college students aged between 18 and 30 years old. Materials and Methods: Sixty students were assigned into two groups. Group 1 (n = 25) who presented moderate or severe TMD dysfunctions and group 2 (n = 25) who had no symptoms of TMD. All subjects completed a sample characterization questionnaire and the Fonseca Questionnaire to identify the prevalence of symptoms and severity of TMD. The selected subjects were submitted to four tests to measure the center of gravity position on several static and dynamic positions, on bilateral and unilateral podal stance with their eyes open and closed. This study followed all the principles of the Declaration of Helsinki. Results: A total of 63 variables were studied. Of these, only 5 obtained significant differences between the group with TMD and the group without. The percentage of anteroposterior oscillation amplitude, the anteroposterior distance in the left unipodal with closed eyes, the anteroposterior oscillation amplitude in left unipedal with closed eyes, the left unipedal oscillation area with closed eyes and the percentage of oscillation velocity in the left unipedal with eyes, were the variables that obtained a p <0.05. Discussion and Conclusion: The most common way to study postural control is to observe body behavior (especially the oscillation) during any task. The observation can be both qualitative and quantitative, with the aid of measuring instruments. Based on our results and according to the existing literature (3), we conclude that there is no relationship between the moderate and severe TMD variables and the changes in the center of pressure. The relationship between moderate and severe TMD with changes in the center of pressure is an approach that is poorly studied and developed.

Association between sleeping time and temporomandibular disorders in a sample of the South Korean population

ABSTRACT Objective: This study investigated the relationship between sleeping time and temporomandibular disorders (TMDs). Methods: This study used data from the Fifth Korea National Health and Nutrition Examination Survey from 2010 to 2011. The final sample size consisted of 11,782 adults aged ≥19 years. Logistic regression analysis was performed to assess the relationship between sleeping time and TMD. Results: The adjusted odds ratios of the TMD group were 1.421 (1.067, 1.892) (Model 1), 1.388 (1.028, 1.873) (Model 2), and 1.360 (1.012, 1.826) (Model 3) for subjects with sleeping time ≤5 hours (p < 0.05) and 1.317 (0.992, 1.748) (Model 1), 1.358 (1.01, 1.827) (Model 2), and 1.352 (0.977, 1.872) (Model 3) for subjects with sleeping time ≥9 hours (p < 0.05). Conclusion: Sleeping time ≤5 hours and ≥9 hours were associated with an increased rate of TMD.

Temporal Summation of Painful Heat Stimulation Is Facilitated in Trigeminal and Extratrigeminal Regions in Painful Myofascial Temporomandibular Disorders: Evidence from a Case-Control Study.

To determine whether patients with painful myofascial temporomandibular disorders (TMD) demonstrate facilitated temporal summation (TS) responses to painful heat stimuli applied to the painful trigeminal and extratrigeminal regions and whether there is a side difference in the trigeminal region for myofascial TMD pain patients compared to healthy controls. Twenty female Chinese myofascial TMD pain patients and 20 age-matched female volunteers participated in this case-control study. Thermal detection thresholds, thermal pain thresholds, and TS of 20 repetitive noxious thermal stimuli were measured on the skin above the masseter muscle on both sides and the thenar eminence of the less painful side/dominant hand. Numeric rating scale (NRS) scores of pain were provided after the 1st, 5th, 10th, 15th, and 20th stimuli, and TS was calculated as the highest NRS score minus the first NRS score in each test. Evidence of TS was found in the trigeminal and extratrigeminal regions for both groups, but with facilitated TS responses in myofascial TMD pain patients (P < .001). Within the myofascial TMD group and control group, there were no side-to-side differences (P > .289). Interestingly, the repetition of the TS test was associated with facilitated responses in myofascial TMD pain patients (P < .001). The current findings suggest TS of painful heat stimulation is facilitated in myofascial TMD pain patients with no side difference in the trigeminal region.

The Effect of Microdialysis Catheter Insertion on Glutamate and Serotonin Levels in Masseter Muscle in Patients with Myofascial Temporomandibular Disorders and Healthy Controls.

Myofascial temporomandibular disorders (TMD) are the most common cause of chronic pain in the orofacial region. Microdialysis has been used to study metabolic changes in the human masseter muscle. The insertion of the microdialysis probe causes acute tissue trauma that could affect the metabolic milieu and thereby influence the results when comparing healthy subjects to those with TMD. This study aimed to investigate the levels of serotonin and glutamate during the acute tissue trauma period in healthy subjects and in patients with TMD. Microdialysis was carried out in 15 patients with TMD and 15 controls, and samples were collected every 20 min during a period of 140 min. No significant alterations of serotonin or glutamate were observed over the 2 h period for the healthy subjects. For the TMD group, a significant decrease in serotonin was observed over time (p < 0.001), followed by a significant increase between 120 and 140 min (p < 0.001). For glutamate, a significant reduction was observed at 40 min compared to baseline. The results showed that there was a spontaneous increase of serotonin 2 h after the insertion of the catheter in patients with TMD. In conclusion, the results showed that there are differences in the masseter muscle levels of serotonin and glutamate during acute nociception in patients with myofascial TMD compared to healthy subjects.