Immediate and short-term effects of phototherapy on pain,muscle activity,and joint mobility in women with temporomandibular disorder: a randomized,double-blind,placebo-controlled,clinical trial

Objectives: The aim of the present study was to evaluate the immediate and short-term effects of phototherapy on pain intensity, the pressure pain threshold (PPT), maximum vertical mandibular movement, and the electrical activity of the masseter and temporal muscles in women with temporomandibular disorder (TMD).

Methods: Sixty women were randomly allocated to four different groups and submitted to phototherapy with a combination of super-pulsed laser (905?nm), red (640?nm), and infrared (875?nm) light emitting diodes in the same equipment on the masseter (three points) and temporal (two points) muscles bilaterally in a single session. The following doses were used in each point of application: Group 1 – 2.62 J; Group 2 – 5.24 J; Group 3 – 7.86 J; placebo group. Pain intensity was determined using the visual analog scale. The PPT was analyzed using a digital algometer. Vertical mandibular movement was measured using digital calipers. Myoelectrical activity of the masseter and temporal muscles was measured using electromyography. Four evaluations were performed: pre-intervention, immediately after, 24 and 48?hours after phototherapy.

Outcomes: A significant reduction in pain intensity during the post-treatment evaluations in comparison to the pretreatment evaluation was observed in group 1 (Median difference?=?2.60 [95% CI?=?1.35–3.85]) and group 2 (Median difference?=?2.2 [95% CI?=?0.98–3.42]) especially after 48?hours and group 3 (Median difference?=?2.50 [95% CI: 0.56–4.46]) especially after 24?hours, with a moderate effect size, but no effect was found regarding the other variables.

Conclusions: A single session of combined phototherapy was capable of reducing pain intensity in individuals patients with TMD.

ClinicalTrials.gov (NCT02018770).

• Implications for Rehabilitation

• Phototherapy device combining two light sources (LED and laser), and different densities in the same device is a novelty in the rehabilitation market, and has proved to be a useful intervention for people with temporomandibular disorders.

• This mode of phototherapy is another option that assists in the rapid intervention in pain symptoms, promoting a considerable degree of comfort to the patient moments after its application.

     

Effects of 4-Week Diacutaneous Fibrolysis on Myalgia,Mouth Opening,and Level of Functional Severity in Women With Temporomandibular Disorders: A Randomized Controlled Trial

ObjectiveThe purpose of this study was to assess the effects of 4-week protocol of diacutaneous fibrolysis (DF) compared with simulated DF (sham-DF) on myalgia and mouth opening.MethodsIn a sham randomized controlled trial, 34 women with temporomandibular disorders and myofascial pain were randomly divided as intervention group (IG) and sham-DF group (SG). The IG received 4 weeks of real DF, and the SG received sham. Pain was assessed through the visual analog scale and pressure pain thresholds (PPTs) on the temporomandibular joint (TMJ), and over the temporal and masseter muscles. The Mandibular Function Impairment Questionnaire was used to classify the participants regarding to the severity of the functional limitation related to TMD.ResultsPain scores decreased for both groups, but the IG showed lower values at week 4, with between-group differences. Bilateral temporal PPT showed higher values at week 4, with between-group differences. The SG had lower PPTs but the IG had higher PPTs, both compared to baseline results. The time-by-group interaction and the frequency of participants above 40 mm of mouth opening showed a significant difference for the IG over time with higher results at the 4-week assessment compared to its own baseline. Both groups showed lower MFIQ scores from baseline to 4-week assessment. There was a lower frequency of a moderate level of severity for the IG. No differences were observed for TMJ or for the masseter muscles PPT.ConclusionImprovements were observed for visual analog scale scores and PPTs on temporal muscles. There was a group-by-time interaction in the IG, suggesting a possible potential use of DF for mouth opening.     

Breathing and temporomandibular joint disease

Temporomandibular joint disease (TMD) refers to a collection of pain related conditions in the masticatory muscles and temporomandibular joint. Occlusal factors have been implicated in TMD pathogenesis, yet despite decades of research no causal relationship between occlusion and TMD has been found. The significance of psychosocial factors in both the assessment and the long-term management of patients with TMD is receiving increased recognition. The teaching of relaxation skills and coping strategies are effective, proven TMD therapies. The role of breathing re-education in temporomandibular joint (TMJ) disorders is rarely mentioned. A focus on breathing patterns and their disorders potentially explains how biomechanical factors associated with psychosocial influences might lead to pathophysiological changes within the TMJ as well as in the associated muscles. Attention to factors such as breathing and postural rehabilitation provides health professionals valuable, additional tools to help care for patients with TMD.     

Sensory Neuron-TRPV4 Modulates Temporomandibular Disorder Pain Via CGRP in Mice

Temporomandibular disorder (TMD) pain that involves inflammation and injury in the temporomandibular joint (TMJ) and/or masticatory muscle is the most common form of orofacial pain. We recently found that transient receptor potential vanilloid-4 (TRPV4) in trigeminal ganglion (TG) neurons is upregulated after TMJ inflammation, and TRPV4 coexpresses with calcitonin gene-related peptide (CGRP) in TMJ-innervating TG neurons. Here, we extended these findings to determine the specific contribution of TRPV4 in TG neurons to TMD pain, and examine whether sensory neuron-TRPV4 modulates TMD pain via CGRP. In mouse models of TMJ inflammation or masseter muscle injury, sensory neuron-Trpv4 conditional knockout (cKO) mice displayed reduced pain. Coexpression of TRPV4 and CGRP in TMJ- or masseter muscle-innervating TG neurons was increased after TMJ inflammation and masseter muscle injury, respectively. Activation of TRPV4-expressing TG neurons triggered secretion of CGRP, which was associated with increased levels of CGRP in peri-TMJ tissues, masseter muscle, spinal trigeminal nucleus, and plasma in both models. Local injection of CGRP into the TMJ or masseter muscle evoked acute pain in naïve mice, while blockade of CGRP receptor attenuated pain in mouse models of TMD. These results suggest that TRPV4 in TG neurons contributes to TMD pain by potentiating CGRP secretion.PerspectiveThis study demonstrates that activation of TRPV4 in TG sensory neurons drives pain by potentiating the release of pain mediator CGRP in mouse models of TMJ inflammation and masseter muscle injury. Targeting TRPV4 and CGRP may be of clinical potential in alleviating TMD pain.     

Head and Neck Pain Drawing Area Correlates With Higher Psychosocial Burden But Not With Joint Dysfunction in Temporomandibular Disorders: A Cross-Sectional Study

Head and neck pain drawings have been introduced as part of the diagnostic gold standard for temporomandibular disorders (TMD). We aimed to quantify the spatial extent of pain in TMD patients and to analyze its association with further clinical findings. In a cross-sectional study, 90 patients (median age = 38 years; n women = 68) were diagnosed according to the DC/TMD. Intra-articular disorders were either confirmed or rejected by magnetic resonance imaging. The patients shaded all painful areas in a sketch of the left and right side of a face. A grid template was placed over the drawings and each region that contained markings was scored as painful. The correlation between the calculated area and the psychosocial variables (DC/TMD axis II) as well as the influence of pain lateralization were investigated using Spearman correlation, Mann-Whitney-U and chi-square tests. Pain affected all facial areas but concentrated on the regions of the temporomandibular joint and masseter origin. Thirty-nine percent reported purely unilateral pain, which was associated with structural TMJ findings in 77% of cases. Individuals with bilateral pain and those with greater spatial spread of pain had significantly higher scores on all axis II variables, except for functional limitation of the jaw.PerspectiveHead and neck pain drawings can contribute to a stratification of TMD patients. A greater extent of pain as well as pain bilateralization is associated with higher levels of emotional distress, pain chronicity and somatization, but not with functional impairment. Unilateral reporting of pain is associated with more intra-articular disorders.     

Effects of low-power laser auriculotherapy on the physical and emotional aspects in patients with temporomandibular disorders: A blind,randomized, controlled clinical trial

ObjectivesThis study evaluated the effects of low-power laser auriculotherapy (LA) on the physical and emotional symptoms of patients with temporomandibular disorders (TMDs), in comparison with occlusal splints (OS).DesignRandomized, blinded, prospective, non-inferiority clinical trial.InterventionsThe patients received OS (control group) or LA (experimental group).Main outcome measuresFollowing the Consolidated Standards of Reporting Trials (CONSORT) guidelines, patients with TMD were evaluated by using axes I and II of the Research Diagnostic Criteria for RDC-TMD. Both intra- and intergroup quantitative variables were analyzed with ANOVA (p < 0.05), while qualitative variables were analyzed with the Kruskal–Wallis (intergroup evaluations; p < 0.05) or Mann–Whitney tests (intragroup analyses; p < 0.05).ResultsOS improved five physical symptoms of TMD (pain in the right temporal muscle, right and left masseter muscles, left joint, and left intraoral region), while LA improved six (jaw functioning; pain in left masseter muscle, right and left joints, and right and left intraoral regions). Similarly, OS improved seven emotional symptoms (degree of depression, degree of non-specific physical symptoms, excluding pain, degree of non-specific physical symptoms including pain, average pain value in the past 6 months, presence of depression, intensity and characteristics of pain, non-specific physical symptoms including pain), while LA improved five (degree of non-specific physical symptoms including pain, presence of depression, intensity and characteristics of pain, non-specific physical symptoms including pain, non-specific physical symptoms excluding pain).ConclusionLA improved the physical and emotional symptoms of TMD, with results similar to OS.Clinical relevanceFor the physical and emotional symptoms associated with TMD, LA showed similar outcomes as OS.     

Use of orthopedic manual physical therapy to manage chronic orofacial pain and tension-type headache in an adolescent

Temporomandibular dysfunction (TMD) is frequently associated with multiple headache types. While the efficacy of orthopedic manual physical therapy (OMPT) intervention for TMD with/without headache symptoms has been investigated, it has received less attention than other musculoskeletal conditions. This case describes the OMPT treatment and outcome of a 14 year-old female with a 2-year history of facial pain surrounding the right temporomandibular joint (TMJ), and bilateral occipital and temporal tension-type headaches (TTHs). Intervention included manual mobilization of the TMJ and surrounding cervical/facial soft tissue structures, postural re-education, and patient/family education on prevention, self-treatment, and postural adaptations.Outcomes included pain free and maximal mouth opening (MMO), pressure pain threshold (PPT) over the masseter muscle belly, fear avoidance beliefs questionnaire-physical activity subscale (FABQ-PA), jaw pain and function questionnaire (JPFQ), visual analog pain scale (VAS) for facial pain, and headache frequency, duration, and intensity on a VAS. Results included increased pain free and MMO by 22 mm, improved PPT bilaterally by 403.05 kPa on the affected, and 360.88 kPa on the unaffected side, and decreased reported headache frequency, duration, and intensity. Score decreases of 5 points on VAS with MMO, 8 points on FABQ-PA, and 5 points on JPFQ were also noted. Further research is warranted to investigate the effects of OMPT on pain processing and functional outcomes in patients with TMD and headache.     

Relationship between osteopathic manipulative treatment of the temporomandibular joint,molar shim and the orthostatic position: A randomized,controlled and double blinded study

This randomized, controlled, double-blinded study related the effect of osteopathic manipulative treatment (OMT) of the temporomandibular joint (TMJ) and the orthostatic posture using the molar shim (MS) as a postural adjustment factor. Twenty individuals classified with temporomandibular disorder (TMD) were randomly assigned to a treated group (TG, n = 10) and placebo (PG, n = 10). The independent variables were: MS and OMT of the TMJ. The dependent variables were: DC-TMD data; local pressure pain using algometry; and orthostatic posture assessed by the distribution of plantar pressures (baropodometry), in the evaluation periods before and immediately after the interventions. Results: pain did not show a statistically significant difference after the interventions. However, when comparing the Effect Size (ES) between the groups in the post-intervention moment, a moderate relationship was observed for the left trapezius muscle (0.51) and right and left TMJ (0.41 and 0.54 respectively). When correlating the pain and percentage of anteroposterior postural dislocation variables, a significant moderate inverse correlation was observed in the post-intervention moment. The results of the MS pointed to a significant decrease (p ≤ 0.05) of the average peak pressure (Medium P) during the use of the MS (503.4 ± 44.1 kgf/cm2) and after performing the OMT (516.5 ± 49.6 kgf/cm2), both for the TG compared to the pre intervention moment (519.3 ± 42.9 kgf/cm2). There is a correlation between TMJ and orthostatic posture. OMT of the TMJ influences orthostatic posture. The MS can be added to the evaluative context of TMD.     

Correlations between the Helkimo indices and the maximal mandibular excursion capacities of patients with temporomandibular joint disorders

Temporomandibular disorders (TMD) may present with diverse signs and symptoms, and one very significant is the limitation of mandibular movements. Additionally, the Helkimo indices allow for the reliable quantification of the signs and symptoms of TMD. The purpose of this study was to ascertain whether there are any correlations between the Helkimo indices and the maximal mandibular excursion capacity in a group of patients with TMD. Eighty patients (72 women and 8 men, mean age 33.6 years) with diagnosis of TMD according to the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) were evaluated to obtain the Helkimo indices and their maximal mandibular excursion capacities. Normal or decreased maximum mandibular movements, i.e., opening, lateral and protrusion were compared with the anamnestic index, muscular pain symptoms, joint pain symptoms and the dysfunction index. Chi-squared analysis was used to compare normal and decreased movement capacities in terms of the Helkimo indices, and the muscle and temporomandibular joint (TMJ) pain. The statistical analyses were performed using the Statistical Package for Social Sciences (SPSS) version 19.0. There were statistically significant differences in the clinical dysfunction index with the maximum opening (p = .011) and lateral movements (p = .024) but not with the maximum protrusion. There were no significant differences in the anamnestic index or the muscle pain and TMJ pain items of the clinical dysfunction index according to the mandibular excursions. The occurrences of limitations in the maximum opening and lateral movements are indications of greater TMD intensity.     

The use of surface electromyography as a tool in differentiating temporomandibular disorders from neck disorders

The aim of this study was to assess the electromyographic characteristics of the masticatory muscles (masseter and temporalis) of patients with either “temporomandibular joint disorder” or “neck pain”. Surface electromyography of the right and left masseter and temporalis muscles was performed during maximum teeth clenching in 38 patients aged 21–67 years who had either (a) temporomandibular joint disorder (24 patients); (b) “neck pain” (13 patients). Ninety-five control, healthy subjects were also examined. During clenching, standardized total muscle activities (electromyographic potentials over time) were significantly different in the three groups: 75 μV/μV s % in the temporomandibular joint disorder patients, 124 μV/μV s % in the neck pain patients, and 95 μV/μV s % in the control subjects (analysis of variance, P<0.001). The temporomandibular joint disorder patients also had significantly (P<0.001) more asymmetric muscle potentials (78%) than either neck pain patients (87%) or control subjects (92%). A linear discriminant function analysis allowed a significant separation between the two patient groups, with a single patient error of 18.2%. Surface electromyographic analysis during clenching allowed to differentiate between patients with a temporomandibular joint disorder and patients with a neck pain problem.     

Bilateral Widespread Mechanical Pain Sensitivity in Women With Myofascial Temporomandibular Disorder: Evidence of Impairment in Central Nociceptive Processing

Our aim was to investigate bilateral, widespread pressure-pain hypersensitivity in nerve, muscle, and joint tissues in women with myofascial temporomandibular disorders (TMD) without concomitant comorbid conditions. Twenty women with myofascial TMD (aged 20 to 28 years old), and 20 healthy matched women (aged 20 to 29 years), were recruited. Pressure-pain thresholds (PPT) were bilaterally assessed over supra-orbital (V1), infra-orbital (V2), mental (V3) nerves, median (C5), radial (C6) and ulnar (C7) nerve trunks, the C5-C6 zygapophyseal joint, the lateral pole of the temporo mandibular joint (TMJ), and the tibialis anterior muscle in a blinded design. The results showed that PPTs were significantly decreased bilaterally over the supra-orbital, infra-orbital, and mental nerves, median, ulnar, and radial nerve trunks, the lateral pole of the TMJ, the C5-C6 zygapophyseal joint, and the tibialis anterior muscle in patients with myofascial TMD as compared to healthy controls (all sites: P < .001). There were no significant differences in the magnitude of PPT decreases between the trigeminal and extratrigeminal test sites. PPT over the mental nerve, the TMJ, C5-C6 zygapophyseal joint and tibialis anterior muscle were negatively correlated to both duration of pain symptoms and TMD pain intensity (P < .05). Our findings revealed bilateral, widespread pressure hypersensitivity in women presenting with myofascial TMD, suggesting that widespread central sensitization is involved in myofascial TMD women.

Perspective

This article reveals the presence of bilateral and widespread pressure-pain hypersensitivity in women with myofascial TMD, suggesting that widespread central sensitization is involved in myofascial TMD. This finding has implications for development of management strategies.     

Experimental pain sensitivity in women with temporomandibular disorders and pain-free controls: the relationship to orofacial muscular contraction and cardiovascular responses

OBJECTIVE: Chronic pain may result both from a generalized hypersensitivity to acute pain, suggestive of central sensitization processes, and dysfunction of the endogenous pain regulatory system. One purpose of this study was to compare experimental pain sensitivity at several anatomic sites in temporomandibular disorder (TMD) patients and pain-free controls during baseline and after standardized mechanical load of the orofacial region. A second purpose was to compare the pain-modulating effects of cardiovascular responses in TMD patients and pain-free controls. METHODS: Experimental pain was induced by electrocutaneous stimulation of the dorsal left hand and pressure algometry at the right masseter muscle and the sternum. The pain sensitivity of the orofacial region was manipulated by isometric contraction of the masseter muscles. Elevations of mean arterial pressure and heart rate were induced by a simulated job interview. RESULTS: At baseline, the TMD patients exhibited a significantly higher electrocutaneous pain threshold. Relative to the healthy controls, the TMD patients reported increased electrocutaneous and pressure pain sensitivity after isometric contraction of the orofacial region. In addition, there were correlations between mean arterial pressure and pain sensitivity in the TMD group only. DISCUSSION: Significant increases in generalized pain sensitivity occurred in the TMD group, but not in the control group, after isometric contraction of the orofacial muscles, suggestive of a central sensitization process in TMD. Moreover, only in the TMD group there were significant associations between cardiovascular responsesand pain sensitivity, challenging previous assumptions of this relationship occurring mainly in pain-free individuals.     

The correlation between scapulocostal syndrome and masticatory myofascial pain on selected pain and functional parameters- an observational study

ObjectivesAlthough scapulocostal syndrome (SCS) and masticatory myofascial pain (MMP) occur in different regions, the concept of myofascial linkage and neurophysiology may be proven per the connection of the two disorders. Therefore, this study aimed to investigate the correlation between SCS and MMP on selected pain and functional parameters.Method75 participants with SCS participated in the protocol. The diagnosis of SCS was considered by the presence of muscle referred pain in the medial scapular muscles. All participants were measured for pain intensity, pressure pain threshold (PPT), and craniovertebral angle (CV-angle) for pain and functional parameters related to SCS. They were measured for pain intensity, PPT, and mouth distance for the pain and functional parameters related to MMP. The diagnosis of MMP was considered by the presence of muscle tenderness of the masticatory muscle and the decreasing of mouth opening distance. The correlation between SCS and MMP was determined using Pearson's correlation coefficient and Spearman's correlation.ResultsParticipants exhibiting SCS were diagnosed for MMP at 74.67%. The results showed positive correlations in pain intensity and PPT between SCS and MMP (r = 0.367, r = 0.478, p < 0.01), PPT of SCS, and mouth distance amid both pain-free and maximum mouth opening conditions, respectively (r = 0.290, r = 0.282, p < 0.05).ConclusionIn conclusion, SCS and MMP present an association with each other in terms of both selected pain, and functional parameters. Thus, a treatment program for SCS patients should be concerned with the masticatory muscles even if they did not report any pain at the jaw area.     

Effect of dextrose phonophoresis versus pulsed electromagnetic field on temporomandibular dysfunction: A randomized,controlled study

ObjectiveThis study investigated and compared the efficacy of dextrose phonophoresis and Pulsed Electromagnetic Field (PEMF) on pain, range of motion (ROM) and function in patients with Temporomandibular Dysfunction (TMD).Methods45 patients with TMD aging from 25 to 45 years, with mean age 29 ± 2.5 years were included in this study, they were assigned randomly into 3 equal groups each contain fifteen TMJ dysfunction patients. Group (A) in which each patient received 50% dextrose phonophoresis for 5 min and therapeutic ultrasound for 5 min, Group (B) in which each patient received Pulsed Electromagnetic Field (PEMF) with frequency of 50 HZ for 50 min, and traditional physiotherapy ultrasound for 5 min, while in the control group (C) the patients received traditional physiotherapy ultrasound for 5 min only, the frequency of treatment session in the three groups was 3 days per week for 4 weeks. The assessment tools were visual analog scale (VAS) for pain evaluation, plastic ruler for TMJ ROM measurements while Fonseca's questionnaire was used for evaluation of TM function at baseline and 4 weeks later.ResultsPaired t-test for comparison between pre and post treatment measurements in each group showed significant decrease pain as well as improvement of ROM and Fonseca's questionnaire in group A and B than placebo group.ConclusionsThe results found that both dextrose phonophoresis and PEMF have beneficial effects considering pain, ROM and function in patients with (TMD).     

Correlation Between Severity of Temporomandibular Disorder,Pain Intensity,and Pressure Pain Threshold

Objective

The aim of the present study was to correlate the severity of temporomandibular disorder (TMD) with the pressure pain threshold over the temporomandibular joint and masticatory muscles.

Masticatory muscle activity during maximum voluntary clench in different research diagnostic criteria for temporomandibular disorders (RDC/TMD) groups

The research diagnostic criteria for temporomandibular disorders (RDC/TMD) are used for the classification of patients with temporomandibular disorders (TMD). Surface electromyography of the right and left masseter and temporalis muscles was performed during maximum teeth clenching in 103 TMD patients subdivided according to the RDC/TMD into 3 non-overlapping groups: (a) 25 myogenous; (b) 61 arthrogenous; and (c) 17 psycogenous patients. Thirty-two control subjects matched for sex and age were also measured. During clenching, standardized total muscle activities (electromyographic potentials over time) significantly differed: 131.7 microV/muVs % in the normal subjects, 117.6 microV/microVs % in the myogenous patients, 105.3 microV/microVs % in the arthrogenous patients, 88.7 microV/microVs % in the psycogenous patients (p<0.001, analysis of covariance). Symmetry in the temporalis muscles was larger in normal subjects (86.3%) and in myogenous patients (84.9%) than in arthrogenous (82.7%), and psycogenous patients (80.5%) (p=0.041). No differences were found for masseter muscle symmetry and torque coefficient (p>0.05). Surface electromyography of the masticatory muscles allowed an objective discrimination among different RDC/TMD subgroups. This evaluation could assist conventional clinical assessments.     

Clinical,psychological, and sensory characteristics associated with headache attributed to temporomandibular disorder in people with chronic myogenous temporomandibular disorder and primary headaches

BackgroundHeadache attributed to Temporomandibular Disorder (HATMD) is a secondary headache that may have features resulting in diagnostic overlap with primary headaches, namely, tension-type (TTH) or migraine. This cross-sectional study of people with both chronic myogenous TMD and primary headaches evaluated characteristics associated with HATMD.MethodsFrom a clinical trial of adults, baseline data were used from a subset with diagnoses of both TMD myalgia according to the Diagnostic Criteria for TMD (DC/TMD) and TTH or migraine according to the International Classification of Headache Disorders, 3rd edition. HATMD was classified based on the DC/TMD. Questionnaires and examinations evaluated 42 characteristics of facial pain, headache, general health, psychological distress, and experimental pain sensitivity. Univariate regression models quantified the associations of each characteristic with HATMD (present versus absent), headache type (TTH versus migraine), and their interaction in a factorial design. Multivariable lasso regression identified the most important predictors of HATMD.ResultsOf 185 participants, 114 (61.6%) had HATMD, while the numbers with TTH (n = 98, 53.0%) and migraine (n = 87, 47.0%) were similar. HATMD was more likely among migraineurs (61/87 = 70.1%) than participants with TTH (53/98 = 54.1%; odds ratio = 2.0; 95%CL = 1.1, 3.7). In univariate analyses, characteristics associated with HATMD included pain-free jaw opening and examination-evoked pain in masticatory muscles and temporomandibular joints (TMJ) as well as frequency and impact of headache, but not frequency or impact of facial pain. Lowered blood pressure but not psychological or sensory characteristics was associated with HATMD. Multiple characteristics of facial pain, headache, general health, and psychological distress differed between TTH or migraine groups. Few interactions were observed, demonstrating that most characteristics’ associations with HATMD were consistent in TTH and migraine groups. The lasso model identified headache frequency and examination-evoked muscle pain as the most important predictors of HATMD.ConclusionsHATMD is highly prevalent among patients with chronic myogenous TMD and headaches and often presents as migraine. In contrast to primary headaches, HATMD is associated with higher headache frequency and examination-evoked masticatory muscle pain, but with surprisingly few measures of facial pain, general health, and psychological distress. A better understanding of HATMD is necessary for developing targeted strategies for its management.Trial identification and registrationSOPPRANO; {"type":"clinical-trial","attrs":{"text":"NCT02437383","term_id":"NCT02437383"}}NCT02437383. Registered May 7, 2015.Supplementary InformationThe online version contains supplementary material available at 10.1186/s10194-021-01255-1.     

Efficacy of laser therapy for temporomandibular disorders: A systematic review and meta-analysis

ObjectiveThe aim of this systematic review was to evaluate the efficacy of laser therapy in temporomandibular disorders (TMD).MethodsRandomized controlled trials (RCTs) in regard to this issue were searched in electronic databases. Three investigators independently screened the eligible studies, and the quality of the included studies was assessed according to the risk of bias tool recommended by the Cochrane handbook. The primary outcome measure was the degree of pain, reported on a visual analog scale (VAS), and the secondary outcome measures were TMJ function, including maximum active vertical opening (MAVO), maximum passive vertical opening (MPVO), left and right lateral movement (LLE, RLE). Pooled effect sizes were calculated using random effects models and 95% confidence interval (95% CI).ResultsA total of 28 randomized controlled trials were included. Laser therapy had a more significant effect in terms of VAS (SMD=﹣1.88; 95% CI=﹣2.46 to﹣1.30; P < 0.00001; I² =93%), MAVO (MD = 4.90; 95% CI= 3.29–6.50; P < 0.00001; I² =72%), MPVO (MD=5.8²; 95% CI= 4.62–7.01; P < 0.00001; I² =40%) and RLE (MD = 0.73; 95% CI= 0.23–1.22; P = 0.004; I² = 0%) as compared to placebo group. However, there was no significant difference in LLE between two groups (MD= 0.35; 95% CI=﹣0.31–1.01; P = 0.30; I² =0%).ConclusionsLaser therapy can effectively reduce pain but have small effect on improving mandibular movement of TMD patients. More well-designed RCTs with large sample sizes are needed for further validation. And these studies should report detailed laser parameters and provide complete outcome measure data.     

Pain in temporomandibular joint dysfunction

The temporomandibular joint (TMJ) structure alteration may be genetic or acquired. If genetic, the deformity is usually severe and leads to marked functional disorders. In other cases, alterations may be induced by trauma, tumor, infection, or radiation. TMJ morphofunctional alterations may also be caused by occlusal disorders or muscle dysfunction. TMJ lesions induce pain through the auriculo-temporal nerve nociceptors in the joint capsule and retrodiscal attachment. Moreover, TMJ lesions may provoke muscle function alterations with increased contraction of the elevator muscles during opening. This eccentric contraction may induce mechanical damage to the muscle and delayed onset of muscle soreness as a consequence.