Effectiveness of botulinum toxin type A for the treatment of chronic masticatory myofascial pain: A case series

Background

The aim of this study is to evaluate the effectiveness of botulinum toxin type A (BTX-A) for the treatment of chronic masticatory myofascial pain (MMP) over 12 months and to test a standardized protocol.

A vibratory stimulation-based inhibition system for nocturnal bruxism: a clinical report

For the single subject tested to date, the bruxism-contingent vibratory-feedback system for occlusal appliances effectively inhibited bruxism without inducing substantial sleep disturbance. Whether the reduction in bruxism would continue if the device no longer provided feedback and whether the force levels applied are optimal to induce suppression remain to be determined.     

Correlation of splint therapy outcome with the electromyography of masticatory muscles in temporomandibular disorder with myofascial pain

Abstract

Objectives. The aim of this study was to assess the effect of occlusal splint therapy on the electromyographic amplitude records (μV) of masticatory muscles in temporomandibular disorder (TMD) with myofascial pain and to detect a possible existence of a relationship between this effect and the treatment outcome. Materials and methods. Forty patients (23 females and 17 males) having TMD with myofascial pain were included in this study. They were randomly divided into two equal groups (20 of each). The first group (A) was treated by occlusal splints for 6 months while the second group (B) acted as a control. A clinical assessment and surface electromyography (EMG) for the masticatory muscles were performed at the beginning of the study, then 6 months later. The collected data were statistically analyzed using paired t-test. The differences were considered significant at p < 0.05. Results. The results showed that 85% of group A either completely recovered (35%) or clinically improved (50%) while only 20% of group B had a spontaneous improvement. In group A, the means of the electromyographic amplitude records (μV) of the monitored muscles have decreased after 6 months. However, the decrease was statistically insignificant (p > 0.05) in the patients (15%) who had no clinical changes. In group B, the means of the muscles' records (μV) in the left side slightly increased while those of the right side slightly decreased. These changes were statistically insignificant (p > 0.05). Conclusions. Occlusal splint could eliminate or improve the signs and symptoms of TMD patients with myofascial pain. It reduces the electromyographic amplitude records (μV) of the masticatory muscles. The splint therapy outcome has a correlation with the electromyographic amplitude changes of the masticatory muscles.     

Muscle hardness and masticatory myofascial pain: Assessment and clinical relevance

The impression of increased muscle hardness in painful muscles is commonly reported in the clinical practice but may be difficult to assess. Therefore, the aim of this review was to present and discuss relevant aspects regarding the assessment of muscle hardness and its association with myofascial temporomandibular disorder (TMD) pain. A non‐systematic search for studies of muscle hardness assessment in patients with pain‐related TMDs was carried out in PubMed, Cochrane Library, Embase and Google Scholar. Mechanical devices and ultrasound imaging (strain and shear wave elastography) have been consistently used to measure masticatory muscle hardness, although an undisputable reference standard is yet to be determined. Strain elastography has identified greater masseter hardness of the symptomatic side in patients with unilateral myofascial TMD pain when compared to the contralateral side and healthy controls (HC). Likewise, shear wave elastography has shown greater masseter elasticity modulus in patients with myofascial TMD pain when compared to HC, which may be an indication of muscle hardness. Although assessment bias could partly explain these preliminary findings, future randomised controlled trials are encouraged to investigate this relationship. This qualitative review indicates that the muscle hardness of masticatory muscles is still a rather unexplored field of investigation with a good potential to improve the assessment and potentially also the management of myofascial TMD pain. Nonetheless, the current evidence in favour of increased hardness in masticatory muscles in patients with myofascial TMD pain is weak, and the pathophysiological importance and clinical usefulness of such information remain unclear.     

Headache attributed to masticatory myofascial pain: impact on facial pain and pressure pain threshold

There is no clear evidence on how a headache attributed to temporomandibular disorder (TMD) can hinder the improvement of facial pain and masticatory muscle pain. The aim of this study was to measure the impact of a TMD‐attributed headache on masticatory myofascial (MMF) pain management. The sample was comprised of adults with MMF pain measured according to the revised research diagnostic criteria for temporomandibular disorders (RDC/TMD) and additionally diagnosed with (Group 1, n = 17) or without (Group 2, n = 20) a TMD‐attributed headache. Both groups received instructions on how to implement behavioural changes and use a stabilisation appliance for 5 months. The reported facial pain intensity (visual analogue scale – VAS) and pressure pain threshold (PPT – kgf cm^?2) of the anterior temporalis, masseter and right forearm were measured at three assessment time points. Two‐way anova was applied to the data, considering a 5% significance level. All groups had a reduction in their reported facial pain intensity (P < 0·001). Mean and standard deviation (SD) PPT values, from 1·33 (0·54) to 1·96 (1·06) kgf cm^?2 for the anterior temporalis in Group 1 (P = 0·016), and from 1·27 (0·35) to 1·72 (0·60) kgf cm^?2 for the masseter in Group 2 (P = 0·013), had significant improvement considering baseline versus the 5th‐month assessment. However, no differences between the groups were found (P > 0·100). A TMD‐attributed headache in patients with MMF pain does not negatively impact pain management, but does change the pattern for muscle pain improvement.     

Association between rhythmic masticatory muscle activity during sleep and masticatory myofascial pain: a polysomnographic study

AIMS: To test for an association between rhythmic masticatory muscle activity during sleep, as assessed according to polysomnographic criteria for sleep bruxism (RMMA-SB), and myofascial pain (MFP), as well as the chance of occurrence of MFP in patients with RMMA-SB. METHODS: Thirty MFP patients (diagnosed according to the Research Diagnostic Criteria for Temporomandibular Disorders) and 30 age- and gender-matched asymptomatic controls underwent a polysomnographic examination. Also, any self-reporting of daytime clenching (DC) was registered in 58 of these subjects. RESULTS: Most MFP patients reported mild or moderate pain (46.67% and 43.33%, respectively), and only 3 (10%) reported severe pain. Pain duration ranged from 2 to 120 months (mean 34.67 +/- 36.96 months). Significant associations were observed between RMMA-SB and MFP as well as between DC and MFP. CONCLUSIONS: (1) RMMA-SB is significantly associated with MFP; (2) although RMMA-SB represents a risk factor for MFP, this risk is low; and (3) DC probably constitutes a stronger risk factor for MFP than RMMA-SB.     

Effect of controlled masticatory exercise on pain and muscle performance in myofascial pain patients: A pilot study

The aim of this study was to test the hypothesis that strengthening masticatory muscles using a controlled chewing exercise protocol improves muscle function, as evaluated quantitatively by electromyogram, and reduces pain at rest and during function. The study included 20 patients diagnosed with myofascial pain according to the Research Diagnostic Criteria for Temporomandibular Disorders with low masseter volume increase during maximal clench. The exercise group (ten patients) was subjected to a controlled gum chewing exercise protocol for eight weeks: the control group (ten patients) received only support and encouragement. Patients were examined at the beginning and at the end of the experiment which included an electromyogram (EMG) to assess muscle performance, masticatory muscle tenderness to palpation, mouth opening range, subjective anamnestic indices to evaluate pain perception and pain relief, and chewing tests. The EMG showed that the masticatory muscle exercise did produce objective physiologic results. In the exercise group, a significant increase was found in the electric muscle activity of the masseters during maximal voluntary clench (p=0.007). The exercise group showed significant reduction in pain during rest, pain during the chewing test, and a disability score. At the end of the study, a difference between the two groups was shown in the Pain Relief Scale: significantly greater pain relief was found in the exercise group as compared to the control group (p=0.019). For all other clinical parameters, there was no difference between the two groups or interaction between time and treatment. The results of this study seem to be equivocal. Additional experiments on larger population groups with extended chewing protocols are necessary before a more substantial conclusion can be reached.     

Pressure pain threshold in the detection of masticatory myofascial pain: an algometer-based study

AIMS: To compare pressure pain threshold (PPT) values for masticatory muscles in patients with signs and symptoms of myofascial pain and in asymptomatic individuals. METHODS: Fifty women with masticatory myofascial pain comprised the symptomatic group (group 1), while 49 TMD symptom-free women were selected as controls (group 2). The PPT was obtained with the aid of an algometer by applying pressure to the masseter and to the anterior, middle, and posterior temporalis. A 90.8% specificity value was used to determine the appropriate PPT cutoff values for all 4 muscles studied. Receiver operator characteristic (ROC) curve areas and the likelihood ratio (LR) were also evaluated. RESULTS: The 3-way ANCOVA test (group, muscle, and side) revealed a significantly lower PPT for all muscles in the symptomatic group (P < .001). The lowest overall PPT was found for the masseter muscle, followed by the anterior, middle, and posterior temporalis (P < .001). The 90.8% specificity was obtained with PPT values of 1.5 kgf/cm2 for the masseter, 2.47 kgf/cm2 for the anterior temporalis, 2.75 kgf/cm2 for the middle temporalis, and 2.77 kgf/cm2 for the posterior temporalis. The anterior temporalis had the highest LR. ROC curve areas of 0.84, 0.92, 0.90, and 0.90 were obtained for the masseter, anterior, middle, and posterior temporalis, respectively. CONCLUSION: The masseter and temporalis muscles require different pressures for distinguishing masticatory myofascial pain patients from asymptomatic individuals. Because the highest sensitivity (77%) and LR were found for the anterior temporalis, this muscle was considered to have the most suitable discriminative capacity.     

Stabilization splint therapy for the treatment of temporomandibular myofascial pain: a systematic review

The aim of this review is to establish the effectiveness of stabilization splint (SS) therapy in reducing symptoms in patients with myofascial pain. Searching of electronic databases, handsearching of relevant key journals, and screening of reference lists of included studies were undertaken. There was no language restriction, and unpublished research was sought. The selection criteria were randomized controlled trials comparing splint therapy to either no treatment or another active treatment. Data extraction and validity assessment were carried out independently and in duplicate. Studies were grouped according to treatment type. Twenty potentially relevant Randomized Controlled Trials (RCTs) were identified. Only twelve met the inclusion criteria. There is insufficient evidence either for or against the use of stabilization splint therapy over other active interventions for the treatment of temporomandibular myofascial pain. However, it appears that stabilization splint therapy may be beneficial for reducing pain severity at rest and on palpation and depression when compared to no treatment. The authors suggested the need for well conducted RCTs that pay attention to method of allocation, blind outcome assessment, sample size, and duration of follow-up. Various measures were adopted to assess the outcomes of treatment. Standardization of the methods used to measure outcomes of the treatment of myofascial pain should be established in future RCTs.     

Soft occlusal splint therapy in the management of myofascial pain dysfunction syndrome: A follow-up study

Background and Objectives: Myofascial Pain Dysfunction Syndrome (MPDS) has been recognized as the most common, nontooth-related chronic orofacial pain condition that confronts dentists. A variety of therapies has been described in literature for its management. The present study is a prospective study carried out to evaluate the efficacy of occlusal splint therapy and compare it with pharmacotherapy (using analgesics and muscle relaxants) in the management of Myofascial Pain Dysfunction Syndrome. Materials and Methods: Forty patients in the age range of 17-55 years were included in the study and randomly assigned to one of two equally sized groups, A and B. Group A patients received a combination of muscle relaxants and analgesics while Group B patients received soft occlusal splint therapy. All the patients were evaluated for GPI, VAS, maximum comfortable mouth opening, TMJ clicking and tenderness during rest and movement as well as for the number of tender muscles at the time of diagnosis, after the 1 st week of initiation of therapy and every month for three months of follow-up. Results: There was a progressive decrease in GPI scores, number of tender muscles, TMJ clicking and tenderness with various jaw movements and significant improvement in mouth opening in patients on occlusal splint therapy during the follow-up period as compared to the pharmacotherapy group. Conclusion: Occlusal splint therapy has better long-term results in reducing the symptoms of MPDS. It has better patient compliance, fewer side effects, and is more cost-effective than pharmacotherapy; hence, it can be chosen for the treatment of patients with MPDS.     

Analysis of muscle hardness in patients with masticatory myofascial pain.

PURPOSE: The aim of the present study was to access any changes in the muscle hardness of the masseter muscle between normal subjects and patients with myofascial pain during brief sustained isometric contractions at various bite force levels, and to compare muscle hardness, especially in terms of the recovery phase, after a clenching task. MATERIALS AND METHODS: Ten patients with masticatory myofascial pain and 10 age- and weight-matched normal healthy controls participated in this study. First, the hardness of the right masseter muscle was measured at the bite force of 0, 3, 6, and 9 kgf with a hand-held hardness meter. Then, the subjects were requested to exert a 9 kgf-clenching task for 30 seconds. The muscle hardness was again measured at 5, 30, and 120 seconds after the task, and the data obtained were compared with the muscle hardness before the clenching task. RESULTS: The results showed that there was no significant difference between the patients and the normal controls, while the muscle hardness increased with contraction in all subjects. The present findings also showed that the patients had a delayed return to baseline after the clenching task compared with the normal subjects, although an immediate increase after the clenching task was seen in all subjects. CONCLUSION: The results indicated that patients with masticatory myofascial pain have different muscle properties in the recovery phase after contraction, probably because of a slower intramuscular reperfusion.