Temporomandibular joint pain referred from muscles of the head and neck

Botulinum Toxin-A for the Treatment of Myogenous Temporomandibular Disorders: An Umbrella Review of Systematic Reviews

OBJECTIVE

Temporomandibular disorders (TMDs) encompass several conditions that cause pain and impair function of the masticatory muscles (M-TMDs) and temporomandibular joints. There is a large interest among clinicians and researchers in the use of botulinum toxin-A (BoNT-A) as a treatment for M-TMD. However, due to the lack of consistent evidence regarding the efficacy as well as adverse events of BoNT-A, clinical decision making is challenging. Therefore, this umbrella review aimed to systematically assess systematic reviews (SRs) evaluating BoNT-A treatment effects on pain intensity, mandibular movements, and adverse events in patients with M-TMDs.

METHOD

An electronic search was undertaken in the databases MEDLINE, EMBASE, CINAHL, Cochrane Central Registry of Controlled Trials (CENTRAL), Web of Science, Epistemonikos, ClinicalTrials.gov, and ICTRP to identify SRs investigating BoNT-A effects on M-TMDs, published from the inception of each database until 6 December 2023. The quality of evidence was rated according to the critical appraisal checklist developed by the umbrella review methodology working group. Only high-quality SRs were included.

RESULTS

In total, 18 SRs were included. BoNT-A was shown to be more effective than placebo to reduce pain intensity, but not compared to standard treatments. Additionally, BoNT-A was not superior to placebo or standard treatments regarding improvement of mandibular movements. BoNT-A was considered to have a higher risk for adverse events on muscle and bony tissue compared with other treatments.

CONCLUSION

The synthesis in this umbrella review provides the highest level of evidence present. Taken together, there are indications of effectiveness of BoNT-A for treatment of M-TMDs, supported by moderate evidence. However, considering the risk of causing serious adverse events, treatment with BoNT-A is recommended to be the last treatment alternative.

Temporomandibular disorder in individuals with spinal cord injuries

OBJECTIVE

This study evaluated Temporomandibular Disorder (TMD) in individuals with Spinal Cord Injuries (SCI) compared to individuals without physical disabilities.

DESIGN

Cross-sectional.

SETTING

International Fair of Technologies in Rehabilitation and Accessibility (REATECH) and School of Dentistry at the University of São Paulo (USP), Brazil.

PARTICIPANTS

In total, 19 patients with SCI and 19 patients without SCI (36.9 ± 11.4 years old) were examined by a calibrated examiner.

METHODS

using the following parameters: cervical spine mobility, palpation of muscle groups of the head and neck, functional manipulation of the lateral and medial pterygoids, and joint palpation (Diagnostic Criteria). The pattern and amplitude of mandibular movements were determined during screening using the Helkimo index.

STATISTICAL ANALYSES

Student's t-test, chi-square, Fisher's exact and Shapiro-Wilk test were used.

RESULTS

The groups did not differ in the presence of noise, pain, temporomandibular joint palpation, locking, dislocation, jaw pain, muscle sensitivity, or in pain, mobility of the cervical spine and functional manipulation. With respect to the jaw mobility index, the groups differed in range of movement (P = 0.020) and maximum right lateral movement (P = 0.007), with the worst values in the SCI group. The groups also differed in relation to lateral flexion in cervical mobility, in which the group without SCI presented better results (P = 0.046).

CONCLUSION

The Spinal Cord Injuries group showed higher levels of TMD in terms of range of movement, lateral flexion, and maximum right lateral movement, than the individuals without physical disabilities, demonstrating a clinical significance between cervical and mandibular disability in this group.

Effect of Dry Needling on the Masseter Muscle in the Tinnitus Perception of Patients with Temporomandibular Disorder

Objective

To evaluate the effect of dry needling on the masseter muscle in the perception of tinnitus in patients with temporomandibular disorder.

Methods

Twenty-five patients with tinnitus and muscular temporomandibular disorders were randomly assigned to groups study (n = 13) and control (n = 12). Three sessions of dry needling (study) and sham (control) were performed. Follow-up was performed 30, 60 and 90 days after the end of treatment. The Analog Visual Scale and Tinnitus Handicap Inventory (THI) were used to evaluate the treatment.

Results

In study group, 76.9% presented a reduction in the intensity and tinnitus discomfort and total THI. In control group, 66.7% presented a decrease in tinnitus intensity and total THI, and 58.3% reported a decrease in tinnitus discomfort. After 90 days, in the study group, 84.6% maintained improvement in pain intensity and reduction in THI score and 69.2% reported improvement in both intensity and discomfort caused by tinnitus. In control group, 75% achieved improvement in pain intensity, 33.2% maintained improvement in tinnitus intensity, and 41.7% maintained improvement in discomfort caused by tinnitus and total THI. In the total THI score, the study group presented improvement (p = 0.041).

Conclusion

Dry needling combined with counseling was associated with improvement in pain intensity and tinnitus, decrease in tinnitus discomfort and reduction in total THI score.

Location of mechanically-evoked referred sensations within the trigeminal region are not altered following a heterotopic painful stimulus

To investigate whether the location, area and frequency of referred sensations occurring during palpation of the masseter muscle can be influenced by application of a conditioning painful stimulus to the temporalis muscle. Thirty healthy participants were included in this cross-over study, performed in two sessions with > 48 h in between. At each session, palpation of the masseter muscle was performed before and after 0.2 ml of glutamate (1 mol/L) or isotonic saline (control) were injected into the anterior portion of the temporalis muscle. Palpation of the masseter muscle was done using four different forces (0.5 kg, 1 kg, 2 kg and 4 kg). Participants rated the perceived intensity of the palpation and any referred sensations on a 0-50-100 numeric rating scale, the perceived pain intensity following the injections on an electronic visual analogue scale and drew any referred sensations they experienced. No difference in referred sensations location, area and frequency was shown r during palpation either before or after injections (P > 0.05). A moderate correlation was found between perceived sensation scores and referred sensations intensity for the temporalis muscle following glutamate injection (r = 0.407, P < 0.05). Moreover, significantly more participants reported referred sensations for glutamate injections into the temporalis muscle when compared to isotonic saline (P < 0.05). Finally, a significant decrease in the perceived intensity of palpation of the masseter muscle was seen after glutamate injection in the temporalis muscle (P < 0.05). In the current study, location, area and frequency of referred sensations following mechanical stimulation of the masseter muscle were not altered by the application of a painful stimulus to the temporalis muscle. In addition, there seems to be a positive relationship between painful stimuli and referred sensations frequency and intensity elicited from the temporalis muscle.

Efficacy of Kinematic Parameters for Assessment of Temporomandibular Joint Function and Disfunction: A Systematic Review and Meta-Analysis

The aim of this review was to answer the following PICO question: "Do TMJ kinematic parameters (intervention and comparison) show efficacy for assessment of mandibular function (Outcome) both in asymptomatic and TMD subjects? (Population)". PubMed, Scopus, Web of Science, Embase, Central databases were searched. The inclusion criteria were (1) performed on human, (2) English only, (3) on healthy, symptomatic or surgically altered TMJ, (4) measured dynamic kinematics of mandible or TMJ (5) with six degrees of freedom. To assess the Risk of Bias, the Joanna Briggs Institute tool for non-randomised clinical studies was employed. A pairwise meta-analysis was carried out using STATA v.17.0 (Stata). The heterogeneity was estimated using the Q value and the inconsistency index. Ninety-two articles were included in qualitative synthesis, nine studies in quantitative synthesis. The condylar inclination was significantly increased in female (effect size 0.03°, 95% CI: -0.06, 0.12, p = 0.00). Maximum mouth opening (MMO) was increased significantly in female population in comparison with males (effect size 0.65 millimetres (0.36, 1.66). Incisor displacement at MMO showed higher values for control groups compared with TMD subjects (overall effect size 0.16 millimetres (-0.37, 0.69). Evidence is still needed, considering the great variety of devices and parameters used for arthrokinematics. The present study suggests standardising outcomes, design, and population of the future studies in order to obtain more reliable and repeatable values.

Neuro-Muscular Dentistry: the "diamond" concept of electro-stimulation potential for stomato-gnathic and oro-dental conditions

Oro-Pharyngeal Dysphagia - or simply dysphagia - is the difficulty (persistent) in swallowing/passing food and/or liquid from the mouth to the pharynx into the esophagus and finally the stomach; a deglutition disorder (a symptom, by definition, often due to neuro-degenerative/−muscular, drug-induced or localized structural pathologies such as head and neck tumors, lesions and associated surgical and/or radiation injuries) linked to severe consequences on Quality of Life (QoL), including malnutrition, dehydration, and even sudden death. Likewise, Temporo-Mandibular Jaw and Joint disorder(s) – or simply TMD – is a multifactorial etiological condition, regularly encountered in the dental office. Whether due to malocclusion, bruxism, stress and/or trauma, TMD destabilizes the whole cranio-mandibular system structurally and functionally, via affecting mastication, teeth, supporting structures, comfort and aesthetics, and thus, QoL, again. While several treatment regimens do exist for such conditions, some of which have been standardized for use over the years, most continue to lack proper evidence-based literature support. Hence, (1) caution is to be exercised; and (2) the need for alternative therapeutic strategies is amplified, subsequently, the door for innovation is wide open. Indeed, neuromuscular electrical stimulation or “NMES”, is perhaps a fine example. Herein, we present the interested oro-dental health care provider with an up-dated revision of this therapeutic modality, its potential benefits, risks and concerns, to best handle the dysphagic patient: an intra-disciplinary approach or strategy bridging contemporary dentistry with speech and language therapy; a rather obscure and un-discovered yet critical allied health profession. A pre-clinical and clinical prospectus on employing inventive NMES-based regimens and devices to manage TMD is also highlighted.

A patient's view on the location of the temporomandibular joint

ObjectiveA survey was held to establish whether laypeople knew the location of their temporomandibular joint. MethodsA sample of 61 participants, visiting their dental office for a routine check-up, was given a three-question survey of whether they knew the location of their temporomandibular joint and could point to this location. ResultsThirty-eight participants answered the question affirmatively. Only 13 pointed to the correct location. Of these, six participants received consultation for TMD in the past, three participants were healthcare providers, and four participants actually had knowledge of the exact location. Out of 23 participants who did not know the location, one accidently designated the correct position. ConclusionThe location of the temporomandibular joint is not a well-known site for many patients. In the presence of orofacial pain, it seems advisable to let the patient designate and record the site of the pain on a drawing on the patient chart.

Pathophysiology, Diagnosis and Treatment of Somatosensory Tinnitus: A Scoping Review

Somatosensory tinnitus is a generally agreed subtype of tinnitus that is associated with activation of the somatosensory, somatomotor, and visual-motor systems. A key characteristic of somatosensory tinnitus is that is modulated by physical contact or movement. Although it seems common, its pathophysiology, assessment and treatment are not well defined. We present a scoping review on the pathophysiology, diagnosis, and treatment of somatosensory tinnitus, and identify priority directions for further research. Methods: Literature searches were conducted in Google Scholar, PubMed, and EMBASE databases. Additional broad hand searches were conducted with the additional terms etiology, diagnose, treatment. Results: Most evidence on the pathophysiology of somatosensory tinnitus suggests that somatic modulations are the result of altered or cross-modal synaptic activity within the dorsal cochlear nucleus or between the auditory nervous system and other sensory subsystems of central nervous system (e.g., visual or tactile). Presentations of somatosensory tinnitus are varied and evidence for the various approaches to treatment promising but limited. Discussion and Conclusions: Despite the apparent prevalence of somatosensory tinnitus its underlying neural processes are still not well understood. Necessary involvement of multidisciplinary teams in its diagnosis and treatment has led to a large heterogeneity of approaches whereby tinnitus improvement is often only a secondary effect. Hence there are no evidence-based clinical guidelines, and patient care is empirical rather than research-evidence-based. Somatic testing should receive further attention considering the breath of evidence on the ability of patients to modulate their tinnitus through manouvers. Specific questions for further research and review are indicated.

Effects of breathing type on electromyographic activity of respiratory muscles at different body positions

AIM

To compare the effect of breathing type on the activity of respiratory muscles at different body positions.

METHODOLOGY

Two groups of 20 subjects each, one with upper costal and the other with costodiaphragmatic breathing, were studied. Electromyographic activity of sternocleidomastoid (SCM), diaphragm (DIA), external intercostal (EIC), and latissimus dorsi (LAT) muscles was recorded at standing and lateral decubitus positions during swallowing and maximal voluntary clenching.

RESULTS

All muscles showed higher activity during standing in upper costal breathing subjects except the SCM muscle. EIC activity was higher during standing in the costodiaphragmatic breathing group. Subjects with upper costal breathing showed higher DIA activity than subjects with costodiaphragmatic breathing at both body positions and higher SCM activity at lateral decubitus position, whereas, EIC activity was only higher during swallowing.

CONCLUSIONS

Subjects with upper costal breathing presented higher respiratory effort than subjects with costodiaphragmatic breathing, being most prominent at the lateral decubitus position.

Effect of proper oral rehabilitation on general health of mandibulectomy patients

Here, we aimed to assess whether postoperative oral rehabilitation for mandibulectomy patients is necessary to improve patients’ general health in terms of health-related quality of life.

[Craniomandibular disorder/dysfunction. Characteristics and disorders of the masticatory organ]

The practising physician often meets patients with pain located in different parts of the face and facial skull, mouth opening restriction or other motion disorder of the mandible. It is not always easy to identify and explain the cause. It is not widely known among doctors that most of these problems are due to masticatory dysfunction. There is a special group of patients showing functional disorders and there are some others who present a variety of different symptoms and visit several doctors. The masticatory organ, a functional unit of the human organism has a definite and separate task and function. In the early years of life it is capable of adaptation, while later on it tends to compensation. The authors outline the functional anatomy of the masticatory organ and the characteristics of multicausal pathology, the dynamics of the process of the disease and their interdisciplinary aspects. They discuss the basic elements of craniomandibular dysfunction. Based on the diagnostic algorithm, they summarize treatment options for masticatory function disorders. They emphasize the importance that physicians should offer treatment, especially an irreversible treatment, without a diagnosis. It occurs very often that the causes are identified after the patients become symptom-free due to treatment. The aim of this report is to help the general practitioners, dentists, neurologists, ear-nose-throat specialists, rheumatologists or any other specialists in the everyday practice who have patients with different symptoms such as pain in the skull, acoustic phenomenon of the joint or craniomandibular dysfunction.

Correlation of condylar kinematics in children with gender, facial type and weight

OBJECTIVE

The aim of the study has been to describe the normal range of mandibular movements and condylar kinematics in children as well as to test the null hypothesis that these variables are not associated with gender, facial type and weight.

MATERIALS AND METHODS

The sample was comprised of 92 healthy children (7.2-10.6 years old) and 40 adult controls (18-34.7 years old). Examinations included the maximal mouth opening capacity and laterotrusion to the right and to the left. The condylar path inclination angle was calculated at 3mm and 5mm protrusion of the mandible. Kinematic variables were registered using the ultrasonic JMA system.

RESULTS

Maximal mouth opening capacity averaged 46.73 mm for the children and 53.53 mm for the adults. The mean values of the lateral movements were 9.36 mm to the right and 9.62 mm to the left for the boys, and 9.91 mm and 9.68 mm for the girls, respectively. Mean condylar path inclination in the children was 36.5° (right) and 36.2° (left) at 3mm of protrusive movement, and 34.3° (right) and 34.0° (left) at 5mm of protrusive movement. Associations of the kinematic variables with gender, weight, or facial type were insignificant.

CONCLUSION

Younger school children have not yet reached the maximum mouth-opening capacity. Correlation analysis suggests some weak, but insignificant associations of gender, facial type and weight with mouth opening, laterotrusion and the condylar path inclination angle. The null hypothesis was not rejected.

Efficacy of myofascial trigger point deactivation for tinnitus control

Chronic pain in areas surrounding the ear may influence tinnitus.

Objective

To investigate the efficacy of myofascial trigger point deactivation for the relief of tinnitus.

Method

A double-blind randomized clinical trial enrolled 71 patients with tinnitus and myofascial pain syndrome. The experimental group (n = 37) underwent 10 sessions of myofascial trigger point deactivation and the control group (n = 34), 10 sessions with sham deactivation.

Results

Treatment of the experimental group was effective for tinnitus relief (p < 0.001). Pain and tinnitus relieves were associated (p = 0.013), so were the ear with worst tinnitus and the side of the body with more pain (p < 0.001). The presence of temporary tinnitus modulation (increase or decrease) upon initial muscle palpation was frequent in both groups, but its temporary decrease was related to the persistent relief at the end of treatment (p = 0.002).

Conclusion

Besides medical and audiological investigation, patients with tinnitus should also be checked for: 1) presence of myofascial pain surrounding the ear; 2) laterality between both symptoms; 3) initial decrease of tinnitus during muscle palpation. Treating this specific subgroup of tinnitus patients with myofascial trigger point release may provide better results than others described so far.

Evidence-based pain management: is the concept of integrative medicine applicable?

This article is dedicated to the concept of predictive, preventive, and personalized (integrative) medicine beneficial and applicable to advance pain management, overviews recent insights, and discusses novel minimally invasive tools, performed under ultrasound guidance, enhanced by model-guided approach in the field of musculoskeletal pain and neuromuscular diseases. The complexity of pain emergence and regression demands intellectual-, image-guided techniques personally specified to the patient. For personalized approach, the combination of the modalities of ultrasound, EMG, MRI, PET, and SPECT gives new opportunities to experimental and clinical studies. Neuromuscular imaging should be crucial for emergence of studies concerning advanced neuroimaging technologies to predict movement disorders, postural imbalance with integrated application of imaging, and functional modalities for rehabilitation and pain management. Scientific results should initiate evidence-based preventive movement programs in sport medicine rehabilitation. Traditional medicine and mathematical analytical approaches and education challenges are discussed in this review. The physiological management of exactly assessed pathological condition, particularly in movement disorders, requires participative medical approach to gain harmonized and sustainable effect.

Review of aetiological concepts of temporomandibular pain disorders: towards a biopsychosocial model for integration of physical disorder factors with psychological and psychosocial illness impact factors

Several studies have reported that musculoskeletal disorders of the stomatognathic system, commonly known as temporomandibular disorders (TMD) resemble musculoskeletal disorders and chronic pain disorders in general. There is also general consensus that combined biomedical and biopsychosocial methods best support the assessment and management of the cardinal features of TMD, i.e., pain and dysfunction or physical (peripheral) and psychosocial (central) factors. This overview of the aetiology of TMD will outline conceptualizations of past models and present the current view that patients with TMD should be assessed according to both the physical disorder and the psychosocial illness impact factors. The conceptual theories outlined in this review include biomedical models related to temporomandibular joints, muscles of mastication and occlusal factors, psychological models and the biopsychosocial models. An integrated and multidimensional approach concerning physical and psychosocial factors in temporomandibular pain and dysfunction is presented as an example of how the biopsychosocial model and information processing theory may apply in the conceptualization and management of TMD for various health care professionals.

Diagnosis and management of somatosensory tinnitus: review article

Tinnitus is the perception of sound in the absence of an acoustic external stimulus. It affects 10-17% of the world's population and it a complex symptom with multiple causes, which is influenced by pathways other than the auditory one. Recently, it has been observed that tinnitus may be provoked or modulated by stimulation arising from the somatosensorial system, as well as from the somatomotor and visual-motor systems. This specific subgroup -somatosensory tinnitus - is present in 65% of cases, even though it tends to be underdiagnosed. As a consequence, it is necessary to establish evaluation protocols and specific treatments focusing on both the auditory pathway and the musculoskeletal system.

Immediate effects of microsystem acupuncture in patients with oromyofacial pain and craniomandibular disorders (CMD): a double-blind, placebo-controlled trial

BACKGROUND

Patients presenting with oromyofacial disorders and pain in the head and neck area are often resistant to conventional therapy. Acupuncture has been shown to be effective in pain reduction.

METHODS

Twenty-three patients with craniomandibular disorders, headache and, in particular, local pain in the orofacial, cervical and temporomandibular joint areas were randomised into acupuncture or placebo laser therapy groups. Pain was assessed by a visual analogue scale (VAS) and by palpation of 14 muscles and groups of muscles immediately before and after treatment, the assessor being blinded to the patients' allocation. Applicable acupuncture points were searched and pricked using the 'very-point' technique.

FINDINGS

Pain reduction measured by VAS was significantly more pronounced after acupuncture than after placebo treatment (p=0.031). Sum of pain scores across 14 muscles was considerably more reduced after acupuncture as compared to sham laser treatment.

INTERPRETATION

Acupuncture may bring about immediate pain relief in patients with oromyofacial disorders, increasing the chance to initiate other therapeutic measures.

Clinical measurement of normal maximum mouth opening in children

This study was designed to find a method of assessing maximum mouth opening (MMO), using a tool that is proportional to the body size. One hundred two (102) children were selected to participate in the study. MMO, the width of three fingers (index, middle and ring fingers), four fingers (index, middle, ring and little fingers), body height, weight and age of each child were recorded, and the ability of each subject to position the fingers, vertically aligned between the upper and lower central incisors with the mouth maximally open, was documented. All subjects were able to position three fingers between the upper and lower central incisors, while only 37 (36.3%) were able to position four fingers. MMO was significantly different from the width of three and four fingers and was positively correlated with both weight and height and with age. Height, weight, and age showed a moderate to strong correlation with all finger measurements; no gender significant difference was observed for MMO. The findings of this study suggest that the ability to position three fingers between the upper and lower incisors with the mouth wide open can be considered a simple method to quickly evaluate MMO, but that it is not highly reliable.

Myofascial trigger point:a possible way of modulating tinnitus

In order to investigate whether myofascial trigger points can modulate tinnitus, as well as the association between tinnitus and myofascial trigger points, 94 individuals with and 94 without tinnitus, matched by age and gender, were analyzed by means of bilateral digital pressure of 9 muscles. Temporary modulation of tinnitus was frequently observed (55.9%) during digital pressure, mainly in the masseter. The rate of tinnitus modulation was significantly higher on the same side of the myofascial trigger point subject to examination in 6 out of 9 muscles. An association between tinnitus and the presence of myofascial trigger points was observed (p < 0.001), as well as a laterality association between the ear with the worst tinnitus and the side of the body with more myofascial trigger points (p < 0.001). Thus, this relationship could be explained not only by somatosensory-auditory system interactions but also by the influence of the sympathetic system.

Does head posture have a significant effect on the hyoid bone position and sternocleidomastoid electromyographic activity in young adults?

The aim of this study was to evaluate the associations between head posture (head extension, normal head posture, and head flexion) and anteroposterior head position, hyoid bone position, and the sternocleidomastoid integrated electromyographic (IEMG) activity in a sample of young adults. The study included 50 individuals with natural dentition and bilateral molar support. A lateral craniocervical radiograph was taken for each subject and a cephalometric analysis was performed. Head posture was measured by means of the craniovertebral angle formed by the MacGregor plane and the odontoid plane. According to the value of this angle, the sample was divided into the following three groups: head extension (less than 95 degrees); normal head posture (between 95 degrees and 106 degrees); and head flexion (more than 106 degrees). The following cephalometric measurements were taken to compare the three groups: anteroposterior head position (true vertical plane/pterygoid distance), anteroposterior hyoid bone position (true vertical plane-Ha distance), vertical hyoid bone position (H-H' distance in the hyoid triangle), and CO-C2 distance. In the three groups, IEMG recordings at rest and during swallowing of saliva and maximal voluntary clenching were performed by placing bipolar surface electrodes on the right and left sternocleidomastoid muscles. In addition, the condition with/without craniomandibular dysfunction (CMD) in each group was also assessed. Head posture showed no significant association with anteroposterior head position, anteroposterior hyoid bone position, vertical hyoid bone position, or sternocleidomastoid IEMG activity. There was no association to head posture with/without the condition of CMD. Clinical relevance of the results is discussed.

Review of enigmatic MTrPs as a common cause of enigmatic musculoskeletal pain and dysfunction

This article explores how myofascial trigger points (MTrPs) may relate to musculoskeletal dysfunction (MSD) in the workplace and what might be done about it. The cause of much MSD and pain is often enigmatic to modern medicine and very costly, just as the cause of MTrPs has been elusive for the past century, despite an extensive literature that is confusing because of restricted regional approaches and a seemingly endless variety of names. MTrPs are activated by acute or persistent muscle overload, which is characteristic of MSD in the workplace. MTrPs can involve any, and sometimes many, of the skeletal muscles in the body and are a major, complex cause of musculoskeletal pain. The clinical and etiological characteristics of MTrPs have been underexplored by investigators, leading to undertraining of health care professionals, underappreciation of their clinical importance. MTrPs have no gold standard diagnostic criterion, and no routinely available laboratory or imaging test. MTrPs require a specific non-routine examination and muscle-specific treatment for prompt relief when acute, and also resolution of perpetuating factors when chronic. After identifying a critical false assumption, electrodiagnostic studies are now making encouraging progress toward clarifying the etiology of MTrPs based on the 5- or 6-step positive-feedback model of the integrated hypothesis. Specific research needs are noted. MTrPs are treatable and they deserve increased attention and consideration by research investigators and clinicians.

The normal range of mouth opening in an Irish population

The aims of this study were to estimate the average maximum mouth opening and range of mouth opening in a representative sample of the Irish adult population, to compare mouth opening in patients with and without signs or symptoms of temporomandibular joint (TMJ) dysfunction syndrome and to investigate the association between mouth opening and stature among populations. As part of the Irish National Survey of Adult Oral Health, maximum mouth opening was measured and questionnaire data collected for 1513 adults, aged 16-99 years. The average maximum mouth opening was 43 mm for males and 41 mm for females. Mouth opening was found to reduce with age, independent of gender. No link was found between reduced mouth opening and TMJ dysfunction or between mouth opening and stature in populations.

Effect of muscle relaxants on experimental jaw-muscle pain and jaw-stretch reflexes: a double-blind and placebo-controlled trial

A randomised, double-blind, placebo-controlled three-way cross-over study was performed to investigate the effect of two muscle relaxants (tolperisone hydrochloride and pridinol mesilate) on experimental jaw-muscle pain and jaw-stretch reflexes. Fifteen healthy men participated in three randomised sessions separated by at least 1 week. In each session 300 mg tolperisone, 8 mg pridinol mesilate or placebo was administered orally as a single dose. One hour after drug administration 0.3 ml hypertonic saline (5.8%) was injected into the right masseter to produce muscle pain. Subjects continuously rated their perceived pain intensity on an electronic 10-cm visual analogue scale (VAS). The pressure pain threshold (PPT) was measured and short-latency reflex responses were evoked in the pre-contracted (15% maximal voluntary contraction) masseter and temporalis muscles by a standardised stretch device (1 mm displacement, 10 ms ramp time) before (baseline), 1 h after medication (post-drug), during ongoing experimental muscle pain (pain-post-drug), and 15 min after pain had vanished (post-pain). Analysis of variance demonstrated significantly lower VAS peak pain scores (5.9 +/- 0.4 cm) after administration of tolperisone hydrochloride compared with pridinol mesilate (6.8 +/- 0.4 cm) and placebo (6.6 +/- 0.4 cm) (P=0.020). Administration of pridinol mesilate was associated with a significant decrease in PPTs compared with tolperisone hydrochloride and placebo (P=0.002) after medication, but not after experimental jaw-muscle pain. The normalised peak-to-peak amplitude of the stretch reflexes were not significantly influenced by the test medication (P=0.762), but were in all sessions significantly facilitated during ongoing experimental jaw-muscle pain (P=0.034). In conclusion, tolperisone hydrochloride provides a small, albeit significant reduction in the perceived intensity of experimental jaw-muscle pain whereas the present dose had no effect on the short-latency jaw-stretch reflex.

Effects of laterotrusive occlusal scheme and body position on bilateral sternocleidomastoid EMG activity

This study was conducted to determine the effects of laterotrusive occlusal scheme and body position on bilateral sternocleidomastoid electromyographic (EMG) activity. The study was performed on 20 healthy subjects with natural dentition and bilateral molar support. During laterotrusive occlusal excursion (working side), each individual had to present canine guidance on one side and group function on the opposite side, without balancing-side contacts. Integrated EMG (IEMG) recordings were performed by placing bipolar surface electrodes on the right and left sternocleidomastoid muscles. IEMG activity was recorded seated upright with the head unsupported and in the right and the left lateral decubitus body positions (head, neck and body horizontally aligned), under the following experimental conditions: 1. Maximal voluntary clenching in the intercuspal position; 2. Laterotrusive occlusal excursion with canine guidance; 3. Laterotrusive occlusal excursion with group function. Bilateral sternocleidomastoid IEMG activity with canine guidance or group function was significantly lower than the intercuspal position in both body positions. In the seated upright position, significantly lower activity was observed with canine guidance than in group function. In the lateral decubitus position activity was similar with both laterotrusive occlusal schemes and significantly higher than seated upright. Results suggest that both laterotrusive occlusal scheme and body position have significant influence on sternocleidomastoid IEMG activity. The clinical relevance of both factors is discussed.

ORAL HABITS OF TEMPOROMANDIBULAR DISORDER PATIENTS WITH MALOCCLUSION

The purpose of this study was to clarify the relationship between oral habits and symptoms of temporomandibular joint disorder in patients who had sought orthodontic treatment by analyzing their present and past history. The subjects were 57 female patients (average age: 23 years and 6 months old) who had visited the "Temporomandibular Disorder Section" in our orthodontic department. Their chief complaints were the symptom of TMJ and the abnormalities of occlusion such as maxillary protrusion, open bite, crowding, mandibular protrusion, cross bite, deep bite, edge-to-edge bite, and spacing. Their present conditions and past histories were examined and evaluated. The most typical primary symptom was joint sound (23 patients, 40.0%). The second was joint sound and pain (15 patients, 26.3%). Of the symptoms present at the time of examination, the most prevalent were joint sound and pain (20 patients, 35.1%). The 48 patients (82.8%) had significant oral habits. Unilateral chewing was seen in 35 patients (72.9%), bruxism in 27 (56.3%), abnormality of posture in 14 (29.2%), habitual crunching in 10 (20.8%) and resting the check on the hand in 4 (8.3%), respectively. When comparing the primary symptoms to those at the time of examination, the patients with unilateral chewing and bruxism tended to have more complicated symptoms. In conclusion, the TMD symptoms of the patients with notable oral habits did not change or become worse during a period of about 5 years.

Myofascial pain syndrome misdiagnosed as odontogenic pain: a case report

The aim of this report is to illustrate the case of a patient whose myofascial pain syndrome was misdiagnosed as odontogenic pain, and who was treated using irreversible dental procedures. Even if dental pain commonly has an odontogenic etiology, it is also possible that pain arising from different orofacial sites such as jaw muscles, maxillary sinus, or nervous structures can be referred to the teeth. When the etiology of a dental pain condition cannot be clearly identified, it is necessary to consider all possible causes of dental pain, which may also be nonodontogenic. The need for comprehensive examination and careful diagnosis before irreversible dental treatment is emphasized.

Vertical dimension. Part 2: the changes in electrical activity of the cervical muscles upon varying the vertical dimension

This study was conducted in order to determine the effect of vertical dimension variation on the electromyographic (EMG) activity of the sternocleidomastoid and trapezius muscles. The study was performed on 15 healthy subjects. Basal tonic electromyographic (BT-EMG) recordings were performed by placing surface electrodes on the left sternocleidomastoid and trapezius muscles. BT EMG activity was recorded upon varying the vertical dimension every five millimeters from vertical dimension of occlusion to 45 millimeters of jaw opening (series 1), following the habitual opening path. Afterward, BT-EMG activity was recorded every millimeter from vertical dimension of occlusion to 4 mm, and then every two millimeters from four to ten millimeters (series 2). In series 1, a significant increase of BT-EMG activity was observed in both muscles (simple logarithmic regression analysis). In series 2, a significant increase was observed in the sternocleidomastoid muscle whereas trapezius muscle did not present a significant change. BT-EMG behavior of the sternocleidomastoid muscle in series 2 could be relevant when dentists increase vertical dimension by means of intermaxillary appliances during a short-term period. Moreover, these results add further information to the concept of the interrelatedness between the different components of the cranio cervical-mandibular system.

Referred craniofacial pain patterns in patients with temporomandibular disorder

BACKGROUND

Referred pain is prevalent in the craniofacial region, and it would be helpful for dental practitioners to have drawings delineating regions with a high probability for a patient's referred pain source.

METHODS

The author applied firm pressure for approximately five seconds to trigger points, nodules of spot tenderness, and selected masticatory structures within the head and neck region on 230 patients with temporomandibular disorder, or TMD. As firm pressure was being applied, subjects were asked whether pain was developing or intensifying in a location different than that being palpated.

RESULTS

One hundred ninety-six subjects (85 percent) reported that referred pain was being generated. The cheek area, ear and forehead were the most frequently reported sites of referred pain generation; palpation over the trapezius muscle, lateral pterygoid area and masseter muscle were the most common sources of referred pain to the craniofacial region. The author provides figures displaying common referred pain sites and their sources.

CONCLUSIONS

Patients with TMD often report referred craniofacial pain arising from palpation of the head and neck region. The author found that the pattern between referred pain source and site was consistent and predictable.

PRACTICE IMPLICATIONS

Practitioners should consider craniofacial pain's propensity for referral when treating patients with TMD. Practitioners can use the figures presented to determine regions of high probability for a patient's referred pain source.

Effects of head and neck inclination on bilateral sternocleidomastoid EMG activity in healthy subjects and in patients with myogenic cranio-cervical-mandibular dysfunction

This study was conducted in order to determine the effect of head and neck position on bilateral electromyographic (EMG) activity of the sternocleidomastoid muscles. The study was performed on 16 patients with myogenic cranio-cervical-mandibular dysfunction (CMD) and 16 healthy subjects. EMG recordings at rest and during swallowing of saliva and maximal voluntary clenching were performed by placing surface electrodes on the right and left sternocleidomastoid muscles. EMG activity was recorded in the left lateral decubitus position, in a darkened room and with the individual's eyes closed, under the following experimental conditions: 1. Head, neck, and body horizontally aligned; 2. Head and neck upwardly inclined with respect to the body, simulating the effect of a thick pillow, 3. Head and neck downwardly inclined with respect to the body, simulating the effect of a thin pillow. Variation of head and neck positions was determined by measuring the distance from the angle of neck and shoulder and the apex of the shoulder (SND = shoulder-neck distance) of each individual. Then, head and neck were forward or downwardly inclined with respect to the body at one-third of SND. A significantly higher contralateral EMG activity and a more asymmetric EMG activity were observed in the CMD group than in the healthy subjects (Kruskal-Wallis Test). These results suggest a different behavior of bilateral sternocleidomastoid EMG activity in CMD patients than in healthy subjects depending on the positioning of the head and neck.

Effects of two types of pillows on bilateral sternocleidomastoid EMG activity in healthy subjects and in patients with myogenic cranio-cervical-mandibular dysfunction

This study was conducted in order to determine the effects of two types of pillows on bilateral electromyographic (EMG) activity of the sternocleidomastoid muscles. The study was performed on 15 patients with myogenic cranio-cervical mandibular dysfunction (CMD) and 15 healthy subjects. EMG recordings at rest and during swallowing of saliva and maximal voluntary clenching were performed by placing surface electrodes on the right and left sternocleidomastoid muscles. EMG activity was recorded in the supine position and in the lateral decubitus position (according to each individual's normal resting habit), with their eyes closed and with the head supported by means of: 1. a Sleep Easy Pillow (Interwood Marketing Groups, Concord, Ontario, Canada) and 2. a Standard Pillow (INDUVET). In the lateral decubitus position a significantly higher contralateral than ipsilateral EMG activity at rest in the sternocleidomastoid muscles was observed with both types of pillows in all the sample studied (ANOVA and Duncan's Multiple-Range Test). Asymmetrical bilateral EMG activity in the lateral decubitus position with both types of pillows in healthy subjects and in patients with myogenic CMD, suggests that if this body posture is prolonged, it could be important in the genesis of sternocleidomastoid hyperactivity.

Physical medicine modalities and trigger point injections in the management of temporomandibular disorders and assessing treatment outcome

Temporomandibular disorders (TMDs) are principally musculoskeletal, orthopedic, and neurologic in nature. The use of trigger point injections and physical medicine modalities has become commonplace in the management of TMDs. These modalities have a long and successful history in the management of similar disorders in other areas of the body, and it is only natural that they would be included in the management of TMD as well.

Linear and angular measurements of the mandible during maximal mouth opening

PURPOSE

There are numerous reports of the translatory movement of the condyle in maximal mouth opening; however, the rotatory movement is less well understood. The purpose of this study was to investigate the rotatory condylar movement and the factors associated with it in normal subjects.

PATIENTS AND METHODS

To study the role of facial morphology in maximal mouth opening, linear and angular measurements of the mandible in both the closed and maximal open positions were made by means of cephalometry. Dental students, 29 men and 31 women with no functional disorders of the masticatory system, were investigated.

RESULTS

When the mouth was fully opened, the linear measurement of condylar movement was 20.5 +/- 4.0 mm in men and 18.1 +/- 2.5 mm in women, and the angular measurements of the rotation of the mandibular ramus were 39.1 +/- 5.9 degrees in men and 36.3 +/- 4.3 degrees in women. These differences were statistically significant (P < .01).

CONCLUSIONS

During condylar movement and rotation of the mandible, mandibular length and the inclination of the mandibular ramus in the former, and the inclination of the mandibular ramus, the mandibular angle and the position of the condyle in the latter, were important factors.

Body position effects on EMG activity of sternocleidomastoid and masseter muscles in patients with myogenic cranio-cervical-mandibular dysfunction

This study was conducted in order to determine the effects of body position on integrated electromyographic (IEMG) activity of sternocleidomastoid and masseter muscles in 17 patients with myogenic cranio-cervical-mandibular dysfunction. EMG recordings at rest and during swallowing of saliva and maximal voluntary clenching were performed by placing surface electrodes on the sternocleidomastoid and masseter muscles (contralateral to the habitual side of sleeping of each patient), in the following body positions: standing, seated, supine, and lateral decubitus position. Significant higher EMG activities were recorded in the sternocleidomastoid muscle in the lateral decubitus position and in the supine position (except during swallowing), whereas a significant higher EMG activity was recorded in the masseter muscle during maximal voluntary clenching in standing and seated positions. The EMG pattern observed suggests that the presence of parafunctional habits and body position could be closely correlated with the clinical symptomatology in the sternocleidomastoid and masseter muscles at wakening and during waking hours, respectively, in patients with myogenic cranio-cervical-mandibular dysfunction.

The relationship between maximal jaw opening and size of skeleton: a cephalometric study

The purpose of this study was to investigate the correlation between maximal mouth opening and size of the skeleton. The subjects were dental students at the Dental School of the Health Sciences University of Hokkaido with no functional disorders of the masticatory system. The stature and maximal mouth opening were recorded in 29 males and 31 females. These subjects agreed to have a lateral cephalogram taken at the closed and maximal mouth opening positions. The correlations between the maximal mouth opening and the body height, mandibular length and mandibular angle were significant. The correlation between the maximal mouth opening and the movement of the condyle was also significant.

Management of masticatory myofascial pain

Masticatory myofascial pain is a relatively frequent occurrence in patients seen by the orthodontist. Thus it is important to understand the management of this condition. Treatment is generally directed toward the restoration of a more physiological state in the muscles of mastication and involves medications, appliances, various forms of behavioral modification, as well as the use of muscle exercises and trigger point therapy. This article focuses on the role of the latter modalities in the management of myofascial pain and dysfunction.

Influence of variation in jaw posture on sternocleidomastoid and trapezius electromyographic activity

This study was conducted in order to determine the influence of variation in the occlusal contacts on electromyographic (EMG) cervical activity in 20 patients with myogenic cranio-cervical-mandibular dysfunction. EMG recordings during maximal voluntary clenching were performed by placing surface electrodes on the left sternocleidomastoid and upper trapezius muscles in the following conditions: intercuspal position; edge to edge left laterotrusive contacts (ipsilateral); edge to edge right laterotrusive contacts (contralateral); edge to edge protrusive contacts; and retrusive occlusal contacts. A significant higher EMG activity was recorded in both muscles during maximal voluntary clenching in retrusive occlusal contact position, whereas no significant differences in EMG activity were observed between intercuspal position, ipsilateral, contralateral and protrusive contact positions. The EMG pattern observed suggests that a more frequent intensity and duration of tooth clenching in retrusive occlusal contact position could result in more clinical symptomatology in these cervical muscles in patients with myogenic cranio-cervical-mandibular dysfunction.