The efficacy of oral splints in the treatment of myofascial pain of the jaw muscles: a controlled clinical trial

Long-term fluctuations of pressure pain thresholds in healthy men, normally menstruating women and oral contraceptive users

The aim of this investigation was to evaluate whether the pressure pain threshold (PPT) in masticatory muscles of symptom-free subjects was influenced by fluctuations of the sex hormones. The PPT was measured with an electronic algometer for at least 10 consecutive menstrual cycles in 10 women using oral contraceptives and 10 women not using oral contraceptives, with a regular menstrual cycle (26-31 days). In addition, 10 men were measured in a regular pattern over a period of 1 year. All subjects were symptom-free with an age range between 18 and 39 years. Measurement sessions were held during three different cycle phases (follicular, luteal, perimenstrual) and each session consisted of four consecutive PPT measurements. By means of a linear mixed model (SAS), the PPTs of the masster, temporalis and thumb muscles were compared between: (1) groups, (2) sex-hormonal phases, (3) the four consecutive measurements of each muscle per session and (4) time. The PPTs of the masseter (p = 0.8419) and temporalis muscles (p = 0.2786) did not change significantly over time. There was no significant difference in variance for the masseter (p = 0.6250), temporalis (p = 0.9705) and thumb (p = 0.7446) between the three groups. The PPTs of all muscles were significantly lower during the perimenstrual phases in the two female groups. The present data showed similar patterns of PPTs for the three muscle groups. Moreover, the results have shown a very good consistency of the PPTs over a long time period, both in males and females.

Analysis of stimulus-evoked pain in patients with myofascial temporomandibular pain disorders

The pathophysiological mechanisms of myofascial temporomandibular disorders (TMD) are still under investigation. The hypothesis that TMD pain is caused by a generalized sensitization of higher order neurons in the nociceptive pathways combined with a decreased efficacy of endogenous inhibitory systems has recently gained support in the literature. This study was designed to further investigate the somatosensory sensibility within and outside the craniofacial region. Twenty-two patients fulfilled the research diagnostic criteria for TMD for myofascial pain (Dworkin and LeResche, J Craniomandib Disord Facial Oral Pain 6 (1992) 301) and 21 age- and sex-matched subjects served as a control group. The somatosensory sensibility to a deep tonic input was tested by standardized infusions of hypertonic saline into the masseter and anterior tibialis muscle. Furthermore, pressure pain thresholds (PPTs) and heat pain thresholds (HPTs) were assessed with phasic stimuli at the same sites before and following the infusions. Myofascial TMD patients reported infusion of hypertonic saline to be more painful on 10 cm visual analogue scales (peak pain 8.8 +/- 0.4 cm) than control subjects (6.8 +/- 0.5 cm, t-test: P = 0.003) in the masseter but not in the anterior tibialis (7.4 +/- 0.5 vs. 6.6 +/- 0.5 cm, P=0.181). The perceived area of experimental masseter pain measured on drawings was marginally larger in TMD patients (2.6+/-0.5 arbitrary units (a.u.)) than in control subjects (1.4 +/- 0.2 a.u., Mann-Whitney: P = 0.048) but no differences were observed for the anterior tibialis (P = 0.771). The PPTs were lower in the myofascial TMD patients compared to the control group, both in the masseter (analysis of variance (ANOVA): P = 0.002) and in the anterior tibialis (P = 0.005), whereas there were no significant differences in HPT (ANOVAs: P = 0.357, P = 0.101). There were no significant correlations between measures of somatosensory sensibility and measures of clinical pain intensity, pain duration, graded chronic pain scores or somatization or depression scores (Pearson: R < 0.304, P > 0.172). The present study in a well-defined group of myofascial TMD patients found that the responsiveness to both tonic and phasic deep stimuli, but not to phasic superficial inputs at the pain threshold level, in the craniofacial region was higher compared with a control group. These findings suggest that myofascial TMD pain is associated with a facilitation of stimulus-evoked pain primarily, but not exclusively related to the painful region.

Occlusal stabilization appliances. Evidence of their efficacy

BACKGROUND

There is substantial controversy regarding the value of occlusal appliances for managing temporomandibular joint disorders. This article specifically assesses whether the evidence is sufficient to judge occlusal appliances as being efficacious for the management of localized masticatory myalgia, arthralgia or both. A major confounder is that few studies have measured or evaluated whether subjects had strong, ongoing parafunctional activity (such as clenching or grinding) and whether appliances influenced this behavior.

LITERATURE REVIEWED

The authors evaluated four placebo-controlled studies, several randomized wait-list controlled studies and several random-assignment treatment-comparison studies. Data from the wait-list condition studies vs. those from the occlusal appliance condition studies consistently suggested that the latter treatment's effect on patient symptom level is far more than that of no treatment on a wait-list group's condition. In contrast, the studies on placebo-controlled vs. occlusal appliance studies yielded a mix of data: two showed a positive benefit of occlusal vs. nonoccluding appliances, and two showed a null effect or no difference.

CONCLUSIONS

Considering all of the available data (pro and con), the authors conclude that the use of occlusal appliances in managing localized masticatory myalgia, arthralgia or both is sufficiently supported by evidence in the literature.

CLINICAL IMPLICATIONS

The mechanism of action by which occlusal appliances affect localized myalgia and arthralgia probably is behavioral modification of jaw clenching. However, if the behavior continues unabated, even the best splint will not work.

Effect of a thick palatal appliance on muscular symptoms in craniomandibular disorders: a preliminary study

Several treatment modalities for myofascial pain dysfunction syndrome (MPD) are being used at present. However, from the standpoint of patients' quality of life, it would be reasonable to seek a more effective treatment modality. This study aimed to show clinical data of a preliminary study regarding the effect of a thick palatal appliance, designed to fill the palatal concavity with a thick resin base, on muscular symptoms in eighteen MPD patients. Shown here are the clinical results of two volunteer patients using palatal appliances of two different thicknesses. In this study, MPD patents were divided into the three following groups: 1. no-treatment group; 2. thick palatal appliance group; and 3. medication group. Based on the results of this study, it was suggested that the thick palatal appliance could bring about early improvement of MPD syndrome. It is suggested that the thickness of the palatal plate was an important factor in obtaining the clinical effect.

An investigation of the effectiveness of exercise and manual therapy in treating symptoms of TMJ osteoarthritis

The background and purpose of this investigation was to evaluate the use of a treatment protocol which included active and passive jaw movements, manual therapy techniques, correction of body posture, and relaxation techniques for the treatment of temporomandibular joint (TMJ) osteoarthrosis (OA). Twenty consecutive patients suffering from TMJ OA participated in this study.

INCLUSION CRITERIA

a. pain in the temporomandibular region; b. symptoms lasting at least three months; and c. radiologically proven OA. All patients were assigned to a waiting list, serving as a no treatment control period. Nineteen patients completed the study. No adverse effects occurred. During the control period (mean duration 35 days), the parameters did not change significantly. After treatment (mean duration 46 days) pain, impairment, and incisal edge clearance improved significantly (Wilcoxon test p < 0.001). At follow-up, pain and impairment were further reduced. The number of patients experiencing no pain at rest (80%), chi-square test p = 0.02) and stress (47%), chi-square test p = 0.03), and no impairment (37%), chi-square test p = 0.05) increased significantly. This therapeutic treatment protocol seems to be useful treatment for the symptoms of clinical dysfunction in OA of the TMJ.

Exercise therapy for craniomandibular disorders

OBJECTIVE

To evaluate the use of exercise therapy for the treatment of craniomandibular disorders (CMDs).

DESIGN

Before-after trial. All patients were assigned to a waiting list, serving as a no-treatment control period.

SETTING

Outpatient clinic for physical medicine and rehabilitation of the University of Vienna.

PATIENTS

Thirty consecutive patients suffering from CMD with anteridr disc displacement with reduction who were consulting a CMD service.

INCLUSION CRITERIA

(1) symptoms lasting at least 3 months, (2) pain in the temporomandibular region, (3) a positive axiography, and (4) evidence of postural dysfunction. Twenty-six patients completed the study; no adverse effects occurred.

INTERVENTIONS

Active and passive jaw movement exercises, correction of body posture, and relaxation techniques.

MAIN OUTCOME MEASURES

(1) Pain at rest, (2) pain at stress, (3) impairment, and (4) mouth opening at baseline, before and after treatment, and at 6-month follow-up.

RESULTS

During the control period, no changes occurred. After the treatment, pain and impairment were significantly reduced (Wilcoxon test, p < .001). Four patients had a restricted mouth opening, in contrast to 15 before treatment (chi2 test, p < .005). Joint clicking vanished in 13.3% and was reduced in another 13.3% (chi2 test, p < .01). These results did not change until follow-up. Seventy-five percent of the patients were treated successfully.

CONCLUSION

Exercise therapy seems to be useful in the treatment of anterior disc displacement with reduction.

Neuropathic Orofacial Pain Part 2-Diagnostic Procedures, Treatment Guidelines And Case Reports

Neuropathic orofacial pain can be difficult to diagnose because of the lack of clinical and radiographic abnormalities. Further difficulties arise if the patient exhibits significant distress and is a poor historian regarding previous diagnostic tests and treatments, such as somatosensory local anaesthetic blockade. Valuable information can be obtained by utilising the McGill Pain Questionnaire that allows the patient to choose words that describe the qualities of his/her pain in a number of important dimensions (sensory and effective). Basal pain intensity should be measured with the visual analogue scale, a simple instrument that can evaluate the efficacy of subsequent treatments. The dentist or endodontist can employ sequential analgesic blockade with topical anaesthetics and perineural administration of plain local anaesthetic to ascertain sites of neuropathology in the PNS. These can be performed in the dental chair and in a patient blinded manner. Other, more specific, tests necessitate referral to a specialist anaesthetist at a multidisciplinary pain clinic. These tests include placebo controlled lignocaine infusions for assessing neuropathic pain, and placebo controlled phentolamine infusions for sympathetically maintained pain. The treatment/management of neuropathic pain is multidisciplinary. Medication rationalisation utilises first-line antineuropathic drugs including tricyclic antidepressants such as amitriptyline and nortriptyline, and possibly an anticonvulsant such as carbamazepine, sodium valproate, or gabapentin if there are sharp, shooting qualities to the pain. Mexiletine, an antiarrhythmic agent and lignocaine analogue, may be considered following a positive patient response to a lignocaine infusion. All drugs need to be titrated to achieve maximum therapeutic effect and minimum side effects. Topical applications of capsaicin to the gingivae and oral mucosa are a simple and effective treatment in two out of three patients suffering from neuropathic orofacial pain. Temporomandibular disorder is present in two thirds of patients and should be assessed and treated with physiotherapy and where appropriate, occlusal splint therapy. Attention to the patient's psychological status is crucial and requires the skill of a clinical psychologist and/or psychiatrist with pain clinic experience. Psychological variables include distress, depression, expectations of treatment, motivation to improve, and background environmental factors. Unnecessary dental treatment to "remove the pain" with dental extractions is contraindicated and aggravates neuropathic orofacial pain.

Profile of TMD and Bruxer compared to TMD and nonbruxer patients regarding chief complaint, previous consultations, modes of therapy, and chronicity

This comparative study by groups assesses the profiles of TMD (temporomandibular dysfunction) and bruxism patients and TMD-nonbruxing patients regarding chief complaint, previous medical and dental consultations, duration of the chief complaint, previous medication, and use of splints. The sample consisted of a group of 340 TMD patients, 275 of whom were bruxers and 65 who were nonbruxers. Both patients and controls were consecutive referrals over a period of five years. The group of TMD and Bruxer was classified according to the degree of severity. One hundred eight (108), 84, and 83 patients demonstrated mild, moderate, and severe bruxism respectively. Information gathered included a set of questionnaires, history of signs and symptoms, and a clinical examination. The most common chief complaints in TMD bruxers and nonbruxers were facial, temporomandibular joint, headache and/or cervical pain, and joint noises. It was observed that the need for medical and dental consultations increased with the severity of bruxism. It was also apparent in this study that the need for medication (analgesics, muscle relaxants, and antidepressants), increased with the severity of bruxism. Moderate and severe subgroups of bruxers used significantly more splints compared to mild bruxers and to TMD-nonbruxer patients. Both groups of TMD + bruxism and TMD - nonbruxism sought medical and dental consultations with dentists (clinicians and specialists) neurologists, and otolaryngologists more frequently compared to other medical professionals. Since the need for health services increased with the severity of bruxism, this study urges the need to include a protocol or questionnaire to assess the severity of bruxing behavior in TMD patients in order to use a customized method of treatment/management. This study also reinforces the point of view that different subgroups of TMD and bruxism do exist and suggests a differentiated therapeutic approach. They show previously confirmed findings that pain is the major complaint of TMD and bruxer patients.

Occlusal treatments in temporomandibular disorders: a qualitative systematic review of randomized controlled trials

Occlusal treatments (occlusal splints and occlusal adjustment) are controversial but widely used treatment methods for temporomandibular disorders (TMD). To investigate whether studies are in agreement with current clinical practices, a systematic review of randomized controlled trials (RCTs) of occlusal treatment studies from the period 1966 to March 1999 was undertaken. Eighteen studies met the inclusion criteria, 14 on splint therapy, and 4 on occlusal adjustment. The trials were scored using the quality scale presented by Antczak et al., 1986a (A.A. Antczak, J. Tang, T.C. Chalmers, Quality assessment of randomized control trials in dental research. I. Methods, J. Periodontal Res. 1986a;21:305-314). The overall quality of the trials was fairly low, the mean quality score was 0.43/1.00 (range 0.12-0.78). The most obvious methodological shortcomings were inadequate blinding, small sample sizes, short follow-up times, great diversity of outcome measures and numerous control treatments, some of unknown effectiveness. Splint therapy was found superior to 3, and comparable to 12 control treatments, and superior or comparable to 4 passive controls, respectively. Occlusal adjustment was found comparable to 2 and inferior to one control treatment and comparable to passive control in one study. Because of the methodological problems, only suggestive conclusions can be drawn. The use of occlusal splints may be of some benefit in the treatment of TMD. Evidence for the use of occlusal adjustment is lacking. There is an obvious need for well designed controlled studies to analyse the current clinical practices.

Medically unexplained chronic orofacial pain. Temporomandibular pain and dysfunction syndrome, orofacial phantom pain, burning mouth syndrome, and trigeminal neuralgia

Orofacial pain syndromes pose a dilemma for physicians. Even when the patient is referred, quality medical care requires that the physician be acquainted with current evidence-based practice. Such practice may be radically different from the traditional view. This article reviews the differential diagnosis and treatment of the most common medically unexplained orofacial syndromes.

Considerations when planning occlusal rehabilitation: a review of the literature

As one of the most demanding tasks facing the restorative dentist, planning and executing an occlusal rehabilitation should not be undertaken lightly. The stakes are high and failure is costly. Treatment planning decisions should be undertaken on the basis of scientific evidence, where this is available, or on the basis of documented experience where it is not. This review article identifies the major biological and clinical considerations used when planning an occlusal rehabilitation. These include the indications for reorganising the occlusion, the choice of condylar position and occlusal scheme, the implications of and indications for increasing the vertical dimension, replacing missing teeth and the choice of materials. Finally, the literature surrounding the controversial issue of occlusal rehabilitation as a means to treat temporo-mandibular disorders is also reviewed.

Oral splints: the crutches for temporomandibular disorders and bruxism?

Despite the extensive use of oral splints in the treatment of temporomandibular disorders (TMD) and bruxism, their mechanisms of action remain controversial Various hypotheses have been proposed to explain their apparent efficacy (i.e., true therapeutic value), including the repositioning of condyle and/or the articular disc, reduction in the electromyographic activity of the masticatory muscles, modification of the patient's "harmful" oral behavior, and changes in the patient's occlusion. Following a comprehensive review of the literature, it is concluded that any of these theories is either poor or inconsistent, while the issue of true efficacy for oral splints remains unsettled. However, the results of a controlled clinical trial lend support to the effectiveness (i.e., the patient's appreciation of the positive changes which are perceived to have occurred during the trial) of the stabilizing splint in the control of myofascial pain. In light of the data supporting their effectiveness but not their efficacy, oral splints should be used as an adjunct for pain management rather than a definitive treatment. For sleep bruxism, it is prudent to limit their use as a habit management aid and to prevent/limit dental damage potentially induced by the disorder. Future research should study the natural history and etiologies of TMD and bruxism, so that specific treatments for these disorders can be developed.

Digital assessment of occlusal wear patterns on occlusal stabilization splints: a pilot study

STATEMENT OF PROBLEM

If masticatory load distribution is task-dependent, then the pattern of wear on an acrylic resin occlusal splint over time may affect clinical outcome.

PURPOSE

This pilot study quantitatively assessed posterior wear after 3 months on the occlusal surfaces of maxillary stabilization splints.

MATERIAL AND METHODS

Subjects with known history of nocturnal bruxism were given heat-cured full-arch acrylic resin occlusal stabilization splints to be worn nocturnally for 3 months. Splint occlusion was adjusted at appliance delivery and was refined at the baseline session 1 to 2 weeks later. No further adjustment of the splint surface was performed during the 3-month study period. Sequential impressions of the splint occlusal surface provided epoxy resin models that were digitized and analyzed through specialized software. Changes in the digitized splint surface from baseline to 3 months allowed comparison of wear facets between splint sides and among tooth locations.

RESULTS

Splint wear was asymmetric between sides and uneven between dental locations.

CONCLUSIONS

For full coverage occlusal splints, the appliance wear phenomenon can be site specific and, if left undisturbed, may yield two extremes of high wear and a zone of low wear in-between.

Psychological and physiological parameters of masticatory muscle pain

The objective of this research was to identify the psychological and physiological variables that differentiate persons reporting masticatory muscle pain (MMP) from normal controls (NC). This study examined the characteristics of 35 MMP patients in comparison to 35 age-, sex-, and weight-matched NCs. All subjects completed a series of standardized questionnaires prior to undergoing a laboratory evaluation consisting of a psychosocial stressor and pressure pain stimulation at multiple body sites. During the evaluation, subjects' emotional and physiological responses (heart rate, blood pressure, respiration, skin temperature, and muscle activity) were monitored. Results indicated that persons with MMP reported greater fatigue, disturbed sleep, depression, anxiety, menstrual symptoms, and less self-deception (P's < 0.05) than matched controls. At rest, MMPs had lower end tidal carbon dioxide levels (P < 0.04) and lower diastolic blood pressures than the NCs (P < 0.02). During laboratory challenge, both groups responded to the standard stressor with significant physiological activity and emotional responding consistent with an acute stress response (P < 0.01), but there were no differences between the MMPs and NCs. Muscle pain patients reported lower pressure pain thresholds than did NCs at the right/left masseter and right temporalis sites (P's < 0.05); there were no differences in pressure pain thresholds between MMPs and NCs for the left temporalis (P < 0.07) and right/left middle finger sites (P's > 0.93). These results are discussed in terms of the psychological and physiological processes that may account for the development of muscle pain in the masticatory system.

A pilot study comparing the efficacy of hard and soft stabilizing appliances in treating patients with temporomandibular disorders

STATEMENT OF PROBLEM

Soft and hard stabilizing appliances have been used to treat temporomandibular disorders. No data exist to suggest whether a hard or soft appliance is beneficial.

PURPOSE

This study compared soft and hard acrylic resin stabilizing appliances in the reduction of masticatory muscle pain in patients with temporomandibular disorders.

MATERIALS AND METHODS

Twenty-three patients with at least one clinical sign from the list of diagnostic subgroups of temporomandibular disorders were alternately assigned a hard or soft appliance for temporomandibular disorder treatment. No other temporomandibular disorder treatment (self-care, physical therapy, biofeedback, or muscle or joint injections) was rendered. Each patient was seen by two dentists at each visit. One dentist initially fabricated the appliance and adjusted the appliance on each visit and an examining dentist examined the patient each visit and recorded signs of temporomandibular disorders. The appliance material (soft or hard) was not disclosed to the examining dentist, only to the dentist who fabricated and adjusted the appliance. Patients were examined and appliances were adjusted every 2 to 3 weeks for a minimum of 10 weeks. Masticatory muscles were palpated and charted on each visit. Data were analyzed and subjected to nonparametric Mann-Whitney test.

RESULTS

Eighteen of the initial 23 patients, 7 in the hard appliance group and 11 in the soft appliance group finished the study over 10- to 15-week period. Soft and hard appliances performed the same in reduction of masticatory muscle pain.

CONCLUSION

This study suggests, based on the limited number of participants, that soft and hard stabilizing appliances may be equally useful in reducing masticatory muscle pain in short-term appliance therapy.

Assessing change in quality of life using the Oral Health Impact Profile

Traditionally, longitudinal studies of oral health have measured only disease progression and ignored improvements in health.

OBJECTIVES

This study examines methodological issues that arise in longitudinal assessment of change in oral health-related quality of life (OHRQOL).

METHODS

Baseline and 2-year follow-up data were used from an observational longitudinal study of 498 people aged 60 years or more living in South Australia. Oral health-related quality of life was measured using the Oral Health Impact Profile (OHIP). Three hypothesized risk predictors (tooth loss, problem-based dental visits and financial hardship) were selected to examine the effects of four methods of measuring change: categorical measures of improvement, deterioration and net change, and a quantitative measure of net change in OHIP scores.

RESULTS

Some 31.7% of people experienced some improvement and 32.7% experienced some deterioration in OHRQOL. All three high-risk groups had approximately twice the rate of deterioration in OHRQOL compared with their corresponding low-risk groups. Surprisingly, high-risk groups also had higher rates of improvement. When measured categorically, these effects did not cancel one another, indicating that improvement and deterioration in OHRQOL can be experienced simultaneously. However, quantitative analyses cause improvements and deteriorations to cancel, and analysis of mean OHIP scores created a spurious impression that change in OHRQOL did not differ between dental visit groups. Furthermore, changes in mean OHIP scores were masked by regression to the mean.

CONCLUSIONS

Oral health-related quality of life measures capture both improvement and deterioration in health status, creating new complexities for conceptualizing and analyzing change in longitudinal studies.

Liaison psychiatry and psychology in dentistry

Dentists are trained to provide treatment for patients with straightforward problems that respond to routine therapy and do not recur. However, patients may present to dentists and complain solely of physical symptoms such as toothache, headache, and facial pain: only after much inappropriate treatment these symptoms are revealed to be due to emotional disturbance. The dentist may spend hours investigating such patients, in some of whom dental pathology may be present, but the symptoms and ensuing disability cannot be satisfactorily explained as a result. There are other patients who are preoccupied by physical symptoms or by their appearance. In others, anxiety may manifest itself as a phobia, or a dysmorphic concern about certain aspects of their appearance. This article reviews the role of liaison psychiatry and psychology in dentistry.

Use and effectiveness of splint appliance therapy: review of literature

Interocclusal orthopedic appliances of varied design and application have been employed in the treatment of myofascial pain dysfunction (MPD) and temporomandibular joint disorders (TMD). These appliances provide the practitioner with a non-invasive, reversible form of intervention to manage the patient's symptoms. Literature on the use and effectiveness of these appliances has become readily available and now requires retrospective evaluation. However, comparison of results from studies making use of interocclusal orthopedic appliance therapy is difficult due to the employment of various outcome measurement scales, subjective evaluation of patient outcome, and variability in reporting of treatment outcomes. The aim of this paper is to review the effects and success rates of the various appliances reported in the literature and provide the practitioner with useful information that may be of assistance in the prediction of outcome and success of splint appliance therapy.

Mandibular repositioning can be effective in treatment of reducing TMJ disk displacement. A long-term clinical and MR imaging follow-up

In order to evaluate the long term clinical and morphologic results of recapture of a displaced TMJ disk, we recalled for follow-up MR imaging 75 patients who had been treated by attempted disk recapture based on pre-treatment MR imaging 1-6 years earlier. The treatment included a day appliance with inclines to guide the mandible into the therapeutic position and a telescopic night appliance which prevented retrusion of the mandible during sleep. Appliance treatment was followed by rebuilding or resurfacing the posterior teeth of one arch to permanently support the mandible in the therapeutic position. After treatment of 115 joints with displaced disks, 52% of the disks were normally positioned, 23% were improved in position, and 25% showed persistent disk displacement. Symptom relief was 92% in patients with normalized (recaptured) disks, 84% in patients with improved disk position, and 49% in patients with persistent disk displacement. Failure to improve disk position occurred in 7% of the joints with anterior disk displacement and in 44% of the joints with a transverse (sideways) component to the displacement. Forty-five percent of the recaptured-disks improved in contour. We concluded that anterior mandibular repositioning was effective in the treatment of patients with reducing displaced disks primarily when the disks were displaced only in an anterior direction. This treatment can be recommended in anterior disk displacements if the patient has failed more conservative treatment measures, permanent occlusal reconstruction can be justified, and the patient understands that long-term use of a night appliance may be necessary. Anterior mandibular repositioning appears much less effective in cases with a transverse component to the disk displacement.

History and evolution of TMD concepts

Historically the field of temporomandibular disorders (TMD) has been based on testimonials, clinical opinion, and blind faith rather than on science. Reparative procedures to the joints, jaws, or occlusal surfaces of the teeth to develop idealized structural relationships that may be required for dental health and function are less likely to be required for the management of chronic musculoskeletal disorders. Because of the concerns of many people today regarding professional credibility and intellectual honesty, the need for a scientific foundation to support the various belief systems is of paramount importance. In fact, therapeutic approaches for TMD are undergoing a major evolution away from the traditional mechanistic dental concepts of the past to the more current biopsychosocial medical concepts that emphasize multidisciplinary approaches. Recent advances in the understanding of pain mechanisms and management of chronic pain have improved long-term treatment outcome. The emphasis is on treatment that involves the patient in the physical and behavioral management of their own problem. The majority of patients with TMD achieve good relief of their symptoms with noninvasive, conservative therapy.

Future directions in the treatment of chronic musculoskeletal facial pain: the role of evidence-based care

Evidence-based care, using principles of clinical epidemiology, promises to alter the treatment of chronic musculoskeletal facial pain. With use of a set of "rules of evidence," research studies may be rigorously evaluated. Clinicians can master this methodology, which may usher in a paradigm shift in clinical care.

Pain perception in idiopathic cervical dystonia (spasmodic torticollis)

Cervical spinal pain is frequently found in conjunction with idiopathic cervical dystonia (ICD), a focal dystonia characterized by sustained deviation of the head. Since the perception of noxious stimuli has never been studied in ICD, we performed a controlled study to obtain more insight into the psychophysics of dystonia-related muscle pain by evaluating pressure-induced pain levels. In nine ICD patients and five gender- and age-matched asymptomatic control subjects, pain-pressure thresholds (PPTs) were determined in the sternocleidomastoid and upper trapezius muscles, both at resting activity and at maximal voluntary contraction (MVC). The masseter muscles served as non-pathological control regions. To determine the accuracy of PPT values, pain intensity and unpleasantness were rated at threshold on 100-mm visual analogue scales. Four replication measurements were obtained. The data were analyzed by multilevel procedures. For all muscles under investigation, average PPTs of the ICD patients were about two times lower than those of the control subjects (P < 0.001-0.0005) and showed a smaller intra-subject variance. Further, average PPTs at MVC were about two times higher than those at resting activity (P < 0.005). These results provide psychophysical evidence to suggest that, at controlled levels of muscle contraction, the threshold of pain perception is decreased in ICD. In addition, ICD patients seem to be better able to establish their own PPTs than control subjects, which might be due to a different setting of the discriminative aspect of pain in ICD. Surprisingly, lower intensity and unpleasantness scores were found in ICD patients with coinciding painful and deviated sides than in ICD patients for whom the painful side was opposite to the deviated one (P < 0.05). This finding might be of clinical importance for defining functional disability and predicting treatment outcome.

Temporomandibular pain and dysfunction syndrome. History, physical examination, and treatment

A stepwise method for treating TMPDS is presented. Step 1-start patient on a regimen of chloroethane or chlorofluorocarbon spray and exercise. Step 1A--if a clicking joint is the chief complaint, start with click exercise. Step 1B--if restricted mouth opening is the chief complaint, start with range of motion exercise; employ exercises sequentially, not simultaneously. Step 2--if pain is moderate to severe, start with amitriptyline 10 mg at bedtime, increasing the dose in 10-mg increments to 40 mg. Step 3--for nonresponders, add injections of tender points with lidocaine and consider a trial of a different tricyclic. Step 4--for nonresponders, consider a trial of tender point injections combining dexamethasone with local anesthetic. Start by injecting the three most painful tender points with 0.5 mL of a solution of 1 mg of dexamethasone combined with two thirds bupivacaine and one third lidocaine to reach the desired volume. Repeat injections, varying the sites as required. Do this once weekly for 4 to 6 weeks for an adequate trial. This regimen can be continued for an extended period of time with appropriate precautions in place. The value of judgment-free psychosocial support cannot be overemphasized. Patients with TMPDS are faced with long-term problems of pain management. An understanding clinician can provide the sustained support required to prevent the cycle of ever more invasive treatments with their potential for harm.

TMD diagnostic decision-making and probability theory. Part I

This article is an educational analysis and discussion of some recently proposed diagnostic criteria, diagnostic methods, and diagnostic decision processes, pertaining specifically to temporomandibular disorders (TMD). On the basis of a discussion of classic probability theory, classic measurement theory, and examples using nonparametric inferential statistical tests, it is suggested that certain TMD diagnostic criteria and methods, and their associated decision matrix, favor subjective clinical opinions (largely pseudoscientific observations) and arbitrary clinical indices rather than objective scientific facts.

Gum chewing and jaw muscle fatigue and pains

To study possible associations between gum chewing and fatigue and pains in the jaw muscles, eight healthy adults performed prolonged idling, prolonged unilateral chewing of gum, and brief vigorous clenching of the teeth (MVC). Through surface electromyography (EMG), the authors monitored the cumulative (microV.s) as well as the average rates (microV.s-1) of contractile activities in the right and left masseter muscles. During 10 min of idling there was an absence of muscle fatigue and muscle pains when the EMG rates of the right and left masseter muscles were 2% and 3%, respectively, of those required to elicit isometric muscle pains through MVC. During 10 min of right-sided gum chewing at a rate of 1.2 Hz, the majority of subjects (75%) experienced weak jaw muscle fatigue-not jaw muscle pains-when the EMG rates of the right and left masseter muscles were 38% and 19%, respectively, of those required to elicit isometric pains through MVC. In comparison with 10 min of idling, the weak muscle fatigue of 10 min of unilateral gum chewing appeared when the total contractile activities of the right and left masseter muscles were increased by 1664% and 519%, respectively. It seemed as if prolonged unilateral gum chewing and previous pain-releasing MVC caused some sensitization of muscle nociceptors which, in turn, aggravated subsequent isometric jaw muscle pains elicited through MVC. Even though the right masseter muscle was the most frequent site of clinical fatigue and pains, the authors found no evidence supporting the theoretical foundation of the myofascial pain/dysfunction syndrome.

Sensory-motor interactions of human experimental unilateral jaw muscle pain: a quantitative analysis

Experimental muscle pain was elicited by bolus injection of 0.15 ml of 5% hypertonic saline into the human masseter muscle. The sensory experience was described using 10-cm visual analogue scales (VAS) and the McGill Pain Questionnaires (MPQ) on 10 subjects. Effects of pain on deliberately unilateral mastication were quantitatively assessed in 13 other male subjects using kinematic recordings of the mandible and jaw muscle electromyography (EMG). Jaw movement and EMG data were transformed into single masticatory cycles which were averaged within subjects to produce mean masticatory cycles. Injection of 5% saline through normal and anesthetized skin produced similar VAS profiles and MPQ features. Displacement of the mandible during painful mastication was significantly smaller in the vertical axis (10.0 +/- 11.5%, P < 0.05) and in the lateral axis (22.6 +/- 20.9%, P < 0.05) as compared to pre-pain values. The mean opening and closing velocities of the mandible were significantly reduced (10.5 +/- 16.3% and 15.3 +/- 21.2%, P < 0.05) and the cumulated distance of the jaw movement was also significantly smaller during pain (10.5 +/- 11.8%, P < 0.05). Moreover, agonist EMG activity during pain was significantly lower in the ipsilateral masseter muscle (20.3 +/- 25.4%, P < 0.05) as compared to pre-pain root-mean-square (RMS) values. The observed sensory-motor interactions can be explained by a facilitatory effect of activity in nociceptive muscle afferents on inhibitory brain-stem interneurons during agonist action. Thus, generated movements have smaller amplitudes and they are slower which most likely represents a functional adaptation to experimental jaw muscle pain.

Is myofascial pain of the temporal muscles relieved by oral sumatriptan? A cross-over pilot study

There is evidence that serotonin may be implicated in the pathophysiology of myofascial pain (MFP). Because of this, we used oral sumatriptan (Imitrex, Glaxo), a peripherally acting agonist of 5-HT1D receptors, in a double-blind, randomized, placebo-controlled double crossover pilot study of 7 patients with episodic MFP of the temporalis muscles. The results showed that there was a significant reduction in pain intensity and increase in pain relief over time with both the active medication and the placebo, but no significant difference between treatments. All but 1 patient reported that they are not interested in retaking the same medication. These data suggest that oral sumatriptan may not be the drug of choice in the control of episodic MFP.

Validity of diagnostic and monitoring tests used for temporomandibular disorders

Currently, diagnosis of temporomandibular disorders (TMD) depends on a comprehensive history and physical examination, supplemented, when indicated, by images of hard and soft tissues. However, there are electronic diagnostic devices being marketed to acquire other measures described as relevant to TMD and to use these for diagnosis of TMD and for monitoring the effects of treatment. This paper reviews the capacity of several devices to measure these variables accurately and reliably and to assess the theoretical basis of each of these tests. Diagnostic ability was established, when possible, according to the commonly accepted measures of sensitivity, specificity, and positive predictive values. It was found that many tests lack theoretical validity, that measurement validity tends to be poor, and that diagnostic ability can be even worse than chance, because of a high percentage of false-positive diagnoses. Based on these findings, the use of these instruments in clinical practice is inappropriate at this time and may lead to the treatment of large numbers of subjects who have no disorder.

Dental splint prescription patterns: a survey

A random sample of U.S. dentists was surveyed with a mailed questionnaire to determine the number of splints that they fabricated over the preceding year for bruxers, patients with myofascial pain-dysfunction syndrome and patients with TM joint pain. The results indicate that a significant number of dentists treat these disorders with dental splints. Estimates are provided for the dental profession's yearly splint output for each disorder.

Pain responses to experimental chewing in myofascial pain patients

Although patients with myofascial pain of the masticatory muscles often report that chewing exacerbates their pain, this has never been verified experimentally. In this study, pain was assessed before and after chewing in 20 asymptomatic subjects and in 61 patients with muscle pain. First, self-reports of pain were obtained with a checklist and on five-point category scales (CAT) at the screening visit. None of the asymptomatic subjects reported that mastication or other jaw movements caused pain. On the other hand, the majority of patients reported that movements were painful (67.2%, checklist; 78.7%, CAT). Afterward, pain intensity at rest and after chewing on wax for 3 min was reported on 100-mm Visual Analogue Scales (VAS). No asymptomatic subjects had pain before or after the chewing test, while about 50% of the patients reported an increase of pain after chewing. In this subgroup, mean pain intensity increased by 102.6%. However, mean pain intensity after chewing decreased by 56.6% in about 30% of the patient sample. These patients had significantly higher resting pain than the first subgroup. These data show that a short chewing test can exacerbate pain in most myofascial pain patients but has no effect in asymptomatic subjects. Surprisingly, the exercise decreased pain in an important subgroup of patients. These results suggest that two subgroups of myofascial pain patients may exist with opposite reactions to exercise. It remains to be seen if these reactions are due to two different pathologies or to the fact that the pre-exercise pain levels were significantly different in the two groups.