Temporomandibular joint disfunction syndrome and myofascial pain dysfunction syndrome: a critical review

Botulinum toxin and occlusal splints for the management of sleep bruxism in individuals with implant overdentures: A randomized controlled trial

BACKGROUND

The available treatment options fail to provide definitive or curative management for bruxer patients rehabilitated with implant overdentures (OD). The data regarding Botulinum toxin (BTX) injection as a management strategy for bruxism remains unclear. This randomized, single-blinded, control-group, pretest-posttest prospective trial evaluated the occlusal guard and Botox injections (BTX) effectiveness in managing sleep bruxism (SB) in subjects whose one of the edentulous arches had been restored with the implant-supported OD.

METHODS

Forty-two patients diagnosed with definite bruxism were selected, all of which had implant-retained ODs opposing natural dentition. The participants were allocated randomly to three equal groups. Participants in group I (control group) were instructed to remove the OD at night; group II was managed with conventional occlusal stents. Those in group III were given BTX injections. New ODs were constructed for all groups, and all ball attachments were replaced with a new nylon cap. A baseline assessment (one month of OD insertion) of patient satisfaction and sleep quality was conducted, and then again at 3, 6, 9, and 12 months of treatment. Subjective sleep quality was evaluated using Pittsburgh Sleep Quality Index (PSQI). Patients' satisfaction was evaluated using Temporomandibular disorders/numeric scales (TMD/NS). Prosthodontic (mechanical) complications were recorded during the follow-up period.

RESULTS

Group III showed a statistically significant improvement in patient satisfaction and sleep quality compared to the other two groups at 3, 6, 9, and 12 months follow-up period ( P  = 0 0.001, 0.0001, 0.0013, and 0.0001 respectively). Regarding prosthodontic (mechanical) complications, the highest number of events was revealed in the control group.

CONCLUSIONS

BTX and occlusal appliances effectively improve patient satisfaction and sleep quality of Bruxer patients rehabilitated with single arch implant overdentures.

The Case for Comorbid Myofascial Pain-A Qualitative Review

Myofascial pain syndrome is widely considered to be among the most prevalent pain conditions, both in the community and in specialized pain clinics. While myofascial pain often arises in otherwise healthy individuals, evidence is mounting that its prevalence may be even higher in individuals with various comorbidities. Comorbid myofascial pain has been observed in a wide variety of medical conditions, including malignant tumors, osteoarthritis, neurological conditions, and mental health conditions. Here, we review the evidence of comorbid myofascial pain and discuss the diagnostic and therapeutic implications of its recognition.

Evaluation of tissue oxygen saturation of the masseter muscle during standardised teeth clenching

BACKGROUND

Haemodynamics during recovery after teeth clenching is poorly understood.

OBJECTIVE

To clarify factors influencing tissue blood oxygenation recovery after clenching with altered muscle activity and duration, but constant total muscle activity.

METHODS

The following tasks were based on constant maximum voluntary clenching (100% MVC): (a) 50% MVC × 30 seconds; (b) 30% MVC × 50 seconds; and (c) 10% MVC × 150 seconds. Tissue oxygenated (oxy-Hb), deoxygenated (deoxy-Hb) and total haemoglobin (total-Hb) were recorded using near-infrared spectroscopy in the masseter muscle during recovery after each task. Participants rested for 30 seconds before each task; average resting values were set as baseline. Respective ratios to baseline at 20, 60, 120 and 180 seconds after each task were calculated; the tasks were compared at each time point using one-way repeated-measures ANOVA.

RESULTS

Oxy-Hb and total-Hb decreased and deoxy-Hb increased during the tasks and recovered thereafter. For Task 3, not all values recovered to baseline, even after 180 seconds (oxy-Hb: 96.85%, total-Hb: 98.31%, deoxy-Hb: 102.98%). Oxy-Hb (after 180 seconds, Task 1-Task 3: P < .001, Task 2-Task 3: P = .013) and total-Hb (after 180 seconds, Task 1-Task 3: P < .001, Task 2-Task 3: P = .005) were significantly lower, and deoxy-Hb (after 180 seconds, Task 1-Task 3: P < .001, Task 2-Task 3: P = .005) was significantly higher for Task 3 than other tasks, at all times during and after recovery.

CONCLUSION

Despite the same total muscle activity, weak-force, long-duration clenching is more harmful than strong-force, short-duration clenching, suggesting a greater effect of awakening bruxism than sleep bruxism on myalgia.

Effect of water-soluble titanium microparticle-permeated tape on temporomandibular disorders-related pain: a preliminary study

OBJECTIVE

Recent research has focused on the applicability of titanium particle-impregnated materials in healthcare and medical products. This preliminary study was undertaken to investigate the effect of water-soluble titanium microparticle-permeated (WSTi) tape on temporomandibular disorder (TMD)-related pain.

MATERIALS AND METHODS

The study included 32 patients (41.5 ± 14.4 years, 26 women) who had visited the Temporomandibular Joint Clinic, Tokyo Medical and Dental University, for treatment of TMD-related pain. The subjects were instructed to apply the WSTi tape (AquaTitan tape) on the most painful area before going to sleep and remove the tape on awakening daily for 2 weeks. Seven outcome variables were statistically analyzed: maximum mouth-opening ranges with and without pain, spontaneous pain intensity, mouth-opening pain intensity, chewing pain intensity, TMD-related limitation of daily functions (LDF-TMD) and subjective evaluation of any change in TMD-related pain.

RESULTS

The mean maximum mouth-opening ranges with (p = 0.011) and without (p = 0.002) pain were significantly greater and mean pain intensities on mouth opening (p < 0.001) and chewing (p = 0.001) were significantly lower at the 2-week follow-up than at the baseline. The mean LDF-TMDQ scores were also significantly lower at the 2-week follow-up (p = 0.004). After 2 weeks of using the WSTi tape, 53.1% and 12.5% of the subjects reported a slight improvement and an improvement, respectively, in TMD-related pain.

CONCLUSION

WSTi tape seems to have beneficial effects on TMD-related pain and LDF.

Influence of psychosocial factors and habitual behavior in temporomandibular disorder-related symptoms in a working population in Japan

Background:

The symptoms of temporomandibular disorders (TMD) are directly influenced by numerous factors, and it is thought that additional factors exert indirect influences. However, the relationships between TMD-related symptoms (TRS) and these contributing factors are largely unknown. Thus, the goal of the present study was to investigate influences on TRS in a working population by determining the prevalence of TRS, analyzing contributing factors, and determining their relative influences on TRS.

Materials and Methods:

The study subjects were 2203 adults who worked for a single company. Subjects completed a questionnaire assessing TRS, psychosocial factors (stress, anxiety, depressed mood, and chronic fatigue), tooth-contacting habit, and sleep bruxism-related morning symptoms, using a 5-point numeric rating scale. Our analysis proceeded in 2 phases. First, all variables of the descriptor were divided into parts by using an exploratory factor analysis. Second, this factorial structure was verified by using a confirmatory factor analysis with structural equation modeling.

Results:

Of 2203 employees, 362 reported experiencing TRS (16.4%). Structural equation modeling generated a final model with a goodness of fit index of 0.991, an adjusted goodness of fit index of 0.984, and a root mean square error of approximately 0.021. These indices indicate a strong structural model. The standardized path coefficients for “habitual behavioral factors and TRS,” “psychosocial factors and habitual behavioral factors,” “psychosocial factors and TRS,” and “gender and habitual behavior factors” were 0.48, 0.38, 0.14, and 0.18, respectively.

Conclusions:

Habitual behavioral factors exert a stronger effect on TRS than do psychosocial factors.

Emotional distress and medication use in two acute pain populations: jaw and low back

The present study was undertaken to compare emotional distress and functional ability between two common pain populations--acute jaw pain (JAW; n = 135) and acute low back pain (LB; n = 71). Patient groups were evaluated and compared on a variety of biopsychosocial measures, including the Beck Depression Inventory (BDI), Multidimensional Pain Inventory (MPI), Characteristic Pain Intensity (CPI), and Ways of Coping Questionnaire. Specific diagnoses were assessed using the Structured Clinical Interview of the Diagnostic and Statistical Manual (DSM-IV)--I and II, and rates of Axis I and II diagnoses in these groups were further compared to base rates in the general population. Additionally, medication usage was evaluated to determine group differences. Results revealed that JAW patients had lower BDI and CPI scores, as well as a higher level of functioning on the Global Assessment of Functioning assessed by the DSM-IV. Both acute pain groups also had significantly more Axis I and II disorders than the general population. Additionally, it was found that the JAW group used more benzodiazepines, while the LB group used more schedule II narcotics. A logistic regression model created from these variables found a six-factor model, composed of the CPI, MPI coping style anomalous, Ways of Coping problem-solving, Global Assessment of Functioning, anxiety disorders, and Cluster C personality disorder diagnoses, that differentiated the JAW from the LB group. Overall, these findings suggest that the differences identified between these two groups should be considered in developing tailored treatments for individuals with acute low back and jaw pain.

Prevalence of temporomandibular disorder signs in patients with complete versus partial dentures

OBJECTIVES

To determine the prevalence of signs of a temporomandibular disorder (TMD) in completely edentulous patients wearing upper and lower complete dentures (CD) and to compare this to the prevalence of signs in partially edentulous patients wearing upper and lower clasp-retained acrylic removable partial dentures (RPD).

MATERIALS AND METHODS

A questionnaire and a clinical examination were used to assess 200 patients. One hundred of these were complete denture wearers being treated for the provision of replacement CD. The other 100 patients were partially edentulous patients, who had RPD replacing upper and lower partially missing teeth and their supporting structures.

RESULTS

It was shown that there was a statistically significant difference between the two groups regarding the presence of temporomandibular signs. Partially edentulous patients wearing upper and lower RPD had a significantly higher prevalence of TMD signs than edentulous patients wearing CD (36% compared to 17%). They also exhibited significantly (P<0.04) more signs of joint tenderness (18%) on clinical examination compared to (5%) only in the CD-wearing patients. Tenderness upon palpation in the periauricular region was the most common site reported in both groups.

CONCLUSIONS

The partially edentulous patients (wearing RPD) exhibited more TMD signs when compared with the CD-wearing patients. Significantly, more partially edentulous patients had joint tenderness (P<0.04) than did CD-wearing patients. The masseter muscle most commonly demonstrated muscle tenderness.

The comparison between pains, difficulties in function, and associating factors of patients in subtypes of temporomandibular disorders

The aim of this study was to compare the multidimensional properties among subtypes of painful temporomandibular disorders (TMD): myofascial pain (group I), disc displacement (group II), arthralgia (group IIIa) and osteoarthritis (group IIIb). A total of 511 patients answered a battery of questionnaires, which included questions relating to intensity and duration of pain, the Japanese version of the McGill Pain Questionnaire, limitation of daily functions, the Hospital Anxiety and Depression Scale, the Eysenck Personality Questionnaire short-form and 34 items of behavioural contributing factors. Group IIIb showed significantly the highest age in all subtypes. Those in group I had higher depression scores than those in group II (P = 0.005). Group IIIa had a lower women's ratio than in group II (P = 0.001) and the patients showed a shorter pain duration than those in groups I (P = 0.000) and II (P = 0.001). Group IIIa patients also showed lower visual analogue scale (VAS) ratings for pain descriptors 'heavy' (P = 0.002) and 'tiring' (P = 0.004) than those of group I, and 'dull' (P = 0.005), 'heavy' (P = 0.001) and 'tiring' (P = 0.005) than those of group II. Group IIIa showed lower ratios of contributing factors of 'an awareness of grinding/clenching during sleep' (P = 0.000) and 'an awareness of clenching sensation when waking up at night' (P = 0.002) than those of group I, and also showed a higher ratio of 'a liking for a hard food' (P = 0.000) and lower ratio of 'talking for a long time on the telephone' (P = 0.001) than those of group II. In conclusion, although several properties were different between subtypes, the majority of them were similar in the four subtypes of TMD.

Efficiency of occlusal appliance therapy in secondary otalgia and temporomandibular disorders

In clinical practice, it is commonly assumed that occlusal splints have therapeutic value in the treatment of temporomandibular disorders CTMD), but the evidence based on randomized controlled trials is scarce. This study evaluated the short-term (10-week) efficacy of a stabilization splint in subjects with recurrent secondary otalgia and active TMD treatment need using a randomized, controlled, double-blind design. Thirty-six subjects were randomly allocated to the two treatment groups: the stabilization splint and the control splint group. After 10 weeks' treatment, the intensity of secondary otalgia, measured on a VAS scale (from 0 to 100 mm), decreased statistically significantly in the stabilization splint group (t 2.12; P 0.006), but not in the control group. Improvement in active TMD treatment need in subjects showing moderate or severe signs and symptoms of TMD was reported significantly more often in the stabilization splint group than in the control splint group (chi2 5.71; P.017). A statistically significant decrease in the Helkimo clinical dysfunction index was seen in the subjects with stabilization splint (Z-2.63; P.009), but not in the subjects with control splint. The results indicate that the use of a stabilization splint is beneficial with regard to secondary otalgia and active TMD treatment need.

A biopsychosocial overview of pretreatment screening of patients with pain

The prevalence and excessive cost of pain, especially when the pain becomes chronic, remains a major health-care problem in the United States. Currently, a biopsychosocial perspective of pain has been found to be the most heuristic approach to understanding and managing it. Using this perspective, an important advance has been made in the possibility of individually tailoring treatment for each patient, with the result being better outcomes. The author reviews the extant literature demonstrating a robust "psychosocial disability factor" among injured workers that is important not only in pain perception, but also in the subsequent development of chronic pain-related disability. Such results emphasize the importance of taking into account how psychosocial and physical factors are intertwined in a complex way in determining pain symptomatology. On the basis of these findings, a number of surgical pre-screening approaches have been developed and found to be effective for maximizing surgical outcomes as described by Carragee, Epker, and Block in other papers in this special topics series. Recently, several organizations in the U.S. have also developed new standards for the evaluation of pain. For example, the Joint Commission on Accreditation of Health Organizations (JCAHO) now requires that physicians consider pain as a "5th vital sign" in evaluating patients. Such initiatives have created a new mandate to regularly assess and manage all types of pain. The use of opioids, as well as implantable pain-management modalities, are among the options. The author notes that the literature on these modalities focuses on interdisciplinary patient-screening approaches prior to their administration as a way of maximizing treatment outcomes. The papers by Praeger, Jacobs, and Robinson et al. in this special topics series describe the approach to pretreatment assessment for these modalities in detail. Finally, the author presents a stepwise, biopsychosocial approach as the basis for assessment before decisions regarding surgery, opioid maintenance therapy, and implantable pain-management modalities. The author suggests that systematic pretreatment interventions will facilitate a more structured standard of care in the evaluation and treatment of patients with pain and ultimately better outcomes.

Role of temporomandibular disorders (TMD) in facial pain: occlusion, muscle and TMJ pain

Temporomandibular disorders (TMD) which comprise myogenic and arthralgic components have been reported to predispose subjects to headache and facial pain. The aim of this study was to evaluate the role of these components in patients with facial pain and to investigate the influence of treatment of TMD on pain of these patients. The subject group consisted of 25 patients suffering from facial pain. The clinical stomatognathic examination was performed before conservative treatment of TMD, and one-two weeks, three months and one year after treatment. The severity of TMD was assessed using the anamnestic (AI) and clinical dysfunction (DI) indices of Helkimo. The intensity of pain was evaluated on a numerical rating scale (NRS). According to clinical findings the patients were classified to following diagnostic subgroups: TMD myo (mainly myogenic), TMD arthro (mainly arthrogenous) and TMD comb (both myogenic and arthrogenous components involved). Fifteen patients were classified in the TMD myo group, nine in the TMD comb group and one in the TMD arthro group. The DI index decreased significantly one-two weeks after treatment and remained at this level at three month and one year follow-up examinations. At the first examination the TMD myo group had the highest level of NRS index, which decreased significantly during the time of follow-up, while no significant changes were found in other groups. Bruxism reported by the patient had a positive correlation with the amount of painful muscles on the right side at first examination. The results show that facial pain combined with TMD may be mostly of myogenic origin, and myogenic pain seems to have most favorable response to conservative treatment of TMD.

Health care utilization by patients with temporomandibular joint disorders

The claims data base of a large New England managed care organization was used to compare the health care utilization patterns of patients with TMJ disorders to non-TMJ subjects. Inpatient, outpatient and psychiatric claims data were examined over a wide range of diagnostic categories. Age and sex adjusted results showed that, overall, patients with TMJ disorders were greater utilizers of health care services and had higher associated costs than non-TMJ subjects. For some of the major diagnostic categories, such as nervous, respiratory, circulatory, and digestive, the inpatient and outpatient claims differences in utilization and costs were as large as 3 to 1. For only one diagnostic category, pregnancy and childbirth, were utilization and costs greater for non-TMJ subjects than TMJ patients. The psychiatric claims for TMJ patients exhibited differences that were at least twice as large as those for the non-TMJ subjects.

Occlusal appliance therapy in patients with temporomandibular disorders. A double-blind controlled study in a short-term perspective

Stabilization appliances are commonly used in the treatment of temporomandibular disorders (TMD), although the treatment effects are not fully understood. This study evaluated the short-term efficacy of a stabilization appliance in patients with TMD of arthrogeneous origin, using a randomized, controlled, and double-blind design. Sixty patients were assigned to two equally sized groups: a treatment group given a stabilization appliance and a control group given a control appliance. Improvement of overall subjective symptoms was reported in both groups but significantly more often in the treatment group than in the control group (P = 0.006). Frequency of daily or constant pain showed a significant reduction in the treatment group (P = 0.02) compared with the control group. The results of this short-term evaluation showed that both the stabilization appliance and the control appliance had an effect on temporomandibular joint (TMJ) pain. It is improbable that the difference observed between the groups is due to chance alone.

Distúrbios craniomandibulares em pacientes edentados unilaterais inferiores com e sem próteses parciais removíveis (PPR): um estudo transversal utilizando o índice craniomandibular

No presente trabalho, foi feito um estudo clínico em 102 pacientes, 78 mulheres e 24 homens, com idade variando entre 18 e 61 anos, com a finalidade de analisar comparativamente a severidade de sinais e sintomas das desordens craniomandibulares (DCM). Procedeu-se a anamnese, o exame clínico e as moldagens e estabeleceu-se um método de escores, através do qual se avaliou o grau de severidade das DCM. Os pacientes foram divididos em três grupos de 34 pessoas, assim constituídos: a) portadores de prótese parcial removível corretiva para arcos com ausência unilateral de dentes inferiores (classe II de Kennedy); b) edentados unilaterais inferiores, sem tratamento protético (ausência unilateral de dentes naturais ou artificiais); e c) pacientes com todos os elementos dentais. Todos os indivíduos estudados apresentavam alguma queixa de dor facial ou desconforto muscular. Foram analisados e comparados estatisticamente todos os dados, e concluiu-se que o grau de severidade dos sinais e sintomas das DCM, refletido pelos diversos escores obtidos, mostrou comportamento diferente nos grupos de pacientes estudados. Os edentados unilaterais não portadores de PPR, com ausência de dentes por período superior a cinco anos, foram os que apresentaram maior grau de severidade dos sinais e sintomas das DCM. Os resultados ainda nos permitiram sugerir que o emprego de uma PPR corretamente planejada poderá diminuir significativamente o grau de severidade dos sinais e sintomas das DCM, em pacientes edentados unilaterais mandibulares, correspondentes à classe II de Kennedy. A utilização do índice craniomandibular (ICM) permitiu avaliar com segurança sinais e sintomas dos distúrbios craniomandibulares.

Body position effects on sternocleidomastoid and masseter EMG pattern activity in patients undergoing occlusal splint therapy

This study was conducted in order to determine the effects of body position on electromyographic (EMG) activity of sternocleidomastoid and masseter muscles, in 15 patients with myogenic cranio-cervical-mandibular dysfunction undergoing occlusal splint therapy. EMG activity was recorded by placing surface electrodes on the sternocleidomastoid and masseter muscles (contralateral to the habitual sleeping side of each patient). EMG activity at rest and during swallowing of saliva and maximal voluntary clenching was recorded in the following body positions: standing, supine and lateral decubitus. In the sternocleidomastoid muscle significant higher EMG activities at rest and during swallowing were recorded in the lateral decubitus position, whereas during maximal voluntary clenching EMG activity did not change. In the masseter muscle significant higher EMG activity during maximal voluntary clenching in a standing position was observed, whereas EMG activity at rest and during swallowing did not change. The opposite pattern of EMG activity supports the idea that there may exist a differential modulation of the motor neuron pools of the sternocleidomastoid and masseter muscles, of peripheral and/or central origin. This suggests that the presence of parafunctional habits and body position could be closely correlated with the clinical symptomatology in these muscles in patients with myogenic craniomandibular dysfunction.

Morphometric analysis of the insertion of the upper head of the lateral pterygoid muscle

OBJECTIVE

This article reports on the morphometric characteristics of the upper head of the lateral pterygoid muscle.

STUDY DESIGN

Several morphologic characteristics were initially examined in 40 postmortem specimens. The length of the upper head of the lateral pterygoid muscle was determined in 34 specimens. Of the 26 specimens in which the upper head of the lateral pterygoid muscle was found to be inserted into the meniscus and condyle, 22 specimens were examined microscopically to morphometrically quantify the proportion of muscle fibers to their respective insertions.

RESULTS

The upper head of the lateral pterygoid muscle was approximately 33.3 mm in length and was significantly longer in males. There were no age-related differences. Approximately 29.5% of the fibers of this muscle were inserted into the meniscus of the temporomandibular joint.

CONCLUSION

This study demonstrated that the insertion of the upper head of the lateral pterygoid muscle to the meniscus ranged from a fleshy mass to a few fibers. The number of fibers entering both the meniscus and the condyle decreased correspondingly as they approached the joint and could be interpreted as this muscle having a tendon of insertion into the meniscus.

Medical claims profiles of subjects with temporomandibular joint disorders

The primary goal of this study was to evaluate the claims profiles of subjects with TMJ disorders relative to a control group without the disorders and to provide a characterization of the type of healthcare services received and the associated costs of healthcare for patients with TMJ disorders. The administrative data base of a major medical insurer was used to compare the claims history of 1,819 patients diagnosed with TMJ disorders to matched controls. The analysis was based only on medical claims. The study found that total medical claim payments for the patients with TMJ disorders were double that of the subjects without TMJ disorders, and similarly, the utilization of institutional and professional care services was found to be approximately twice as high, though not uniformly distributed across all Major Diagnostic Categories, physician specialties or types of service. The level and nature of the differences in the quantity and costs of healthcare between subjects with and without TMJ disorders were unexpectedly large. The majority of these differences were attributed to conditions that were not usually considered related to TMJ disorders. These utilization and cost differences extended, in varying degrees, over a wide range of diagnostic and healthcare provider categories.

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.

The concepts prevalence, need for treatment, and prevention of temporomandibular disorders: a suggestion for terminology

The concepts active and passive treatment need and active and passive prevention need are suggested, to systematize some concepts used in discussions about temporomandibular disorders (TMD), to separate the treatment need figures from the prevalence figures, and to understand the great variation among TMD prevalence studies. On the basis of a summary of recently published papers and on a clinical 2-year follow-up study of 411 subjects, the suggestions seem to provide a reasonably good fit with clinical experience and earlier epidemiologic studies of TMD.

Elongated styloid process in a temporomandibular disorder sample: prevalence and treatment outcome

An elongated styloid process is an anatomic anomaly present in 2% to 30% of adults; it is occasionally associated with pain. Its prevalence among patients with classic temporomandibular disorder pain symptoms is unknown. The effect of conservative treatment on patients who have symptoms of temporomandibular disorders and an elongated styloid process is also unknown. The objectives of this study were to determine the prevalence of the elongated styloid process in a sample of patients with temporomandibular disorders and to compare patients with and without the elongated styloid process on initial presenting signs and symptoms and treatment outcome. A total of 100 panoramic radiographs of patients with symptomatic temporomandibular disorders were examined to ascertain the presence or absence of an elongated styloid process. All patients participated in a conservative treatment program of biofeedback and stress management and a flat-plane intraoral appliance. Initial symptoms and treatment outcome of patients with and without an elongated styloid process were compared by use of multivariate analysis of variance on several oral-paraoral and psychosocial-behavioral methods. The prevalence of an elongated styloid process in this clinic sample of temporomandibular disorders was 27%. The patients with or without an elongated styloid process were not significantly different in pretreatment symptoms, and both groups exhibited substantial treatment gains. However, patients with an elongated styloid process showed significantly less improvement on unassisted mandibular opening without pain than did patients who did not have an elongated styloid process. This suggests that an elongated styloid process may place structural limitations on pain-free maximum mandibular opening. The results support conservative management of patients with symptoms of temporomandibular disorders when an elongated styloid process is present.

Psychological factors related to the prevalence of temporomandibular joint sounds

This study focuses on the association between psychological factors and TMJ sounds, and the most suitable research design to establish this relation. A traditional research design is simulated to demonstrate how self-report may bias findings. A refined design is presented to obtain unbiased estimates of the role of psychological variables. In the 'naïve' design the importance of psychological variables was overestimated and the role of physiological variables was underestimated. It was concluded that future studies in the aetiology of TMJ clicking should abandon the use of self-report as a proxy for objective findings. With the refined design it was found that psychological factors play only a minor role in the prevalence of TMJ sounds. Findings do not support speculation about mechanisms that relate psychological factors to the presence of TMJ sounds.

Effects of occlusal splints on the asymmetry of masticatory muscle activity during maximal clenching

The effects of stabilization splints on the electromyographic activity patterns of the masseter and anterior temporal muscles during maximal clenching in healthy subjects and subjects with different types of stomatognathic dysfunction syndrome were investigated. No marked effect of splints on the asymmetry of muscle activity during bilateral clenching was revealed immediately after splint insertion. During unilateral clenching in the intercuspal position (ICP), the relative asymmetry index (rAI) of the masseter muscles, detecting the imbalance of left and right muscular activity, was significantly increased. The use of splints suppressed the asymmetry of masseter muscle activity during unilateral clenching. This result suggests that the use of a splint is a method of suppressing clench-caused aggravation of stomatognathic dysfunction in the presence of an imbalance between left and right muscle activities.

Asymmetry of masticatory muscle activity during intercuspal maximal clenching in healthy subjects and subjects with stomatognathic dysfunction syndrome

The present study investigated the asymmetry of masticatory muscle activity during maximal intercuspal clenching in healthy subjects and subjects with stomatognathic dysfunction syndrome. Stomatognathic dysfunction syndrome, unilateral mastication and the asymmetry of masticatory muscle activity appear to be related to each other. The asymmetry of masseter muscle activity was greater as stomatognathic dysfunction became increasingly severe. Because fatigue and pain are produced more quickly by unilateral clenching than bilateral clenching, clenching under conditions of left and right muscular imbalance can further aggravate stomatognathic dysfunction. It is suggested the asymmetry of masseter muscle activity during maximal clenching correlates with the onset of the stomatognathic dysfunction syndrome. Stomatognathic dysfunction syndrome is closely related to the asymmetry of masseter muscle activity and only slightly related to the asymmetry of temporal muscle activity. The asymmetry of anterior temporal muscle activity appears to have little clinical significance.

Vectorial analysis of the equilibrium of forces transmitted to TMJ and occlusal biteplane splints

A mechanical model (link quadrilateral bell crank) is used to demonstrate the equilibrium of normal force vectors transmitted to the masticatory system and maxillary occlusal biteplane splints with different designs. Occlusal contacts were imposed on the proposed models under the action of a masticatory force vector with an arbitrary value of 40 kgf. The consequence of this force action created different responses within the joint and at the level of the dentition. When compared to the intercuspal position in centric occlusion, intra-oral appliances with either smooth contacting surfaces or indentations, both with increased vertical dimension, forced the mandible to assume an anterior position with a concurrent increase of joint forces. The bite-splint that produced the least amount of joint force was the stabilization type with minimal increase of vertical dimension.

Oral habits and TMJ dysfunction in facial pain and non-pain subjects

Multifactorial theories for facial pain aetiology have been proposed in the past, although little research has been produced to support a multifactorial aetiology. The present study assessed self-rated oral habits over a 7 day period for facial pain and non-pain subjects with and without a clinical symptom of TMJ dysfunction. The results indicate a significant effect for TMJ dysfunction and teeth clenching and an interaction between TMJ dysfunction and facial pain for biting of the lips and mouth. A significant chi-square test showed that most non-pain controls with TMJ dysfunction reported that they never clenched. The results are discussed in terms of support for a multifactorial aetiology in some facial pain patients and the need for future research to delineate subgroups of facial pain and non-pain subjects.

Occlusion and craniomandibular function among patients treated with removable partial dentures

Forty patients treated with removable partial dentures (RPDs) at the Institute of Dentistry, University of Oulu, were selected for this study. The type of occlusion, horizontal and vertical overlap, the slide between retruded contact position and intercuspal position, and the occlusal interferences were investigated as occlusal parameters. Helkimo's anamnestic and clinical indices were used to measure the craniomandibular function and the clinical index score was used to compare the differences between different groups. The RPD-generated occlusal interferences seemed to cause most harmful effects in point centric, interference free occlusions, when the damage was directed at the temporomandibular joint. These interferences were most frequently found in the retruded contact position and caused by the RPD teeth.

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

Oral splints are widely used in the treatment of myofascial pain of masticatory muscles, even though their mechanism of action is unknown. The present study evaluated the therapeutic efficacy of splints using a parallel, randomized, controlled and blind design. Following a sample size estimation, 63 subjects were recruited and assigned to 3 groups: (1) passive control: full occlusal splint worn only 30 min at each appointment; (2) active control: palatal splint worn 24 h/day; and (3) treatment: full occlusal splint worn 24 h/day. On each of 7 visits over 10 weeks, subjects rated on 100 mm visual analogue scales their pain intensity and unpleasantness at rest and after experimental mastication. The effect of pain on the quality of life was also rated on category scales. All pain ratings decreased significantly with time, and quality of life improved for all 3 groups. However, there were no significant differences between groups in any of the variables. These data suggest that the gradual reduction in the intensity and unpleasantness of myofascial pain, as well as the improvement of quality of life during the trial, was non-specific and not related to the type of treatment.

Temporomandibular disorders: assessment of psychological factors

Factors such as psychological stress, anxiety, depression, oral habits, and chronic pain behaviors have been found in subgroups of Temporomandibular Disorders (TMD) patients. This paper reviews the current status of diagnostic methods and instruments designed to identify various psychological factors. The authors offer the following general conclusions: Although the DSM-III-R has significant limitations, it is currently the most common gold standard with which other psychological instruments are compared. There are several specific assessment instruments, such as the Beck Depression Inventory and the Zung Self-Rating Depression Scale, which have been found to have acceptable sensitivity and specificity scores. In addition, certain simple screening questions may be cost-effective for the identification of psychological factors. Because of studies indicating that the dentists' recognition of psychological factors is inaccurate, a brief screening questionnaire may be useful in TMD patients. The literature does not support the routine use of the MMPI. A major conclusion of this review is that there are several psychological instruments available which have demonstrated reasonable validity through a blind comparison with a gold standard. There is need for further development and testing of brief screening instruments using clinical decision methods.

Temporomandibular joint dysfunction syndrome: a close association with systemic joint laxity (the hypermobile joint syndrome)

Sixty-two patients admitted for elective reconstructive surgery of the temporomandibular joint (TMJ) and eight seen as outpatients with a chief complaint of TMJ dysfunction during the same time interval were evaluated for possible etiologic factors contributing to the disease. All hospitalized patients had severe, end-stage degenerative changes within the TMJ, whereas outpatients had less severe disease and did not require surgery. TMJ dysfunction in some patients was said to be a result of established causes including bruxism, malocclusion, and trauma. No patient in this series had evidence of a systemic inflammatory polyarthritis. Of the 70 patients, 38 (54%) met criteria, based on those of Carter and Wilkinson, as modified by Beighton et al., sufficient to warrant a diagnosis of the hypermobile joint syndrome. Five patients had classic Ehlers-Danlos syndrome and therefore were not patients with "benign hypermobility," and an additional two cases were described as "marfanoid" and as possible Ehlers-Danlos syndrome, respectively. Radiographs showed TMJ hyperextensibility in four hypermobile patients. Long-term surgical outcome was identical in the hypermobile and nonhypermobile groups. The incidence of hypermobility in this series is strikingly higher than the expected incidence in an otherwise population. Magnetic resonance images of the TMJs on separate groups of asymptomatic normal and hypermobile women identified excessive anterior movement in the hypermobile group, together with abnormal anterior disk position in some. We hypothesize that hypermobility within the TMJ may cause accelerated disk destruction and degenerative disease.

Occurrence of temporomandibular disorder symptoms in healthy young adults with and without evidence of bruxism

Few studies have specifically examined the association between bruxism and symptoms of temporomandibular disorders in adults. In this study 569 freshmen dental students entering the Medical College of Georgia over a 10-year period completed an 18-item "yes/no" questionnaire relating to awareness of tooth clamping/clenching/grinding and signs and symptoms of oral, facial, and craniomandibular discomfort, pain, and disorders. A higher proportion of females than males reported that they were aware of clamping and clenching their teeth, as well as symptoms of stiff jaw, sore jaw or teeth, cracking or locking jaw joint, and headaches in the morning. Reported awareness of tooth clamping and clenching and of someone having heard tooth grinding was significantly associated with reported pain, discomfort, or other sensations in, in front of, or behind the ear in the overall subject group.

Soft occlusal splint therapy in the treatment of migraine and other headaches

Fifty-seven patients suffering from migraine, tension headache or tension vascular headache were prescribed a soft occlusal splint for night-time wear. Dental, psychosocial/psychiatric and neurological data were recorded prior to commencement of therapy and at the conclusion of a 3 month treatment period. A statistically significant number of patients presenting with migraine or tension vascular headache experienced marked improvement or complete relief of headache symptoms, but most patients suffering from tension headache failed to benefit from splint therapy. A majority of patients displaying intercurrent features of craniomandibular dysfunction experienced reduction in these symptoms also. There was a statistically significant association between TMJ improvement and headache type. Prior to treatment, patients who subsequently benefited from splint therapy in terms of headache improvement had experienced significantly fewer headaches than patients who failed to respond, although headache intensity and duration were similar in both groups. It is suggested that headache type and frequency may be prognostic indicators of the likely success of dental splint therapy in treatment of headache. Nevertheless, the use of occlusal splints in the treatment of patients complaining of headache in the absence of evidence of craniomandibular dysfunction should not be embarked upon until medical examination has excluded the possibility of organic neurological disorder.

A dynamic model of etiology in temporomandibular disorders

A dynamic model is proposed to depict the etiology of temporomandibular disorders. A balance is described between destructive factors in the masticatory system that result in dysfunction, and adaptive factors that tend to return it homeostatically to normal. Five factors that cause or potentiate muscle hyperfunction are included on one side of the model with five other factors that affect the ability of the system to adapt on the other side. Relationships among the etiologic factors are discussed, and literature support for each is cited.

Presence of type III collagen in disc attachments of human temporomandibular joints

Samples of discs and disc attachments were extracted by dissociative methods and the resultant collagenous residues cleaved with cyanogen bromide. Soluble peptides thus released were characterized by their electrophoretic mobility following SDS-PAGE and by Western blot staining with specific antibodies against type I and type III collagens. Type III collagen was identified in samples taken from the posterior discal attachments. This may explain why this disc is prone to detachment and internal derangement and the high incidence of patients with temporomandibular joint dysfunction.

A short-term evaluation of the effectiveness of stabilization-type occlusal splint therapy for specific symptoms of temporomandibular joint dysfunction syndrome

To clarify the short-term effectiveness of stabilization-type occlusal splint therapy, a specific symptom approach was used toward 30 temporomandibular joint dysfunction patients with more than two major symptoms (temporomandibular joint and/or masticatory muscle pain, temporomandibular joint sounds, and limitation of mandibular movement). Eighty-seven percent of the patients with pain responded with this therapy and more than 50% had complete relief of pain 4 weeks after insertion of the splint. Temporomandibular joint sounds and limitation of mandibular movement responded more slowly than pain. These results suggest that the stabilization-type occlusal splint should be selected as a first choice among several therapies and that temporomandibular joint pain is particularly susceptible to this therapy.

Effect of elimination of occlusal interferences on signs and symptoms of craniomandibular disorder in young adults

Sixty-two dental students judged not to be in need of treatment for craniomandibular disorder (CMD) were randomly divided into two groups, one receiving occlusal adjustment and the other mock adjustment. A double-blind study design was applied. After 2 years of education in dentistry, including courses in stomatognathic physiology, the increase in the subjective symptoms of CMD was significantly greater in the placebo control group than in the treatment group. The difference between the groups in the increase of sites tender to palpation was less clear, showing only a trend. However, the increase was statistically significant within the placebo group but not within the treatment group. Prophylactic occlusal adjustment thus appears to be effective in reducing the occurrence of symptoms of CMD, and possibly also the occurrence of clinical signs.

Effect of experimental stress on masseter and temporalis muscle activity in human subjects with temporomandibular disorders

Temporomandibular (TM) disorders have an uncertain aetiology. The purpose of this study was to replicate and extend the work of Yemm (1969) (Archs oral Biol. 14, 873-878, 1437-1439; Br. dent. J. 127, 508-510), who reported a lack of habituation to experimentally induced stress in subjects with TM disorders. In this study, 20 TM disorder patients and 20 controls, matched for age and sex, performed a timed psychomotor task while bilateral masseter and anterior temporalis electromyographic (EMG) activity, finger temperature and skin admittance were monitored. These data were sampled, stored every 4s and averaged by an Apple II Plus/ISAAC interface. A significant trials effect for finger temperature (F[4/152] = 34.99, p less than 0.001) and skin admittance (F[4/152] = 41.90, p less than 0.001) was found, suggesting that the independent variable (stress) had been successfully manipulated. A significant trials by groups effect was found for right temporalis EMG activity (F[3/144] = 3.94, p less than 0.05); the left temporalis showed a similar, but not significant, trend. The masseter muscles did not show differences or trends between groups. No significant differences were found in resting EMG levels or in the initial magnitude of EMG responses during baseline. These results provide support for the hypothesis that TM disorder and control groups respond differently to stress in terms of habituation to stressful stimuli.

Masseter and temporalis electromyographic activity in asymptomatic, subclinical, and temporomandibular joint dysfunction patients

The research and clinical literature on biofeedback treatment of temporomandibular joint (TMJ) dysfunction is devoid of normative or comparative electromyographic (EMG) studies examining muscle activity in either patient or normal samples. For the present study, resting EMG levels for each masseter and temporalis were obtained from three groups of subjects: asymptomatic (female, N = 24, mean age = 26.4); subclinical (female, N = 31, mean age = 28.6); and patient (N = 61, female 70%, mean age = 31.9). A Biocomp 2001 biofeedback system was used to gather the EMG data from each of the four sites during a six- to eight-minute resting baseline period. The patient group demonstrated significantly higher EMG activity than the asymptomatic or subclinical groups for all variables except the right masseter (F (8,220) = 6.65, p less than 0.001). The temporalis was found to be the site of greatest EMG activity more frequently than the masseter. These findings strengthen diagnostic and assessment procedures and criteria, as well as suggest alternate treatment and research protocols.

Value of EMG analysis of mandibular elevators in open-close-clench cycle to diagnosing TMJ disturbance syndrome

The EMGs of the temporal and masseter muscle, in sixty patients with temporomandibular joint disturbance syndrome (TMJDS) and thirty normal controls, were recorded during rhythmical open-close-clench cycle movement and before and after occlusal splint therapy. The duration of the muscle contraction before initial tooth contact (DMC), the latent period (LP) and the silent period (SP) of the myoelectrical activity were used as indices for exploring their diagnostic value. In contrast with the controls, DMC, LP and SP lengthened in the patients. The DMC was prolonged in those patients where there were TMJ sounds, the inter-cuspated position did not coincide with the muscular contact position and there was deviated mandibular movement. An increase of the SP was related to tooth contact on the balancing side. After treatment, the DMC and SP in the patients returned to the level of the controls. It was found that the internal correction rate of Fisher's linear discriminate function established for the DMC and SP of the temporal and masseter muscles was 80.9% and 85.1% respectively. The results show that the DMC and SP of the temporal and masseter muscles have some value in diagnosing muscular dysfunction and discriminating therapeutic effectiveness.

Systemic joint laxity (the hypermobile joint syndrome) is associated with temporomandibular joint dysfunction

A consecutive series of 37 individuals admitted to the hospital for elective temporomandibular joint (TMJ) reconstructive surgery and 3 seen as outpatients with TMJ disease were evaluated for rheumatic disease or for another etiologic factor that might account for this problem. These 40 patients were screened by history, physical examination, and laboratory study. We soon noticed that many patients had generalized joint laxity. Eighteen of the first 40 individuals satisfied established criteria for the hypermobile joint syndrome. An additional 3 were found to have Ehlers-Danlos syndrome or a forme fruste of this disorder. Many were markedly hypermobile and could perform a number of flexible maneuvers. Although excessive joint laxity is known to be associated with a variety of rheumatic conditions, TMJ disease has not been recognized as one of them. No patient in this series had a systemic inflammatory disorder or any other apparent etiologic factor for TMJ disease. We suggest that there is a cause-and-effect relationship between generalized joint laxity and TMJ disease.

The concept of primary fibromyalgia (fibrositis): clinical value, relation and significance to other chronic musculoskeletal pain syndromes

PFS, MPS and TMPDS can be identified using positive diagnostic criteria among patients presenting with chronic pain. A directed rather than exhaustive search for organic diseases known to coexist with these syndromes is usually all that is necessary. Criteria are presently empirical but do identify homogeneous populations of patients for study and treatment. Some patients, however, provide examples of overlap and it may be useful to think of CMPS in terms of the Venn diagram depicted in Fig. 2. In this report we have attempted an initial classification for a group of common and perplexing chronic pain disorders of the musculoskeletal system which at present have no identifiable cause. Previous investigations have been hampered by erroneous pathological concepts, heterogeneous patient populations and poor study design particularly with respect to treatment modalities. We hope that this classification, while empirical, will lead to needed epidemiological studies outlining the similarities and differences between these clinically observable and different musculoskeletal syndromes. We hope, further, that it will foster cooperation between different medical disciplines so that clinical biases might be tested in light of current concepts of the scientific method.

Identification of patients at risk for unnecessary or excessive TMJ surgery

Musculoskeletal pain in the head and neck may be associated with a variety of psychological and psychiatric conditions. Therefore, patients with persistent temporomandibular (TMJ) and masticatory muscle complaints must also be evaluated for affective disorders. Identification of patients at risk for unnecessary or excessive TMJ surgery is enhanced when the surgeon is aware of a pattern of persistent pain and illness insistence that characterizes these patients. This article presents a list of characteristics that may identify a patient with an undiagnosed affective disorder who may be exposed to unnecessary treatment.

Quantitative electromyographic response to therapy for myo-oral facial pain: a pilot study

In this pilot report, four of the five patients in the myofascial pain dysfunction group reported subjective improvement after 6 weeks of therapy, concomitant with a statistically significant decrease in integrated EMG Hz values in the clenched jaw position. Our results agree with those of other investigators who demonstrated a positive contribution by masticatory EMG data to confirm and quantify objectively the subjective symptoms.

Functional disturbances of the masticatory system related to temporomandibular joint involvement by rheumatoid arthritis

Several theories have been proposed concerning the aetiology of dysfunction of the temporomandibular joint (TMJ). To analyse the relationship of radiographic changes to clinical signs and symptoms of TMJ dysfunction, the present study was conducted in subjects highly predisposed to TMJ involvement, i.e. in patients with rheumatoid arthritis (RA). The aim of the study was to estimate the frequency of disturbances in the masticatory system of RA patients. In addition, the relationship between TMJ abnormalities and the signs and symptoms of dysfunction was investigated. The study consisted of sixty patients with RA and forty control subjects. Asymptomatic subjects were more frequent in the RA group than in the controls. Muscle pain during palpation was recorded in 53.3%, clicking in 53.3%, crepitation in 21.7%, reduced movement capacity of the TMJ in 41.7%, and restricted mouth opening in 31.7% of the RA patients examined. In the control group the most common symptoms and signs were clicking (57.5%), muscle pain during palpation (57.5%) and restricted opening (25.0%). Normal radiographic appearance of the TMJ in RA patients was found in 31.7%. Minor changes comprised 31.7%, moderate changes 21.6%, and severe changes or total loss of the condyle 15.0%. In the control group a normal joint was detected in 87.5%, while minor changes were encountered in 7.5%, and moderate or severe changes only in 5.0%. No relationship was found between Helkimo's anamnestic, clinical or occlusal indices and the severity of the disease graded according the criteria outlined by the American Rheumatism association (ARA). In the ARA group the frequency of signs and symptoms of dysfunction increased with the destructive changes in the TMJ area. In the controls, muscle pain during palpation and clicking sounds in the TMJ were most commonly connected with normal radiographic appearance of the TMJ. In the discriminant analysis the most discriminating factors were crepitation, tenderness to palpation of muscles and movement of TMJ.