Journal of Oral & Facial Pain and Headache, 03/1994

This study used low-power light microscopy to examine the histologic organization of the lateral pterygoid muscle interface with the temporomandibular joint. The sample included parasagittal sections of 20 intact temporomandibular joints from young adults (mean age 26.2 years) at autopsy. The lateral pterygoid muscle showed no consistent divisions into separate anatomic muscle heads at the insertion. The muscle fibers attached to the pterygoid fovea of the condyle immediately inferior to the articular surface in all cases. Some additional fibers inserted superiorly into the more anterior part of the articular disc in a minority of cases (31%). Fibers inserting into the disc represented only 2.4% to 6% of the total superior-inferior length of the muscle insertion. It is hypothesized that the muscular force exerted by these few fibers inserting into the disc would not be sufficient to displace the disc anteriorly to the condyle. There were two histologic types of insertion of the lateral pterygoid muscle to the condyle. The superior part of the insertion was characterized by an identifiable tendon inserting through fibrocartilage. In the inferior part of the insertion, the muscle attached to periosteum without an obvious tendon. The presence of this tendon must be recognized in interpretation of soft tissue temporomandibular joint imaging.

The measurement of the pain-pressure threshold in the human jaw muscles may be affected by variables such as the size of the pressure-transducer recording surface and the rate of applied pressure. The jaw muscles have a complex architecture that results in changes in muscle stiffness and compliance when different motor tasks are performed. Such changes in the jaw muscles are likely to affect the pain-pressure threshold. The central motor program associated with different tasks may also affect the pain-pressure threshold. A pressure algometer was used to measure the pain-pressure threshold in various regions of the masseter and temporalis muscles at different magnitudes of tooth clenching and jaw gape. The pain-pressure threshold increased at all recording sites as muscle contraction associated with tooth clenching increased. The pain-pressure threshold was not affected when the jaw gape changed. There were no apparent regional differences in pain-pressure thresholds in the masseter or temporalis muscles at different amounts of tooth clenching or jaw gapes. Pain-pressure thresholds were consistently higher in the temporalis muscle. When quantitative measures of jaw muscle pain-pressure thresholds are planned, the nature of the motor task should be controlled.

This study examined masseter and temporalis pain-pressure thresholds in 29 patients with chronic bilateral myogenous temporomandibular disorder and in 11 controls. Patients with evidence of temporomandibular joint pathosis were omitted. The influence of time, facial side, muscle site, and side of greatest spontaneous pain on pain-pressure thresholds was measured. No significant pain-pressure threshold differences were found between the more and less painful sides, as indicated by the patients, which lends support to theories of centrally mediated pain. Mean pain-pressure thresholds in patients differed over the four sessions, which is consistent with recent reports of fluctuating levels of pain in patients with temporomandibular disorders. Additional findings included significant pain-pressure threshold differences among muscle sites in patients and controls, and lower patient pain-pressure thresholds relative to controls. Within- and between-session reliability was adequate for patients (r = .85 and r = .75, respectively) and controls (r = .90 and r = .75, respectively).

A system was developed for continuous, full-night, polysomnographic recording of sleep using manual sleep scoring and automatic electromyographic analysis of craniomandibular muscle activity. In the sleep laboratory, data are stored on tape with hard copy on paper followed by off-line, computer-controlled digital processing. Muscle activity is described by the Amplitude Probability Distribution Function and by parameters of time and intensity. Sleep and electromyographic data are available graphically on screen, and the results are presented in tables and graphics after statistical treatment. The system was developed to provide a differentiated, detailed analysis of sleep and nocturnal muscle activity in the craniomandibular system that is suitable for comparing groups of individuals, effects of treatments, and physical load of muscles. Applications of the system are demonstrated.

This study assessed electronic thermography as a diagnostic alternative for evaluation of temporomandibular disorders. The study populations consisted of 50 temporomandibular joint patients having internal derangement or osteoarthrosis and 30 normal temporomandibular joint subjects. An Agema 870 thermovision unit was used for analysis. Diagnostic evaluations by expert interpreters were made using standard procedures. Thermography measurements included mean absolute temperature measurements and right-left temperature differences for five anatomic zones and four spot areas. Statistical analysis of data included both linear discriminant analysis and classification-tree analysis. Results indicated that when differentiating between abnormal and ormal temporomandibular joints using classification-tree analysis, correct classifications were made in 89% of the cases and observer diagnostic accuracy was 84%. When evaluating for specific diagnoses (eg, osteoarthrosis, internal derangement, or normal temporomandibular joint), correct classifications using classification-tree analysis were made in 73% of the cases and observer evaluation was correct in 59%. The three best temperature measures found were: (1) delta T of the zone immediately overlying the temporomandibular joint; (2) the zone temperature of the half-face; and (3) the spot temperature anterior to the external auditory meatus. Additional studies are needed before thermographic diagnosis of craniomandibular disorders is accepted clinically.

Clinical studies have suggested that the presence of litigation in chronic pain syndromes may complicate diagnostic and treatment strategies. In addition, psychosocial factors may be prevalent in such cases. The present study explored the possible correlation in the facial pain population between patients in litigation and psychological disturbance as measured by the Minnesota Multiphasic Personality Inventory. Beck Depression Inventory and Wahler Symptom Checklist scores also were compared. One hundred eleven patients diagnosed with chronic facial pain were asked if they currently were involved in litigation related to their medical complaints. The result revealed that 18% of the 111 patients were in litigation at the time of their initial visit. The Minnesota Multiphasic Personality Inventory profiles showed that 45% of the litigation patients had four or more clinical scales above 70 (significantly elevated) on the Minnesota Multiphasic Personality Inventory. In contrast, only 18% of the patients who were not in litigation had four or more scales above the 70 criteria. Beck and Wahler scores also were more elevated for the litigation group. The results of the study indicate that chronic facial pain patients in litigation may present with more psychological disturbance as compared to those patients not in litigation.

The association of the severity of temporomandibular arthropathy to ear, nose, and throat symptoms in patients with temporomandibular disorders has been poorly investigated in spite of its importance in clinical practice. The aim of this study was to see whether persons with more severe arthropathy have more ear, nose, and throat symptoms. Anamnestic and clinical evaluations were obtained at admission for 815 subjects with signs and symptoms of temporomandibular disorders of arthrogenic origin in physical tests. The severity of arthropathy was evaluated by a clinical index scoring joint sounds, tenderness to temporomandibular palpation, and pain severity in the temporomandibular joint region. Univariate analysis showed that the severity of arthropathy was significantly associated with ear, nose, and throat symptoms as a whole (P .001) and specifically with deafness (P .001) and dizziness (P .05); however, tinnitus and earache were not statistically significantly associated. Multiple analysis showed deafness to be the only ear, nose, and throat variable independently associated with severity of arthropathy (P .01). These findings lead to the conclusion that there is a considerable association between temporomandibular disorders of arthrogenic origin and ear, nose, and throat symptoms, especially deafness. They also suggest that further investigations should be done to compare the specific roles of craniocervical arthritis versus temporomandibular disorders in the etiology of ear, nose, and throat symptoms related to craniomandibular and craniocervical joint involvement.

Temporomandibular disorder literature contains serious misunderstandings and misapplications of statistical concepts, including predictive values, in evaluating diagnostic modalities and in clinical decision making. The use of general population prevalence data for temporomandibular disorders to evaluate positive predictive values of diagnostic modalities is shown to be invalid. The positive predictive value of a diagnostic tool should not be used to evaluate the efficacy of the tool or to confirm the presence of temporomandibular disorders when the pretest likelihood of temporomandibular disorder is low (eg, 10%). In such a situation, the TMJ Scale's negative predictive value of 98% supports the dentist's clinical impression of the absence of temporomandibular disorders. When the pretest likelihood of TMD is high (eg, 90%), the TMJ Scale's positive predictive value of 97% supports the dentist's clinical impression of the presence of temporomandibular disorders. The predictive values of the subscales of the TMJ Scale that measure joint dysfunction and stress may be used to further refine the diagnostic impression. When the dentist is unsure of the presence of TMD and makes a pretest estimate of 50%, the TMJ Scale's positive predictive value of 81% and negative predictive value of 83% substantially improve the accuracy of clinical decisions.

The severity of symptoms of craniomandibular disorders was studied during a 2-year period in 195 patients treated with conservative therapeutic schemes. Results revealed a continuing improvement and a statistically significant tendency for the great majority of patients to become asymptomatic or show a decrease in the severity of symptoms. By the end of the 2 years, 66.7% of the patients were symptom free, 25.6% presented with slight symptomatology, and 3.1% were recorded with a fluctuating recurrence of symptoms. This investigation provided the data to develop an exponential model for the hypothesis that stabilization of effectiveness of conservative treatment is achieved between 6 months and 1 year after the initiation of treatment.

Three operators each made five recordings from 15 symptomatic patients using the electronic mandibular position indicator. The method consisted of measuring bilateral spatial changes of the hinge axis recalculated by the computer to an intercondylar distance of 110 mm and a third position, calculated from the rotation of the hinge axis, at the incisal guidance table. All individual patient recordings were related to the origin of the same coordinate system. This origin is designated and defined as the reference position, with purposeful elimination of any stated joint position for this definition. The measurements were in all planes of space at 10-millimicron increments, including the rotation of the transverse hinge axis in hundredths of degrees. These data showed that the reproducibility of hinge axis positions, ie, reference positions, to hinge axis condylar positions dictated by the maximum intercuspation of teeth was in average less than 0.2 mm for each record from all operators and patients.