Glenn T. Clark

Psychological distress and diagnostic subgroups of temporomandibular disorder patients

&NA; This study examined the nature and extent of psychological differences among diagnostic subgroups of temporomandibular disorder (TMD) patients. Three subgroups were identified and labeled as:primary myalgia,primary temporomandibular joint (TMJ) problems, orcombination myalgia and TMJ problems. Patients (n = 112) levels of pain and distress were measured using a VAS pain scale, the McGill Pain Questionnaire, the Beck Depression Inventory, the State‐Trait Anxiety Scale and the MMPI. Patients with primary myalgia had the highest scores on the pain and distress measures while patients in the combination group scored between the myalgia and TMJ problem subgroups. When differences in pain levels were controlled, the differences among groups on measures of anxiety and depression were attenuated while the differences on measures of somatic overconcern remained significant. Discriminant function analysis using psychological variables to predict diagnostic grouping produced correct identification of 74% of the structural patients and 46% of the myalgia patients. Implications for different etiological factors among the 3 groups are discussed.

Use of sodium hyaluronate in treating temporomandibular joint disorders: A randomized, double-blind, placebo-controlled clinical trial

This study assessed the efficacy of high-molecular-weight sodium hyaluronate as a treatment for certain intracapsular temporomandibular joint (TMJ) disorders. One hundred twenty-one patients were studied at three test sites using a randomized, double-blind, placebo-controlled experimental design. Patients were selected on the basis of 1) confirmed diagnosis of either degenerative joint disease (DJD), reducing displaced disc (DDR), or nonreducing displaced disc (DDN); 2) nonresponsiveness to nonsurgical therapies; and 3) severe dysfunction as established by the Helkimo indices (HI), visual analog scales (VASs), and physical measurements of joint movement and joint noise (arthrophonometry [APM]). Subjects received a unilateral upper joint space injection of either 1) 1% sodium hyaluronate in physiologic saline (MedChem Products, Woburn, MA) or 2) USP physiologic saline. Clinical evaluations were performed using HI, VAS, and APM at weekly intervals for the first month and then at monthly intervals up to 6 months postinjection. Statistical analyses for both categorical and continuous variables were performed for each diagnostic category at each examination interval. For DJD, no difference in outcome was seen between treatment groups. For DDN, significant between-group differences were seen through 1 month; however, beyond this time point, the number of DDN patients was insufficient to draw meaningful conclusions concerning efficacy. For DDR, statistically significant within-group and between-group improvement in all three measures (HI, VAS, APM) was seen for the hyaluronate group compared to the saline group throughout the 6-month test period. At the month-2 and month-3 examination intervals, twice as many patients treated with hyaluronate (90%) showed improvement compared to patients given placebo. Further, only 3% of patients with DDR who were treated with hyaluronate relapsed compared with 31% of patients with DDR given placebo.

Sixty-eight years of experimental occlusal interference studies: what have we learned?

STATEMENT OF PROBLEMnUnderstanding is needed regarding the effect that occlusal interferences have on the teeth, periodontium, and especially on jaw function.nnnPURPOSEnThis article summarizes research in which experimental occlusal interferences have been placed on the teeth of animals and human volunteers.nnnMATERIAL AND METHODSnData from 18 human and 10 animals studies were reviewed. Experimental occlusal interferences were grouped into those that alter intercuspal position and those contacting on lateral jaw movement only. The outcome of these interferences were analyzed according to their local pulpal-periodontal, jaw function, or bruxism effects.nnnRESULTSnExperimental occlusal interferences in maximum intercuspation had a deleterious effect on periodontal and pulpal tissues of the affected tooth; sometimes this produces a disruption of smooth jaw function and occasionally jaw muscle pain and clicking. Experimental occlusal interferences that contact only in a lateral jaw movement are infrequently harmful to jaw function. Furthermore, no reliable evidence demonstrates that occlusal interferences can cause nocturnal bruxism, or stop it.nnnCONCLUSIONnTransient local tooth pain, loosening of the tooth, a slight change in postural muscle tension levels, chewing stroke patterns, and sometimes a clicking joint can be induced by an experimental occlusal interference. Because such findings are present in relatively asymptomatic patients, these data do not prove that occlusal interferences are causally related to a chronic jaw muscle pain or temporomandibular joint dysfunction problems.

Co-activation of Sternocleidomastoid Muscles During Maximum Clenching

In an attempt to determine the degree of co-activation present in selected cervical muscles during clenching, we instructed 12 male subjects to produce four brief maximum voluntary contraction (MVC) efforts (clenching) in a position of maximum intercuspation. Surface EMG activity was recorded bilaterally from the masseter and sternocleidomastoid (SCM) muscles. The contraction level for the SCM during clenching was reported as a percentage of the SCMs maximum activity achieved during maximum neck flexion against resistance. All EMG signals for the masseter and SCM were converted to a true RMS voltage signal and digitized at a 100-Hz sampling rate. Mean peak EMG voltage levels were determined for the activity recorded during each brief MVC task. All subjects demonstrated co-activation of the SCM during strong abrupt clenching efforts. The mean levels (± S.D.) of SCM activity were 11.8 ± 9.6% (right) and 14.2 ± 9.4% (left) of the MVC capacity. Fifty percent of masseter activity was required to achieve 5% activity of the SCM bilaterally, and there was a progressive development of the SCM co-activation which paralleled the masseter activation.

Electromyographic study of human jaw-closing muscle endurance, fatigue and recovery at various isometric force levels

The effect of a sustained isometric clenching, at various force levels or maximum voluntary bite-force levels, was evaluated on normal jaw-function subjects. Surface electromyographic (EMG) recordings of the masseter and temporalis were taken and bite force was measured using an intra-oral force transducer placed unilaterally in the 2nd premolar-1st molar region. Subjects sustained isometric force at the 25, 50, 75 and 100 per cent force level. Maximal bite force and EMG contraction levels were measured before, during and after these sustained isometric tasks. Subjects showed no change in their brief maximal contraction or force levels during or after various fatigue-inducing isometric tasks. The findings suggested a lack of contractile failure in the jaw-closing muscles. Pain intolerance rather than neuromuscular fatigue is the limiting factor of a sustained submaximal or even maximal clenching effort.

Haemodynamic changes induced by submaximal isometric contraction in painful and non-painful human masseter using near-infra-red spectroscopy

Although mechanisms underlying chronic muscle pain are poorly understood, one prevalent theory is that it is due, in part, to localized hypoxia. The purpose of this study was to evaluate this theory using non-invasive near-infra-red spectroscopy that monitors relative changes in intramuscular haemoglobin (Hb) concentration and oxygen saturation levels. Data were collected for the human masseter muscle during and following three isometric 30-s trials at 50% maximum voluntary contraction. Ten females, with a history of chronic muscle pain in the jaw, and eight matched healthy females without muscle pain (controls) participated. Results showed that, upon initiation of masseter muscle contraction, there was a rapid reduction in the intramuscular Hb concentration concomitant with a reduction in oxygen saturation levels. After cessation of the contraction, the Hb concentration increased rapidly and then fell toward the baseline. Significant differences in the recovery profile for oxygen saturation were found between the first trial and the following two trials for both the muscle pain- and control group. Looking at the first trial only, and adjusting for covariates of height, weight and bite-force in the analysis, revealed a marginally significant postcontraction difference between the two groups with a lower level of oxygen saturation during recovery in the group with chronic muscle pain. Significant group differences were found in Hb concentrations without any significant trial effect. It is likely that the well-known changes in intramuscular blood flow that occur during and after contraction in human muscles are reflected in these altered relative Hb concentrations. The group with chronic muscle pain showed a clearly reduced magnitude of the Hb concentration change in the postcontraction recovery period. The results support the concept that patients with chronic muscle pain have a slower intramuscular reperfusion during the recovery phase after sustained isometric contractions.

Arthroscopic treatment of temporomandibular joint locking resulting from disc derangement: Two-year results

This article reports 2-year postarthroscopic surgical treatment data for 18 subjects (17 female and 1 male) who had a diagnosis of restricted mandibular movement due to an internal derangement of the temporomandibular joint (TMJ). These subjects had been treated by an average of 2.1 +/- 1.1 doctors for their TMJ problem before seeing the surgeon for arthroscopic treatment. The subjects mean pain score at the final time point (21 to 30 months after surgery) was decreased by 57% in usual pain intensity. Jaw function showed an average improvement of 67%. These subjects also showed a 13-mm mean increase in their maximum active opening ability at the 2-year postsurgical time point. Slight to definite clicking noises were present presurgically in 11 of 18 patients, and similar joint noises were reported in 14 of 18 patients postsurgically. The mean overall improvement was rated as 8.18 +/- 2.4, with 10 the highest possible rating. One subject rated her improvement as 0, two subjects rated their improvement as 6 out of 10. No significant morbidity was reported by the subjects as a result of their surgery.

Nocturnal Masseter Muscle Activity and Urinary Catecholamine Levels in Bruxers

Nocturnal electromyographic recordings of masseter muscle activity were performed on 20 bruxist and ten control subjects. Each subject collected two 24-hour urine samples. An analysis of urinary catecholamine content was performed. A positive relationship was found between increased epinephrine contentand high levels of nocturnal masseter muscle activity.

Diagnostic value of 4 criteria to interpret temporomandibular joint normal disk position on magnetic resonance images

OBJECTIVEnThis study was undertaken to evaluate different criteria to establish normal disk position on magnetic resonance images.nnnSTUDY DESIGNnMagnetic resonance image findings of 137 consecutive patients with temporomandibular disorders and 23 asymptomatic volunteers were used in this study. Three calibrated observers interpreted the images individually. Four closed-mouth and 1 open-mouth criteria were tested for their ability to define normal and abnormal temporomandibular joint disk positions on magnetic resonance images.nnnRESULTSnFor the 46 joints in the asymptomatic volunteers, the criterion that yielded the highest percentage of normal disk position diagnoses was the disks intermediate zone (93.5%). Clock face criteria produced the following declining percentages of normal disk position diagnoses: 10 oclock, 82.6%; 11 oclock, 63.0%; and 12 oclock, 39.1%. Similar results were obtained for the patients with temporomandibular disorders. In both groups, as the number of normal disk position diagnoses declined, the percentage of joints with a diagnosis of disk displacement with reduction increased. Conversely, the percentage of joints with a diagnosis of disk displacement without reduction (in the group of patients with temporomandibular disorders) did not appear to be substantially affected by the 4 closed-mouth disk position criteria.nnnCONCLUSIONSnThese results suggest that the intermediate zone criterion for disk displacement is the more stringent criterion and the one that would yield the lowest number of false positives when the disk position is being judged in the closed-mouth sagittal view.

Reliability, validity, and utility of various occlusal measurement methods and techniques

STATEMENT OF PROBLEMnThe controversy continues regarding the efficacy of several commercially available devices that are used as aids in the diagnosis of occlusal abnormalities.nnnPURPOSEnThis article reviews the reliability, validity, and utility of instruments that claim to detect occlusal interferences and abnormal vertical dimension of occlusion.nnnMATERIAL AND METHODSnData, opinions, and technical information from 37 published articles were reviewed. Evidence for method reliability, validity, and utility was assessed.nnnRESULTSnAlthough occlusal contact detection devices can document the occlusal contact patterns on teeth, the basic in vivo testing of their reproducibility and validity has not been performed. Moreover, while EMG and jaw tracking systems can indeed measure jaw muscle activation and jaw position, no cost-benefit analysis of these devices has yet been conducted. One manufacturer suggests that these instruments be used in conjunction with an electrical muscle stimulation device to find a new resting jaw position that is more open vertically. This new, more open position has been inappropriately labeled as evidence of vertical dimension of occlusion over-closure.nnnCONCLUSIONnNone of the instruments reviewed can be said to be more than ancillary documentation devices and they have been inadequately tested for reliability and validity. Moreover, because scientifically acceptable disease definitions are not available for these 2 conditions, the issue of over-diagnosing becomes a substantial concern.