Journal of Oral & Facial Pain and Headache, 02/1999

AIMS: An 8-week parallel, placebo-controlled, double-blind trial evaluated the efficacy of the antidepressant trazodone in the treatment of chronic burning mouth pain. METHODS: Thirty-seven carefully selected women aged 39 to 71 (mean 58.6 years) were randomized to receive either 200 mg of trazodone or a placebo in a similar manner. Pain and pain-related symptoms were evaluated on a visual analogue scale and other measures at 0, 2, 4, and 8 weeks. RESULTS: There were no significant differences between the groups in treatment effects for pain or pain-related symptoms. Seven patients in the trazodone group and 2 in the placebo group failed to complete the trial because of side effects. The most common side effects were dizziness and drowsiness. CONCLUSION: In this controlled trial, trazodone failed to relieve burning mouth pain.

AIMS: Chronic neurogenic facial pain is commonly resistant to treatment and is often the source of significant patient morbidity. Adrenergic mechanisms are postulated to play a role in producing this type of pain, and adrenergic blocking agents are frequently used in clinical practice for pain control therapy. The analgesic effectiveness of an adrenergic blocking agent, intravenous phentolamine, was compared to saline and intravenous lidocaine in the present study using a single-blind protocol in patients with chronic neurogenic facial pain. METHODS: Thirty patients were studied whose common clinical features included pain for more than 6 months, unilateral trigeminal distribution, constant dysesthesia, and no evidence of pathology or known etiology. Phentolamine (30 mg), lidocaine (100 mg), and saline were each infused over periods of 5 to 10 minutes. Pain ratings were assessed every 4 minutes throughout each study period using a 10-point pain intensity scale. RESULTS: No patient reported subjective improvement of pain during or immediately following phentolamine or saline infusions alone. Sixteen of the 30 patients reported decreased pain following lidocaine infusion. In the majority of the patients, the duration of lidocaine analgesia was less than 30 minutes; however, some patients reported decreased pain for a longer time. CONCLUSION: The results do not support an adrenergic mechanism for chronic neurogenic facial pain. The response to lidocaine, a nonadrenergic, membrane-stabilizing agent, suggests that it may have clinical effectiveness in certain neurogenic facial pain patients.

AIMS: The pressure pain threshold (PPT) in the superficial masseter muscle was measured with and without cutaneous anesthesia to determine whether there would be a difference in PPT scores. METHODS: In 14 healthy male subjects, cutaneous tissues in the target areas were anesthetized with lidocaine with the help of an iontophoretic device. As a control, physiologic saline solution was applied iontophoretically to the contralateral masseter site. The subject and the PPT examiner did not know which side contained anesthesia, and the selection of which side to anesthetize was done in a random fashion. Multiple PPT measurements were made in the target sites before and immediately after the iontophoretic anesthesia. RESULTS: The PPT level on the lidocaine side was not statistically different from the PPT level recorded on the control side (339.0 ± 87.6 kPa and 337.5 ± 77.7 kPa, respectively). CONCLUSION: Pressure pain sensation in the human masseter is not derived predominantly from the cutaneous tissues, but from the muscle itself.

AIMS: Pain in some bruxers has been suggested to represent a state of postexercise muscle soreness. This study examined the effect of voluntary, controlled grinding movements on the development of pain and soreness in the masticatory system. METHODS: Twelve healthy men (21 to 42 years old) without signs or symptoms of temporomandibular disorders (TMD) participated. Nine trials of 5 minutes of repeated grinding from the intercuspal position to the right canine-canine position (0.5 Hz) were performed on the first day. During the lateral excursions, the electromyographic (EMG) activity of the right masseter muscle was kept above 50% of maximal voluntary occlusal force (MVOF) with the use of visual feedback. The subjects rated pain intensity, unpleasantness, and soreness on 100-mm visual analogue scales (VAS); other pain measures, including the McGill Pain Questionnaire, were also used. Before and after the exercise trials, the MVOF was determined, and pain detection thresholds (PDT) to pressure stimuli were measured at 9 different sites on the masseter muscles. The subjects returned to the laboratory the 3 following days, where VAS, PDT, and MVOF were measured. RESULTS: Immediately following the last grinding trial, there was a significant increase in VAS and MPQ scores of pain intensity, unpleasantness, and soreness, as compared to baseline values (analysis of variance, P < 0.001). There was still a significant effect from grinding on the VAS score of muscle soreness on the following days, with a peak the first day after the exercise (Tukey test, P < 0.023). Pain was frequently (in 7 of 12 subjects) reported in or around the temporomandibular joint. There was a significant effect from grinding on PDT at both masseter muscles (analysis of variance, P < 0.043), with significantly lower PDT the first day after the grinding exercise (Tukey test, P < 0.046). There were no effects from grinding on MVOF. CONCLUSION: These findings suggest that significant but low levels of postexercise muscle soreness can be elicited by standardized grinding movements in the masticatory system of healthy subjects.

AIMS: Symptoms of jaw dysfunction are often associated with neck muscle dysfunction or other musculoskeletal problems. This study attempted to quantify the effect of jaw clenching on the electromyographic (EMG) activity of certain neck, trunk, and jaw muscles. METHODS: The authors recorded EMG muscle activity in the sternocleidomastoid, trapezius, paravertebral, and rectus abdominis muscles in 10 university students at rest and during strong jaw clenching in supine and sitting positions. RESULTS: In both positions, jaw clenching resulted in increases in neck muscle activity ranging from 7.6 to 33 times resting muscle activity; for the trunk muscles, the increases ranged from 1.4 to 3.3 times resting activity. CONCLUSION: These results add further information to the concept of the interrelatedness of jaw, neck, and trunk muscle activity.

AIM: The purpose of this study was to compare the variation in movement traces of the kinematic center of the temporomandibular joint with that of 4 nearby condylar reference points. METHODS: Jaw movement recordings were made with an optoelectronic jaw movement recording system. Four asymptomatic participants performed 14 to 18 open-close mandibular movements. The movements were performed with deliberate alterations of the rotation/translation ratio during opening. The kinematic center of the condyle and 4 nearby condylar points (the corner points of a square placed in the condylar sagittal plane, centered around the kinematic center, and with an edge length of 10 mm) were used as reference points. The standard deviations in the downward displacements at the halfway point in the mandibular opening of these reference points were calculated as a quantification of the variation in the movement tracings of these points. RESULTS: The movement traces of the kinematic center showed the smallest variation in comparison to the traces of the 4 nearby reference points (2-way analysis of variance and subsequent contrast analysis; P = 0.0026). CONCLUSION: In comparison to 4 nearby condylar reference points, the movement traces of the kinematic center show the lowest sensitivity to variations in the way mandibular movements are performed.