Faculty Bibliography

OBJECTIVE: We have previously reported that patients with temporomandibular disorders (TMD) exhibit enhanced sensitivity to experimentally evoked pain (1); however, the clinical relevance of this increased pain sensitivity remains unclear. The purpose of this study was to investigate the relationship of experimental pain sensitivity to clinical and psychosocial variables among patients with TMD. DESIGN: Thirty-six TMD patients were studied, half of whom were pain sensitive (PS) and the other half pain tolerant (PT), based on their ability to tolerate an ischemic pain task. Responses to painful thermal and nonpainful visual stimuli as well as clinical/diagnostic symptoms and psychosocial variables were compared for the two groups (i.e., PS vs. PT). RESULTS: Results indicated that, compared with PT patients, the PS group exhibited greater sensitivity to thermal pain and rated innocuous visual stimuli as more intense. PS patients also reported greater clinical pain, but in general the groups did not differ on diagnostic and psychosocial measures. CONCLUSIONS: The results suggest that ischemic pain tolerance is a clinically relevant marker of pain sensitivity in TMD patients. These findings are consistent with the hypothesis that impairments in CNS inhibitory pathways may contribute to the pain associated with TMD.

Experimental pain can elevate vibrotactile threshold, a phenomenon attributed in the literature to the operation of a 'touch gate.' It is not known, however, whether clinical pain produces similar effects. To explore this possibility, we measured vibrotactile threshold in patients with temporomandibular disorders (TMD) whose pain had a prominent myalgic component. Two-interval forced-choice tracking was used to determine threshold for a 25-Hz vibratory stimulus presented on the cheek. Threshold was found to be significantly elevated in the TMD group, compared to an age- and gender-matched control group of pain-free individuals. Within the TMD group, those with a supra-median level of muscle tenderness (corrected for background levels of spontaneous pain) had significantly higher threshold than those with lower levels of palpation pain. These findings are consistent with the idea of a touch gate, and suggest the usefulness of further research in this area with clinical pain populations. The effects of an adapting stimulus (25 Hz, 20 dB SL) were also studied, and found to produce parallel elevations in vibrotactile threshold in the TMD and pain-free groups. This result indicates that at least some adaptation occurs at a higher (subsequent) level of somatosensory information processing than does the touch gating implied by the unadapted thresholds.

A major reason for referral to an endodontic practice is management of pain. Most cases are diagnosed as being of pulpal or periapical origin. However, some turn out quite differently than their initial appearance. This case report presents a patient referred to the endodontic clinic because of symptoms mimicking an irreversible pulpitis. On examination no obvious cause of the symptoms could be found. The patient was treated conservatively after which a herpes zoster viral infection was diagnosed. This case stresses the importance of a thorough investigation of all signs and symptoms and the delay of definitive treatment until a diagnosis is made.

Temporomandibular disorders (TMD) represent a group of chronic painful conditions involving the muscles of mastication and the temporomandibular joint. We determined whether patients with painful TMD are more sensitive to noxious stimuli than age-matched control subjects. Fifty-two TMD patients (16 with muscle pain and 36 with combined muscle and joint pain) and 23 age-matched and gender-matched volunteers participated. Forearm thermal pain threshold and tolerance values were determined. A submaximal effort tourniquet procedure was used to evoke ischemic muscle pain. Relative to control subjects, TMD patients had significantly lower thermal pain threshold, ischemic pain threshold, and ischemic pain tolerance values; and thermal pain tolerance values also tended to be lower. Pain sensitivity did not differ between the two groups of TMD patients. Furthermore, the submaximal effort tourniquet procedure, which is capable of altering acute orofacial pain (Sigurdsson and Maixner, 1994) did not produce a consistent reduction in orofacial pain associated with TMD. We concluded that TMD patients are more sensitive to noxious stimuli than pain-free controls. These findings provide additional evidence that TMD is a psychophysiological disorder of the central nervous system which modulates emotional, physiological and neuroendocrine responses to emotional and physical stressors.

It is commonly accepted that application of a sustained noxious stimulus frequently suppresses the perception of pain. In this investigation, we have determined whether painful forearm ischemia suppresses tooth pain resulting from an acute irreversible pulpitis. We have also determined whether the physiological responses to toothache alter the perception of pain evoked by experimental procedures. Ten male subjects experiencing a painful toothache (group TA) and 7 age-matched pain-free male subjects (group PF) participated in these studies. During session 1, heat pain threshold and tolerance values were determined for both groups. The times to ischemic pain onset and ischemic pain tolerance were determined for both groups using the submaximal effort tourniquet procedure. The effect of the tourniquet procedure on the intensity, unpleasantness, and spatial distribution of toothache was also assessed. Session 2 was conducted on 7 TA and 7 PF subjects 1 week later and was conducted like session 1 with the exception that group TA was not experiencing tooth pain during this session. Measures of thermal pain perception and forearm ischemic pain perception were not altered by the occurrence of toothache. In contrast, sustained noxious forearm ischemia produced a marked reduction in the intensity, unpleasantness and spatial distribution of pulpal pain. These effects on pulpal pain remained for at least 5 min after removal of the tourniquet while the arm was pain free. These findings suggest that a noxious conditioning stimulus does not universally inhibit pain perception but instead depends on unidentified interactions between the noxious test and conditioning stimuli.

Ten extracted human maxillary first molars were selected with a variety of root curvatures. The distofacial roots were resected and the mesiofacial canals were instrumented to a size #25 K file. Three techniques were used to introduce Ca(OH)2 paste into the instrumented canals. These techniques were evaluated for their ability to carry the Ca(OH)2 to working length and also to produce a dense fill. The Lentulo spiral was most effective in carrying the paste to working length. The Lentulo spiral also produced the highest quality fill. The Calasept injection system followed by a #25 finger plugger was the second most effective technique. Counterclockwise rotation of a #25 K file was the least effective of the techniques tested.