Faculty Bibliography

AIM: To radiographically compare periapical repair of roots with infected root canals obturated in one-step or with calcium hydroxide (Ca(OH)2) intracanal medication in two steps. METHODOLOGY: Standardized preoperative periapical radiographs were taken of 72 roots of vital dogs' teeth. All roots were then aseptically instrumented to ISO size 45. As negative controls, 12 roots were aseptically obturated. The remaining roots were infected with dental plaque and closed. Six weeks later, apical periodontitis was radiographically confirmed in the infected roots. The roots were divided into the following groups: group 1, one-step (n = 24); roots were irrigated with 10 cc saline, obturated, and permanently restored. Group 2, Ca(OH)2 (n = 24); roots were treated as in group 1, except that after saline irrigation Ca(OH)2 medicament was placed in the canal 1 week before obturation. Group 3, positive control (n = 12); the roots were irrigated with saline, access permanently closed but canals not obturated. Group 4, negative control (n = 12); previously aseptically obturated roots were permanently restored. After 6 months, standardized postoperative radiographs were obtained. Three independent evaluators blinded to the treatment groups evaluated the preoperative and postoperative radiographs. The evaluators were instructed to rate each root, based on changes on the radiographs, as failed, improved or healed. RESULTS: Radiographically, the percentage of cases that completely healed were similar for the one-step and Ca(OH)2 groups (35.3% vs. 36.8%). However, the Ca(OH)2 group had fewer failed cases (15.8% vs. 41.2%) and more improved cases (47.4% vs. 23.5%) than the one-step group. CONCLUSION: Power statistics demonstrated that at 43 cases per group, Ca(OH)2 treatment would be statistically superior to one-step treatment. We consider this number to be clinically important.

OBJECTIVE: Considerable research suggests that females exhibit greater sensitivity to laboratory pain procedures than do males; however, whether the presence of acute clinical pain influences this sex difference in pain sensitivity has not been investigated. The present experiment investigated the effects of sex and acute dental pain on laboratory pain responses. DESIGN: Thermal pain onset and tolerance were determined in 46 dental patients (15 male, 31 female) experiencing pain due to acute irreversible pulpitis and in 33 healthy controls (13 male, 20 female). In addition, measures of mood and coping were obtained in all participants. All subjects participated in two experimental sessions. The first session took place immediately before the patients underwent endodontic treatment for relief of pulpal pain. The second session took place approximately 1-2 weeks later, when pulpitis patients were pain free after treatment. During each session, thermal pain onset and tolerance were assessed with a 1-cm2 contact thermode applied to the right volar forearm using an ascending method of limits. RESULTS: During both sessions, thermal pain onset and tolerance were lower in control females than in control males; however, male and female pulpitis patients did not differ in their thermal pain responses during either session. Pulpitis patients also showed greater affective distress than controls. CONCLUSIONS: These data suggest that the sex difference in thermal pain sensitivity frequently reported in pain-free subjects appears to be absent in patients presenting with acute dental pain. However, this effect cannot be explained solely based on the presence of clinical pain because the effect on pain threshold and tolerance persisted into session 2, when pulpitis patients were pain free. Potential explanations for these results are discussed.

This report presents the findings from a psychophysical study of vibrotactile responses in a patient diagnosed with temporomandibular disorder (TMD). This patient unexpectedly reported pain due to innocuous vibrotactile stimulation, and this allodynia appeared to have a component of temporal summation. The pain response occurred not only in the region of the clinical pain (the face), but also on the volar forearm, where the patient reported no clinical pain. Administration of the N-methyl-D-aspartate (NMDA) receptor antagonist dextromethorphan (DM), but not vehicle, attenuated the vibration-induced pain at both sites.

Temporomandibular disorders (TMD) represent a group of chronic painful conditions involving the muscles of mastication and the temporomandibular joint. Several studies have reported that TMD is associated with enhanced sensitivity to experimental pain. Twenty-three TMD subjects and 24 pain-free matched control subjects participated in a set of studies which were designed to evaluate whether the temporal integrative aspects of thermal pain perception are altered in TMD patients compared with control subjects. Specifically, we have examined in both TMD patients and in age- and gender-matched control subjects: (1) the time-course and magnitude of perceived pain evoked by the application of sustained 7-s noxious thermal stimuli (45-48 degrees C) to the face and forearm, (2) the central summation of C-fiber-mediated pain produced by applying brief trains of noxious heat pulses to the skin overlying the ventral aspect of the right palm and (3) the ability to discriminate small increments in noxious heat applied to facial and volar forearm skin. Data collected from these studies indicate that TMD patients show enhanced temporal integration of thermal pain compared with control subjects. TMD patients show greater thermal C-fiber-mediated temporal summation than pain-free subjects and they report a greater magnitude of sustained noxious heat pulses applied to either the face or the forearm than control subjects. In contrast to these findings, TMD and pain-free subjects are equally able to discriminate and detect small increments of heat applied to noxious adapting temperatures. These findings suggest that the augmented temporal integration of noxious stimuli may result from alterations in central nervous system processes which contribute to the enhanced pain sensitivity observed in TMD patients.

The purpose of this study was to determine whether the elevation in vibrotactile detection threshold, found in many individuals with temporomandibular disorders (TMD), is paralleled by suprathreshold impairments. Participants with TMD were compared with pain-free control subjects in their ability to discriminate on the basis of differences in amplitude and frequency between vibratory stimuli delivered to the face. The TMD group was significantly impaired with respect to frequency discrimination, but not amplitude discrimination. This dissociation suggests that the cortical processing of vibrotactile signals may be affected in TMD patients. TMD participants' estimates of the intensity of their spontaneous and palpation-evoked pain did not significantly correlate with performance on either discrimination task; this finding makes it unlikely that impaired vibrotaction in TMD is primarily the result of a pain-dependent gating of tactile signals.