Journal of Oral & Facial Pain and Headache, 02/2006

Aims: To use 2 well-characterized stimuli, the intraoral capsaicin model and the "nociceptive-specific" electrode, to compare superficial nociceptive function between patients with atypical odontalgia (AO) and matched healthy controls. Furthermore, the authors aimed to describe the sensitivity, specificity, and positive predictive values (PPV) of the techniques if group differences could be established. Methods: Thirty-eight patients with AO and 27 matched healthy controls participated in this study. Thirty microliters of 5% capsaicin was applied to the gingiva on the left and right sides of all participants as a pain-provocation test. The participants scored the capsaicin-evoked pain continuously on a 0-to-10 visual analog scale (VAS). Furthermore, individual electrical sensory and pain thresholds to stimulation with a "nociceptive-specific" electrode on the facial skin above the infraorbital or mental nerve were determined. Results: AO patients had higher VAS pain scores for capsaicin application than healthy controls (ANOVA: F > 4.88; P < .029). No differences between the painful sides and the nonpainful sides of the patients were found (ANOVA: F < 1.26; P > .262). No main effects of group or stimulation side on the electrical sensory and pain thresholds were detected (ANOVA: F < 0.309; P > .579). Sensitivity was 0.51; specificity, 0.81; and PPV, 0.77 when a VAS value of >= 8 for capsaicin-evoked pain was used. Conclusion: AO patients show increased sensitivity to intraoral capsaicin but normal sensitivity to "nociceptive-specific" electrical stimulation of the face in an area proximal to the painful site. The use of the intraoral pain-provocation test with capsaicin as a possible adjunct to the diagnostic workup is hampered by the only moderately good sensitivity and specificity. Keywords: atypical odontalgia, capsaicin, neuropathic pain, trigeminal pain

Aims: To examine the psychometric characteristics of a measure of self-efficacy for managing temporomandibular disorders (TMD) and to determine whether scores on this measure were related to pain, disability, and psychological distress in patients with chronic TMD pain. Methods: Patients seeking treatment for chronic TMD pain (n = 156, 87% female, mean age = 37 years) completed measures assessing pain, disability, mental health, pain-coping strategies, and self-efficacy for managing their pain. Results: The self-efficacy measure, which was adapted from arthritis research, demonstrated good psychometric characteristics (Cronbach's alpha = 0.91, minimal floor and ceiling effects, and validity). Greater self-efficacy was associated with significantly (P < .05) lower levels of pain, disability, and psychological distress. Self-efficacy remained significantly associated with disability and mental health measures even after controlling for demographic variables and pain intensity. In addition, patients with higher self-efficacy reported significantly (P < .05) greater use of an active, adaptive chronic pain-coping strategy (task persistence) and less use of a passive, maladaptive chronic pain-coping strategy (rest). Conclusion: Self-efficacy for managing pain appears to be important in the adjustment of patients with chronic TMD pain. Research is needed to determine whether treatments designed to increase self-efficacy improve TMD patient outcomes. Keywords: chronic pain, coping strategies, disability, self-efficacy, temporomandibular disorders

Aims: To describe patients' daily coping with the pain of chronic temporomandibular disorders (TMD), the conservative treatment received, and the self-care strategies used, and to examine the relationships between these strategies and daily pain intensity, activity interference, and jaw use limitations. Methods: TMD clinic patients (n = 137, 88% women) completed electronic diary measures of pain, interference, jaw use limitations, and use of 20 strategies 3 times daily for 2 weeks. Results: Reliability and validity were demonstrated for 4 scales of related coping items: cognitive coping, relaxation, activity reduction, and emotional support. Average scores were higher on the relaxation and activity reduction scales than on the cognitive coping and emotional support scales. Among the coping items not included in the scales, "did something to try to reduce pain" (direct action) was endorsed most frequently (reported in a median of 74% of interviews). Heat, cold, and seeking spiritual support were used least ( Keywords: chronic pain, electronic diaries, pain coping strategies, temporomandibular disorders

Aims: To evaluate the reliability and validity of self-reported pain associated with temporomandibular disorders (TMD) in adolescents and to determine how this validity may change over time. The authors' hypothesis was that self-reported pain can be used to reliably and accurately detect adolescents with TMD pain. Methods: One hundred twenty adolescents, 60 with self-reported TMD pain and 60 age- and gender-matched controls without TMD pain, were examined twice. At the first examination at a Public Dental Service clinic, self-reported TMD pain was recorded for each patient. At the second examination, a clinical examination was completed, blind to the patients' self-report of pain symptoms, after which self-reported TMD pain was again recorded. The clinical examination was based upon the Research Diagnostic Criteria for TMD (RDC/TMD). Self-reported TMD pain in this investigation was based upon the subjects' responses to 2 questions: (1) Do you have pain in your temples, face, temporomandibular joint (TMJ), or jaws once a week or more? and (2) Do you have pain when you open your mouth wide or chew once a week or more? Results: Test-retest reliability of .83 (kappa) was found for the 2 questions. The sensitivity was .98 (95% CI, .90 to 1.0) and specificity was .90 (95% CI, .81 to .95) for comparison of assessments made on the same day. Sensitivity was .96 (95% CI, .85 to .99) and specificity .83 (95% CI, .72 to .90) for assessments made 2 to 4 weeks apart. Conclusion: Very good reliability and high validity were found for the self-reported pain questions. A short time interval between the screening question and examination slightly increased the accuracy of the measure. In adolescent populations, the questions in this study can be used to screen for TMD pain. Keywords: adolescents, diagnosis, reliability, sensitivity, specificity, temporomandibular pain

Aims: Since sleep bruxism (SB) is characterized by grinding and clenching of the teeth during sleep and could be an exaggerated manifestation of normal spontaneous rhythmic masticatory muscle activity, the aim of this study was to obtain a neurophysiological assessment of the excitability of the central jaw motor pathways in patients with signs and symptoms suggestive of SB. Methods: A total of 30 subjects diagnosed with SB on the basis of self-report of tooth grinding were studied using the "recovery cycle" of the masseter inhibitory reflex (MIR) elicited by electric and magnetic stimulation of the mental nerves and by recording the motor potentials evoked in masseter muscles by transcranial magnetic stimulation. Tests were done during daytime, when the subjects were awake. The data obtained were compared with data from a population of normal subjects. Results: In the putative SB patients and in normal subjects, the MIRs evoked by single electric and magnetic stimuli were similar. With paired stimuli, the degree of suppression of the late silent period was significantly lower (P < .01) in the patients compared to normal subjects, particularly for magnetic stimuli, at various interstimulus intervals. No significant differences were found between the 2 groups of subjects in the masseter motor potentials evoked by transcranial magnetic stimulation. Conclusion: Although the data were only obtained during wakefulness in patients self-reporting signs and symptoms suggestive of SB, the findings suggest that an abnormal excitability of the central jaw motor pathways may be present in SB subjects. This increased excitability could derive from an impaired modulation of brainstem inhibitory circuits and not from altered cortical mechanisms. These results support the view that bruxism is mainly centrally mediated and that it involves subcortical structures. The study also indicates that use of the MIR elicited by the double-shock technique could be valuable in the evaluation of bruxism. Keywords: bruxism, excitability, masseter inhibitory reflex, masticatory system, neurophysiology

Aims: To investigate the expression of aromatase in temporomandibular joints(TMJs) of male and female rats of different ages. Methods: The expression of aromatase in terms of protein and mRNA was examined by immunohistochemistry, Western blot, and in situ hybridization in the TMJs of Sprague-Dawley rats. The expression level of aromatase protein was also quantified by the density of aromatase-positive chondrocytes in TMJ condylar cartilage. A tritiated water assay was used to analyze the activity of aromatase in cartilage chondrocytes. Results: Strong aromatase protein and mRNA hybridization signals were detected in hypertrophic and mature chondrocytes in all the cases examined. The density of aromatase-positive chondrocytes was relatively stable at higher levels before 8 weeks of age. The density decreased gradually in females after 8 weeks of age but not in males. Conclusion: These results demonstrate that aromatase is expressed intensely in condylar cartilage and suggest that it may play an important role in pathophysiological mechanisms in condylar cartilage. Keywords: aromatase, cartilage, chondrocytes, estrogen, temporomandibular joint

Aims: To develop an animal model of anterior disc displacement (ADD) without the need for opening the temporomandibular joint (TMJ) capsule. Methods: Thirty-two healthy adult Japanese white rabbits were used in this study. Four rabbits were dissected to familiarize the investigators with the anatomy of the TMJ. Sixteen animals were subjected to surgical ADD in the right TMJ, 8 animals had a sham operation, and 4 animals were not operated (normal controls). Four rabbits from the experimental ADD group and 2 from the sham group were sacrificed 1, 2, 4, and 8 weeks, respectively. The rabbits in normal control group were sacrificed at the beginning of the experiment. Animal behaviors as well as macro- and microchanges in the TMJs were investigated. Results: Fifteen right TMJ discs in the 16 experimental rabbits were successfully displaced anteriorly, and the degree of ADD in the experimental group was similar. The mandible of each ADD rabbit deviated to the left side with inclined attrition of the incisors. Some histologic changes appeared in the experimental TMJs. Conclusion: This ADD technique without the need for opening the TMJ capsule is effective, and the model is suitable for studying ADD of the TMJ. Keywords: animal model, anterior disc displacement, rabbits, temporomandibular joint