Journal of Oral & Facial Pain and Headache, 04/2015

Aims: To describe the characteristics of headaches attributed to temporomandibular disorders (TMD) and assess the effects of two management strategies used for the management of TMD on headache intensity and frequency. Methods: The initial sample (n = 60) of this randomized controlled trial comprised patients with masticatory myofascial pain according to the Research Diagnostic Criteria for TMD (RDC/TMD), and headache. The patients were divided into two groups: group 1 received only counseling for behavioral changes, and group 2 received counseling and an occlusal appliance. A 5-month followup period included three assessments. TMD-related headache characteristics, eg, headache intensity (scored on a visual analog scale [VAS]) and frequency were measured by a questionnaire. Two-way analysis of variance, chi-square, Friedman, and Mann-Whitney tests were used to test for differences considering a 5% significance level. Results: The main clinical features of headache attributed to masticatory myofascial pain were the long duration (≥ 4 hours), frontotemporal bilateral location, and a pressing/tightening quality. Forty-one subjects (group 1, 17 subjects; group 2, 24 subjects) were included in the final analysis. There was a reduction in headache intensity and frequency, with no significant differences between groups (P > .05). The mean (± SD) baseline VAS was 7.6 (± 2.2) for group 1 and 6.5 (± 1.6) for group 2; final values were 3.1 (± 2.2) (P < .001) and 2.5 (± 2.3) (P < .001), respectively. Conclusion: Headache attributed to masticatory myofascial pain was mainly characterized by long duration, frontotemporal bilateral location, and a pressing/tightening quality. Also, counseling and behavioral management of masticatory myofascial pain improved headache, regardless of the use of an occlusal appliance. Keywords: diagnosis, myofascial pain, occlusal splint, secondary headache, temporomandibular joint disorders

Aims: To investigate the effects of the application of an acute alteration of the occlusion (ie, interference) on the habitual masseter electromyographic (EMG) activity of females with temporomandibular disorders (TMD)-related muscular pain during wakefulness. Methods: Seven female volunteers with masticatory myofascial pain participated in a crossover randomized clinical trial. Gold foils were glued on an occlusal contact area (active occlusal interference, AI) or on the vestibular surface of the same molar (dummy interference, DI) and left for 8 days. The masseter electromyogram was recorded during wakefulness in the natural environment by portable recorders under interference-free, dummyinterference, and active-interference conditions. The number, amplitude, and duration of EMG signal fractions with amplitudes above 10% of the maximum voluntary contraction (activity periods, APs) were computed in all experimental conditions. Muscle pain, headache, and perceived stress were each assessed with a visual analog scale (VAS), and an algometer was used to assess masseter and temporalis pressure pain thresholds. Data were analyzed by means of analysis of variance. Results: The frequency and duration of the recorded APs did not differ significantly between the experimental conditions (P > .05), but a small and significant reduction of the EMG mean amplitude of the APs occurred with AI (P < .05). Neither the VAS scores for muscular pain, headache, and perceived stress nor the pressure pain thresholds changed significantly throughout the entire experiment (P > .05). Conclusion: An active occlusal interference in female volunteers with masticatory muscle pain had little influence on the masseter EMG activity pattern during wakefulness and did not affect the pressure tenderness of the masseter and temporalis. Keywords: craniomandibular disorders, electromyography, masseter muscle, occlusal interference, occlusion, temporomandibular disorders

Aim: To assess whether patients with persistent neck pain display evidence of altered masticatory muscle behavior during a jaw-clenching task, despite the absence of orofacial pain or temporomandibular disorders. Methods: Ten subjects with persistent, nonspecific neck pain and 10 age- and sex-matched healthy controls participated. Maximal voluntary contractions (MVCs) of unilateral jaw clenching followed by 5-second submaximal contractions at 10%, 30%, 50%, and 70% MVC were recorded by two flexible force transducers positioned between the first molar teeth. Task performance was quantified by mean distance and offset error from the reference target force as error indices, and standard deviation of force was used as an index of force steadiness. Electromyographic (EMG) activity was recorded bilaterally from the masseter muscle with 13 × 5 grids of electrodes and from the anterior temporalis with bipolar electrodes. Normalized EMG root mean square (RMS) was computed for each location of the grid to form a map of the EMG amplitude distribution, and the average normalized RMS was determined for the bipolar acquisition. Between-group differences were analyzed with the Kruskal Wallis analysis of variance. Results: Task performance was similar in patients and controls. However, patients displayed greater masseter EMG activity bilaterally at higher force levels (P < .05). Conclusion: This study has provided novel evidence of altered motor control of the jaw in people with neck pain despite the absence of orofacial pain or temporomandibular disorders. Keywords: bite force, electromyography, masticatory muscles, motor control, neck pain

Aims: (1) To determine the brain regions activated by dentoalveolar pressure stimulation in persistent dentoalveolar pain disorder (PDAP) patients, and (2) to compare these activation patterns to those seen in pain-free control subjects. Methods: A total of 13 PDAP patients and 13 matched controls completed the study. Clinical pain characteristics and psychosocial data were collected. Dentoalveolar mechanical pain thresholds were determined with a custom-made device over the painful area for patients and were used as the stimulation level during functional magnetic resonance imaging (fMRI) data acquisition. Control subjects received two stimulation levels over matched locations during fMRI scanning: one determined (as above) that evoked equally subjective pain ratings matching those of patients (subjective-pain match) and another nonpainful stimulation level matching the average stimulus intensity provided to patients (stimulus-intensity match). Clinical and psychosocial data were analyzed using independent samples t tests, Mann-Whitney U test, and Spearman rank-order correlation coefficient. fMRI data were analyzed using validated neuroimaging software and tested using a general linear model. Results: PDAP patients had greater anxiety (P < .0001) and depression scores (P = .001), more jaw function impairment (P < .0001), and greater social impact (P < .0001) than controls. No significant differences were found for brain activation spatial extent (PDAP × Controls subjective pain: P = .48; PDAP × Controls stimulus intensity: P = .12). Brain activations were significantly increased for PDAP patients compared to control subjects when matched to stimulus intensity in several regions related to the sensory-discriminative and cognitive components of pain perception, including the primary and secondary somatosensory cortices, inferior parietal lobule, insula, premotor cortex, prefrontal cortex, and thalamus. When matched to subjective pain ratings, increased brain activations were still present for PDAP patients compared to controls, although to a lesser extent. Conclusion: The present results suggest that dentoalveolar pressure is processed differently in the brain of PDAP patients, and the increased activation in several brain areas is consistent with amplified pain processing. Keywords: atypical odontalgia, functional neuroimaging, neuropathic pain, orofacial pain, sensory testing

Aims: To evaluate the psychometric properties of the Multidimensional Pain Inventory (MPI) in a Brazilian sample of patients with orofacial pain. Methods: A total of 1,925 adult patients, who sought dental care in the School of Dentistry of São Paulo State University's Araraquara campus, were invited to participate; 62.5% (n = 1,203) agreed to participate. Of these, 436 presented with orofacial pain and were included. The mean age was 39.9 (SD = 13.6) years and 74.5% were female. Confirmatory factor analysis was conducted using χ2/df, comparative fit index, goodness of fit index, and root mean square error of approximation as indices of goodness of fit. Convergent validity was estimated by the average variance extracted and composite reliability, and internal consistency by Cronbach's alpha standardized coefficient (α). The stability of the models was tested in independent samples (test and validation; dental pain and orofacial pain). The factorial invariance was estimated by multigroup analysis (Δχ2). Results: Factorial, convergent validity and internal consistency were adequate in all three parts of the MPI. To achieve this adequate fit for Part 1, item 15 needed to be deleted (λ = 0.13). Discriminant validity was compromised between the factors "activities outside the home" and "social activities" of Part 3 of the MPI in the total sample, validation sample, and in patients with dental pain and with orofacial pain. A strong invariance between different subsamples from the three parts of the MPI was detected. Conclusion: The MPI produced valid, reliable, and stable data for pain assessment among Brazilian patients with orofacial pain. Keywords: facial pain, pain measurement, psychometrics, validation studies

Aims: To evaluate the association between signs of temporomandibular disorders (TMD) and psychological distress in a general population-based sample of Finnish adults. Methods: The Health 2000 Survey was conducted in 2000-2001 by the National Institute for Health and Welfare in Finland. Of the sample of adults aged 30 or over (n = 8,028), 79% participated in a clinical oral health examination, which included examination of TMD signs. The participants (n = 6,155) also completed questionnaires, including the 12-item General Health Questionnaire (GHQ-12), which measured psychological distress. Associations between TMD signs and psychological distress measured by the GHQ-12 were examined in both genders. Statistical measures included chi-square tests, t tests, and logistic regression analyses. Results: The prevalence of the TMD signs (limited opening, clicking, crepitation, temporomandibular joint [TMJ] palpation pain, and muscle palpation pain) was 11.2%, 17.6%, 10.5%, 5.1%, and 18.9% in women, and 6.1%, 12.9%, 5.3%, 2.4%, and 7.2% in men, respectively. High GHQ-12 scores, measured as continuous variables and in quartiles by distress level, were significantly associated with masticatory muscle pain on palpation in both genders (P < .05) and with TMJ pain on palpation in women (P < .05). Additionally, high GHQ-12 scores as continuous were associated with TMJ crepitation in men (P < .05). The logistic regression analyses showed that higher GHQ-12 scores were associated significantly with masticatory muscle pain on palpation both in women (odds ratio [OR] = 2.18; 95% confidence interval [CI] = 1.6-2.9) and men (OR = 2.03; 95% CI = 1.3-3.1). Conclusion: TMD signs and psychological distress appear to be associated. However, due to the limitations of the study, the findings can be regarded as preliminary. Keywords: GHQ, Health 2000 Survey, psychological distress, temporomandibular disorders, TMD

Aims: To evaluate whether a combination of locally administered morphine (1 mg) and lidocaine as part of a multimodal analgesic approach is safe, and whether it improves pain control during the first 24 hours after odontogenic maxillary cyst removal under general anesthesia compared to local lidocaine alone. Methods: In a double-blind, sham-controlled, single-center trial, patients scheduled for surgical removal of an odontogenic maxillary cyst under general anesthesia were randomly assigned to receive a local injection of lidocaine solution with either 1 mg of morphine (MLA group) or with no morphine (LA group). Pain management included intravenous acetaminophen (1 g every 6 hours) in all patients. Upon request, the patients could additionally receive ketoprofen (first-line additional analgesia) or tramadol (second-line additional analgesia). Pain intensity was assessed using a numeric rating scale. Primary outcome measures were (1) no need for any additional analgesic therapy and (2) time to the first rescue analgesic therapy during the first 24 hours after the surgery. Results: Of 48 eligible patients, 24 were allocated to the MLA group and 24 to the LA group. The necessity of additional ketoprofen therapy did not differ significantly between the groups (25.0% vs 50.0%, P = .074). According to the Kaplan-Meier analysis, the probability of remaining without additional analgesic intervention was significantly higher in the MLA group (log-rank test, P = .040), but there were no significant (P > .05) differences in overall and maximum pain severity between the two groups. No adverse effects of morphine were recorded. Conclusion: Within the limitations of this study, local administration of 1 mg of morphine prior to the surgical removal of an odontogenic maxillary cyst was safe, but it did not prove to be very effective as an add-on therapy for postoperative pain control. Keywords: inflammatory pain, odontogenic cysts, opioid receptors, oral surgery, peripheral opioid analgesia

Aims: To determine the prevalence and the awareness of migraine among university students in Harbin, China. Methods: A cross-sectional study of students was conducted in Harbin Medical University from April 1 to June 30, 2012. The Chinese version of the Identification of Migraine Screener (IDMigraine) was used as the screening tool, and the awareness of migraine was evaluated by a structured questionnaire. A subgroup of the students was randomly selected to fill out the questionnaire again to evaluate its testretest reliability. The internal consistency reliability and structured validity were tested using Cronbach's alpha coefficient and exploratory factor analyses. Results: Of the 5,129 registered students, 4,406 students (85.9%) signed a consent form and completed the questionnaire. Three hundred ninety-five students were screened positive for migraine, with a prevalence of 9.0%, and the migraine prevalence increased with age (z = -2.82, P < .01). Gender (χ2 = 0.12, P = .73) and body mass index (χ2 = 0.51, P = .78) did not significantly influence migraine prevalence, and the prevalence showed no significant difference between medical and nonmedical students (χ2 = 2.10, P = .15). The awareness of fundamental details (definition, classification, symptoms), treatment, and trigger factors of migraine were 40.4%, 42.4%, and 68.6%, respectively. The test-retest reliability of these parts of the questionnaire was 0.61 (95% confidence interval [CI]: 0.48-0.75), 0.77 (95% CI: 0.66-0.88), and 0.80 (95% CI: 0.69-0.91), respectively. Three components accumulatively explained 52.1% of the total variance of the scale, and the rotated factor loadings (the correlation coefficient between the items and the common factor) in each part were all higher than 0.50 excluding item C11. Conclusion: The prevalence of migraine in university students was 9.0%, which is comparable to the prevalence found in Chinese adults from the general population in two previous studies. University students have limited awareness of migraine. Keywords: awareness, ID-Migraine, migraine, prevalence, university students

Aims: To determine whether noxious stimulation of the rat tooth pulp induces learning and memory impairment through the induction of apoptosis in the hippocampus. Methods: Thirty-five adult rats were divided randomly into five groups (each n = 7) as follows: control, sham-operated, sham-vehicle, capsaicintreated, and capsaicin plus ibuprofen-treated group. After preparing dental cavities via cutting 2 mm of the distal extremities of the mandibular incisors, polyethylene crowns were placed on the teeth. Based on the study groups, different injections were administered into the cavities. Nociceptive scores for each block were obtained by measuring the number of seconds that the animal spent rubbing and flicking the lower jaw. After recording the nociceptive behaviors, spatial learning and memory were assessed by using the Morris Water Maze (MWM) test. The hippocampal levels of Bcl-2, Bax, and caspase-3 protein were determined by immunoblotting. Statistical analyses were performed using one- or two-way analysis of variance. Results: Noxious pulp stimulation induced by intradental application of capsaicin significantly increased time and traveled distance in the MWM test. Capsaicin stimulation of the pulp also significantly increased the Bax:Bcl-2 ratio and activated caspase-3 in the hippocampus (P < .01), which was inhibited by ibuprofen pretreatment (P < .05). Conclusion: Memory and learning impairment induced by noxious stimulation of the rat tooth pulp may be correlated with activation of apoptotic pathways in the hippocampus. Keywords: apoptosis, capsaicin, hippocampus, learning and memory, tooth pulp