Journal of Oral & Facial Pain and Headache, 02/2013

Aims: To perform a systematic review of the literature dealing with the prevalence of bruxism in adult populations. Methods: A systematic search of the medical literature was performed to identify all peer-reviewed English-language papers dealing with the prevalence assessment of either awake or sleep bruxism at the general population level by the adoption of questionnaires, clinical assessments, and polysomnographic (PSG) or electromyographic (EMG) recordings. Quality assessment of the reviewed papers was performed according to the Methodological evaluation of Observational REsearch (MORE) checklist, which enables the identification of flaws in the external and internal validity. Cut-off criteria for an acceptable external validity were established to select studies for the discussion of prevalence data. For each included study, the sample features, diagnostic strategy, and prevalence of bruxism in relation to age, sex, and circadian rhythm, if available, were recorded. Results: Thirtyfive publications were included in the review. Several methodological problems limited the external validity of findings in most studies, and prevalence data extraction was performed only on seven papers. Of those, only one paper had a flawless external validity, whilst internal validity was low in all the selected papers due to their selfreported bruxism diagnosis alone, mainly based on only one or two questionnaire items. No epidemiologic data were available from studies adopting other diagnostic strategies (eg, PSG, EMG). Generically identified "bruxism" was assessed in two studies reporting an 8% to 31.4% prevalence, awake bruxism was investigated in two studies describing a 22.1% to 31% prevalence, and prevalence of sleep bruxism was found to be more consistent across the three studies investigating the report of "frequent" bruxism (12.8% ± 3.1%). Bruxism activities were found to be unrelated to sex, and a decrease with age was described in elderly people. Conclusion: The present systematic review described variable prevalence data for bruxism activities. Findings must be interpreted with caution due to the poor methodological quality of the reviewed literature and to potential diagnostic bias related with having to rely on an individual's self-report of bruxism. Keywords: awake bruxism, bruxism, epidemiology, prevalence, sleep bruxism, systematic review

Aims: To combine empirical evidence and expert opinion in a formal consensus method in order to develop a quality-assessment tool for experimental bruxism studies in systematic reviews. Methods: Tool development comprised five steps: (1) preliminary decisions, (2) item generation, (3) face-validity assessment, (4) reliability and discriminitive validity assessment, and (5) instrument refinement. The kappa value and phi-coefficient were calculated to assess inter-observer reliability and discriminative ability, respectively. Results: Following preliminary decisions and a literature review, a list of 52 items to be considered for inclusion in the tool was compiled. Eleven experts were invited to join a Delphi panel and 10 accepted. Four Delphi rounds reduced the preliminary tool-Quality-Assessment Tool for Experimental Bruxism Studies (Qu-ATEBS)- to 8 items: study aim, study sample, control condition or group, study design, experimental bruxism task, statistics, interpretation of results, and conflict of interest statement. Consensus among the Delphi panelists yielded good face validity. Inter-observer reliability was acceptable (k = 0.77). Discriminative validity was excellent (phi coefficient 1.0; P .01). During refinement, 1 item (no. 8) was removed. Conclusion: Qu-ATEBS, the seven-item evidence-based quality assessment tool developed here for use in systematic reviews of experimental bruxism studies, exhibits face validity, excellent discriminative validity, and acceptable inter-observer reliability. Development of quality assessment tools for many other topics in the orofacial pain literature is needed and may follow the described procedure. Keywords: bruxism, Delphi technique, masticatory muscles, pain measurement

Aims: To investigate the hypothesis that the presence of transient morning masticatory muscle pain in young, healthy sleep bruxers (SBr) is associated with sex-related differences in sleep electroencephalographic (EEG) activity. Methods: Data on morning masticatory muscle pain and sleep variables were obtained from visual analog scales and a second night of polysomnographic recordings. Nineteen normal control (CTRL) subjects were age- and sex-matched to 62 tooth-grinding SBr. Differences in sleep macrostructure (stage distribution and duration, number of sleep-stage shifts), number of rhythmic masticatory muscle activity (RMMA) events/ hour, and EEG activity were analyzed blind to subject status. The influence of pain and gender in SBr and CTRL subjects was assessed with the Fisher's exact test, Mann-Whitney U test, two-sample t test, and analysis of variance (ANOVA). Results: Low-intensity morning transient orofacial pain was reported by 71% of SBr, with no sex difference. RMMA event frequency was higher in SB than CTRL subjects (4.5/hour vs 1.3/hour; P .001). SBr had fewer sleep-stage shifts, irrespective of sex or pain status. Female SBr had significantly lower theta and alpha EEG activity compared to female CTRL subjects (P = .03), irrespective of pain. Conclusion: Female SBr had lower theta and alpha EEG activity irrespective of transient morning pain. Keywords: EEG power spectral analysis, pain, sex, sleep bruxism, theta wave activity

Aims: To identify potential predictors of self-reported sleep bruxism (SB) within children's family and school environments. Methods: A total of 65 primary school children (55.4% males, mean age 9.3 ± 1.9 years) were administered a 10-item questionnaire investigating the prevalence of self-reported SB as well as nine family and school-related potential bruxism predictors. Regression analyses were performed to assess the correlation between the potential predictors and SB. Results: A positive answer to the self-reported SB item was endorsed by 18.8% of subjects, with no sex differences. Multiple variable regression analysis identified a final model showing that having divorced parents and not falling asleep easily were the only two weak predictors of self-reported SB. The percentage of explained variance for SB by the final multiple regression model was 13.3% (Nagelkerke's R2 = 0.133). While having a high specificity and a good negative predictive value, the model showed unacceptable sensitivity and positive predictive values. The resulting accuracy to predict the presence of self-reported SB was 73.8%. Conclusion: The present investigation suggested that, among family and school-related matters, having divorced parents and not falling asleep easily were two predictors, even if weak, of a child's self-report of SB. Keywords: children, family, school, sleep bruxism

Aims: To test whether temporomandibular disorders (TMD) case-control differences in conditioned pain modulation (CPM) exist, using a mechanically evoked temporal summation (TS) model. Methods: A series of 10 repetitive, mildly noxious, mechanical stimuli were applied to the fingers of 30 women with TMD, who had a primary diagnosis of masticatory myofascial pain, and 30 age-matched healthy women. The subjects rated the pain intensity caused by the 1st, 5th, and 10th stimuli in the series. To evaluate CPM, the same series of mechanical stimulations were applied with concomitant exposure of the other hand to a painfully cold water bath. Statistical inferences were based on t tests, chi-square tests, or analysis of variance (ANOVA), as appropriate. Results: Pain ratings increased significantly with stimulus repetition (P .01) and CPM significantly reduced TS of pain (P .01). Of particular note, both groups showed very similar degrees of CPM, with no significant group difference. Conclusion: Painful TMD is not necessarily associated with a compromised ability to engage the endogenous analgesic system in an experimental setting. Keywords: chronic pain, conditioned pain modulation, temporal summation, temporomandibular disorders

Aims: To examine the long-term prognosis of 46 previously examined atypical odontalgia (AO) patients. Methods: In 2002 and 2009, AO patients completed validated instruments measuring pain characteristics (pain frequency and intensity), physical functioning (Graded Chronic Pain Severity, GCPS) and emotional functioning (Symptoms Checklist, SCL-90R). The main outcome was global improvement. Baseline data on quantitative somatosensory testing and responsiveness to lidocaine injection were available for a subgroup of patients. Paired tests compared baseline and follow-up data, and logistic regression explored the possible prognostic value of baseline data. Results: Data from 37 patients (80%) were obtained. Thirteen patients (35%; 95% confidence intervals [CI] 20.2%-52.5%) rated their overall pain status as significantly improved, 22 (60%; 95% CI 42.1%-75.3%) as a little improved or unchanged, and two patients (5%; 95% CI 0.7%-18.2%) as worse. Five patients (14%; 95% CI 4.5%-28.8%) were pain-free, indicated by a characteristic pain intensity score of 0. Average pain intensity decreased (from 5.7 ± 2.0 to 3.5 ± 2.4; P .001). Pain frequency (P .001) and GCPS (P .001) also decreased, whereas SCL-90R scores remained unchanged and 26 of the 37 patients reported ongoing treatment. Low baseline pain intensity was the only factor predictive of favorable outcome. Conclusion: A third of the AO patients improved considerably over time, but for many of the patients, AO was a persistent and treatment-resistant condition. Keywords: neuropathic pain, orofacial pain, prognosis, prospective study, trigeminal nerve

Aims: To assess intraoral inter- and intraexaminer reliability of three qualitative measures of intraoral somatosensory function and to compare these measures between patients with atypical odontalgia (AO) and healthy controls. Methods: Thirty-one AO patients and 47 healthy controls participated. Inter- and intraexaminer reliability was tested on a subgroup of 46 subjects (25 AO; 21 healthy). Sensitivity to touch, cold, and pinprick stimuli was evaluated on the painful gingival site and the corresponding contralateral site in AO patients, and bilaterally on the gingiva of the first maxillary premolars in controls. Patients were asked to report hypersensitivity, hyposensitivity, or normal sensitivity to stimuli on the painful site compared with the nonpainful site. Kappa values were calculated, and chi-square and Fisher's exact tests were used to compare frequencies between groups. Results: Kappa values ranged between 0.63 and 0.75. The frequency of hypersensitivity to either modality was significantly higher in patients (29% to 61%) than in controls (9% to 17%) (P .015), whereas reports of hyposensitivity were similar between groups (2% to 16%) (P > .057). Only 3.2% of the AO patients had no reports of abnormal sensitivity on any of the tests, compared with 59.6% of the healthy subjects (P .001). Conclusion: Intraoral qualitative somatosensory testing can detect intraoral sensory disturbances in AO patients, and the reliability is sufficient for initial screening of orofacial somatosensory function. Keywords: atypical odontalgia, intraoral, neuropathic pain, reliability, somatosensory testing

Aims: To carry out a systematic review of randomized controlled trials (RCTs) to investigate in patients with arthralgia of the temporomandibular joint (TMJ) the effectiveness of TMJ lavage compared to nonsurgical treatment with regard to pain intensity and mandibular range of motion. Methods: The electronic databases Cochrane Controlled Trials Register (1960-2012), PubMed/Medline (1966-2012), and Embase (1966-2012) were systematically searched for relevant RCTs. References of relevant articles were searched for additional studies, as well as citing reports. Two authors independently performed data extraction by using predefined quality indicators. Relevant outcome data included reduction in pain, as assessed by a visual analog scale (VAS) or a pain score, and maximal mouth opening (MMO) before and 6 months after treatment. Included trials were combined using fixed and random effects meta-analysis. Results: Three RCTs (222 patients) were included for meta-analysis. The statistically significant overall standardized mean difference (SMD) (P .001) with regard to pain intensity was -1.07 (95% CI = -1.38, - 0.76) in favor of TMJ lavage. The MMO did not change significantly (P > .05, SMD = .05 [95% CI = -0.33, 0.23]). Conclusions: The results suggest that lavage of the TMJ may be slightly more effective than nonsurgical treatment for pain reduction. However, this difference is not likely to be clinically relevant. Keywords: arthralgia, arthrocentesis, arthroscopy, meta-analysis, temporomandibular joint