Faculty Bibliography

BACKGROUND:Despite advances in temporomandibular disorders' (TMDs) diagnosis, the diagnostic process continues to be problematic in non-specialist settings. OBJECTIVE:To complete a Delphi process to shorten the Diagnostic Criteria for TMD (DC/TMD) to a brief DC/TMD (bDC/TMD) for expedient clinical diagnosis and initial management. METHODS:An international Delphi panel was created with 23 clinicians representing major specialities, general dentistry and related fields. The process comprised a full day workshop, seven virtual meetings, six rounds of electronic discussion and finally an open consultation at a virtual international symposium. RESULTS:Within the physical axis (Axis 1), the self-report Symptom Questionnaire of the DC/TMD did not require shortening from 14 items for the bDC/TMD. The compulsory use of the TMD pain screener was removed reducing the total number of Axis 1 items by 18%. The DC/TMD Axis 1 10-section examination protocol (25 movements, up to 12 sets of bilateral palpations) was reduced to four sections in the bDC/TMD protocol involving three movements and three sets of palpations. Axis I then resulted in two groups of diagnoses: painful TMD (inclusive of secondary headache), and common joint-related TMD with functional implications. The psychosocial axis (Axis 2) was shortened to an ultra-brief 11 item assessment. CONCLUSION/CONCLUSIONS:The bDC/TMD represents a substantially reduced and likely expedited method to establish (grouping) diagnoses in TMDs. This may provide greater utility for settings requiring less granular diagnoses for the implementation of initial treatment, for example non-specialist general dental practice.

Research on myofascial temporomandibular disorder (mTMD) has often focused on potential dysfunction in endogenous pain modulation. However, studies on the specific inhibitory and facilitatory components of endogenous pain modulation using conditioned pain modulation (CPM) and temporal summation of second pain (TSSP) have shown mixed results. This study aimed to 1) examine whether women with mTMD demonstrated efficient CPM compared to controls; 2) explore the association between independent measures of CPM and TSSP in women with mTMD relative to controls; and 3) determine whether resulting modulatory profiles differentially predicted pain intensity among cases. All participants were recruited from dental clinics. Cases were women who met the research diagnostic criteria for mTMD. Controls did not have facial pain on exam and were selected to be sociodemographically similar to cases. CPM and TSSP were assessed via independent psychophysical protocols. CPM was examined in linear mixed models predicting pain thresholds adjusted for age and stratified by TSSP. Mean CPM was estimated at a 2.2 (SD = 2.8) degree increase in pain thresholds (P ≤ .001), similar in cases and controls (P = .67). CPM was less efficient in cases with enhanced TSSP (P = .031), but not in controls. Although the double-pronociceptive profile of both low CPM and high TSSP trended higher among cases than controls, it did not predict higher levels of pain intensity among cases. This study does not support deficient inhibitory endogenous pain modulation in mTMD, but results suggest that inhibitory and facilitatory pain modulation should be examined concomitantly in the study of endogenous pain modulation. PERSPECTIVE: This manuscript presents a novel examination of inhibitory modulation by the level of facilitatory modulation in mTMD. The findings and approach may prove useful for mechanistic researchers studying endogenous pain modulation and clinical researchers seeking to jointly examine conditioned pain modulation and temporal summation in future research on chronic pain.

Pain is undesirable, whether it is a symptom of mild or severe illness or instead indicates disorder in the nervous system's ability to perceive and process sensory information. Nonetheless, pain is part of the body's ability to defend itself and promote its own survival-this is its fundamental evolutionary function. This normal expression of pain is not limited to what is considered useful because it alerts us to the initiation of illness. It also applies to pain that continues when illness or noxious stimuli persist. However, the parameters of what is here termed functional pain are not fully understood and are seldom explicitly the focus of research. This paper posits that failure to appreciate the functional role of pain in research has had significant unintended consequences and may be contributing to inconsistent research findings. To that end, the paper describes the misclassification issue at the core of chronic pain research-whether a given pain reflects functional or pathological processes-and discusses research areas where reconsidering the functional role of pain may lead to advancements.

PURPOSE/UNASSIGNED:Mechanisms underlying myofascial temporomandibular disorder (mTMD) are poorly understood. One theory is dysfunction in the central mediation of pain, specifically in enhanced facilitatory pain modulation. Because mechanisms leading to central sensitization may differ for joint and muscle pain, this study of mTMD addressed phenotypic heterogeneity by temporomandibular (TM) joint pain in the examination of quantitative sensory testing (QST). PATIENTS AND METHODS/UNASSIGNED:The stimulus dependent increase in second pain (temporal summation (TS)) and associated aftersensations (AS) were examined across groups of women with mTMD with TM joint pain and without, and a demographically matched control group. RESULTS/UNASSIGNED:TS was slightly more evident in mTMD without joint pain vs with (p = 0.035), but AS were most robustly persistent in the group with joint pain vs without (p < 0.002). CONCLUSION/UNASSIGNED:While both subgroups demonstrated evidence of central sensitization relative to controls on one of two measures, differences in QST results, if replicated, may point to possible differences in the mechanisms that yield central sensitization. Alternatively, it may represent methodological artifacts that need to be addressed. Therefore, greater consideration should be given to symptom-based phenotypes in studies examining TS and AS.

BACKGROUND:Adverse effects of masticatory muscle injections of Botulinum Toxin (Btx) have been noted in animal and, less dramatically, human studies. OBJECTIVE:Among women treated in multiple community-based private practices, to compare TMJ bone density and mandibular condylar volume between patients with myofascial TMJD receiving multiple masticatory muscle Btx treatments and similarly diagnosed women not receiving such treatment. METHODS:Cohorts consisted of women whose treatment charts indicated a diagnosis of myofascial TMJD: 35 received at least 2 Btx treatment cycles; 44 received none. Bone density at prespecified regions of interest (ROI) was defined by grey scale values from Cone Beam CT, adjusting for a fixed density phantom included in each scan. Mean bone density and mandibular condyle volume were compared between groups. Dose response effects were tested within the Btx-exposed group. RESULTS:The mean density of primary and secondary ROIs was similar between exposure groups, as was condylar volume. Among Btx-exposed women, increasing dose of Btx to the temporalis muscle was inversely proportional to the density of the trabecular area of the mandible body. Many Btx-exposed women received smaller doses of Btx to the masseter muscles than in most TMJD Btx clinical trials. CONCLUSION/CONCLUSIONS:Masticatory muscle injections of Btx failed to produce clinically significant TMJ bone-related changes. Should Btx receive regulatory approval for treatment of myofascial TMJD, a phase IV study is recommended to evaluate potential adverse effects of Btx on bone and muscle when administered at higher doses and/or for more treatment cycles.

BACKGROUND:Although development of reliable diagnostic criteria for temporomandibular disorders (TMD) have operationalized identification of a subgroup with myofascial pain (mTMD), causal mechanisms remain elusive. OBJECTIVES/OBJECTIVE:This study examines masticatory muscle activity (MMA) in more homogenous research subgroups of mTMD. METHODS:Data from an existing case-control study of women were used to subcategorize mTMD cases based on joint pain with palpation to isolate muscle-only pain (M-pain) vs muscle and joint pain (MJ-pain). Differences in laboratory indicators of MMA, specifically research diagnostic criteria for sleep bruxism (SB) and high background EMG activity, and other clinical and sociodemographic indicators were examined between groups. RESULTS:Compared to controls, the MJ-pain subgroup did not show elevated background EMG or sleep bruxism. In contrast, the M-pain subgroup showed significantly higher background EMG and a trend toward elevated prevalence of sleep bruxism. CONCLUSIONS:These results may explain why it has been difficult for studies of SB in mixed TMD and even mTMD samples to find a consistent positive association, since a positive association may be limited to mTMD without joint pain. The subcategorizing of mTMD based on joint pain with palpation (i.e., M-pain, MJ-pain) appears to reveal subgroups with relatively high and low sleep masticatory muscle-specific activity. Findings need replication in a larger study with updated mTMD diagnostic criteria, but may prove useful for understanding mechanism of pain maintenance in mTMD with and without joint pain. This article is protected by copyright. All rights reserved.

OBJECTIVE:This study examined whether patients with myofascial temporomandibular disorder (mTMD) comorbid with fibromyalgia (FM) receive different treatments or respond differently to these treatments than mTMD-only patients. MATERIALS AND METHODS/METHODS:A total of 125 mTMD+ women were enrolled (26 FM+ and 98 FM-). mTMD and FM were assessed via clinical research examinations. Treatment histories and self-reported treatment-related improvement were obtained via interview. RESULTS:The top 3 most common treatments reported were oral appliances (59%), physical therapy (54%), and jaw exercises at home (34%). Use of alternative medicine was reported more frequently among FM+ women, but self-reported improvement did not differ by comorbid FM. Physical therapy was as likely reported by FM status but self-reported improvement scores trended higher for FM+ women. CONCLUSIONS:Oral appliances were as likely to be reported by FM comorbid as FM- women. Oral appliances did not outperform self-management treatments on self-reported improvement of facial pain. CLINICAL RELEVANCE/CONCLUSIONS:Results support the use of self-management as first-line treatment for mTMD and potential utility of inquiring about widespread pain for treatment planning.

AIMS:To (1) examine differences in self-rated health (SRH) between a group of women with myofascial temporomandibular disorders (mTMD) and controls; (2) determine the extent to which pain, mental health, and physical function mediate these differences; and (3) explore specific mTMD symptoms and impairments explaining SRH among mTMD cases. METHODS:An existing dataset of a sample of women with mTMD (n = 125) and a group of demographically similar controls (n = 49) was used. SRH was measured via a single item with 5 answer options ranging from poor (SRH = 1) to excellent (SRH = 5). Bodily pain, mental health, and physical function were measured with the Short-Form Health Survey. Regression analyses with SRH as the outcome were conducted. RESULTS:mTMD cases reported poorer SRH compared to controls, and bodily pain score fully mediated these lower scores. Physical function partially mediated the association between mTMD and SRH, while mental health did not explain much of the variance in SRH. This pattern held in case-only analyses. The association was not explained by mTMD-specific symptoms or by localized mTMD pain severity, although mTMD disability was independently associated with lower SRH. CONCLUSION:SRH is a simple and useful tool to consider in mTMD research, as it discriminates between cases and controls based on pain and physical function and is associated with mTMD disability.

In 2013, consensus was obtained on a definition of bruxism as repetitive masticatory muscle activity characterised by clenching or grinding of the teeth and/or by bracing or thrusting of the mandible and specified as either sleep bruxism or awake bruxism. In addition, a grading system was proposed to determine the likelihood that a certain assessment of bruxism actually yields a valid outcome. This study discusses the need for an updated consensus and has the following aims: (i) to further clarify the 2013 definition and to develop separate definitions for sleep and awake bruxism; (ii) to determine whether bruxism is a disorder rather than a behaviour that can be a risk factor for certain clinical conditions; (iii) to re-examine the 2013 grading system; and (iv) to develop a research agenda. It was concluded that: (i) sleep and awake bruxism are masticatory muscle activities that occur during sleep (characterised as rhythmic or non-rhythmic) and wakefulness (characterised by repetitive or sustained tooth contact and/or by bracing or thrusting of the mandible), respectively; (ii) in otherwise healthy individuals, bruxism should not be considered as a disorder, but rather as a behaviour that can be a risk (and/or protective) factor for certain clinical consequences; (iii) both non-instrumental approaches (notably self-report) and instrumental approaches (notably electromyography) can be employed to assess bruxism; and (iv) standard cut-off points for establishing the presence or absence of bruxism should not be used in otherwise healthy individuals; rather, bruxism-related masticatory muscle activities should be assessed in the behaviour's continuum.