Waking-state oral parafunctional behaviors: specificity and validity as assessed by electromyography

An exploratory data-driven approach to classify subgroups of patients with temporomandibular disorders based on pain mechanisms

Temporomandibular disorders (TMDs) are a common musculoskeletal condition, presenting treatment challenges due to their non-specific nature. Categorizing patients with TMDs into clusters based on neurobiological pain mechanisms could provide a promising approach to facilitate targeted treatments. This observational study (1) used a network analysis (NA) to explore the complexity of TMDs by investigating relationships among biopsychosocial variables, and (2) validated potential TMD subgroups based on mechanism-specific pain categories. One hundred and two patients with TMD were included. Biopsychosocial variables covered: general health, psychosocial features, TMD pain, and TMD characteristics. A NA evaluated the associations between variables and determined the role of each feature within the network. Hierarchical clustering was used to identify TMD subgroups. The NA revealed significant correlations primarily within the same feature domains, indicating a strong interplay between symptoms and psychological factors. Cluster analysis identified two subgroups driven by nociceptive and nociplastic pain mechanisms; the nociplastic group exhibited higher levels of anxiety, depression, pain catastrophization, central sensitization, pain duration, and more pain locations, along with poorer sleep quality, quality of life, and health status. In contrast, the nociceptive group exhibited restricted maximal mouth opening (MMO), heightened pain during TMJ palpation and mouth opening, and a greater positive response to manual therapy. Across all features, psychological factors, pain locations, and MMO primarily contributed to the separation of subgroups. By adopting a data-driven approach, these results support the significant role of considering the neurobiological basis of pain to improve patient classification. This knowledge may facilitate clinical reasoning and personalized treatments. PERSPECTIVE: This study used a network analysis to explore the complex biopsychosocial interactions present in people with TMDs, identifying important variables such as the Central Sensitization Inventory and pain-free maximal mouth opening. The findings distinguish potential nociceptive and nociplastic pain subgroups, offering important insights for targeted therapeutic strategies.

Phenotyping of somatosensory tinnitus and its associations: An observational cross-sectional study

BACKGROUND

Somatosensory tinnitus (ST) is associated with activation of the auditory pathway by trigeminal or cervical afferents.

OBJECTIVE

This is a cross-sectional observational study that aims to verify the association of ST with TMD, bruxism, migraine and psychosocial aspects.

METHODS

This study was conducted at the Tinnitus Outpatient Clinic of the Clinical Hospital Complex of the Federal University of Paraná. Specific ST characteristics, were evaluated according to the last consensus for the diagnosis of ST. Two groups with 39 individuals each one were formed, the ST group (STG) and the comparison group (CG). TMD was classified according to the Diagnostic Criteria for Temporomandibular Disorders and migraine by the International Classification of Headaches. The presence of probable sleep and awake bruxism was associated with individual's reports and clinical inspections. The applied questionnaires investigated oral behaviours (OB), sleep quality (SQ), psychosocial aspects (PA), central sensitization (CS), tinnitus impact on quality of life (TIQF), and graded chronic pain scale (GCPS).

RESULTS

The STG showed a significant association with modulation manoeuvres and trigger points; myalgias and arthralgia; disc displacement with and without reduction; subluxation; bruxism; and presence of migraine. For the same group, we found a significant association with OB, PA, CS, TIQF and GCPS. There was no significant difference between groups regarding SQ.

CONCLUSION

There is a significant association between the presence of ST and the occurrence of TMD, probable sleep and awake bruxism, and migraine. There is also a greater impairment of OB, PA, CS and TIQF.

Reciprocal effects of scleroderma and temporomandibular dysfunction between patient cohorts

OBJECTIVE

To estimate the prevalence of temporomandibular dysfunction in scleroderma patients according to the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) and to correlate it with disease variables.

METHODS

Temporomandibular dysfunction was evaluated in 75 scleroderma patients and 74 healthy controls using DC/TMD. Gastrointestinal symptoms were evaluated through the University of California Los Angeles (UCLA) score in scleroderma patients.

RESULTS

There was no difference of prevalence in temporomandibular dysfunction [30 (40%) vs 30 (40.5%); p > 00.05] between scleroderma patients and healthy controls. Scleroderma patients had a significant reduction in all oral movements compared to healthy controls. Scleroderma patients with temporomandibular dysfunction had a statistically higher score in the UCLA distention/bloating item [1.75 (0.5-2.38) vs 0.75 (0.25-1.75); p < 0.05] than scleroderma patients without temporomandibular dysfunction.

DISCUSSION

Temporomandibular dysfunction prevalence between scleroderma patients and healthy controls is similar. In scleroderma patients, temporomandibular dysfunction reduces oral mobility and opening, which worsens distension/bloating.

Signal to noise ratio of masticatory muscle activity of functional and non-functional oral tasks

BACKGROUND

Electromyographic activity (EMG) of masticatory muscles during wakefulness is understudied. It is unclear if single channel ambulatory EMG devices are sensitive enough to detect masticatory muscle activity (MMA) during wakefulness.

OBJECTIVES

To compare the MMA of various oral tasks recorded with a single channel EMG device ((Grindcare4-datalogger Prototype device) (GC4-β)) and a conventional EMG (cEMG) device.

METHODS

EMG activity of 30 standardised oral tasks was recorded unilaterally from the masseter and anterior temporalis muscle in 24 healthy volunteers using GC4-β and a cEMG device. To compare the EMG data, signal-to-noise ratios (SNR) were calculated as a way to normalise EMG activity across tasks. Analysis of variance was used to compare the SNR between the devices, muscles and oral tasks.

RESULTS

SNR measured from GC4-β was overall significantly higher than the cEMG device (p =.001). The SNR for maximum voluntary contraction (MVC) was significantly higher than all other tasks (p <.001). SNR for temporalis with GC4-β was significantly higher for MVC, hard food, soft food, gum chewing (dominant side), rhythmic clenching and upper lip biting compared to the cEMG device (p <.021). The SNR for masseter with GC4-β was significantly higher for hard food and gum chewing (dominant side), rhythmic clenching, rhythmic biting of an object and yawning compared to the cEMG device (p <.022).

CONCLUSIONS

This study provides novel insight into the EMG patterns of numerous oral tasks enhancing knowledge of physiological differences between the masticatory muscles. Further, single channel EMG devices can effectively measure the EMG activity of various oral tasks during wakefulness.

Transcriptomic Profiles Associated with Experimental Placebo Effects in Chronic Pain

Gene expression networks associated with placebo effects are understudied; in this study, we identified transcriptomic profiles associated with placebo responsivity. Participants suffering from chronic pain underwent a verbal suggestion and conditioning paradigm with individually tailored thermal painful stimulations to elicit conditioned placebo effects. Participants reported pain intensity on a visual analog scale (VAS) anchored from zero = no pain to 100 = maximum imaginable pain. RNA was extracted from venous blood and RNA sequencing and validation tests were performed to identify differentially expressed genes (DEGs) associated with placebo effects, controlling for sex and level of pain. Unbiased enrichment analyses were performed to identify biological processes associated with placebo effects. Of the 10,700 protein-coding genes that passed quality control filters, 667 were found to be associated with placebo effects (FDR <0.05). Most genes (97%) upregulated were associated with larger placebo effects. The 17 top transcriptome-wide significant genes were further validated via RT-qPCR in an independent cohort of chronic pain participants. Six of them (CCDC85B, FBXL15, HAGH, PI3, SELENOM, and TNFRSF4) showed positive and significant (P < 0.05) correlation with placebo effects in the cohort. The overall DEGs were highly enriched in regulation of expression of SLITs and ROBOs (R-HSA-9010553, FDR = 1.26e-33), metabolism of RNA (R-HSA-8953854, FDR = 1.34e-30), Huntington's disease (hsa05016, FDR = 9.84e-31), and ribosome biogenesis (GO:0042254, FDR = 2.67e-15); alternations in these pathways might jeopardize the proneness to elicit placebo effects. Future studies are needed to replicate this finding and better understand the unique molecular dynamics of people who are more or less affected by pain and placebo.

Is there a relationship between the presence of external root resorption in second molars adjacent to impacted mandibular third molars with awake bruxism and masticatory muscle activity?

OBJECTIVES

This study aimed to assess whether awake bruxism and masticatory muscle activity could be related to external root resorption (ERR) in second molars adjacent to impacted mandibular third molars.

MATERIALS AND METHODS

Sixty patients, with requests for a cone-beam, computed tomography, were divided into two groups: ERR (patients with ERR in the second molar, n = 30), and control group (n = 30). Awake bruxism was assessed through the Oral Behaviors Checklist (OBC) and an ecological momentary assessment (EMA). Surface electromyography (EMG) was used to assess the masseter and anterior temporal muscle function. Normality and homogeneity of variances were demonstrated. Descriptive analysis was performed, using the T-test and Chi-square test to compare the characteristics of the groups. A multiple regression model was performed.

RESULTS

The ERR group presented more non-functional oral activities related to awake bruxism than the control group, according to OBC (p = 0.027) and EMA (p = 0.035). In addition, the ERR group had higher EMG activity than the control group in rest and isotonic protocols (p < 0.05).

CONCLUSIONS

Awake bruxism and greater masticatory muscle activity seem to be related to the presence of ERR in second molars adjacent to impacted mandibular third molars.

CLINICAL RELEVANCE

The results of the present study can reinforce the theory that triggering ERR in the second molars adjacent to impacted mandibular third molars may be related to mechanical forces coming from the masticatory function.

Why am I grinding and clenching? Exploration of personality traits, coping strategies, oral parafunctional behaviors, and severe sleep bruxism in a polysomnographic study

Introduction

Causal relationships between psychopathological symptoms, personality traits, coping mechanisms, and sleep bruxism (SB) were studied in the past, giving inconsistent results mostly based on self-assessment evaluations. This polysomnography-based cross-sectional study aimed to explore the relationships between severe SB, personality traits (according to the Big Five model), and coping strategies with objective polysomnographic verification.

Methodology

The study included 66 participants divided into severe SB (SSB) (n=32) and no or mild SB (n=34) groups based on video-polysomnography performed in the sleep laboratory. Questionnaire assessment included the use of the Beck Depression Inventory, Beck Anxiety Inventory, Mini-COPE, International Personality Item Pool Big Five Markers 20-Item version, and Oral Behavior Checklist.

Results

Participants with SSB presented with fewer self-reported anxiety (p=0.008) and depressive (p=0.01) symptoms than the non- or mild-SB groups. The SSB group scored significantly higher in Big Five personal traits such as extraversion (p=0.007), emotional stability (p=0.013), and intellect (p=0.004), while regarding coping strategies, the SSB group was less likely to use negative strategies: self-distraction (p=0.036), denial (p=0.006), venting (p=0.03), behavioral disengagement (p=0.046), and self-blame (p=0.003), and turning to religion (p=0.041). The intensity of oral parafunctional behaviors was comparable in both groups (p=0.054). Emotional stability was a moderate protective factor (p=0.004), and the self-blame strategy was a strong risk factor (p<0.001) for increased oral parafunctional behavior intensity. Phasic activity negatively correlated with anxiety symptom severity (p=0.005), whereas tonic (p=0.122) and mixed (p=0.053) phenotypes did not. SB intensity was a protective factor against anxiety symptoms (p=0.016).

Conclusion

In terms of psychopathology, severe sleep bruxers tend to present less severe anxiety and depressive symptoms, while some of their personality traits (extraversion, emotional stability, and intellect) were more strongly pronounced. SSB is possibly related to the lesser use of the "maladaptive" coping strategies and there were no specific coping strategies preferred by SSB participants, compared to the other group. These observations require further studies, as it should be determined whether SB (especially phasic activity) might be a form of a somatization/functional disorder. Further research should focus on the psychogenic background of oral parafunctional behaviors, which occur more often in less emotionally stable personalities and in people using self-blame coping strategies.

Relationship between masseter muscle activity during wakefulness and temporomandibular disorder-related symptoms

BACKGROUND

Masseter muscle activity during wakefulness may be associated with temporomandibular disorder (TMD)-related symptoms, psychosocial status and pain-related disability; however, this relationship is unclear.

OBJECTIVES

This study aimed to determine the relationship between masseter muscle electromyography (EMG) burst/duration during wakefulness and TMD-related symptoms, psychosocial status and pain-related disability.

METHODS

Sixty participants were assessed masseter muscle activity during wakefulness using a data-logger-type ultraminiature EMG system and TMD-related symptoms, psychosocial status and pain-related disability through Axis I and II of the diagnostic criteria for TMD (DC/TMD). EMG bursts lasting longer than 0.25 s but less than 2.0 s and those lasting longer than 2.0 s were classified as phasic and tonic bursts, respectively.

RESULTS

Participants with palpation-related pain in the temporalis and masseter muscles, as assessed through the DC/TMD examination form in Axis I, had more bursts (number/h) (p = .035 and p = .009, respectively) and longer duration (time/h) (p = .013 and p = .004, respectively) of tonic bursts of the masseter muscle during wakefulness. Participants with palpation-related pain in the masseter muscles had higher oral behaviour scores during wakefulness using Axis II (p = .001), which affected the number and duration of tonic bursts of the masseter muscle activity during wakefulness (p = .011 and p = .007, respectively).

CONCLUSION

As tonic bursts mainly reflect clenching, individuals with pain in the masseter muscles by palpation may have a high frequency and longer duration of clenching, as well as a high frequency of oral behaviours during wakefulness.

Awake and Sleep Oral Behaviours in Patients With Painful Temporomandibular Disorders

OBJECTIVES

The aim of this research was to explore the oral behaviours exhibited by individuals with and without temporomandibular disorders (TMD) pain, and with various pain characteristics; and to determine which oral behaviour is correlated with painful TMD.

METHODS

328 patients with TMD who visited Orofacial Pain Clinic were included in this retrospective cross-sectional study. The patients were categorised into 2 groups-painful TMD and non-painful TMD-based on pain status; their other pain characteristics were recorded. To evaluate oral behaviours, researchers utilised the Oral Behaviors Checklist (OBC) and categorised into 3 levels based on the Diagnostic criteria for TMD scoring manual. To investigate the associations amongst demographic information, oral behaviour levels, and TMD pain status and characteristics, logistic regression was employed, whilst t tests were used to analyse OBC scores. Logistic regression was also used to examine individual oral behaviours in relation to specific pain characteristics.

RESULTS

Age and marital status were associated with TMD pain status. Significantly higher OBC scores were observed in chronic pain compared to acute pain group, but the scores were not significantly different for pain status and other pain characteristics. OBC score and level were associated solely with TMD pain chronicity. According to multivariate logistic regression, "clench or grind teeth when sleeping" was the strongest predictor of TMD pain and "place tongue forcibly against teeth" was the strongest predictor of chronic painful TMD.

CONCLUSIONS

High oral behaviour level and OBC scores were associated with chronic painful TMD. Sleep bruxism was the strongest predictor of TMD pain. Age and marital status were correlated with TMD pain status. In the treatment of TMD, there can be potential benefits in addressing and managing oral parafunctional behaviours.

Smartphone application to report awake bruxism: Development and testing of the Swedish version and a pilot study to evaluate family history in young adults and their parents

BACKGROUND

Together with psychosocial and hereditary factors, bruxism is a possible risk factor for orofacial pain. Bruxism is defined as a masticatory muscle activity characterized by repetitive or sustained tooth contact, or by bracing or thrusting of the mandible. A smartphone application to report awake bruxism (AB) has been developed and translated into more than 25 languages.

OBJECTIVE(S)

To translate the application into Swedish, adapt it to Swedish culture and conduct a study to evaluate the usability of the application for studies on family history and associated risk factors.

METHODS

Translation and cultural adaption of the Swedish version of the application (BruxApp) was carried out in a four-step sequential process. Ten young adults (22-30 years) were recruited together with ten parents (42-67 years) and reported their AB with the application over two seven-day periods. Pain, stress and parafunctional behaviours were assessed by questionnaires.

RESULTS

The back translation check showed minimal discrepancies between the translation and the English version. Participants did not report any problems with the application. Response rates for both groups were 65%. A difference in frequency of AB was shown between young adults and parents (22.0% vs. 12.5%, p < .001). A positive moderate correlation was found between AB and stress (r = 0.54, p = .017).

CONCLUSION

The use of application strategies enables data collection on AB which can be used in both clinical and research settings. The results suggest that the Swedish version is ready for implementation and for studies on the relationships between AB, family history and psychosocial factors.

The effect of passive clear aligners on masticatory muscle activity in adults with different levels of oral parafunction

BACKGROUND

There is limited knowledge of the possible side-effects of clear aligners on jaw function.

OBJECTIVES

To determine the short-term effect of passive clear aligners (PCAs) on masticatory muscle activity (MMA), occlusal discomfort (OD) and temporomandibular disorder (TMD) symptoms in adults with different levels of self-reported oral parafunction.

MATERIALS AND METHODS

Participants were screened for oral parafunctional behaviours using the oral behavioural checklist. Respondents in ≥85th and ≤15th percentiles were invited to participate and allocated to a high (HPF: N = 15) or low (lower parafunction [LPF]: N = 16) parafunction group. Participants underwent a TMD clinical examination; somatisation and somatosensory amplification were assessed by questionnaires; OD and stress were assessed by visual analogue scales. While wearing PCAs, awake-time MMA was assessed three times over 9 days using a wearable electromyography device, along with OD, stress and TMD symptoms.

RESULTS

The wearing of PCAs was associated with a significant decrease in mean contraction episode amplitude in both groups (p = 0.003). OD levels increased and remained raised in all participants after insertion of the PCAs (p < 0.001), more so in the HPF group (p = 0.048). The HPF group had higher somatisation scores (p = 0.006) and reported more TMD symptoms at all time points (p ≤ 0.004). No significant changes in stress or TMD symptoms were found in either group during the study period.

CONCLUSIONS

PCAs were associated with a decrease in MMA in all participants. HPF individuals had greater somatisation and reported greater discomfort when wearing PCAs than LPF individuals.

Biological and psychological factors affecting the sensory and jaw motor responses to orthodontic tooth movement

Orthodontic tooth movement (OTM) is associated with an inflammatory response, tooth pain (i.e. orthodontic pain) and changes in dental occlusion. Clinical realms and research evidence suggest that the sensory and jaw motor responses to OTM vary significantly among individuals. While some adjust well to orthodontic procedures, others may not and can experience significant pain or not adjust to occlusal changes. This is of concern, as clinicians cannot anticipate an individual's sensorimotor response to OTM. Converging evidence shows that some psychological states and traits significantly affect the sensorimotor response to OTM and may considerably affect an individual's adaptation to orthodontic or other dental procedures. We performed a topical review to synthesize the available knowledge about the behavioural mechanisms regulating the sensorimotor response to OTM, with the intent of informing orthodontic practitioners and researchers about specific psychological states and traits that should be considered while planning orthodontic treatment. We report on studies focusing on the role of anxiety, pain catastrophising, and somatosensory amplification (i.e. bodily hypervigilance), on sensory and jaw motor responses. Psychological states and traits can significantly affect sensory and jaw motor responses and a patient's adaptation to orthodontic procedures, although large interindividual variability exists. Clinicians can use validated instruments (checklists or questionnaires) to collect information about patients' psychological traits, which can assist in identifying those individuals who may not adjust well to orthodontic procedures. The information included in this manuscript also assists researchers investigating the effect of orthodontic procedures and or/appliances on orthodontic pain.

ASSOCIATIONS BETWEEN SCREENING FOR FUNCTIONAL JAW DISTURBANCES AND PATIENT REPORTED OUTCOMES ON JAW LIMITATIONS AND ORAL BEHAVIORS

OBJECTIVES

Temporomandibular disorders (TMDs) is a collective term for pain and functional disturbances related to the jaw muscles and the temporomandibular joint. In contrast to screening for orofacial pain, knowledge is limited on the association between patient-reported outcomes and screening for joint-related functional jaw disturbances. Therefore, our aim was to evaluate the association between a screening question for functional jaw disturbances, and disease-specific outcome measures for functional jaw limitations and oral behaviors.

METHODS

This study included 299 individuals (201 women; 20-69 years, median 37.0) in a general population sample from Västerbotten, Northern Sweden in 2014. A single screening question for functional jaw disturbances "Does your jaw lock or become stuck once a week or more?" was used to categorize individuals as cases or controls. Patient-reported outcomes on functional jaw disturbances were assessed with the 20-item jaw functional limitation scale (JFLS-20) and oral behaviors with the 21-item Oral Behaviors Checklist (OBC-21).

RESULTS

The strongest predictive probability to have a positive screening outcome was functional jaw limitations related to mobility (AUCboot=0.78, 95 CI:0.71-0.86, P < .001), followed by limitations related to communication (AUCboot = 0.74, 95 CI:0.63-0.80, P < .001) and mastication (AUCboot = 0.73, 95 CI:0.66-0.81, P < .001). The frequency of oral behaviors was not significantly associated with a positive screening outcome (AUCboot = 0.65, 95 CI:0.55-0.72, P = .223).

CONCLUSIONS

Self-reported functional limitations, but not oral behaviors, are strongly associated with a single screening question for frequent functional jaw disturbances. This finding provides support for incorporating a question on jaw catching/locking once a week or more in screening instruments for TMDs.

Oral behaviors in young adults: a multidimensional evaluation of the influence of personality, coping, and distress

OBJECTIVES

This study explored the relationship of oral parafunction to the psychological variables of personality, coping, and distress. Correlates of sleeping/waking-state oral activities with the different psychological factors were also examined, along with psychological predictors for high parafunction.

MATERIALS AND METHODS

Young adults from a large private university were enrolled. The frequency of oral behaviors was appraised with the oral behavior checklist (OBC), and participants were stratified into low and high parafunction (LP/HP) groups following the DC/TMD. Personality traits, coping styles, and psychological distress were assessed with the Big Five Personality Inventory-10 (BFI-10), brief-COPE Inventory (BCI), and Depression, Anxiety, Stress Scales-21 (DASS-21) correspondingly. Statistical evaluations were performed using the chi-square/Mann-Whitney U tests, Spearman's correlation, and logistic regression analyses (α = 0.05).

RESULTS

Among the 507 participants (mean age 22.2 ± 1.5 years), 84.6% and 15.4% had low and high parafunction respectively. While personality profiles did not vary substantially, the HP group exhibited significantly greater emotion-focused/dysfunctional coping, general distress, depression, anxiety, and stress scores than the LP group. Associations between OBC and the various psychological variables were weak when significant or insignificant. Neuroticism and dysfunctional coping were moderately correlated to general distress, depression, anxiety, and stress (rs = 0.44-0.60/0.45-0.51). Multivariate analyses indicated that high parafunction was predicted by dysfunctional coping style (OR = 2.55) and anxiety (OR = 1.33).

CONCLUSIONS

Dysfunctional coping was the main risk factor for high parafunction, increasing its odds by about 2.5 times.

CLINICAL RELEVANCE

Oral parafunction appears to be a dysfunctional coping response to psychological distress.

Wearables for personalized monitoring of masticatory muscle activity - opportunities, challenges, and the future

Wearable devices are worn on or remain in close proximity of the human body. The use of wearable devices specific to the orofacial region is steadily increasing. Orofacial applications of wearable devices include supplementing diagnosis, tracking treatment progress, monitoring patient compliance, and understanding oral parafunctional behaviours. In this short communication, the role of wearable devices in advancing personalized dental medicine are highlighted with a specific focus on masticatory muscle activity monitoring in naturalistic settings. Additionally, challenges, opportunities, as well as future research areas for successful use of wearable devices for precise, personalized care of muscle disorders are discussed.

Evaluation of prevalence of temporomandibular disorders based on DC / TMD Axis I diagnosis in Turkish population and correlation with Axis II

PURPOSE

The prevalence of DC / TMD diagnosis of individuals with internal derangement of TMJ who want to receive TMD treatment in a tertiary clinic in the Turkish population and comparison of the criteria applied in Axis I and Axis II.

METHODS

This study was carried out on 200 individuals older than 18 years of age who have internal disorder of Temporomandibular Joint (TMJ). Diagnostic Criteria for Temporomandibular Disorders (DC / TMD) Axis I and II were applied.

RESULTS

The female to male ratio of individuals with internal derangement of TMJ in the Turkish population was 3.5. The Pearson correlation coefficient between the internal derangement of the Right TMJ and the internal derangement of the Left TMJ is 0.804 and has a statistically significant relationship (p <0.05).

CONCLUSIONS

For DC / TMD, a more comprehensive study is needed to compare the results found in the Turkish population with other populations.

Investigation of temporomandibular disorders in patients with fibromyalgia syndrome: A case-control study

INTRODUCTION

The aim of this study is to compare the frequency of temporomandibular disorders and to examine the temporomandibular pain and functionality levels between healthy female participants and female patients diagnosed with fibromyalgia.

MATERIALS AND METHODS

Our study included 300 participants. Patients were evaluated according to the Diagnostic Criteria for Temporomandibular Disorders: Assessment Instruments (DC/TMD). While evaluating the patients using DC/TMD, TMD Pain Screener and Symptom questionnaire were used within the scope of Axis I, and Graded Chronic Pain Scale, Jaw Functional Limitation Scale-8 (JFLS-8), Patient Health Questionnaire (PHQ-4) and Oral Behaviors Checklist were applied.

RESULTS

Bruxism, tooth grinding and masseter hypertrophy were found to be significantly higher in fibromyalgia patients compared to healthy volunteers (p<0.001). The pain screener, JFLS-8, PHQ-4 and OBC scores and GCPS levels were found to be increased in the fibromyalgia group compared to healthy individuals (p<0.001). Considering the post-examination diagnoses of the participants, the diagnoses of myalgia (p=0.022) and disc displacement with reduction (p<0.001) were significantly higher than healthy individuals.

CONCLUSIONS

Fibromyalgia is a common pathology, therefore, TMD symptoms, which are more difficult to diagnose and often missed, should be questioned in fibromyalgia patients and should be kept in mind in the management of fibromyalgia patients.

Prevalence of oral behaviours in general dental patients attending a university clinic in Italy

BACKGROUND

Oral behaviors represent a diverse array of habits beyond the physiological behaviors of the stomatognathic system.

OBJECTIVE

To describe the prevalence of different oral behaviors, as reported with the Oral Behavior Checklist (OBC-21), in a convenience sample of patients attending an Italian university clinic for routine dental cares.

METHODS

In this study, charts of adult patients presenting to the dental department of a regional hospital in Trieste, Italy, from January 2018 and January 2019 were reviewed. Patients with complete files were retrieved, and those with orofacial pain complaints were excluded. OBC-21 scores and grades (score of 0 corresponding to no risk, 1-24 to low risk, and higher than 24 to high risk) were analyzed and stratified according to age and sex.

RESULTS

Data from a total of 1424 patients were reported. The overall mean OBC score was 13.3 ± 9.9, with 6.7% no-risk grade, 79.6% low-risk grade, and 13.7% high-risk grade. In general, mean OBC scores decreased with increasing age. Females showed a higher frequency of high-risk grade than males. Most frequent prevalent habits included yawning (73.1%), eating between meals (66.9%) and chewing food on one side only (63.3%). Other behaviors were also highly prevalent, including pressing, touching, or holding teeth together other than while eating (52.7%) and awake clenching (47.5%).

CONCLUSION

A low-risk grade of oral behaviors has been found to be frequent in our sample. Future studies are warranted to confirm these findings in larger, representative general populations and to assess if any of these habits are linked to negative effects on the stomatognathic system.

Predictors of pain reduction following a program of manual therapies for patients with temporomandibular disorders: A prospective observational study

BACKGROUND

Clinical guidelines recommend conservative treatment for the management of temporomandibular disorders (TMD), and manual therapy (MT) is commonly applied to reduce pain and improve function.

OBJECTIVES

To identify predictors of pain reduction and functional improvement following a program of manual therapies (MTP) in patients with TMD and develop a first screening tool that could be used in clinical practice to facilitate decision-making.

DESIGN

A cohort of 102 adults with a diagnosis of TMD were treated with four weekly sessions within a MTP applied to craniomandibular structures. Candidate predictors were demographic variables, general health variables, psychosocial features, TMD characteristics and related clinical tests. A reduction of pain intensity by at least 30% after the MTP was considered a good outcome. Logistic regression was adopted to develop the predictive model and its performance was assessed considering the explained variance, calibration, and discrimination. Internal validation of the prediction models was further evaluated in 500 bootstrapped samples.

RESULTS

Patients experiencing pain intensity greater than 2/10 during mouth opening, positive expectations of outcome following a MTP, pain localized in the craniocervical region, and a low Central Sensitization Inventory score obtained a good outcome following the MTP. Predictive performance of the identified physical and psychological variables was characterized by high explained variance (R2 = 58%) and discrimination (AUC = 89%) after internal validation. A preliminary screening clinical tool was developed and presented as a nomogram.

CONCLUSIONS

The high discrimination of the prediction model revealed promising findings, although these need to be externally validated in future research.

TRIAL REGISTRATION NUMBER

NCT03990662.

Temporomandibular Disorders and Bruxism among Sex Workers-A Cross Sectional Study

Sex workers are a highly underprivileged population which is present all around the world. Sex work is associated with negative social stigma which affects all aspects of the sex workers' lives including healthcare, service providers and police. The stigma may result in increased stress, mental health problems, feelings of isolation and social exclusion. In the present study, 36 sex workers (SW) and 304 subjects from the general population in Israel (GP) were evaluated for the presence of bruxism and Temporomandibular disorders (TMD), with the use of Diagnostic Criteria for Temporomandibular Disorders (DC/TMD- Axis I). When compared to the general population, sex workers presented larger maximal assisted mouth opening and higher prevalence of the following TMD diagnoses: Disc displacement with reduction, Myalgia, Myofascial pain with referral, Arthralgia (left and right) and Headache attributed to TMD. The odds of sex workers suffering from one of these diagnoses were twice to five times higher than those of the general population. The study shows that health problems of sex workers go beyond venereal diseases, HIV and mental disorders which are commonly studied. Oral health, TMD and oral parafunctions are some of the additional health issues that should be addressed and explored in this population.

Comparison between Ecological Momentary Assessment and Questionnaire for Assessing the Frequency of Waking-Time Non-Functional Oral Behaviours

Over the years, several tools have been proposed to measure oral behaviours (OB). Recently, a smartphone-based application for ecological momentary assessment (EMA) has been introduced to collect real-time data on waking-time OB. The aim of this study was to compare the self-reported frequency of OB by means of a standardised questionnaire with that recorded with a smartphone-based application for EMA. A total of 151 participants, recruited from the general population, were invited to fill in the Oral Behaviour Checklist (OBC). Scores for four questions concerning grinding, clenching, tooth contact, and mandible bracing were computed. Afterwards, participants were provided with a smartphone application for prolonged real-time reporting of OB. One-way analysis of variance (ANOVA) and a general linear mixed model (GLMM) were used to compare the responses to each OBC question with the frequencies of the same condition recorded with the EMA. Results showed significant association between OBC responses and the EMA recordings. In particular, increased frequencies of clenching, grinding, and teeth contact were recorded by individuals who provided higher OBC scores. On the other hand, a nonlinear association was observed for “mandible bracing”, pointing out difficulties in the comprehension of this condition.

Headache Because of Problems with Teeth, Mouth, Jaws, or Dentures in Chronic Temporomandibular Disorder Patients: A Case–Control Study

This study aimed to characterize self-reported headaches because of problems with the teeth, mouth, jaws, or dentures (HATMJD) in chronic patients with temporomandibular disorders (TMDs) in order to compare their results with those of TMD patients without such headaches and to investigate the associations of HATMJD with depression, anxiety, physical symptoms, oral behaviors, and sleep quality. We conducted a case–control study on consecutive chronic TMD patients referred to the University Medical Center of Ljubljana, Slovenia. A self-reported HATMJD was extracted from item #12 in the 49-item version of the Oral Health Impact Profile questionnaire. Axis II instruments of the Diagnostic Criteria for TMD (i.e., for screening of depression, anxiety, specific comorbid functional disorders, and oral behaviors) and the Pittsburgh Sleep Quality Index were used in this study. In total, 177 TMD patients (77.4% women; mean age: 36.3 years) participated in this study; 109 (61.6%) patients were classified as TMD patients with HATMJD. TMD patients with at least mild depressive and anxiety symptoms, with at least low somatic symptom severity, and a high number of parafunctional behaviors had more HATMJD. Parafunctional behavior and sleep quality were the most prominent predictive factors of the occurrence of HATMJD. TMD patients with HATMJD have more psychosocial dysfunction, a higher frequency of oral behaviors, and poorer sleep quality than TMD patients without such headaches.

Painful Temporomandibular Disorders, Bruxism and Oral Parafunctions before and during the COVID-19 Pandemic Era: A Sex Comparison among Dental Patients

Aim: To evaluate the effect of the current coronavirus pandemic on the prevalence of bruxism, oral parafunctions and painful Temporo-Mandibular Disorders (TMDs) and to evaluate the influence of the pandemic on both sexes. Methods: This retrospective study included 288 dental patients who underwent complete anamnesis and examination according to the Diagnostic Criteria for TMD. The study evaluated two patient populations according to the date of examination: (a) pre-COVID-19 pandemic era (108 patients); (b) COVID 19 pandemic era, where 180 patients were examined during the pandemic. Results: A significant increase in parafunction activity was found in both men and women (p < 0.001) during the COVID-19 pandemic. Awake bruxism (AB) and sleep bruxism (SB) was more prevalent during the COVID-19 pandemic solely in women (AB-p < 0.001; SB-p = 0.014). Conclusions: Men and women were affected by the ongoing stress due to the COVID-19 pandemic, yet women showed a higher influence as compared to men. The long-term exposure to elevated levels of anxiety and stress may aggravate or trigger stomatognathic detrimental conditions. Dentists should be aware and regularly monitor their patients regarding the possible existence and consequences of bruxism and TMD.

Association of visual display terminal time with prevalence of temporomandibular disorder among Japanese workers

OBJECTIVES

Visual display terminal (VDT) time has been reported to affect the development of temporomandibular disorders (TMDs). However, no study has investigated the association between VDT time at and outside of work with TMDs Adjusting for known TMJ risk factors. This study aimed to investigate whether TMDs were associated with VDT time at and outside of work after adjusting for various working conditions in Japanese workers.

METHODS

This cross-sectional study was based on an internet survey of 3930 workers (2057 men and 1873 women), The TMD Screening Questionnaire (SQ-TMD), occupational factors, VDT time at and outside of work, psychosocial factors, and habits were assessed. We applied logistic regression to estimate the odds ratio (OR) of VDT time on SQ-TMD with adjustment for confounders.

RESULTS

The mean age of the respondents was 43.3 ± 11.7 years, and 778 (19.8%) and 3152 (80.2%) subjects were at high and low TMD-related symptoms (TRS). Logistic regression analysis adjusting for all covariates (Model 2), the prevalence of high TRS was significantly higher among those with VDT time at work of 60-179 min (OR = 1.52, 95% CI 1.18-1.94), 180-359 min (OR = 1.27, 95% CI 1.00-1.62), and more than 360 min (OR = 1.44, 95% CI 1.10-1.88) compared to those with 0-59 min. However, there was no significant difference in the prevalence of high TRS for VDT time outside of work.

CONCLUSION

VDT time at work, but not VDT time outside of work, influences the prevalence of TRS. Since the association between VDT time at work and the prevalence of TRS was found even after adjusting for sociopsychological factors and habits generally associated with TMD, further investigation of other factors is needed.

Are oral overuse behaviours associated with painful temporomandibular disorders? A cross-sectional study in Portuguese university students

BACKGROUND

Many different types of oral overuse behaviours occur frequently in adult populations with painful temporomandibular disorders (TMDs). Less is known regarding these behaviours and their associations with TMDs in university students.

OBJECTIVES

Test the association between frequency of different oral overuse behaviours evaluated by the Oral Behaviour Checklist (OBC) and the severity of painful TMDs.

METHODS

In this cross-sectional study, 1381 students from 19 universities in the Oporto District, Portugal, completed the Research Diagnostic Criteria for TMD (RDC/TMD) Personal History Questionnaire and the OBC, and they received an RDC/TMD clinical examination. The OBC sum score (ranging from 0 to 84 points) was classified as normal (0 ≤ 16 points), low overuse (17 ≤ 24) or high overuse (≥25). Painful TMD subtypes (myalgia, arthralgia or combined) were identified. Associations were tested using multivariable binary logistic regression models (α = .05), adjusted for age and sex, and referencing the normal parafunction group.

RESULTS

University students with high overuse were more likely to have a painful TMD: myalgia (OR = 1.9, 95% CL: 1.3-3.0); arthralgia (OR = 2.2; 95% CL: 1.4-3.4), combined (OR = 5.0; 95% CL: 3.1-8.1). Students with low overuse were more likely to have only the combined painful TMD (OR = 2.4; 95% CL: 1.4-4.0) but not the individual painful disorders. Of the 21 different behaviours, 13 were reported at least 50% of the time.

CONCLUSIONS

In this university student sample, oral overuse behaviours are widespread, and their overall extent exhibited a dose-response relationship with respect to severity of painful TMDs based on pain and chronicity. Only some behaviours were independently associated with painful TMDs, suggesting the value of further OBC instrument development.

Oral behaviours and wake-time masseter activity in patients with masticatory muscle pain

BACKGROUND

Little is known about wake-time masseter activity of patients with masticatory muscle pain in real-life settings.

OBJECTIVES

The aims of this study were (1) to assess wake-time masseter activity of women with masticatory muscle pain (MMP) and compare it with that of pain-free women; and (2) to investigate the association between objectively measured masseter contractions and self-reported oral behaviours.

METHODS

Adult women (N = 27) diagnosed with MMP were age-matched with pain-free women (N = 26). The electromyographic (EMG) activity of the masseter muscle when awake was recorded unilaterally for two consecutive days. The number of contraction episodes and relative contraction time (%) were calculated using cut-off thresholds of 3%, 5% and 10% of maximum voluntary contraction (MVC). Self-reported daytime oral activity was assessed using the Oral Behaviours Checklist (OBC, items 3-21). Data were analysed using univariate tests and mixed-model analyses.

RESULTS

The number of contraction episodes was similar between groups for all detection thresholds, but the relative contraction time at the lower detection thresholds (i.e. 3% MVC and 5% MVC) was significantly longer (1.5-fold) in the MMP than in the pain-free group. The OBC scores were significantly higher in the women with MMP than in controls, but no positive association could be found between EMG variables and OBC scores.

CONCLUSION

Women with MMP engage in low-level masseter muscle contractions, which last longer than those of pain-free controls. There was no relationship between self-reported oral behaviours and masseter activity when awake. These findings support the notion that prolonged low-level clenching when awake may play a role in the pathophysiology of MMP.

Association between waking-state oral behaviours, according to the oral behaviors checklist, and TMD subgroups

OBJECTIVES

To assess the association between waking-state oral behaviours and temporomandibular disorder (TMD) subgroups and to develop new scoring methods for the Oral Behavior Checklist (OBC).

METHODS

Patients with any TMD diagnosis, according to the diagnostic criteria for TMD (DC/TMD), were divided into subgroups: 'Dysfunctional-TMD' (n = 70), only mechanical dysfunction; 'Painful-TMD' (n = 204), only myalgia, arthralgia or both; and 'Painful-Dysfunctional TMD' (n = 95), combined pain and dysfunction. A group of individuals without TMD, 'Non-TMD' (n = 374), was used for testing associations. Participants completed the OBC. An exploratory factor analysis, followed by a confirmatory factor analysis of the OBC responses, identified 2 major factors, named non-functional activities (NFA) and functional activities (FA). Component total scores were computed. Differences among subgroups for OBC-MS (mean score) and NFA and FA factor scores were estimated using one-way ANOVA and Tukey post hoc tests. Significance was set at p < .05.

RESULTS

The OBC-MS in Non-TMD, Painful-TMD and Painful-Dysfunctional TMD subgroups was higher than in the Dysfunctional-TMD subgroup (p ≤ .001). NFA in Painful-TMD and Painful-Dysfunctional TMD subgroups were higher than in the Non-TMD group (p < .05); NFA in the Dysfunctional-TMD subgroup were lower than in the Painful-TMD subgroup (p = .034). In contrast, FA in Painful-TMD, Dysfunctional-TMD and Painful-Dysfunctional TMD subgroups were lower than in the Non-TMD group (p < .0001).

CONCLUSIONS

A new scoring method for the OBC results in item reduction and creation of meaningful subscales for functional and non-functional behaviours, which are differentially associated with painful and dysfunctional TMDs. This may help clinicians to better tailor treatment for the management of subtypes of TMD patients.

Associations among masticatory muscle activity, physical activity and self-reported oral behaviours in adult women

OBJECTIVES

To examine the relationship between masticatory muscle activity (MMA), self-reported oral behaviours (OBs) and overall physical activity (PA) in adult women.

MATERIALS AND METHODS

MMA and PA were assessed by a wearable electromyography (EMG) device and accelerometer respectively, worn over 2 non-consecutive days by 53 women (mean age 27.5 ± 6.4 years). Following the second recording day, self-reported OBs were assessed. MMA was assessed by the number, amplitude and duration of masseter contraction episodes. Masseter muscle EMG outcome measures were number of contraction episodes per hour (CEs/h) and the relative contraction time (RCT%). PA was assessed by time accumulated in moderate to vigorous physical activity (MVPA) and 10-min bouts of MVPA per hour. Data were analysed using mixed model analysis.

RESULTS

MMA in free-living conditions consisted mostly of low-amplitude (<10% maximum voluntary clenching) and short-duration (<10 s) contraction episodes. Masseter CEs/h were not associated with self-reported levels of OB. Masseter CEs/h were positively associated with time accumulated in MVPA (F = 9.9; p = 0.002) and negatively associated with 10-min bouts of MVPA/h (F = 15.8; p <0.001). RCT% was not significantly associated with either.

CONCLUSIONS

Objectively assessed MMA is not associated with self-reported OB in free-moving adult females. Moderate to vigorous exercise and physical inactivity are accompanied with an increase in the number of masseter muscle contractions and thus possibly tooth clenching activity.

CLINICAL RELEVANCE

OB can be influenced by the type and extent of PA. Subjective assessment of MMA by questionnaire and/or interviews may be invalid.

The impact of Covid-19-related distress on general health, oral behaviour, psychosocial features, disability and pain intensity in a cohort of Italian patients with temporomandibular disorders

This study aimed to understand the impact of COVID-19 distress on psychological status, features of central sensitization and facial pain severity in people with temporomandibular disorders (TMDs). In this prospective cohort study, 45 adults (19 chronic, 26 acute/subacute TMD) were recruited prior to the COVID-19 outbreak. Baseline assessment took place before the outbreak while a follow-up was performed immediately after the lockdown period. Multiple variables were investigated including age, gender, perceived life quality, sleep quality, anxiety and depression, coping strategies, central sensitization, pain intensity, pain-related disability and oral behaviour. COVID Stress Scales (CSS) were applied at follow-up to measure the extent of COVID-related distress. CSS were significantly higher in those with chronic TMDs compared to those with acute/subacute TMDs (p<0.05). In people with chronic TMD, the variation in anxiety and depression from baseline to follow-up was significantly correlated with scores on the CSS (r = 0.72; p = 0.002). Variations of the central sensitization inventory (r = 0.57; p = 0.020) and graded chronic pain scale (r = 0.59; p = 0.017) were significantly correlated with scores on the CSS. These initial findings indicate that people with chronic TMD were more susceptible to COVID-19 distress with deterioration of psychological status, worsening features of central sensitization and increased chronic facial pain severity. These findings reinforce the role of stress as a possible amplifier of central sensitization, anxiety, depression, chronic pain and pain-related disability in people with TMDs. Trial Registration: ClinicalTrials.gov ID: NCT03990662.

Effect of electrode characteristics on electromyographic activity of the masseter muscle

OBJECTIVES

The study investigated effects of electrode material, inter-electrode distance (IED), and conductive gel on electromyographic (EMG) activity recorded from the masseter muscle.

MATERIALS AND METHODS

EMG was recorded unilaterally, as ten volunteers performed standardized oral tasks. Ag/AgCl and Ag coated with Au were the gel-based; Ag alloy coated with graphene, pure Ag coated with graphene and silver nanowire embedded electrodes were the gel-free materials tested. Ag/AgCl electrodes were tested at three different IEDs (i.e. 15 mm, 20 mm, 25 mm). An electrode relative performance index (ERPI) was defined and calculated for each of the standardized oral tasks that the volunteers performed. ERPI values obtained for the different oral tasks with different electrode materials and IEDs were compared using two-way repeated-measures ANOVA.

RESULTS

ERPI values were not significantly influenced by IED. However, for the electrode materials statistically significant differences were found in ERPI values for all oral tasks. Of the gel-free electrode materials tested, pure silver electrodes coated with graphene had the highest ERPI values followed by Ag alloy electrodes coated with graphene and silver nanowire embedded electrodes.

CONCLUSIONS

Within the limitations of the study, IED between 15 and 25 mm has a negligible effect on masseter muscle EMG. Graphene coated and silver nanowire embedded electrodes show promise as gel-free alternatives.

Comparison of the pattern of activation of the masticatory muscles among individuals with and without TMD: A systematic review

OBJECTIVE

To verify the characteristics of the electromyographic signal of masticatory muscles in individuals with TMD and asymptomatic individuals.

METHODS

A systematic review was carried out, selecting cross-sectional studies with at least one electromyographic parameter (FM; iEMG; RMS) of the masticatory muscles (anterior temporal, bilateral masseter, and suprahyoid muscles) of individuals with TMD compared to asymptomatic individuals.

RESULTS

This review identified 1656 titles, of which 30 articles were included in the final analysis. It was observed that the data referring to the pattern of activation of masticatory muscles in the rest, isometry, and isotonic conditions of individuals with TMD are heterogeneous. This fact may be related to variability in the methods and analyses applied in the studies.

CONCLUSION

Data referring to the pattern of activation of masticatory muscles in the rest and isometry conditions and in the mastication cycle of individuals with TMD and asymptomatic individuals are diverse.

Placebo hypoalgesia: racial differences

No large-cohort studies that examine potential racial effects on placebo hypoalgesic effects exist. To fill this void, we studied placebo effects in healthy and chronic pain participants self-identified as either African American/black (AA/black) or white. We enrolled 372 study participants, 186 with a diagnosis of temporomandibular disorder (TMD) and 186 race-, sex-, and age-matched healthy participants to participate in a placebo experiment. Using a well-established paradigm of classical conditioning with verbal suggestions, each individual pain sensitivity was measured to calibrate the temperatures for high- and low-pain stimuli in the conditioning protocol. These 2 temperatures were then paired with a red and green screen, respectively, and participants were told that the analgesic intervention would activate during the green screens to reduce pain. Participants then rated the painfulness of each stimulus on a visual analog scale ranging from 0 to 100. Racial influences were tested on conditioning strength, reinforced expectations, and placebo hypoalgesia. We found that white participants reported greater conditioning effects, reinforced relief expectations, and placebo effects when compared with their AA/black counterparts. Racial effects on placebo were observed in TMD, although negligible, short-lasting, and mediated by conditioning strength. Secondary analyses on the effect of experimenter-participant race and sex concordance indicated that same experimenter-participant race induced greater placebo hypoalgesia in TMDs while different sex induced greater placebo hypoalgesia in healthy participants. This is the first and largest study to analyze racial effects on placebo hypoalgesia and has implications for both clinical research and treatment outcomes.

International consensus on the most useful assessments used by physical therapists to evaluate patients with temporomandibular disorders: A Delphi study

OBJECTIVE

To identify assessment tools used to evaluate patients with temporomandibular disorders (TMD) considered to be clinically most useful by a panel of international experts in TMD physical therapy (PT).

METHODS

A Delphi survey method administered to a panel of international experts in TMD PT was conducted over three rounds from October 2017 to June 2018. The initial contact was made by email. Participation was voluntary. An e-survey, according to the Checklist for Reporting Results of Internet E-Surveys (CHERRIES), was posted using SurveyMonkey for each round. Percentages of responses were analysed for each question from each round of the Delphi survey administrations.

RESULTS

Twenty-three experts (completion rate: 23/25) completed all three rounds of the survey for three clinical test categories: 1) questionnaires, 2) pain screening tools and 3) physical examination tests. The following was the consensus-based decision regarding the identification of the clinically most useful assessments. (1) Four of 9 questionnaires were identified: Jaw Functional Limitation (JFL-8), Mandibular Function Impairment Questionnaire (MFIQ), Tampa Scale for Kinesiophobia for Temporomandibular disorders (TSK/TMD) and the neck disability index (NDI). (2) Three of 8 identified pain screening tests: visual analog scale (VAS), numeric pain rating scale (NRS) and pain during mandibular movements. (3) Eight of 18 identified physical examination tests: physiological temporomandibular joint (TMJ) movements, trigger point (TrP) palpation of the masticatory muscles, TrP palpation away from the masticatory system, accessory movements, articular palpation, noise detection during movement, manual screening of the cervical spine and the Neck Flexor Muscle Endurance Test.

CONCLUSION

After three rounds in this Delphi survey, the results of the most used assessment tools by TMD PT experts were established. They proved to be founded on test construct, test psychometric properties (reliability/validity) and expert preference for test clusters. A concordance with the screening tools of the diagnostic criteria of TMD consortium was noted. Findings may be used to guide policymaking purposes and future diagnostic research.

Prior Therapeutic Experiences, Not Expectation Ratings, Predict Placebo Effects: An Experimental Study in Chronic Pain and Healthy Participants

INTRODUCTION

Many clinical trials fail because of placebo responses. Prior therapeutic experiences and patients' expectations may affect the capacity to respond to placebos in chronic disorders.

OBJECTIVE

The scope of this study in 763 chronic orofacial pain and healthy study participants was to compare the magnitude and prevalence of placebo effects and determine the putative role of prior therapeutic experiences vs. expectations.

METHODS

We tested placebo propensity in a laboratory setting by using 2 distinct levels of individually tailored painful stimulations (high pain and low pain) to reinforce expectations and provide a hypoalgesic experience (conditioning phase). Afterwards, both levels of pain were surreptitiously set at a moderate pain level to test for placebo effects (testing phase). Pain and expectation ratings were assessed as primary outcomes using visual analog scales.

RESULTS

In both chronic pain and healthy participants, placebo effects were similar in magnitude, with the larger prevalence of responders in the healthy participants. Although chronic pain participants reported higher pain relief expectations, expectations did not account for the occurrence of placebo effects. Rather, prior experience via conditioning strength mediated placebo effects in both pain and healthy participants.

CONCLUSIONS

These findings indicate that participants with chronic pain conditions display robust placebo effects that are not mediated by expectations but are instead directly linked to prior therapeutic experiences. This confirms the importance of assessing the therapeutic history while raising questions about the utility of expectation ratings. Future research is needed to enhance prediction of responses to placebos, which will ultimately improve clinical trial designs.

Clinical predictors of persistent temporomandibular disorder in people with first-onset temporomandibular disorder: A prospective case-control study

BACKGROUND

When patients first develop a painful temporomandibular disorder (TMD) and seek care, 1 priority for clinicians is to assess prognosis. The authors aimed to develop a predictive model by using biopsychosocial measures from the Diagnostic Criteria for Temporomandibular Disorders (DC-TMD) to predict risk of developing TMD symptom persistence.

METHODS

At baseline, trained examiners identified 260 participants with first-onset TMD classified by using DC-TMD-compliant protocols. After follow-up at least 6 months later, 72 (49%) had examiner-classified TMD (persistent cases), and 75 (51%) no longer had examiner-classified TMD (transient cases). For multivariable logistic regression analysis, the authors used blocks of variables selected using minimum redundancy maximum relevance to construct a model to predict the odds of TMD persistence.

RESULTS

At onset, persistent cases had multiple worse TMD clinical measures and, among Axis II measures, only greater baseline pain intensity (odds ratio [OR], 1.5; 95% confidence interval [CI], 1.04 to 2.2; P = .030) and more physical symptoms (OR, 1.8; 95% CI, 1.2 to 2.9; P = .004) than did transient cases. A multivariable model using TMD clinical measures showed greater discriminative capacity (area under the receiver operating characteristic curve, 0.74; 95% CI, 0.73 to 0.75) than did a model involving psychosocial measures (area under the receiver operating characteristic curve, 0.63; 95% CI, 0.62 to 0.64).

CONCLUSIONS

Clinical measures that clinicians can assess readily when TMD first develops are useful in predicting the risk of developing persistent TMD. Psychosocial measures are important predictors of onset but do not add meaningfully to the predictive capacity of clinical measures.

PRACTICAL IMPLICATIONS

When TMD first develops, clinicians usefully can identify patients at higher risk of developing persistence by using clinical measures that they logically also could use in treatment planning and for monitoring outcomes of intervention.

Are vocalists prone to temporomandibular disorders?

BACKGROUND

As vocalists demand high physical strains of the masticatory system, singing is frequently mentioned as a risk factor for temporomandibular disorders (TMDs).

OBJECTIVES

This study investigated whether vocalists report a higher prevalence of two types of TMDs (viz., TMD pain and temporomandibular joint sounds) compared with instrumentalists who do not load their masticatory system while performing. In addition, we examined which risk indicators are associated with the presence of these TMDs among musicians.

METHODS

A total of 1470 musicians from 50 different music ensembles completed a questionnaire. Of these musicians, 306 were vocalists (mean age ± SD 37.5 ± 17.7 years; 63.9% female) and 209 musicians enrolled the control group (mean age ± SD 42.7 ± 18.0 years; 40.7% female).

RESULTS

The prevalence of self-reported TMD pain among vocalists was 21.9%, as compared to 12.0% in the control group. 20.0% of the vocalists reported TMJ sounds versus 15.1% of the controls. The multiple regression models indicated that being a vocalist was not a risk indicator for the presence of self-reported TMD pain nor for self-reported TMJ sounds. Instead, it appeared that the report of TMD pain among musicians was positively associated with female gender, next to the level of physical workload, depicted as frequency of oral behaviours and the hours of daily practice. Musicians' report of TMJ sounds was associated with oral behaviours.

CONCLUSION

This study shows that singing is not associated with the reports of TMD pain and TMJ sounds, after adjusting for potentially confounding variables included in the models.

Predictors of pain reduction following manual therapy in patients with temporomandibular disorders: a protocol for a prospective observational study

INTRODUCTION

Temporomandibular disorders (TMDs) are principally characterised by pain in the craniomandibular area and probable limitations of jaw opening. Manual therapy, like other recommended conservative treatments included in clinical guidelines, is commonly used to treat patients with TMD to reduce pain and improve function. However, outcomes may be variable. The aim of this study is to identify predictors associated with pain reduction in patients with TMD following manual therapy by analysing a combination of patient-reported outcome measures and clinical tests. Such knowledge will support a more personalised management approach by facilitating clinical decision-making.

METHODS/ANALYSIS

An observational prospective design will recruit a cohort of 100 adults with a diagnosis of TMD (according to Axis I of the Diagnostic Criteria for TMD) at a Dental Hospital in Italy. Patients will be treated with four weekly sessions of manual therapy applied to craniomandibular structures. An array of predictors has been chosen based on previous research on prognostic factors for TMD and altered pain modulation in musculoskeletal disorders. Candidate predictors including demographic variables, general health variables, psychosocial features, TMD characteristics and clinical tests of the temporomandibular joint and masticatory muscles will be collected at baseline. Definition of good outcome is a clinically significant reduction of pain intensity over the last week (≥30% reduction Visual Analogue Scale) immediately following the four week intervention. Exploratory factor analysis will be applied to analyse factor loading of candidate predictors for good outcome at four weeks. Subsequently, a logistic multivariable regression model will be performed to calculate low and high risk of good outcome.

ETHICS AND DISSEMINATION

Ethical approval has been obtained from the 'Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico' and University of Birmingham Ethics Committee. The results will be submitted for publication in a peer-reviewed journal and presented at conferences.

TRIAL REGISTRATION NUMBER

NCT03990662; Pre-results.

Which Treatment Is Effective for Bruxism: Occlusal Splints or Botulinum Toxin?

PURPOSE

The aim of the present study was to compare the efficacy of an occlusal splint and botulinum toxin for the treatment of bruxism.

PATIENTS AND METHODS

Seventy-three patients with myofascial pain due to bruxism were included in the present study. The patients were allocated into 3 groups. Group A was treated with an occlusal splint, group B was treated with botulinum toxin injections, and group C was treated with an occlusal splint and botulinum toxin injections. The Temporomandibular Disorder Pain Screener, Graded Chronic Pain Scale, Oral Behavior Checklist, Jaw Function Limitation Scale, and visual analog scale (VAS) by palpation of the chewing muscles were administered to all patients before treatment and 6 months after treatment.

RESULTS

The questionnaire and VAS scores decreased in all 3 groups (P < .0001). The VAS and questionnaire scores had decreased significantly in groups B and C compared with those in group A (mean VAS score: group A, 5 [range, 3 to 7]; group B, 1.9 ± 0.97; group C, 1.79 [range, 0 to 3]).

CONCLUSIONS

Occlusal splints might not be necessary for patients treated with botulinum toxin injections.

Occlusal sensitivity in individuals with different frequencies of oral parafunction

STATEMENT OF PROBLEM

Oral parafunctional behaviors are characterized by an overuse of the masticatory muscles, thus applying aberrant occlusal force to the teeth for prolonged periods. However, whether increased periodontal receptor activity in individuals with a high degree of oral parafunction alters the occlusal sensitivity is unclear.

PURPOSE

The purpose of this clinical study was to evaluate occlusal sensitivity in adults reporting a high or low frequency of awake oral parafunctional behaviors, as assessed with the short version of the oral behavior checklist (OBC-It 6).

MATERIAL AND METHODS

Self-reporting questionnaires (N=212) were distributed among dental and medical students. Individuals with an OBC-It 6 score below the 20th percentile (low-frequency parafunction (LFP) group: 13 men and 15 women) and above the 80th percentile (high-frequency parafunction [HFP] group: 11 men and 17 women) were selected for the occlusal sensitivity assessment. The occlusal sensitivity was tested with 10 different thicknesses: 9 aluminum foils ranging from 8 μm to 72 μm with a constant increment of 8 μm and 1 sham test without any foil. The testing foils were presented 10 times in random order (100 tests in total). The participants were instructed to close their mouth only once and to report whether they felt the aluminum foil between their teeth. A between-group comparison (HFP versus LFP) was performed for each testing thickness (Student t test for unpaired data, Bonferroni correction) (α=.005).

RESULTS

For the sham test and for the testing thicknesses between 8 μm and 48 μm, no statistically significant differences were found between the 2 groups. The thicknesses 0.56 mm, 0.64 mm, and 0.72 mm were significantly better perceived in the HFP group than in the LFP group (P<.005, P<.001, and P<.001).

CONCLUSIONS

Individuals with a high frequency of self-reported awake oral parafunction presented higher occlusal sensitivity.

Pre-operative parafunctional or dysfunctional oral habits are associated with the temporomandibular disorders after orthognathic surgery: An observational cohort study

BACKGROUND

Temporomandibular disorders (TMDs) are frequent and disabling, and hence, preventing them is an important health issue. Combining orthodontic and surgical treatments for malocclusions has been shown to affect temporomandibular joint (TMJ) health. However, publications regarding the risk factors that predict negative TMJ outcomes after orthognathic surgery are scarce.

OBJECTIVE

Present prospective cohort study was conducted to identify an association between pre-operative dysfunctional/parafunctional oral habits and the presence of TMD symptoms after orthognathic surgery.

METHOD

We included 237 patients undergoing orthodontics and surgical treatment for malocclusions associated with dentofacial deformities within the Department of Oral and Maxillofacial Surgery of the University of Lille. Their parafunctional and dysfunctional oral habits were recorded through clinical examination along with the presence of TMD symptoms before and after the surgery. According to the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) classification, the TMD symptoms studied were myalgia, arthralgia, disc displacement with or without reduction.

RESULTS

Multivariate analysis revealed significant associations among bruxism (odds ratio [OR] 3.17 [1.066; 9.432]), lingual interposition (OR 4.241 [1.351; 13.313]), as well as primary swallowing (OR 3.54 [1.225; 10.234]) and the presence of postoperative symptoms of myalgia. Moreover, a significant association was observed between the presence of any dysfunctional oral habit and postoperative disc displacement with reduction (OR 4.611 [1.249; 17.021]).

CONCLUSION

Bruxism and dysfunctional oral habits were shown to be risk factors for the presence of TMD symptoms also after combined orthodontic and surgical treatment. Treating such habits before orthognathic surgery should help prevent TMD.

Prevalence of temporomandibular disorders and oral parafunctions in adolescents from public schools in Southern Italy

Objective: The aim of this cross-sectional epidemiologic study was to estimate the prevalence of temporomandibular disorders (TMDs) and oral parafunctions in Italian adolescents and to assess the associations between age, gender, oral habits, and TMD. Methods: Three hundred sixty-one adolescents, aged 14-18 years, were examined for TMDs according to the Research Diagnostic Criteria for TMD. Furthermore, oral habits were explored by means of a written questionnaire. Results: Almost one-third of the sample (27.4%) showed at least one TMD diagnosis, with myofascial pain being the most prevalent. Gum chewing was the most prevalent oral habit. The female gender and oral habits were significantly associated with TMD. Conclusion: TMD in adolescents, although lower than in adults, are significantly prevalent. General practitioners should include TMD screening methods in their routine dental examinations of adolescent patients. Adolescents should be instructed on how to avoid incorrect oral behaviors that might predispose them to the onset of TMD.

Experience with bruxism in the everyday oral implantology practice in the Netherlands: a qualitative study

Objective

To explore how bruxism is dealt with by accredited oral implantologists within daily clinical practice.

Materials and methods

Nine semi-structured interviews of oral implantologists practicing in non-academic clinical practices in the Netherlands were performed, and thematic analysis was conducted using a framework-based approach.

Results

Oral implant treatments in bruxing patients were a generally well-accepted practice. Complications were often expected, with most being of minor impact. Contradictive attitudes emerged on the topic of bruxism being an etiologic factor for peri-implant bone loss and loss of osseointegration. Views on the ideal treatment plan varied, though the importance of the superstructure’s occlusion and articulation features was repeatedly pointed at. Similarly, views on protective splints varied, regarding their necessity and material choice. Bruxism was diagnosed mainly by clinical examination, alongside with patient anamnesis and clinician’s intuition. There was little attention for awake bruxism.

Discussion

Bruxism was generally not considered a contraindication for implantological treatments by accredited oral implantologists. Views on the interaction between bruxism and bone loss/loss of osseointegration varied, as did views on the ideal treatment plan.

Conclusions

There is a need for better understanding of the extent to which, and under which circumstances, sleep and/or awake bruxism can be seen as causal factors for the occurrence of oral implant complications.

Effects of trait anxiety, somatosensory amplification, and facial pain on self-reported oral behaviors

OBJECTIVES

Oral behaviors are activities, like gum chewing, teeth clenching, and biting of objects, that go beyond normal functioning demands and contribute to the onset of temporomandibular disorders (TMD). Somatosensory amplification refers to the tendency to experience somatic sensations as intense, noxious, and disturbing and is related to bodily hypervigilance. Clinical experience suggests that individuals with bodily hypervigilance also present with occlusal hypervigilance and continuously check their occlusion. This study aimed at investigating whether somatosensory amplification and trait anxiety, a characteristic correlated with hypervigilance, are associated with a greater incidence of oral behaviors, and verifying how self-reported facial TMD pain affect this relationship.

MATERIALS AND METHODS

The State-Trait Anxiety Inventory, the Somatosensory Amplification Scale, the Oral Behavior Checklist (OBC), and the TMD-Pain Screener Questionnaire were filled out by 255 University students with self-reported facial TMD pain (PAIN group; 47 subjects, 24.8 ± 4.2 years) and without pain (CTR group; 208 subjects, 26.0 ± 4.8 years) using a web survey.

RESULTS

Trait anxiety, somatosensory amplification, and OBC scores were greater in the PAIN than CTR group (all p < 0.05). Trait anxiety and somatosensory amplification were positively associated with the frequency of oral behaviors, as measured with the OBC (all p < 0.05). A significant effect of the interaction study group*trait anxiety (p = 0.028) on OBC scores was found.

CONCLUSIONS

Individuals with greater trait anxiety and somatosensory amplification report more frequent oral behaviors. The relationship between anxiety and oral behaviors is affected by concurrent facial pain.

CLINICAL RELEVANCE

Individuals with increased trait anxiety and concurrent facial pain report more frequent oral behaviors than those without pain. Clinicians should evaluate patients' anxiety and somatosensory amplification before starting dental treatment.

A high prevalence of TMD is related to somatic awareness and pain intensity among healthy dental students

OBJECTIVE

Dental students have been identified as a group with high risks of developing both temporomandibular disorders (TMD) and psychosocial conditions. Our primary aim was to evaluate the cross-sectional prevalence of TMD diagnoses, as defined in the Diagnostic Criteria (DC)/TMD, among dental students. The secondary aim was to evaluate the prevalence and association of behavioural and psychosocial factors in relation to DC/TMD diagnoses.

MATERIALS AND METHODS

The study was conducted among undergraduate dental students during the second semester of their third year at the Department of Odontology, Medical Faculty, Umeå University, Sweden. Three consecutive cohorts were recruited during August in 2013, 2014, 2015. In total, 54 students were included and examined according the DC/TMD procedure.

RESULTS AND CONCLUSIONS

The prevalence of any DC/TMD diagnosis was 30%. The most prevalent TMD diagnosis was myalgia. Individuals with a TMD-pain diagnosis (i.e. myalgia or arthralgia) reported significantly higher pain intensity levels according to the Graded Chronic Pain Scale (GCPS) as compared to individuals without TMD-pain (Fisher's exact test p < .001, two-sided). In addition, individuals with any TMD scored significantly higher jaw functional limitations according to the Jaw Functional Limitation Scale 20 (JFLS-20, p < .001) and oral parafunctions according to the Oral Behavior Checklist (OBC, p = .005) as compared to individuals without TMD. The psychosocial factors evaluated did not differ between individual with or without a TMD diagnosis. The majority of the dental students reported symptoms that are already identified as risk factors for developing TMD and pain conditions. However, longitudinal data are needed to evaluate how this evolves over time.

The Role of Stress in the Etiology of Oral Parafunction and Myofascial Pain

Oral parafunction during waking comprises possible behaviors that can be measured with a comprehensive checklist or behavioral monitoring. Multiple studies lead to largely consistent findings: stressful states can trigger parafunctional episodes that contribute to myofascial pain. However, this simple causal pathway coexists with at least 3 other pathways: anxiety and stress are potent direct contributors to pain, pain results in maladaptive behaviors such as parafunction, and parafunction may be a coping response to potential threat coupled with hypervigilance and somatosensory amplification. Awake parafunction remains an important risk factor for myofascial pain onset and overuse models alone of causation are insufficient.

Oral Behaviors and Parafunctions: Comparison of Temporomandibular Dysfunction Patients and Controls

The aim of this study is to evaluate the frequency of oral behaviors in patients with temporomandibular disorders (TMD) and a control group without TMD.In this baseline case-control study, 260 controls and 260 subjects with TMD completed the oral behaviors checklist defined as a "self-report scale for identifying and quantifying the frequency of jaw overuse behavior" and underwent clinical examinations using the DC/TMJ international examination form (version May 12, 2013). Relationships of oral parafunctions' frequencies between groups were examined. The statistical analysis was performed with IBM SPSS Statistics 23 software.Age and gender distribution in the study groups did not reveal statistical differences (P > 0.05). Multivariate logistic regression analysis was conducted to establish system of independent oral behaviors for prognosis TMD. The stepwise regression analysis demonstrated that very frequent expression of holding, tightening, or tense muscles is associated with 10.83 times (P < 0.05) higher risk of TMD, grinding teeth together during waking hours with 4.94 times (P < 0.05) higher risk, and sustained talking with 2.64 times (P < 0.05) higher risk of TMD. By contrast, it was determined that 3 oral behaviors were less common in the TMD patients compared with the control group: clenching teeth together during waking hours, facing grimaces, and yawning (P < 0.05). The individuals with TMD reported a significantly higher frequency of 10 behaviors (P < 0.05), 3 of which may be regarded as independent risk factors for TMD. In addition, 3 oral behaviors were more frequently observed in the healthy subjects than in the TMD patients.

Benefits of implementing pain-related disability and psychological assessment in dental practice for patients with temporomandibular pain and other oral health conditions

BACKGROUND

Evidence in the field of dentistry has demonstrated the importance of pain-related disability and psychological assessment in the development of chronic symptoms. The Diagnostic Criteria for Temporomandibular Disorders offer a brief assessment for the diagnostic process in patients with orofacial pain (Axis II). The authors describe relevant outcomes that may guide general oral health care practitioners toward tailored treatment decisions and improved treatment outcomes and provide recommendations for the primary care setting.

METHODS

The authors conducted a review of the literature to provide an overview of knowledge about Axis II assessment relevant for the general oral health care practitioner.

RESULTS

The authors propose 3 domains of the Axis II assessment to be used in general oral health care: pain location (pain drawing), pain intensity and related disability (Graded Chronic Pain Scale [GCPS]), and psychological distress (Patient Health Questionnaire-4 [PHQ-4]). In the case of localized pain, low GCPS scores (0-II), and low PHQ-4 scores (0-5), patients preferably receive treatment in primary care. In the case of widespread pain, high GCPS scores (III-IV), and high PHQ-4 scores (6-12), the authors recommend referral to a multidisciplinary team, especially for patients with temporomandibular disorder (TMD) pain.

CONCLUSIONS

The authors recommend psychological assessment at first intake of a new adult patient or for patients with persistent TMD pain. The authors recommend the pain-related disability screening tools for all TMD pain symptoms and for dental pain symptoms that persist beyond the normal healing period.

PRACTICAL IMPLICATIONS

A brief psychological and pain-related disability assessment for patients in primary care may help the general oral health care practitioner make tailored treatment decisions.