Dentists with expertise in sleep medicine play a growing role in screening patients for sleep disorders, particularly sleep-disordered breathing (SDB) and insomnia, while concurrently evaluating and managing sleep bruxism (SB). Once SB is identified, dentists typically focus on mitigating oral complications, like as tooth wear, managing grinding sounds, and addressing associated orofacial pain. In contrast, SB may often be encountered by sleep physicians as an incidental finding during sleep recording performed for the evaluation of other sleep disorders, including SDB, insomnia, periodic limb movement disorder, and REM sleep behavior disorder (RBD). The International Classification of Sleep Disorders, Third Edition - Text Revision (ICSD-3-TR), published in 2023 by the American Academy of Sleep Medicine (AASM), provides a standardized framework for the identification and classification of sleep disorders in medical settings. While this classification reflects international consensus among clinician-scientists in sleep medicine, its adaptation to dental clinical and research contexts remains complex. This paper aims to support clinicians and researchers across disciplines in a consistent interpretation and application of the ICSD-3-TR criteria for SB. We highlight key definitional changes in the revised criteria, examine diagnostic challenges arising from the inclusion of ambiguous signs and symptoms, and discuss conceptual divergences between dental and medical approaches to SB, especially regarding the distinction between SB as a jaw motor behavior or a sleep-related movement disorder. A shared understanding of ICSD-3-TR terminology and limitations is essential to promote interdisciplinary collaborations and to optimize the management of SB, both as an isolated (jaw) motor phenomenon and when it co-occurs with other sleep disorders.

OBJECTIVES: To establish a quantitative method for objectively assessing 3-dimensional (3D) mandibular trajectories and comparing clinical evaluations with computational analyses.

METHODS: In total, 184 volunteers were recruited and grouped into control (n = 121) and temporomandibular disorder (TMD) groups (n = 63) according to the dual-axis DC/TMD checklist. 3D trajectories were generated by integrating mandibular motion and cone beam computed tomography (CBCT) records. Via digitalized data processing, the following 3 outcomes were assessed: (1) smoothness using the best-fitting polynomial curve, (2) open-closure separation by measuring the deviation between open-closure phases, and (3) condylar trajectory symmetry by comparing left and right movements. Intraclass Correlation Coefficients (ICC) were used to determine agreement between expert observations and quantitative results. Reference ranges for each parameter from the normal population were calculated. Mann‒Whitney test was used to analyze the features of the trajectories between the two groups.

RESULTS: ICC confirmed strong consistency between the parametric variations and expert observations (smoothness: 0.797; open-closure separation: 0.820; left-right symmetry: 0.920). Quantitative analyses revealed significant differences (P<0.043 for smoothness, P<0.01 for separation, and P=0.012 for symmetry) in all comparisons between movement trajectories of normal participants and those with TMD, with the latter group exhibiting greater variation and irregularities. The normal range of smoothness was calculated for condylar trajectories between 0-0.25 and 0-0.10 for incisal point trajectories. Open-closure separation normal range was computed between 0-2.28 mm for incisal point trajectory, 0-1.90 mm for left condylar trajectory, and 0-1.76 mm for right condylar trajectory. The normal range of symmetry between condylar trajectories was calculated to be between 0-4.21 mm.

CONCLUSIONS: This quantitative analysis was confirmed to be reliable and consistent with expert observations. This allowed for the discovery of substantially quantified differences in smoothness, open-closure separation, and symmetry of the motion trajectories in TMD patients versus controls.

AIM: To evaluate conditioned pain modulation (CPM) in burning mouth syndrome (BMS) patients with different pain mechanisms.

MATERIALS AND METHODS: Twenty BMS patients (52.0 ± 6.8 years, 17 women and 3 men) and age- and gender-matched 22 healthy controls were enrolled in this randomised controlled trial. The patients received an active lingual nerve block (lidocaine) and a placebo injection (saline) randomly with an interval of 1 week in a double-blinded manner. Patients evaluated their pain intensity on a 0- to 10-cm visual analogue scale (VAS) before and after each injection, with or without CPM. Based on the anaesthesia effect, BMS patients were divided into two groups with presumed different pain mechanisms; a 'central subgroup (n = 11)' with pain relief less than 1 cm and 'peripheral subgroup (n = 9)' with pain relief more than 1 cm on the VAS. Mechanical pain threshold (MPT) and wind-up ratio (WUR) were investigated at two oral mucosa regions: the region with most intense symptoms and a control region for the patient group; tongue and buccal region for the control group. CPM was induced by immersing the left hand into cold water. A moderate level of pain (around five on the VAS) was obtained by adjusting the water temperature. MPT and WUR were measured twice for all the participants with and without CPM, which was analysed and presented as relative change in MPT and WUR. Differences between groups were analysed using two-way ANOVA. Differences within group between tests were assessed by paired t-test.

RESULTS: At baseline, there were no significant group differences for MPT or WUR between BMS patients and healthy controls (p ≥ 0.156). The mean bath temperature to evoke moderate pain for the BMS group was significantly lower than that for the healthy control group (8.9°C vs. 11.9°C, p = 0.003). The CPM evoked an inhibitory modulation in 18.2%-44.4% of BMS patients, while for the healthy group, the ratio was 68.2%-81.8%. Central BMS patients had smaller CPM effects than healthy participants at the painful site and control site, which indicated a decreased CPM function (p ≤ 0.034). Peripheral BMS patients had lower CPM effects than healthy participants only at the painful site (p = 0.037).

CONCLUSIONS: The present findings documented impairment of central nociceptive inhibition processing in BMS patients which was more extensive in central BMS than peripheral BMS. These findings add to the suggestion that BMS may a heterogeneous pain condition with at least two different phenotypes.

AIMS: To investigate the effect of a lingual nerve block on spontaneous pain in patients with burning mouth syndrome (BMS) and to estimate associated somatosensory abnormalities by quantitative sensory testing (QST).

PROTOCOL AND METHODS: A standardised QST battery including cold detection threshold (CDT), warmth detection threshold (WDT), thermal sensory limen (TSL), paradoxical heat sensation (PHS), cold pain threshold (CPT), heat pain threshold (HPT), mechanical pain threshold (MPT), wind-up ratio (WUR) and pressure pain threshold (PPT) was performed at the oral mucosa of the most painful site and intraoral control site in 20 BMS patients, and at the tongue and cheek mucosa in 22 age- and gender-matched healthy controls. The effect of a lingual nerve block on spontaneous burning pain reported by the BMS patients on a 0-10 cm visual analogue scale (VAS) was investigated in a randomised double-blind crossover design using (1 mL) lidocaine (lido) or saline (sal) with an interval of 1 week. The BMS patients were grouped into 'central' and 'peripheral' mechanisms based on the effect of the lingual nerve injections. For each BMS patient, Z-scores and Loss/Gain scores were computed. Differences among groups and sites were analysed using a two-way ANOVA. Differences within group were assessed by paired t-test.

RESULTS: The 20 BMS patients were characterised on the basis of VAS changes (ΔLido-ΔSal) as a peripheral BMS subgroup (n = 9) with pain relief more than 1 cm on the VAS and a central BMS subgroup (n = 11) with pain relief less than 1 cm. BMS patients (n = 20) had lower sensitivity to thermal stimuli (i.e., CDT, WDT, TSL, CPT, HPT and PPT) and higher sensitivity to mechanical stimuli (i.e., PPT) compared with controls (p ≤ 0.007). Based on Loss/Gain coding, L1G0 (loss of thermal somatosensory function with no somatosensory gain, 55.0%) was the most frequent coding in the BMS group, which was higher than 11.4% in the control group (p < 0.001). Surprisingly, there was no significant difference between the peripheral and central BMS subgroups with regard to the Z-scores of any of the nine QST parameters (p > 0.097).

CONCLUSIONS: The results of the lingual nerve blocks demonstrated two distinct phenotypes with either peripheral or central mechanisms but no direct impact on somatosensory function. Overall, somatosensory function in BMS patients seems abnormal in the painful areas compared to matched controls with a conspicuous loss of thermosensory function.

While muscle overload is commonly implicated in musculoskeletal pain conditions, real-time assessment of associated behavioural and physiological features is challenging. This study aims to investigate the relationship between self-reported awake bruxism using Ecological Momentary Assessment (EMA) and jaw muscle activity registered by surface electromyography (sEMG), and differences between individuals with and without temporomandibular disorder (TMD) pain. Seventy participants (38 women, 32 men), of which 31% reported pain, completed 3-day EMA using a smartphone application combined with a sEMG device only for day 1. Overload, defined as muscle activity exceeding 20% of maximum voluntary contraction (MVC), was evaluated for duration and area under curve (AUC). A strong correlation was observed between EMA-reported bruxism and sEMG overload duration (ρ = 0.62, p < 0.001). AUC showed a correlation with EMA only in the TMD group. Participants with TMD pain exhibited shorter high-intensity bursts (60-79% MVC, p ≤ 0.005) but prolonged low-intensity muscle activity (20-39% MVC, p < 0.001). Bruxism behaviour and stress levels were higher in women and in individuals with pain. The results suggest that combining EMA and sEMG provides valid assessment of musculoskeletal overload, capturing both perceptual and physiological dimensions. Incorporating EMA in pain management can identify pain-related risk behaviours, thus supporting tailored patient-centred interventions.

INTRODUCTION: This study evaluated differences in intraoral sensitivity to thermal and mechanical stimuli, and pulp sensibility between patients with myofascial orofacial pain (MOP) and healthy controls. We hypothesized that patients would exhibit increased sensitivity to these stimuli.

METHODS: A controlled study was performed, including 50 MOP patients and 104 controls aged 18-65. Intraoral and extraoral sensitivities were assessed at various sites using simple quantitative sensory testing (sQST, numerical ratings of thermal/mechanical stimuli) and qualitative somatosensory testing (QualST, side-to-side differences in sensitivity to touch, cold and pinprick as hyper-, hypo- or normal). Pulp sensibility was evaluated using cold stimuli. Statistical analyses included repeated-measures ANOVA and Fisher's exact test (α= 0.05).

RESULTS: Patients exhibited significantly higher intraoral hypersensitivity at the buccal gingiva to touch (14%), cold (34%), and pinprick stimuli (36%) compared to controls (0%, 14%, 15%). Similar trends were observed at extraoral sites including the masseter, temporalis, and thenar region. Pulp testing revealed significantly longer pain durations in patients (mean: 5.9 seconds) compared to controls (mean: 3.7 seconds), although pain intensity did not differ significantly. While sQST showed no significant group differences, QualST effectively identified intraoral and extraoral somatosensory abnormalities.

CONCLUSIONS: Patients with MOP exhibited heightened intraoral sensitivity and prolonged pain responses. These findings underscore the diagnostic challenge of distinguishing sensitivity associated with MOP from odontogenic pain, such as pulpitis, which may lead to unnecessary dental procedures. Thorough assessments may help clinicians avoid misdiagnosis and improve outcomes, while longitudinal studies are needed to assess the possibility of clinical consequences.

Background/AimPersistent idiopathic facial pain (PIFP) is a rare condition with a lifetime prevalence of approximately 0.03%. It is characterized by persistent daily facial pain without identifiable cause and presents diagnostic and therapeutic challenges due to unknown pathophysiology, symptom overlap with other painful disorders, and limited evidence-based treatments. The aim of this Delphi study was to establish international consensus-derived guidelines for the management of patients with PIFP.MethodsA three-round Delphi study was conducted with 16 international pain experts, each with ≥10 years of clinical experience in pain management and extensive peer-reviewed publications. The first round involved open-ended questions, and the qualitative data were analyzed using systematic text condensation, resulting in a quantitative questionnaire with 42 statements. Subsequent rounds employed Likert-scale responses to these statements. Consensus was defined as ≥80% agreement or disagreement. In addition, if 11-12 (68-75 percent) out of the 16 experts agreed or disagreed, consensus was not reached, but a majority was considered to have a particular opinion.ResultsConsensus was reached in 35 out of the 42 statements (83%), emphasizing multidisciplinary collaboration and avoidance of invasive procedures in the treatment of PIFP. In an additional three statements (7%) a majority of the experts agreed with each other. In four statements (10%), no consensus or majority was reached. Pharmacological treatments, including tricyclic antidepressants, serotonin-norepinephrine reuptake inhibitors, and gabapentinoids, may be considered; however, opioids should generally be avoided in the treatment of PIFP. Patient education and behavioral therapies are important interventions, and the most important measure of therapeutic success is improved quality of lifeConclusionThe present Delphi study has established internationally derived consensus guidelines and recommendations for the evaluation and comprehensive management of patients with PIFP. This is a first step in gathering knowledge for future evidence-based guidelines and more specific treatment recommendations. These international expert consensus guidelines recommend a multi- or interdisciplinary approach in managing PIFP, avoiding invasive interventions and prioritizing patient-centered outcomes.

Occlusal tactile acuity (OTA) and bite force are essential components of the sensorimotor control of oral behaviors. While these variables have been studied independently, it has not yet been revealed whethercompressive force impacts the occlusal perception mediated by the mechanoreceptive afferents in the periodontal ligament. The present study examined the effect of repetition and maximum bite force on OTA by testingnine aluminum foils of different thicknesses together with a sham test with no foil, three times each, in randomized order in 36 healthy individuals. In addition, the 40 μm foil was tested three more times at the start ofeach session to evaluate possible short-term effects. This test session was repeated with and without an interspersed maximum bite force task in between. The results demonstrated that repeated measurements increasedOTA significantly (p = 0.033); a change mainly driven by the 40 μm thickness, whereas maximum bite force testsdid not affect OTA (p = 0.097). Collectively, the results suggest that the enhanced OTA may be attributed torepetition-mediated learning and neuroplasticity within the pathways related to OTA. Furthermore, thecompressive bite force may have induced a short-term change that lasted seconds and was not detected by thesubsequent OTA measurements or may have altogether inhibited the facilitatory effect of repeated OTA. Thisunderscores the potential for future research to explore the implications of compressive force and pain on OTA inpatient populations, which could provide valuable insights into the adaptive mechanisms of the sensorimotorsystem in pathological conditions.

The aim of this long-term follow-up study was to investigate the relationship between bite force, bruxism, and fractures of teeth and veneer porcelain of fixed dental prostheses. Patients previously assessed as probable bruxers (n = 30) and non-bruxers (n = 21), all rehabilitated with dental implant-supported restorations, underwent a clinical examination and measurement of maximum bite force. A univariate general linear model was used to compare regression lines showing the relationship between fractures and bite force. Bruxers had significantly higher maximum bite force (p = 0.023) and higher proportion of tooth/veneer porcelain fractures per total number of tooth/prosthetic units (p = 0.045). There was no significant difference in the relationship between frequency of tooth/veneer porcelain fractures and maximum bite force between probable bruxers and non-bruxers (p = 0.054). However, there was a significant difference between probable bruxers and non-bruxers when the percentage of fractures in relation to the total number of units was considered instead of the frequency of fractures (p = 0.035). Higher maximum bite force in probable bruxers was related to higher prevalence of fractures of teeth and veneer porcelain, emphasizing the potential benefits of pre-treatment assessment of bruxism as well as bite force. Easy-to-use reliable clinical methods for bite force measurement should be tested and implemented in dental practice.

Background: Bruxism is receiving increasing attention from both clinicians and researchers over the past decades. Recently, it has become clear that some aspects of the currently proposed, expert-driven bruxism definitions raise questions and cause confusion among clinicians, researchers, educators and patients. Objectives: The aim of this report is threefold: (1) to provide the reader with a glossary of the existing definitions, (2) to discuss frequently asked questions regarding these definitions and (3) to suggest a road map for the next steps to be taken towards a better understanding of bruxism. Material and Methods: A closed (invitation-only) full-day workshop at the 2024 General Session & Exhibition of the International Association for Dental, Oral and Craniofacial Research (IADR) convened international bruxism experts to discuss the current definitions. Insights from these discussions were compiled, analysed and summarised. Result: The present report provides a glossary of the constituent terms of the currently proposed definitions, an overview of the frequently asked questions and insights into the next steps to be taken. By current consensus and to avoid any further confusion, the addendum ‘in otherwise healthy individuals’ has been removed from the specific definitions of sleep and awake bruxism. In addition, the grading system's hierarchical organisation, as proposed previously, was revised and clarified, proposing the inclusion of terms based on self-reporting, clinical examination and device-based assessment tools. Conclusion: To ascertain that we all use the same terminology, we recommend using the current publication when referring to the definitions of bruxism and its constituent terms.