Effect of clinical experience and training with visual feedback on standardized palpation outcomes-Potential implications for assessment of jaw muscle sensitivity.

BACKGROUND: The evaluation of muscle pain and sensitivity by manual palpation is an important part of the clinical examination in patients with myalgia. However, the effects of clinical experience and visual feedback on palpation of the masticatory muscles with or without a palpometer are not known. OBJECTIVE: To estimate the effects of clinical experience and visual feedback on the accuracy of palpation in standardized settings. METHODS: Thirty-two dentists (age 35 ± 11 years) classified as either specialists (n = 16) or generalists (n = 16) participated in this experiment. All dentists were instructed to target force levels of 500- or 1000-gf, as determined on an electronic scale using either standardized palpometers or manual palpation (MP). All dentists participated in four different tests: MP, MP with visual feedback (MPVF), palpometer (PAL) and PAL with visual feedback (PALVF). Actual force values for each type of palpation from 0 to 2, 2 to 5 and 0 to 5 s were analysed by calculating target force level. RESULTS: The relative differences during 2-5 and 0-5 s with 1000 gf were significantly lower for generalists than for specialists (p < .05). In generalists and specialists, the coefficients of variation and the relative differences during 2-5 s were significantly lower for PAL and PALVF than for MP (p < .05). CONCLUSIONS: These findings suggest that the use of a palpometer, but not clinical experience with palpation of masticatory muscles, increases the accuracy of palpation, and ≥2 s of palpation with a palpometer is optimal for masticatory muscles.

Diagnostic criteria for temporomandibular disorders-INfORM recommendations: Comprehensive and short-form adaptations for children.

BACKGROUND: The Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) are used worldwide in adults. Until now, no adaptation for use in children has been proposed. OBJECTIVE: The aim of this study was to present comprehensive and short-form adaptations of Axis I and Axis II of the DC/TMD for adults that are appropriate for use with children in clinical and research settings. METHODS: Global Delphi studies with experts in TMDs and in pain psychology identified ways of adapting the DC/TMD for children. RESULTS: The proposed adaptation is suitable for children aged 6-9 years. Proposed changes in Axis I include (i) adapting the language of the Demographics and the Symptom Questionnaires to be developmentally appropriate for children, (ii) adding a general health questionnaire for children and one for their parents, (iii) replacing the TMD Pain Screener with the 3Q/TMD questionnaire and (iv) modifying the clinical examination protocol. Proposed changes in Axis II include (i) for the Graded Chronic Pain Scale, to be developmentally appropriate for children, (ii) adding anxiety and depression assessments that have been validated in children and (iii) adding three constructs (stress, catastrophising and sleep disorders) to assess psychosocial functioning in children. CONCLUSION: The recommended DC/TMD, including Axis I and Axis II, for children aged 6-9 years, is appropriate for use in clinical and research settings. This adapted the first version for children includes changes in Axis I and Axis II changes requiring reliability and validity testing in international settings. Official translations to different languages according to INfORM requirements will enable a worldwide dissemination and implementation.

Diagnostic criteria for temporomandibular disorders-INfORM recommendations: Comprehensive and short-form adaptations for adolescents.

BACKGROUND: The Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) for use in adults is in use worldwide. Until now, no version of this instrument for use in adolescents has been proposed. OBJECTIVE: To present comprehensive and short-form adaptations of the adult version of DC/TMD that are appropriate for use with adolescents in clinical and research settings. METHODS: International experts in TMDs and experts in pain psychology participated in a Delphi process to identify ways of adapting the DC/TMD protocol for physical and psychosocial assessment of adolescents. RESULTS: The proposed adaptation defines adolescence as ages 10-19 years. Changes in the physical diagnosis (Axis I) include (i) adapting the language of the Demographics and the Symptom Questionnaires to be developmentally appropriate for adolescents, (ii) adding two general health questionnaires, one for the adolescent patient and one for their caregivers and (iii) replacing the TMD Pain Screener with the 3Q/TMD questionnaire. Changes in the psychosocial assessment (Axis II) include (i) adapting the language of the Graded Chronic Pain Scale to be developmentally appropriate for adolescents, (ii) adding anxiety and depression assessment that have been validated for adolescents and (iii) adding three constructs (stress, catastrophizing and sleep disorders) to assess psychosocial functioning in adolescents. CONCLUSION: The recommended DC/TMD, including Axis I and Axis II for adolescents, is appropriate to use in clinical and research settings. This adapted first version for adolescents includes changes in Axis I and Axis II requiring reliability and validity testing in international settings. Official translations of the comprehensive and short-form to different languages according to INfORM requirements will enable a worldwide dissemination and implementation.

Standardized palpation of the temporalis muscle evoke referred pain and sensations in individuals without TMD.

OBJECTIVES: This study aimed to determine if standardized palpations of the temporalis muscle evoke referred pain and/or sensations in individuals without TMD. MATERIALS AND METHODS: This was a randomized, single-blinded study. The mechanical sensitivity of the right temporalis muscle was assessed in 32 participants without TMD with nine different stimulations to 15 test sites using palpometers (different stimulus intensities (0.5, 1.0, and 2.0 kg) and durations (2, 5, and 10 s). After each stimulus, participants were asked to score perceived pain intensity and intensity of unpleasantness on a 0-100 numeric rating scale as an indicator of mechanical sensitivity in the temporalis muscle and to indicate any areas of referred pain/sensations on a body chart. RESULTS: Pain intensity significantly differed between palpation durations, intensities, and test sites (P < 0.001). In contrast, unpleasantness significantly differed between palparation duration and intensities (P < 0.001), but not test sites. Participants more frequently reported referred pain/sensations evoked by the 10-s (34.4%) as opposed to the 2-s (6.3%) and 5-s (15.6%) palpation duration at the 2.0-kg stimulus intensity (P < 0.05). CONCLUSIONS: Our present results indicate that referred pain/sensations in the orofacial region can be evoked by standardized palpation of the temporalis muscle and influenced by the palpation duration in individuals without TMD. CLINICAL RELEVANCE: Referred pain/sensations from the temporalis muscle were duration- and intensity-dependent processes originating from local stimuli.

Diagnostic criteria for temporomandibular disorders in children and adolescents: An international Delphi study-Part 2-Development of Axis II.

BACKGROUND: Unlike the psychosocial assessment established for adults in the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD), a standardised psychosocial assessment for children and adolescents with TMD complaints has not yet been established. OBJECTIVES: To develop a new standardised instrument set to assess the psychosocial functioning in children and adolescents by adapting the psychosocial status and pain-related disability (Axis II) of the adult DC/TMD and by including new instruments. METHODS: A modified Delphi method was used to survey 23 international TMD experts and four international experts in pain-related psychological factors for consensus regarding assessment tools for psychosocial functioning and pain-related disability in children and adolescents. The TMD experts reviewed 29 Axis II statements at round 1, 13 at round 2 and 2 at round 3. Agreement was set at 80% for first-round consensus level and 70% for each of the second and third rounds. The psychological experts completed a complementary Delphi survey to reach a consensus on tools to use to assess more complex psychological domains in children and adolescents. For the psychological experts, the first round included 10 open-ended questions on preferred screening tools for depression, anxiety, catastrophising, sleep problems and stress in children (ages 6-9 years old) and adolescents (ages 10-19 years old) as well as on other domains suggested for investigation. In the second round, the psychological experts received a 9-item questionnaire to prioritise the suggested instruments from most to least recommended. RESULTS: The TMD experts, after three Delphi rounds, reached consensus on the changes of DC/TMD to create a form to evaluate Axis II in children and adolescents with TMD complaints. The psychological experts added tools to assess depression and anxiety, sleep disorders, catastrophising, stress and resilience. CONCLUSION: Through international expert consensus, this study adapted Axis II of the adult DC/TMD to assess psychosocial functioning and pain-related disability in children and adolescents. The adapted Axis II protocols will be validated in the target populations.

Comparison of 0.5% chlorhexidine gluconate alcohol with 10% povidone-iodine for skin disinfection in children to prevent blood culture contamination.

INTRODUCTION: Various disinfectants, such as povidone iodine (PVI)1, alcohol preparations, and chlorhexidine gluconate ethanol (CHG-ALC), are used for disinfection prior to blood sampling for culture. METHODS: This retrospective cohort study compared the usefulness and effectiveness of CHG-ALC and PVI in pediatric venipuncture. We applied 0.5% w/v CHG-ALC or 10% PVI as an antiseptic for phlebotomies on pediatric outpatients and inpatients with suspected bacterial infection between November 2017 and April 2019. We conducted logistic regression analysis to define the differences associated with the choice of disinfectant, collection site, and the staff member collecting the blood sample (explanatory variables) and the presence of contamination (objective variable). Based on these results, we performed propensity score matching. RESULTS: The total number of specimens was 1460. The propensity score matching indicated that CHG-ALC reduced the incidence of blood culture contamination more effectively than PVI (0.4%, 2/479 cultures versus 2.5%, 12/479 cultures; relative risk, 0.163 [95% confidence interval, 0.036 to 0.733]; P = 0.012). There were no differences in the contamination rates between cultures of blood drawn from a vascular catheter and those of blood obtained percutaneously. Higher contamination rates were found when junior residents performed the venipuncture. CONCLUSIONS: Compared with PVI, CHG-ALC dries rapidly with no pigmentation and has a long-lasting antiseptic effect. Overall, CHG-ALC skin preparations were more efficacious than the PVI preparations for blood sampling in children.

Relationship between intrapartum antibiotic prophylaxis and group B streptococcal colonization dynamics in Japanese mother-neonate pairs.

INTRODUCTION: In Japan, universal screening for group B streptococcal (GBS) colonization in pregnant women and intrapartum antibiotic prophylaxis (IAP) are recommended to prevent neonatal GBS infection. However, the dynamics of GBS colonization in Japanese mother/neonate pairs have not been adequately studied. METHODS: A prospective cohort study was conducted from July 2018 to March 2019. Rectovaginal samples were collected from pregnant women (33-37 gestation weeks) once. In neonates, nasopharyngeal and rectal samples were collected at three time points: after birth, 1 week after birth, and 1 month after birth. All samples were analyzed for GBS using real-time PCR testing and culture methods. Capsular typing was performed for all GBS isolates and GBS-positive samples using real-time PCR testing. RESULTS: The overall maternal and neonatal GBS-positivity rates were 22.7% (57/251) and 8.8% (22/251), respectively. IAP for GBS-positive mothers (96.5%) was highly administered. Eleven (19.3%) neonates born to GBS-positive mothers were GBS-positive, which was significantly higher than the 11 (5.7%) neonates born to GBS-negative mothers. The rate of GBS-positivity in neonates increased with an increased number of GBS colonies in mothers. More neonates were GBS-positive 1 month after birth than 1 week after birth, and there was a higher rate of GBS-positive rectal swabs than nasopharyngeal swabs. Capsular types of GBS that were isolated from each mother and neonate pair were the same, namely, Ib, III, V, and VI. CONCLUSIONS: These findings indicate that the efficacy of IAP in preventing GBS transmission to neonates might be limited to within a few weeks after birth.

Diagnostic criteria for temporomandibular disorders (DC/TMD) for children and adolescents: An international Delphi study-Part 1-Development of Axis I.

BACKGROUND: Since in children and adolescence prevalence is assessed mainly on self-reported or proxy-reported signs and symptoms; there is a need to develop a more comprehensive standardised process for the collection of clinical information and the diagnosis of TMD in these populations. OBJECTIVE: To develop new instruments and to adapt the diagnostic criteria for temporomandibular disorders (DC/TMD) for the evaluation of TMD in children and adolescents. METHOD: A modified Delphi method was used to seek international consensus among TMD experts. Fourteen clinicians and researchers in the field of oro-facial pain and TMD worldwide were invited to participate in a workshop initiated by the International Network for Orofacial Pain and Related Disorders Methodology (INfORM scientific network) at the General Session of the International Association for Dental Research (IADR, London 2018), as the first step in the Delphi process. Participants discussed the protocols required to make physical diagnoses included in the Axis I of the DC/TMD. Thereafter, nine experts in the field were added, and the first Delphi round was created. This survey included 60 statements for Axis I, and the experts were asked to respond to each statement on a five-item Likert scale ranging from 'Strongly disagree' to 'Strongly agree'. Consensus level was set at 80% agreement for the first round, and at 70% for the next. RESULTS: After three rounds of the Delphi process, a consensus among TMD experts was achieved and two adapted DC/TMD protocols for Axis I physical diagnoses for children and adolescents were developed. CONCLUSION: Through international consensus among TMD experts, this study adapted the Axis I of the DC/TMD for use in evaluating TMD in children and adolescents.

Combination of jaw and tongue movement training influences neuroplasticity of corticomotor pathways in humans.

Since humans in daily life perform multiple motor behaviors that often involve the simultaneous activation of both jaw and tongue muscles, it is essential to understand the effects of combined orofacial sensorimotor tasks on plasticity in corticomotor pathways. Moreover, to establish novel rehabilitation programs for patients, it is important to clarify the possible interrelationships in corticomotor excitability between jaw and tongue motor control. The aim of this study was to examine the effect of a combination of a repetitive tooth bite task (TBT) and a repetitive tongue lift task (TLT) on corticomotor excitability of the tongue and jaw muscles as assessed by transcranial magnetic stimulation (TMS). Sixteen healthy individuals participated in three kinds of training tasks consisting of 41-min TBT, 41-min TLT, and 82-min TBT + TLT. Motor-evoked potentials (MEPs) from the tongue muscle, masseter muscle, and first dorsal interosseous muscle were measured before and after the training tasks. The amplitude of tongue MEPs after training with TLT and TLT + TBT, and masseter MEPs after training with TBT and TLT + TBT, were significantly higher than before training (P < 0.05). Tongue MEPs and masseter MEPs were significantly higher after TLT + TBT than after TBT or TLT (P < 0.05). The present results suggest that a task combining both jaw and tongue movement training is associated with a greater degree of neuroplasticity in the corticomotor control of jaw and tongue muscles than either task alone.

Mechanical sensitivity and psychological factors in patients with burning mouth syndrome.

OBJECTIVES: The aim of this study was to compare mechanical sensitivity on the tongue using quantitative sensory testing (QST) and psychological factors using the General Health Questionnaire (GHQ) between burning mouth syndrome (BMS) patients and healthy participants. MATERIALS AND METHODS: Participants comprised 20 female BMS patients (68.1 ± 7.4 years) and 20 healthy females (65.4 ± 4.6 years). Psychological factors were evaluated with GHQ. Tactile detection thresholds (TDT) and filament-prick pain detection thresholds (FPT) were used to evaluate mechanical sensitivity on the tongue in all participants. TDT and FPT were measured on the tongue within both the painful area and the non-painful area in BMS patients, and on the tongue on both sides in healthy participants. As controls, TDT and FPT were measured with Semmes-Weinstein monofilaments on the skin of the mentum and palm in all participants. RESULTS: GHQ scores were significantly higher in BMS patients than in healthy participants (P = 0.024). No significant differences in TDT or FPT on the tongue, mentum, or palm were seen between BMS patients and healthy participants (P > 0.05). BMS patients showed no significant differences in TDT or FPT between the painful and non-painful areas on the tongue (P > 0.05). There were no significant correlations among TDT/FPT and GHQ score in BMS patients (P > 0.05). CONCLUSIONS: These findings could indicate a more important role for psychological factors than mechanical sensitivity in BMS pathophysiology. CLINICAL RELEVANCE: Pain on the tongue in elderly female patients with BMS may be more related to psychological factors.

Prefrontal modulation during chewing performance in occlusal dysesthesia patients: a functional near-infrared spectroscopy study.

OBJECTIVES: Neuropsychological associations can be considerable in occlusal dysesthesia (OD) patients who routinely complain of persistent occlusal discomfort, and somatization effects in the superior medial prefrontal cortex and the temporal and parietal regions are also present. However, the relationship between physical activity, i.e., chewing, prefrontal cognitive demand, and psychiatric states in OD patients remains unclear. We investigated this relationship in this study. MATERIALS AND METHODS: OD patients (n = 15) and healthy control (n = 15; HC) subjects were enrolled in this study. Occlusal contact, chewing activities of the masticatory muscles, prefrontal activities, and psychiatric states such as depression and somatization, of the participants were evaluated. Functional near-infrared spectroscopy was used to determine prefrontal hemodynamics and the Symptom Checklist-90-R was used to score the psychiatric states. RESULTS: We observed a significant association between prefrontal deactivation during chewing and somatization subscales in OD patients. Further, there were no significant differences with regard to the occlusal state and chewing physical activities between the OD patients and HC subjects. CONCLUSIONS: Chewing-related prefrontal deactivation may be associated with somatization severity in OD patients. CLINICAL RELEVANCE: fNIRS is a functional imaging method that uses the principal of neuro-vascular couplings. It is applicable for evaluation of psychiatric state based on prefrontal cortex blood flow in patients with psychiatric disorders.

Quantitative and qualitative assessment of sensory changes induced by local anesthetics block of two different trigeminal nerve branches.

OBJECTIVES: The aims were to use different techniques to assess the degree of sensory changes and magnitude of perceived size changes in the facial region induced by nerve blocks of two different trigeminal nerve branches in healthy participants. MATERIALS AND METHODS: This placebo-controlled study included 30 healthy volunteers. The participants underwent quantitative and qualitative sensory testing (QST and QualST) thrice: before, 10 min, and 2 h after mental (n = 15) and infraorbital (n = 15) nerve blocks and during control (saline) sessions. Perceived numbness, temperature changes, and perceptual distortion were also measured at all time points during the nerve block and control sessions. Differences in outcome parameters between the sessions and time points were analyzed using analyses of variance and McNemar's tests. RESULTS: There was a significant degree of sensory loss to most QST and all QualST parameters, with significant numbness and increased perceived size at the injection site 10 min and 2 h after the nerve blocks compared with saline (P < 0.030) and the baseline (P < 0.042). Two hours after the nerve blocks, the sensitivity was significantly closer to baseline than after 10 min to most of the QST parameters (P < 0.011). CONCLUSIONS: QST and QualST revealed that the nerve blocks in the orofacial region resulted in complete or partial blockade of afferent nerve fibers mediating thermal and mechanical function for more than 2 h with significant numbness and perceptual distortion. CLINICAL RELEVANCE: Both QST and QualST can provide information on the degree of blockade of afferent nerve fibers after nerve blocks in the orofacial region.

Effect of sleep restriction on somatosensory sensitivity in the oro-facial area: An experimental controlled study.

BACKGROUND: No studies have addressed the effect of SR on somatosensory function in the oro-facial area. OBJECTIVES: The aim of this study was to investigate the effect of sleep restriction (SR) on the somatosensory perception of the tip of the tongue. MATERIALS AND METHODS: Using a crossover study design, 13 healthy participants took part in a random order, to a two arms experiments: the SR and control/no SR-arms. For all participants, the Epworth Sleepiness Scale (ESS) was used to assess sleepiness and mechanical sensitivity, and pain detection threshold was estimated at the tongue tip and right thumb (as a body area control site). In the SR-arm of the study, on day one, we estimated sensory baseline perception and repeated tests on day two, after a night of voluntary SR, and on day 3, after a recovery night. In the second arm, same sensory tests were done but no SR was requested. RESULTS: Significantly more sleepiness was observed after SR in comparison with baseline and recovery testing days (P < 0.05). After SR, mechanical pain threshold on the tip of the tongue was significantly lower on day after SR (day 2) and a rebound, higher values, were observed on the third day (P < 0.05); no difference on thumb site. In the control arm, no SR and no significant differences between days were observed for all the variables of interest. CONCLUSIONS: The present results suggest that SR may affect somatosensory perception in the oro-facial area.

Effects of exercise therapy on painful temporomandibular disorders.

Temporomandibular disorders (TMD) are common chronic musculoskeletal pain conditions among orofacial pain. Painful TMD condition such as myalgia and arthralgia can be managed by exercise therapy. However, as it is hard to access actual effect of each modality that is included in an exercise therapy programme due to multiple choice of the management modality, their efficacy remains controversial. Therefore, this review focused on the effects of exercise therapy for the management of painful TMD. The aims of this review were to summarise the effects of exercise therapy for major symptoms of painful TMD and to establish a guideline for the management of painful TMD, resulting in higher quality and reliability of dental treatment. In this review, exercise modalities are clearly defined as follows: mobilisation exercise, muscle strengthening exercise (resistance training), coordination exercise and postural exercise. Furthermore, pain intensity and range of movements were focused as outcome parameters in this review. Mobilisation exercise including manual therapy, passive jaw mobilisation with oral appliances and voluntary jaw exercise appeared to be a promising option for painful TMD conditions such as myalgia and arthralgia. This review addressed not only the effects of exercise therapy on various clinical conditions of painful TMD shown in the past, but also an urgent need for consensus among dentists and clinicians in terms of the management of each condition, as well as terminology.

Perceptual distortion of the tongue by lingual nerve block and topical application of capsaicin in healthy women.

OBJECTIVES: The aim of this study was to examine reports of perceptual distortion evoked by transient deafferentation and burning pain as models of aspects of burning mouth syndrome (BMS). MATERIALS AND METHODS: Sixteen healthy women took part in three experimental sessions that included exposure to lingual nerve block, capsaicin, and control substance. In each session, reported perceptual distortion and mechanical detection threshold (MDT) were assessed at four areas (the tongue, lower front teeth, lower lip, and right thumb) before and at 5, 15, 30 min and 1 and 3 h after the injection or application. A numerical rating scale (NRS) and a template matching procedure were used to quantify the perceptual distortions. RESULTS: There was a significantly higher MDT on the tongue during the lingual nerve block session at 5 min up until 1 h, with the perceived tongue size significantly increased at 5, 15, and 30 min and at 1 h compared to baseline (P < 0.05). Although the perceived size determined by the NRS scores during the capsaicin session was significantly larger for the lower lip at 5 min compared to baseline (P < 0.001), there were no significant effects on the MDT or the perceived sizes for the tongue, lower front teeth, or right thumb at any of the time points. CONCLUSIONS: Perceptual distortions of the tongue may be influenced by non-nociceptive somatosensory changes rather than nociceptive activity. CLINICAL RELEVANCE: The perceptual distortion of the tongue was investigated with models of aspects of BMS and may have implications for future studies in clinical populations.

Effect of a repeated tongue-lift motor task for tongue function.

This study investigated the effect of repeated tongue motor tasks on suprahyoid muscle activity and tongue pressure. Fourteen participants performed three series of a standardized tongue-lift training (TLT) task on each of five consecutive days. Electromyographic (EMG) activity from suprahyoid muscles and tongue pressure were recorded. In the first and third TLT series, participants were instructed only to target different force levels. During the second TLT series, visual feedback of the force level was given. One series consisted of three measurements [at 10%, 20%, and 40% of maximum voluntary contraction (MVC), respectively]. The coefficient of determination of the target force level-EMG curve and the target force level-tongue pressure curve was calculated from all series. There were no statistically significant day-to-day differences in EMG-root mean square (RMS) values and tongue pressure during MVC. The coefficients of determination of tongue pressure in the first series on day 1 were statistically significantly lower than the coefficients of determination in the first series on day 5. These findings suggest that the control of tongue pressure improved, while the maximum force remained constant. These results could have implications for treatment paradigms related to learning for patients with compromised tongue function, such as swallowing disorders or dysphagia.

Trivalent inactivated influenza vaccine effective against influenza A(H3N2) variant viruses in children during the 2014/15 season, Japan.

The 2014/15 influenza season in Japan was characterised by predominant influenza A(H3N2) activity; 99% of influenza A viruses detected were A(H3N2). Subclade 3C.2a viruses were the major epidemic A(H3N2) viruses, and were genetically distinct from A/New York/39/2012(H3N2) of 2014/15 vaccine strain in Japan, which was classified as clade 3C.1. We assessed vaccine effectiveness (VE) of inactivated influenza vaccine (IIV) in children aged 6 months to 15 years by test-negative case-control design based on influenza rapid diagnostic test. Between November 2014 and March 2015, a total of 3,752 children were enrolled: 1,633 tested positive for influenza A and 42 for influenza B, and 2,077 tested negative. Adjusted VE was 38% (95% confidence intervals (CI): 28 to 46) against influenza virus infection overall, 37% (95% CI: 27 to 45) against influenza A, and 47% (95% CI: -2 to 73) against influenza B. However, IIV was not statistically significantly effective against influenza A in infants aged 6 to 11 months or adolescents aged 13 to 15 years. VE in preventing hospitalisation for influenza A infection was 55% (95% CI: 42 to 64). Trivalent IIV that included A/New York/39/2012(H3N2) was effective against drifted influenza A(H3N2) virus, although vaccine mismatch resulted in low VE.

Repeated clenching causes plasticity in corticomotor control of jaw muscles.

This study tested the effect of short-term tooth-clenching on corticomotor excitability of the masseter muscle using transcranial magnetic stimulation (TMS). Fifteen subjects with normal stomatognathic function participated. All subjects performed a tooth-clenching task (TCT) on five consecutive days. The TCT consisted of 10, 20, and 40% of maximum voluntary contraction in a randomized order within 1 h. All subjects underwent TMS in four sessions: pretask day 1 (baseline), post-task day 1, pretask day 5, and post-task day 5. Motor-evoked potentials (MEPs) from the masseter and the first dorsal interosseous (FDI) muscles were obtained using TMS in four sessions. Motor thresholds decreased, after the TCT, for the masseter muscle MEPs. Masseter muscle MEPs were dependent on stimulus intensity and on session, whereas FDI muscle MEPs were only dependent on stimulus intensity. Post-hoc Tukey tests demonstrated significantly higher masseter muscle MEPs post-task on day 5 with 80 and 90% stimulus intensity and above when compared with pre- and post-task day 1 values. Our results suggest that the performance of repeated TCTs can trigger neuroplastic changes in the corticomotor control of the jaw-closing muscles and that such neuroplastic changes may contribute to the mechanism underlying the clinical manifestations of tooth clenching.

Analysis of definite awake bruxism using a portable electromyography device.

PURPOSE: This study aimed to compare awake bruxism events between subjective and objective evaluations using a questionnaire survey and a modified portable electromyography (EMG) device, and to examine correlations between sleep quality and awake bruxism. METHODS: The Epworth Sleepiness Scale (ESS), Pittsburgh Sleep Quality Index (PSQI), and awareness of awake bruxism as clarified via interviews were conducted on 34 participants as subjective evaluations. The EMG device was used to record left temporal muscle activity for 6.5 h (from 09:00 to 15:30) and the number of awake bruxism episodes per hour. The participants were then classified into "bruxer" and "non-bruxer" groups based on the number of awake bruxism episodes. RESULTS: The mean number of awake bruxism episodes per hour was 33.6 ± 21.4, and 23% of the participants who reported having no awareness of awake bruxism in the interviews were defined as "bruxers" in the objective evaluations. In the bruxer group, positive correlations were found between the number of awake bruxism episodes and both ESS and PSQI scores. CONCLUSION: These findings suggest that objective measurements using a portable EMG device can increase the diagnostic accuracy for awake bruxism, and that sleep quality is a major risk factor for awake bruxism.