Scandinavian Center for Orofacial Neurosciences

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Scandinavian Center for Orofacial Neurosciences

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Skyt I.,University of Aarhus | Dagsdottir L.,University of Aarhus | Dagsdottir L.,Scandinavian Center for Orofacial Neurosciences | Vase L.,University of Aarhus | And 9 more authors.
Journal of Pain | Year: 2015

Anecdotally, orofacial pain patients sometimes report that the painful face area feels "swollen." Because there are no clinical signs of swelling, such illusions may represent perceptual distortions. In this study, we examine whether nociceptive stimulation can lead to perceptual distortion of the face in a way similar to that of local anesthesia. Sixteen healthy participants received injections of.4 mL hypertonic saline to induce short-term nociceptive stimulation,.4 mL mepivacaine (local anesthetic) to transiently block nerve transduction, and.4 mL isotonic saline as a control condition. Injections were administered in both the infraorbital and the mental nerve regions. Perceptual distortions were conceptualized as perceived changes in magnitude of the injected areas and the lips, and they were measured using 1) a verbal subjective rating scale and 2) a warping procedure. Prior to the study, participants filled in several psychological questionnaires. This study shows that both nociceptive stimulation (P <.05) and transient blocking of nerve transduction (P <.05) can lead to perceptual distortion of the face. A test-retest experiment including 9 new healthy subjects supported the results. Perceptual distortions were positively correlated with the psychological variable of dissociation in several conditions (P <.05). Perceptual distortions may therefore be influenced by somatosensory changes and psychological mechanisms. Perspective Knowledge of the factors that influence the perception of the face is important to understand the possible implications of perceptual distortions in orofacial pain disorders (and possibly other chronic pain states). Such information may ultimately open up new avenues of treatment for persistent orofacial pain. © 2015 American Pain Society.


Stuginski-Barbosa J.,University of Sao Paulo | Porporatti A.L.,University of Sao Paulo | Costa Y.M.,University of Sao Paulo | Svensson P.,University of Aarhus | And 3 more authors.
Sleep and Breathing | Year: 2016

Purpose: The aim of this study was to determine an appropriate cutoff value and the number of nights of sleep with the portable single-channel EMG device (GrindCare) necessary for a valid sleep bruxism (SB) diagnosis. Methods: Twenty consecutive post-graduate students and staff at Bauru School of Dentistry composed the sample. Each participant underwent the GrindCare for five consecutive nights and the polysomnography (PSG). The discrimination between bruxers and non-bruxers was based only on the PSG analysis. Data about electromyography per hour with GrindCare (EMG/h) and PSG (bursts/h) were scored. Results: There were positive correlations between the two devices for EMG/h and bursts/h in three and five consecutive nights. Bland-Altman analysis of the EMG bursts/h showed positive agreement between the methods. The receiver operating characteristic (ROC) analyses also showed that using a minimum of 18 EMG/h for three nights and 19 EMG/h for five nights in GrindCare as cutoffs resulted in a 90 % specificity and positive likelihood ratio equal to 5. Conclusions: GrindCare is able to discriminate SB diagnosed by PSG and gold standard criteria, when used for three or five consecutive nights, and it may be a valid choice in clinical practice for SB assessment. © 2015, Springer-Verlag Berlin Heidelberg.


Shimada A.,University of Aarhus | Shimada A.,Scandinavian Center for Orofacial Neurosciences | Baad-Hansen L.,University of Aarhus | Baad-Hansen L.,Scandinavian Center for Orofacial Neurosciences | And 10 more authors.
Nutrition | Year: 2015

Objective: The aim of this study was to determine the relationship of high daily monosodium glutamate (MSG) consumption with glutamate concentrations in jaw muscle, saliva, and serum, and muscle pain sensitivity in healthy participants. Methods: A randomized, double-blinded, placebo-controlled study was conducted to investigate the effect of repetitive consumption of high-dose MSG on glutamate concentration in the masseter muscles measured by microdialysis and muscle pain sensitivity. In five contiguous experimental daily sessions, 32 healthy participants drank MSG (150mg/kg) or NaCl (24mg/kg) diluted with a 400mL soda. The concentrations of glutamate before and after the ingestion were assessed in dialysate and plasma samples on the first and last days. Saliva glutamate concentration was assessed every day. Pressure pain threshold, pressure pain tolerance, autonomic parameters (heart rate, systolic and diastolic blood pressures) and reported side effects also were assessed. Results: No significant change was noted in the baseline concentration of glutamate in the masseter muscle, blood, or saliva, but the peak concentration in the masseter muscle increased significantly between day 1 and 5. A statistically significant increase in systolic and diastolic blood pressures after MSG administration was observed, as well as a significantly higher frequency of reports of nausea and headache in the MSG group. No robust effect of MSG on muscle sensitivity was found. Conclusion: Interstitial glutamate concentration in the masseter muscle is not highly disturbed by excessive repetitive intake of MSG in healthy man. © 2015 Elsevier Inc.


Kothari S.F.,University of Aarhus | Kothari S.F.,Scandinavian Center for Orofacial Neurosciences | Baad-Hansen L.,University of Aarhus | Baad-Hansen L.,Scandinavian Center for Orofacial Neurosciences | And 4 more authors.
Pain | Year: 2015

The pathophysiology and underlying pain mechanisms of temporomandibular disorders (TMD) are poorly understood. The aims were to assess somatosensory function at the temporomandibular joints (TMJs) and to examine whether conditioned pain modulation (CPM) differs between TMD pain patients (n 34) and healthy controls (n 34). Quantitative sensory testing was used to assess the somatosensory function. Z-scores were calculated for patients based on reference data. Conditioned pain modulation was tested by comparing pressure pain thresholds (PPTs) before, during, and after the application of painful and nonpainful cold stimuli. Pressure pain thresholds were measured at the most painful TMJ and thenar muscle (control). Data were analyzed with analyses of variance. Most (85.3%) of the patients exhibited at least 1 or more somatosensory abnormalities at the most painful TMJ with somatosensory gain with regard to PPT and punctate mechanical pain stimuli, and somatosensory loss with regard to mechanical detection and vibration detection stimuli as the most frequent abnormalities. There was a significant CPM effect (increased PPT) at both test sites during painful cold application in healthy controls and patients (P < 0.001). There was no significant difference in the relative CPM effect during painful cold application between groups (P 0.227). In conclusion, somatosensory abnormalities were commonly detected in TMD pain patients and CPM effects were similar in TMD pain patients and healthy controls. © 2015 International Association for the Study of Pain.


PubMed | University of Aarhus, Chinese PLA General Hospital and Scandinavian Center for Orofacial Neurosciences
Type: Journal Article | Journal: European journal of oral sciences | Year: 2016

The aim of this study was to investigate the impact of visual observational conditions on performance during a standardized tongue-protrusion training (TPT) task and to evaluate subject-based reports of helpfulness, disturbance, pain, and fatigue, due to the observational conditions on 0-10 numerical rating scales. Forty-eight healthy participants performed a 1-h standard TPT task. Participants were randomly assigned to one of the following three groups with different observational conditions: group 1, model observation (participants watched a prerecorded video showing standard TPT before optimal TPT being performed); group 2, self-observation (participants watched live video feedback of their own TPT performance); and group 3, control group (participants performed the TPT with no conditioning). There was no overall difference between groups but TPT performance increased over time. A significant grouptime interaction indicated that the self-observation group performed significantly better than the model-observation group in the last 20 min of TPT. The subject-based reports of video helpfulness showed that the model-observation group rated the prerecorded video as more helpful for TPT performance compared with the other groups but there was no significant difference between groups regarding the level of disturbance, pain, or fatigue. Self-observation of tongue-training facilitated behavioral aspects of tongue motor learning compared with model observation but not compared with control.


PubMed | University of British Columbia, University of Aarhus, Scandinavian Center for Orofacial Neurosciences and Linköping University
Type: Journal Article | Journal: European journal of pain (London, England) | Year: 2016

A randomized, double-blinded, placebo-controlled study was conducted to investigate if single monosodium glutamate (MSG) administration would elevate muscle/serum glutamate concentrations and affect muscle pain sensitivity in myofascial temporomandibular disorders (TMD) patients more than in healthy individuals.Twelve myofascial TMD patients and 12 sex- and age-matched healthy controls participated in two sessions. Participants drank MSG (150mg/kg) or NaCl (24mg/kg; control) diluted in 400mL of soda. The concentration of glutamate in the masseter muscle, blood plasma and saliva was determined before and after the ingestion of MSG or control. At baseline and every 15min after the ingestion, pain intensity was scored on a 0-10 numeric rating scale. Pressure pain threshold, pressure pain tolerance (PPTol) and autonomic parameters were measured. All participants were asked to report adverse effects after the ingestion.In TMD, interstitial glutamate concentration was significantly greater after the MSG ingestion when compared with healthy controls. TMD reported a mean pain intensity of 2.8/10 at baseline, which significantly increased by 40% 30min post MSG ingestion. At baseline, TMD showed lower PPTols in the masseter and trapezius, and higher diastolic blood pressure and heart rate than healthy controls. The MSG ingestion resulted in reports of headache by half of the TMD and healthy controls, respectively.These findings suggest that myofascial TMD patients may be particularly sensitive to the effects of ingested MSG. WHAT DOES THIS STUDY ADD?: Elevation of interstitial glutamate concentration in the masseter muscle caused by monosodium glutamate (MSG) ingestion was significantly greater in myofascial myofascial temporomandibular disorders (TMD) patients than healthy individuals. This elevation of interstitial glutamate concentration in the masseter muscle significantly increased the intensity of spontaneous pain in myofascial TMD patients.


PubMed | Scandinavian Center for Orofacial Neurosciences and University of Sao Paulo
Type: | Journal: Clinical oral investigations | Year: 2017

The nociceptive blink reflex (nBR) can be useful to investigate trigeminal nociceptive function. The aim of this study was to estimate the reliability of the nBR evoked by electrical stimulation of the three branches of the trigeminal nerve under the following conditions: over time (test-retest and intrarater reliability) and by two examiners (interrater reliability).Twenty-one healthy participants were evaluated in two sessions (24h apart). The nBR was elicited by a so-called nociceptive-specific electrode placed over the entry zone of the right supraorbital (V1R), infraorbital (V2R), mental (V3R), and left infraorbital (V2L) nerve. The outcomes were individual electrical sensory (I ICCs were fair to excellent in 82% of the psychophysical measures (fair 21%, good 31%, excellent 30%) and in 86% of V1R, V2R, and V2L nBR parameters, whereas 52% of V3R showed poor reliability. ICCs for intrarater reliability were fair to good in 70% of measurements (fair 20%, good 50%) and in 75% of interrater measurements after the recalibration (fair 55%, good 20%). All kappa values showed at least fair agreement and the majority of the nBR measures (93%) presented moderate to excellent reliability.The nBR and its associated psychophysical measures can be considered a sufficiently reliable test.The nBR can be recommended as an electrophysiological technique to assess trigeminal nociceptive function.


Al-Khotani A.,Karolinska Institutet | Al-Khotani A.,Scandinavian Center for Orofacial Neurosciences | Naimi-Akbar A.,Karolinska Institutet | Gjelset M.,Karolinska Institutet | And 7 more authors.
Journal of Headache and Pain | Year: 2016

Background: Temporomandibular disorders (TMD) in children and adolescents is prevalent with pain as a common component, and has a comorbidity with psychosocial problems such as stress, depression, anxiety as well as somatic complaints. Therefore, the aim of the study was to investigate if psychosocial problems in children and adolescents are associated with TMD with pain (TMD-pain) and TMD without pain (TMD-painfree) when compared to children and adolescents without TMD. Methods: This cross-sectional study consisted of 456 randomly selected children and adolescents, enrolled from 10 boy’s- and 10 girl’s- schools in Jeddah, between 10 and 18 years of age. On the examination day, prior to the clinical examination according to Research Diagnostic Criteria for TMD Axis I and II, the participants first answered two validated questions about TMD pain, and after that the Arabic version of the Youth Self Report scale. According to their clinical examination and diagnosis the participants were divided into three groups; non-TMD group, TMD-pain group, and TMD-painfree group. Results: The TMD-pain group presents a higher frequency of the internalizing problems anxiety, depression and somatic complaints than non-TMD group (p < 0.05). Regarding externalizing problems the only significant association found was for aggressive behavior in the TMD-pain group (p < 0.05). The TMD-pain group also shows a higher frequency of social problems than the non-TMD group. However, no such difference was found when compared to the TMD-painfree group. There was also a significant association with a higher frequency of thought problems in the TMD-pain group (p < 0.05). The children’s and adolescents’ physical activities were within border line clinical range for all three groups, whereas the social competence was within the normal range. There were no significant associations between any of the groups in this respect. Conclusions: TMD-pain in children and adolescents does not seem to affect the social activities. However, TMD-pain seem to have a strong association to emotional, behavior and somatic functioning, with higher frequencies of anxiety, depression, somatic problems, aggressive behavior and thought problems, than children and adolescents without TMD-pain. With respect to the biopsychosocial model the present study indicates that there are significant associations to psychosocial, somatic and behavioral comorbidities and TMD-pain in children and adolescents in the Middle East region. © 2016, Al-Khotani et al.


Vilanova L.S.R.,University of Campinas | Vilanova L.S.R.,Malmö University | Vilanova L.S.R.,Scandinavian Center for Orofacial Neurosciences | Garcia R.C.M.R.,University of Campinas | And 6 more authors.
Journal of Headache and Pain | Year: 2015

Background: To investigate the difference in diagnostic reliability between self-instructed examiners and examiners taught in a Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) course and if the reliability of self-instructed examiners improves after the course.Methods: Six examiners were divided into three groups: (1) formal two-day training and calibration course at a DC/TMD training center (Course group), (2) self-teaching through documents and movie (Self group) with three examiners on each and the Self group later participated in the course (Self + course group). Each group examined sixteen subjects, total of 48 volunteers (36 patients with TMD and 12 asymptomatic) and the reliabilities in relation to the diagnoses derived by a Reference Standard Examiner were compared by Cohen’s Kappa coefficient.Results: The reliability was good to excellent in all three groups of examiners for all DC/TMD diagnoses, except for Myofascial pain with referral in the Self + course group. The course seemed to improve the reliability regarding Myalgia and Arthralgia at the same time as the examiners experienced the course to be valuable for self-perceived ability and confidence.Conclusions: This study shows that the diagnostic reliability of formal DC/TMD training and calibration and DC/TMD self-instruction are similar, except for subgroups of Myalgia. Thus, self-instruction seems to be possible to use to diagnose the most common TMDs in general dental practice. The course further improves the reliability regarding Myalgia and Arthralgia at the same time as the examiners experienced the course to be valuable for self-perceived ability and confidence. © 2015, Vilanova et al.; licensee Springer.


PubMed | Karolinska Institutet and Scandinavian Center for Orofacial Neurosciences
Type: | Journal: Clinical oral investigations | Year: 2016

The study was designed to investigate if alteration of different orofacial afferent inputs would have different effects on oral fine motor control and to test the hypothesis that reduced afferent inputs will increase the variability of bite force values and jaw muscle activity, and repeated training with splitting of food morsel in conditions with reduced afferent inputs would decrease the variability and lead to optimization of bite force values and jaw muscle activity.Forty-five healthy volunteers participated in a single experimental session and were equally divided into incisal, mucosal, and block anesthesia groups. The participants performed six series (with ten trials) of a standardized hold and split task after the intervention with local anesthesia was made in the respective groups. The hold and split forces along with the corresponding jaw muscle activity were recorded and compared to a reference group.The hold force and the electromyographic (EMG) activity of the masseter muscles during the hold phase were significantly higher in the incisal and block anesthesia group, as compared to the reference group (P<0.001). However, there was no significant effect of groups on the split force (P=0.975) but a significant decrease in the EMG activity of right masseter in mucosal anesthesia group as compared to the reference group (P=0.006). The results also revealed that there was no significant effect of local anesthesia on the variability of the hold and split force (P<0.677). However, there was a significant decrease in the variability of EMG activity of the jaw closing muscles in the block anesthesia group as compared to the reference group (P<0.041), during the hold phase and a significant increase in the variability of EMG activity of right masseter in the mucosal anesthesia group (P=0.021) along with a significant increase in the EMG activity of anterior temporalis muscle in the incisal anesthesia group, compared to the reference group (P=0.018), during the split phase.The results of the present study indicated that altering different orofacial afferent inputs may have different effects on some aspects of oral fine motor control. Further, inhibition of afferent inputs from the orofacial or periodontal mechanoreceptors did not increase the variability of bite force values and jaw muscle activity; indicating that the relative precision of the oral fine motor task was not compromised inspite of the anesthesia. The results also suggest the propensity of optimization of bite force values and jaw muscle activity due to repeated splitting of the food morsels, inspite of alteration of sensory inputs.Skill acquisition following a change in oral sensory environment is crucial for understanding how humans learn and re-learn oral motor behaviors and the kind of adaptation that takes place after successful oral rehabilitation procedures.

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