Reliability of an intraoral extension for intraoral palpation and assessment of mechanical sensitivity of the temporal tendon.

BACKGROUND: The temporal tendon is a structure often compromised in patients suffering from temporomandibular disorders (TMD), yet its intraoral location makes a standardised assessment difficult. OBJECTIVES: To evaluate the variability and accuracy to target force of a newly designed intraoral extension for a palpometer device (Palpeter, Sunstar Suisse) when compared to manual palpation, in addition to clinically assessing the mechanical sensitivity and referred sensations of the temporal tendon in healthy individuals. METHODS: Experiment 1: 12 individuals were asked to target on a scale 0.5, 1 and 2 kg, for 2 and 5 s by using five different methods (Palpeter, Palpeter with three different extension shapes and manual palpation). Experiment 2: 10 healthy participants were recruited for a randomised double-blinded assessment by applying pressure of 0.5, 1 and 2 kg to the right temporal tendon with the three extensions and manual palpation. Participants rated the intensity of their sensation/pain on a 0-50-100 numeric rating scale (NRS), unpleasantness on a 0-100 NRS, and if present, they rated and drew the location of referred sensations. Repeated measures analysis of variance (ANOVA) was used in both experiments to compare differences between palpation methods. Tukey's HSD tests were used for the post hoc comparisons, and p values below .05 were considered significant. RESULTS: Experiment 1: The extensions showed no significant differences between them regarding reliability and accuracy for all forces and durations (p > .05). The manual method was significantly less reliable and accurate when compared to the other methods (p < .05). Experiment 2: There were no significant differences between the Palpeter extensions regarding pain intensity or unpleasantness NRS scores (p > .05), but all the extensions had significantly increased pain intensity and unpleasantness when compared to manual palpation (p < .05). Similarly, the frequency of referred sensations was similar between extensions but increased when compared to manual palpation. CONCLUSIONS: The new Palpeter extensions proved to be significantly more accurate and have lower test-retest variability than the manual method in a non-clinical setting. Clinically, they showed no significant differences in NRS scores for pain intensity nor unpleasantness, with no major differences in referred sensations, making any of the extensions suitable for clinical testing of the temporal tendon in future studies.

Impact of a mandibular advancement device on corticomotor plasticity in patients with obstructive sleep apnea.

BACKGROUND: Neuroplasticity induced by mandibular advancement appliance (MAD) in patients with obstructive sleep apnoea (OSA) is poorly documented. OBJECTIVE: This randomised placebo-controlled crossover mechanistic study assessed the effects of short-term use of a MAD on corticomotor excitability of the masseter and tongue in patients with OSA. METHODS: Adults (n = 28) with mild or moderate OSA were randomly allocated to sleep with a MAD for 2-weeks with 40% of the maximal protrusion (MAD active position) and without any jaw protrusion (MAD placebo position). The outcomes were assessed at baseline, and after 2 and 6 weeks, with a 2-week washout period. The primary outcome was the amplitude of motor evoked potential (MEP) assessed on the right masseter, right side of tongue and right first dorsal interosseous with transcranial magnetic stimulation. Corticomotor map volume of the same muscles was also assessed. Repeated-measures ANOVAs followed by Tukey test were applied to the data (p < .050). RESULTS: There was a significant increase in the MEP amplitude of the masseter and tongue following the MAD active position compared with the baseline and MAD placebo (Tukey: p < .001). There were no significant MEP amplitude differences between the baseline and placebo positions (p > .050). Moreover, there was a significant increase in corticomotor map volume for the masseter and tongue muscles following the MAD active position compared with baseline and MAD placebo (Tukey: p < .003). CONCLUSION: Excitability of the masseter and tongue motor pathways is, at least transiently, increased in patients with OSA following a short-term use of MAD. This novel finding of MAD-induced neuroplasticity in corticomotor pathways may contribute to a further understanding of the mechanisms of oral appliances for treating OSA.

Impact of oral motor task training on corticomotor pathways and diadochokinetic rates in young healthy participants.

BACKGROUND: Studies addressing the training-induced neuroplasticity and interrelationships of the lip, masseter, and tongue motor representations in the human motor cortex using single syllable repetition are lacking. OBJECTIVE: This study investigated the impact of a repeated training in a novel PaTaKa diadochokinetic (DDK) orofacial motor task (OMT) on corticomotor control of the lips, masseter, and tongue muscles in young healthy participants. METHODS: A total of 22 young healthy volunteers performed 3 consecutive days of training in an OMT. Transcranial magnetic stimulation was applied to elicit motor evoked potentials (MEPs) from the lip, masseter, tongue, and first dorsal interosseous (FDI, internal control) muscles. MEPs were assessed by stimulus-response curves and corticomotor mapping at baseline and after OMT. The DDK rate from PaTaKa single syllable repetition and numeric rating scale (NRS) scores were also obtained at baseline and immediately after each OMT. Repeated-measures analysis of variance was used to detect differences at a significance level of 5%. RESULTS: There was a significant effect of OMT and stimulus intensity on the lips, masseter, and tongue MEPs compared to baseline (p < .001), but not FDI MEPs (p > .05). OMT increased corticomotor topographic maps area (p < .001), and DDK rates (p < .01). CONCLUSION: Our findings suggest that 3 consecutive days of a repeated PaTaKa training in an OMT can induce neuroplastic changes in the corticomotor pathways of orofacial muscles, and it may be related to mechanisms underlying the improvement of orofacial fine motor skills due to short-term training. The clinical utility should now be investigated.

Detrimental impact of temporomandibular disorders (mis)beliefs and possible strategies to overcome.

AIM: This topical review presents common patients' misbeliefs about temporomandibular disorders (TMD) and discusses their possible impact on the diagnosis, treatment and prognosis. We also discussed the possible influence of the beliefs and behaviours of healthcare providers on the beliefs of patients with TMD and suggested possible strategies to overcome the negative impacts of such misbeliefs. METHODS: This topical review was based on a non-systematic search for studies about the beliefs of patients and healthcare professionals about TMD in PubMed and Embase. RESULTS: Patients' beliefs can negatively impact the diagnosis, treatment and prognosis of TMD. These beliefs can be modulated by several factors such as culture, psychosocial aspects, gender, level of knowledge and previous experiences. Moreover, primary healthcare professionals, including dentists, may lack sufficient experience and skills regarding TMD diagnosis and treatment. Misbeliefs of the healthcare professionals can be based on outdated evidence that is not supported by rigorous methodological investigations. Education and dissemination of knowledge to patients and the general population are effective for prevention, promotion of health and disruption of the cycle of misinformation and dissemination of misbeliefs. CONCLUSION: The lack of basic information about TMD and the dissemination of mistaken and outdated concepts may delay the diagnosis, hinder the treatment, and consequently increase the risk of worsening the condition. Education is key to overcome TMD misbeliefs.

CYP450 polymorphisms and clinical pharmacogenetics of ibuprofen after lower third molar extraction.

PURPOSE: This study hypothesized that drugs accumulate in the bloodstream of poor-metabolizing patients and may have more adverse effects and different pain perceptions and aimed to investigate the influence of CYP450 polymorphisms on acute postoperative pain, swelling, and trismus controlled by ibuprofen (600 mg) in 200 volunteers after dental extraction. In addition, surgical outcomes can determine pain, edema, and trismus and indicate inflammatory reactions after oral surgeries. METHODS: Genetic sequencing was performed to identify CYP450 polymorphisms and the surgical parameters evaluated: pre and postoperative swelling, trismus, and temperature; self-reported postoperative pain with visual analog scale (VAS); rescue medication consumed; and severity of adverse reactions. RESULTS: A multiple linear regression model with independent variables [single nucleotide polymorphisms (SNPs), BMI (body mass index), duration, and difficulty of surgery] and dependent variables [postoperative pain by sum of pain intensity difference (SPID), trismus, and swelling] was used for analysis. The duration of surgery was a predictor for pain at 8 h and 96 h after surgery, and BMI was a predictor for both swelling and trismus on the 2nd postoperative day. When evaluating CYP2C8 and C9 genotyped SNPs, it was observed that normal metabolizers showed higher pain levels than the intermediate/poor metabolizers on the postoperative periods as compared with time 0 h. In another analysis, the poor metabolizers for CYP2C8 and C9 presented lower levels of postoperative pain after 8 h and used rescue medication earlier than normal metabolizers. CONCLUSION: Ibuprofen 600 mg was very effective in controlling inflammatory pain after lower third molar surgeries, without relevant adverse reactions; although in a very subtle way, patients with poor metabolism had higher levels of pain in the first hours, and no longer after 8 h, and used pain relief medication earlier. TRIAL REGISTRATION: The study was registered with ClinicalTrials.gov ID (NCT03169127), on March 16th, 2017.

Psychophysical evaluation of somatosensory function in oro-facial pain: achievements and challenges.

AIM: This critical review describes key methodological aspects for a successful oro-facial psychophysical evaluation of the somatosensory system and highlights the diagnostic value of somatosensory assessment and management perspectives based on somatosensory profiling. METHODS: This topical review was based on a non-systematic search for studies about somatosensory evaluation in oro-facial pain in PubMed and Embase. RESULTS: The recent progress regarding the psychophysical evaluation of somatosensory function was largely possible due to the development and application of valid, reliable and standardised psychophysical methods. Qualitative sensory testing may be useful as a screening tool to rule out relevant somatosensory abnormalities. Nevertheless, the patient should preferably be referred to a more comprehensive assessment with the quantitative sensory testing battery if confirmation of somatosensory abnormalities is necessary. Moreover, the identification of relevant somatosensory alterations in chronic pain disorders that do not fulfil the current criteria to be regarded as neuropathic has also increased the usefulness of somatosensory evaluation as a feasible method to better characterise the patients and perhaps elucidate some underpinnings of the so-called 'nociplastic' pain disorders. Finally, an additional benefit of oro-facial pain treatment based on somatosensory profiling still needs to be demonstrated and convincing evidence of somatosensory findings as predictors of treatment efficacy in chronic oro-facial pain awaits further studies. CONCLUSION: Psychophysical evaluation of somatosensory function in oro-facial pain is still in its infancy but with a clear potential to continue to improve the assessment, diagnosis and management of oro-facial pain patients.

The effect of orthodontic separator and short-term fixed orthodontic appliance on inflammatory mediators and somatosensory function.

BACKGROUND: Although inflammation can alter cytokines release and nerve function, it is not yet fully established if orthodontic-induced inflammation can cause significant extraoral trigeminal somatosensory alterations and release of inflammatory chemical mediators. OBJECTIVE: The primary aim of this study was to investigate the impact of orthodontic separator and short-term fixed orthodontic appliance on the extraoral trigeminal somatosensory function and concentrations of cytokines in the gingival crevicular fluid (GCF). METHODS: Twenty-two female patients were evaluated as follow: baseline, 24 hour-after elastomeric separator (-aES), 24 hour- and 1 month-after bonding brackets (-aBB) at both arches. The outcome variables were as follows: self-reported pain (Visual Analog Scale), QSTs (current perception threshold-CPT, cold detection threshold-CDT, warm detection threshold-WDT, mechanical detection threshold-MDT, mechanical suprathreshold-MST and wind-up ratio-WUR. All QSTs were performed at infra-orbital and mental nerve entry zone at patient`s dominant side. In addition, GCF samples in order to assess cytokines profile (IL-1ß,IL-8,IL-6 and TNF-α) were collected. ANOVA and Tukey's post hoc analyses were performed (a = 5%). RESULTS: Patients reported higher pain intensity 24 hour-aBB compared to baseline and 24 hour-aES (P < 0.050). Patients were less sensitive to pin-prick pain (MST) at 24 hour-aBB and 1 month-aBB compared to baseline (P < 0.006). Significant increases in IL-6 levels were observed 24 hour-aBB (P < 0.001). Multiple comparison analysis showed significant increase in IL-1ß levels (P < 0.001) and TNF-α (P < 0.001) 1 month-aBB compared to baseline. CONCLUSION: Elastomeric separators only induced mild pain and were not able to significantly increase proinflammatory cytokines level in the GCF. In addition, orthodontic fixed appliance may induce only minor somatosensory changes at extraoral trigeminal locations.

Referred sensations in the orofacial region are associated with a decreased descending pain inhibition and modulated by remote noxious stimuli and local anesthesia.

ABSTRACT: Referred sensation (RS) as a specific clinical phenomenon has been known for a long time, although the underlying mechanisms remain unclear. The aims of this study were to assess if (1) healthy individuals who experienced RS had a less active endogenous pain system when compared with those who did not; (2) activation of descending pain inhibition mechanisms can modulate RS parameters; and finally, (3) a transient decrease in peripheral afferent input because of a local anesthetic (LA) block in the masseter muscle can modulate RS parameters. To assess these, 50 healthy participants were assessed in 3 different sessions. In the first session, conditioned pain modulation (CPM) as well as mechanical sensitivity and RS at the masseter muscle were assessed. In the same session, participants who experienced RS had their mechanical sensitivity and RS assessed again while undergoing a CPM protocol. In the second and third sessions, participants had their mechanical sensitivity and RS assessed before and after receiving an injection of 2 mL of LA and isotonic saline into the masseter muscle. The main findings of this study were (1) participants who experienced RS during standardized palpation exhibited increased mechanical sensitivity ( P < 0.05, Tukey post hoc test) and decreased CPM ( P < 0.05, Tukey post hoc test) when compared with those who did not; RS incidence ( P < 0.05, Cochran Q test), frequency ( P < 0.05; Friedman test), intensity ( P < 0.05, Tukey post hoc test), and area ( P < 0.05, Tukey post hoc test) were all significantly reduced when assessed (2) during a painful conditioning stimulus and (3) after LA block. These novel findings highlight that RS in the orofacial region are strongly modified by both peripheral and central nervous system factors.

Sleep-related factors and orofacial pain symptoms associated with rhythmic masticatory muscle activity frequency scored by polysomnography recordings: A case-control study.

OBJECTIVE: This study aimed to evaluate the influence of the frequency of rhythmic masticatory muscle activity per hour (RMMA/h) scored by polysomnography (PSG) recordings on sleep-related factors and orofacial pain symptoms. METHODS: According to RMMA/h frequency, participants were assigned either to the control group (i.e., CRMMA, n = 40); or the case group according to high (i.e., HRMMA, n = 12) or low (LRMMA, n = 28) RMMA/h frequency. Fisher's exact (nominal variables), One-way Analysis of Variance followed by post-hoc Tukey (continuous variables) and Poisson Regression tests were used to calculate orofacial pain symptoms and sleep-related breathing, behavior, and architecture differences between controls versus cases at a significance level of 5%. RESULTS: The CRMMA differed from HRMMA and LRMMA subgroups considering orofacial pain, self-reported tooth clenching or grinding, obstructive sleep apnea (OSA), snoring, and most variables considering sleep architecture (P ≤ 0.05). Multivariate adjusted Poisson regression analysis revealed that bruxers, regardless of RMMA/h frequency, presented a significantly higher prevalence rate (PR) related to orofacial pain (PR 1.68; P = 0.025) and self-reported behavior (PR 1.71; P = 0.012). CONCLUSION: Significant differences in N1, N2 and N3 stages, arousals, arousal per hour, and sleep onset latency variables were found comparing bruxer with high or low RMMA/h frequency. Compared to controls, bruxers presented higher PR related to headache and self-reported tooth clenching or grinding.

Effect of standardized training in combination with masseter sensitization on corticomotor excitability in bruxer and control individuals: a proof of concept study.

Recently, it has been proposed that bruxism could represent an overlearned behavior due to the absence of corticomotor plasticity following a relevant tooth-clenching task (TCT). This study assessed the modulatory effects of a nerve growth factor (NGF) injection on masseter muscle corticomotor excitability, jaw motor performance, pain, and limitation in bruxer and control participants following a TCT. Participants characterized as definitive bruxers or controls were randomly assigned to have injected into the right masseter muscle either NGF or isotonic saline (IS), resulting in a study with 4 arms: IS_Control (n = 7), IS_Bruxer (n = 7); NGF_Control (n = 6), and NGF_Bruxer (n = 8). The primary outcome was the masseter motor evoked potential (MEP) amplitude measured at baseline and after a TCT. After the interventions, significantly higher and lower MEP amplitude and corticomotor map area were observed, respectively, in the IS_Control and NGF_Control groups (P < 0.05). Precision and accuracy depended on the series and target force level with significant between-group differences (P < 0.01). NGF-induced masseter muscle sensitization, in combination with a training-induced effect, can significantly impact the corticomotor excitability of the masseter muscle in control participants indicating substantial changes in corticomotor excitability, which are not observed in bruxers. These preliminary findings may have therapeuthic implications for the potential to "detrain" and manage bruxism, but further studies with larger sample sizes will be needed to test this new concept.