RESUMO
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.
Assuntos
Bruxismo , Músculo Masseter , Humanos , Músculo Masseter/fisiologia , Fator de Crescimento Neural/farmacologia , Estudo de Prova de Conceito , Eletromiografia/métodos , Potencial Evocado Motor/fisiologia , Estimulação Magnética TranscranianaRESUMO
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.
Assuntos
Potencial Evocado Motor , Córtex Motor , Eletromiografia , Potencial Evocado Motor/fisiologia , Voluntários Saudáveis , Humanos , Córtex Motor/fisiologia , Músculo Esquelético , Plasticidade Neuronal/fisiologia , Estimulação Magnética TranscranianaRESUMO
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.
Assuntos
Dor Facial , Transtornos da Articulação Temporomandibular , Dor Facial/terapia , Humanos , Transtornos da Articulação Temporomandibular/psicologiaRESUMO
This study aimed to systematically review the literature to identify clinical studies assessing neuroplasticity changes induced by or associated with bruxism or a tooth-clenching task using neurophysiological techniques. Searches were performed in five electronic databases (PubMed, EMBASE, Scopus, Web of Science, and Google Scholar) in April 2020. This review included clinical studies using neurophysiological techniques to assess neuroplasticity changes in healthy participants before and after a tooth-clenching task or comparing bruxers and non-bruxers. The quality assessment was performed with the Joanna Briggs Institute tool and Grading of Recommendations Assessment, Development, and Evaluation. Meta-analyses were conducted with studies reporting similar comparisons regarding masseter motor evoked potential amplitude and signal change outcomes. Of 151 articles identified in the searches, nine were included, and five proceeded to meta-analysis. Included studies presented moderate to very low methodological quality. From these included studies, eight evaluated bruxers and non-bruxers, of which five of them observed brain activity differences between groups, and three found no differences. Even so, all studies have suggested distinct difference in the central excitability between bruxers and non-bruxers, the meta-analysis revealed no statistically significant differences (P > 0.05). It appears that bruxism seems, indeed, to be associated with distinct differences in the neural pathways related to the control of the jaw-closing muscles, but that considerable variability in terms of classification of bruxism and assessment of neuroplasticity hamper a definite conclusion. Future research projects should take these concerns into consideration in order to further the understanding of bruxism physiology and pathophysiology.
Assuntos
Bruxismo , Humanos , Bruxismo/complicações , Imageamento por Ressonância Magnética , Vias NeuraisRESUMO
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.
Assuntos
Dor Crônica , Dor Facial , Dor Facial/diagnóstico , Humanos , Manejo da Dor , Medição da Dor , Reprodutibilidade dos TestesRESUMO
Dentists stand in an optimal position to prevent and manage patients suffering from chronic orofacial pain (OFP) disorders, such as temporomandibular disorders, burning mouth syndrome, trigeminal neuralgia, persistent idiopathic dentoalveolar pain, among others. However, there are consistent reports highlighting a lack of knowledge and confidence in diagnosing and treating OFP among dental students, recent graduates, and trained dentists, which leads to misdiagnosis, unnecessary costs, delay in appropriate care and possible harm to patients. Education in OFP is necessary to improve the quality of general dental care and reduce individual and societal burden of chronic pain through prevention and improved quality of life for OFP patients. Our aims are to emphasize the goals of OFP education, to identify barriers for its implementation, and to suggest possible avenues to improve OFP education in general, postgraduate, and continuing dental education levels, including proposed minimum OFP competencies for all dentists. Moreover, patient perspectives are also incorporated, including a testimony from a person with OFP. General dentists, OFP experts, educators, researchers, patients, and policy makers need to combine efforts in order to successfully address the urgent need for quality OFP education.
Assuntos
Dor Crônica , Dor Crônica/terapia , Competência Clínica , Dor Facial/terapia , Humanos , Assistência ao Paciente , Qualidade de VidaRESUMO
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.
Assuntos
Anti-Inflamatórios não Esteroides/uso terapêutico , Sistema Enzimático do Citocromo P-450/genética , Ibuprofeno/uso terapêutico , Dor Pós-Operatória/tratamento farmacológico , Extração Dentária/efeitos adversos , Adolescente , Adulto , Índice de Massa Corporal , Citocromo P-450 CYP2C8/genética , Citocromo P-450 CYP2C9/genética , Método Duplo-Cego , Edema/tratamento farmacológico , Edema/etiologia , Feminino , Humanos , Masculino , Dente Serotino/cirurgia , Duração da Cirurgia , Medição da Dor , Farmacogenética , Polimorfismo de Nucleotídeo Único , Trismo/tratamento farmacológico , Trismo/etiologia , Adulto JovemRESUMO
The aim of this investigation was to evaluate the effects of local anaesthesia on nerve growth factor (NGF) induced masseter hyperalgesia. Healthy participants randomly received an injection into the right masseter muscle of either isotonic saline (IS) given as a single injection (n = 15) or an injection of NGF (n = 30) followed by a second injection of lidocaine (NGF + lidocaine; n = 15) or IS (NGF + IS; n = 15) in the same muscle 48 h later. Mechanical sensitivity scores of the right and left masseter, referred sensations and jaw pain intensity and jaw function were assessed at baseline, 48 h after the first injection, 5 min after the second injection and 72 h after the first injection. NGF caused significant jaw pain evoked by chewing at 48 and 72 h after the first injection when compared to the IS group, but without significant differences between the NGF + lidocaine and NGF + IS groups. However, the mechanical sensitivity of the right masseter 5 min after the second injection in the NGF + lidocaine group was significantly lower than the second injection in the NGF + IS and was similar to the IS group. There were no significant differences for the referred sensations. Local anaesthetics may provide relevant information regarding the contribution of peripheral mechanisms in the maintenance of persistent musculoskeletal pain.
Assuntos
Anestésicos Locais/administração & dosagem , Dor Facial/tratamento farmacológico , Hiperalgesia/tratamento farmacológico , Lidocaína/administração & dosagem , Músculo Masseter/efeitos dos fármacos , Fator de Crescimento Neural/efeitos adversos , Adulto , Estudos de Casos e Controles , Método Duplo-Cego , Dor Facial/etiologia , Dor Facial/patologia , Feminino , Humanos , Hiperalgesia/etiologia , Hiperalgesia/patologia , Injeções Intramusculares , Masculino , Músculo Masseter/fisiopatologia , Limiar da DorRESUMO
BACKGROUND: Quantification of motor-evoked potentials (MEPs) can contribute to better elucidate the central modulation of motor pathways in response to nociceptive inputs. The primary aim of this study was to assess the modulatory effects of nerve growth factor (NGF) injection on masseter corticomotor excitability. METHODS: The healthy participants of this randomized, double blind placebo-controlled experiment were assigned to have injected into the right masseter muscle either NGF (n = 25) or isotonic saline (IS, n = 17). The following variables were assessed at baseline and 48 hr after the injection: right masseter MEP amplitude and corticomotor mapping and clinical assessment of jaw pain intensity and function. Repeated Measures ANOVA was applied to the data. RESULTS: NGF caused jaw pain and increased jaw functional disability after the injection (p < 0.050). Also, the participants in the NGF group decreased the MEP amplitude (p < 0.001) but the IS group did not present any significant modulation after the injection (p > 0.050). Likewise, the participants in the NGF group reduced corticomotor map area and volume (p < 0.001), but the IS group did not show any significant corticomotor mapping changes after the injection (p > 0.050). Finally, there was a significant correlation between the magnitude of decreased corticomotor excitability and jaw pain intensity on chewing 48 hr after the NGF injection (r = -0.51, p = 0.009). CONCLUSION: NGF-induced masseter muscle soreness can significantly reduce jaw muscle corticomotor excitability, which in turn is associated with lower jaw pain intensity and substantiates the occurrence of central changes that most likely aim to protect the musculoskeletal orofacial structures. SIGNIFICANCE: Intramuscular administration of nerve growth factor into masseter muscle causes inhibitory corticomotor plasticity, which likely occurs to prevent further damage and seems associated with lower pain intensity on function.
Assuntos
Potencial Evocado Motor/fisiologia , Músculo Masseter/efeitos dos fármacos , Músculo Masseter/fisiologia , Fator de Crescimento Neural/farmacologia , Adulto , Método Duplo-Cego , Eletromiografia , Dor Facial , Feminino , Humanos , Masculino , MialgiaRESUMO
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.