Secondary bruxism: A valid diagnosis or just a coincidental finding of additional masticatory muscle activity? A narrative review of literature.

INTRODUCTION: Bruxism is defined as a repetitive masticatory muscle activity that can manifest it upon awakening (awake bruxism-AB) or during sleep (sleep bruxism-SB). Some forms of both, AB and SB can be associated to many other coexistent factors, considered of risk for the initiation and maintenance of the bruxism. Although controversial, the term 'secondary bruxism' has frequently been used to label these cases. The absence of an adequate definition of bruxism, the non-distinction between the circadian manifestations and the report of many different measurement techniques, however, are important factors to be considered when judging the literature findings. The use (and abuse) of drugs, caffeine, nicotine, alcohol and psychoactive substances, the presence of respiratory disorders during sleep, gastroesophageal reflux disorders and movement, neurological and psychiatric disorders are among these factors. The scarcity of controlled studies and the complexity and interactions among all aforementioned factors, unfortunately, does not allow to establish any causality or temporal association with SB and AB. The supposition that variables are related depends on different parameters, not clearly demonstrated in the available studies. OBJECTIVES: This narrative review aims at providing oral health care professionals with an update on the co-risk factors and disorders possibly associated with bruxism. In addition, the authors discuss the appropriateness of the term 'secondary bruxism' as a valid diagnostic category based on the available evidence. CONCLUSION: The absence of an adequate definition of bruxism, the non-distinction between the circadian manifestations and the report of many different measurement techniques found in many studies preclude any solid and convincing conclusion on the existence of the 'secondary' bruxism.

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.

Influence of Reported Physical Activity Level and Psychosocial Features on Orofacial Mechanical Sensitivity: A Pilot Study.

AIMS: To evaluate the influence of self-reported physical activity level on painful mechanical somatosensory profile and psychosocial characteristics. METHODS: A total of 90 participants, male and female, were divided into three groups based on the frequency, duration, and intensity of physical activity over the last 3 months. The classification followed a modified criterion of the short version of the International Physical Activity Questionnaire (IPAQ). Mechanical quantitative sensory tests were performed in the region of the anterior temporalis muscle and on the thenar area of the dominant hand, and psychosocial aspects were assessed using questionnaires measuring state and trait anxiety, pain catastrophizing, lifestyle, and quality of life. RESULTS: There was no significant main effect of group on any of the somatosensory variables (F < 0.34 and P > .416). As for psychosocial aspects, the low level of physical activity group had the lowest scores on the lifestyle questionnaire (P < .009). CONCLUSION: Level of physical activity did not significantly influence mechanical somatosensory thresholds or temporal summation in the orofacial region, and worse quality of life was found in participants reporting a low level of physical activity.

Local anaesthesia decreases nerve growth factor induced masseter hyperalgesia.

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.

Intraoral Somatosensory Alterations Impact Pulp Sensibility Testing in Patients with Symptomatic Irreversible Pulpitis.

INTRODUCTION: This case-control study aimed to compare trigeminal somatosensory sensitivity between patients with a clinical diagnosis of symptomatic irreversible pulpitis (n = 33) and healthy participants (n = 33) and to evaluate the impact of somatosensory stratification of symptomatic irreversible pulpitis on pulp sensibility testing. METHODS: A standardized battery of qualitative sensory assessment measured intra- and extraoral sensitivity to touch, cold, and pinprick stimuli. Dental pain intensity (0-100, numeric rating scale) and duration (seconds) evoked by cold stimuli (refrigerant spray) were applied to, respectively, the nonaffected and affected tooth (cases) and the upper right and left premolars (controls); z score transformation, analysis of variance (ANOVA), and chi-square tests were applied to the data (P = .050). RESULTS: Patients with irreversible pulpitis reported intraoral hypersensitivity more frequently than healthy participants (58% and 33%, respectively; P < .05). In addition, patients with irreversible pulpitis reported higher z scores of pain intensity (ANOVA main effects, F = 37.10, P < .05, partial η2 = 0.37) and duration (ANOVA main effects F = 23.3, P < .05, partial η2 = 0.27) after the pulp sensibility test compared with healthy participants. Nevertheless, subgroup analysis taking into account the presence of intraoral hypersensitivity indicated that the pain lingered most for patients with symptomatic irreversible pulpitis who also presented intraoral hypersensitivity (Tukey test, P < .05) but with no differences between patients with irreversible pulpitis without intraoral hypersensitivity and healthy participants (Tukey test, P > .05). CONCLUSIONS: QualST is able to detect intraoral alterations in patients with symptomatic irreversible pulpitis that seem useful to stratify the patients into distinct subgroups. Therefore, somatosensory assessment of the adjacent tissues may provide diagnostic fine-tuning of dental pulp diseases.

Topical anaesthesia degree is reduced in temporomandibular disorders patients: A novel approach to assess underlying mechanisms of the somatosensory alterations.

BACKGROUND: Changes in quantitative sensory testing (QST) parameters following topical anaesthesia could contribute to better elucidate underlying mechanisms of somatosensory alterations in temporomandibular disorder (TMD) pain patients. This placebo-controlled crossover investigation compared the somatosensory profile following topical anaesthesia between TMD patients (n = 20) and healthy participants (n = 20). METHODS: Cold detection threshold, warm detection threshold, cold pain threshold, heat pain threshold, mechanical detection threshold, mechanical pain threshold, wind-up ratio and pressure pain threshold were assessed on the skin overlying the masseter at three consecutive days (baseline and immediately after lidocaine 4%/placebo cream). Mixed ANOVA and a coding system that accounts for the diversity of types of peripheral axons associated with the somatosensory parameters were applied for data analysis. RESULTS: The lidocaine application caused no changes in the somatosensory sensitivity in the masseter region in TMD patients (P > .050), but sensitivity to cold, cold pain, touch and pinprick stimuli were reduced after topical anaesthesia in healthy participants (P < .050). Also, the degree of topical anaesthesia was greater in healthy participants (P = .008). The coding system suggested that TMD patients presented only Aδ-fibre block, whereas a combination of either Aß- and/or C-fibre block was observed in 35% of healthy participants in addition to Aδ-fibre block following lidocaine application. CONCLUSION: Quantitative sensory testing can be successfully applied to identify meaningful differences in the degree of hypoalgesia and hypoesthesia following short-time topical anaesthesia.

Mobility of the upper cervical spine and muscle performance of the deep flexors in women with temporomandibular disorders.

BACKGROUND: Cervical spine disorders are frequently associated with temporomandibular disorders (TMDs). Although headache is common in TMD, few studies have considered headache regarding the functional performance of the cervical spine in TMD. OBJECTIVES: To evaluate TMD subjects with and without self-reported headache, assess the active and passive range of motion (ROM) of the upper cervical spine (C1-C2) and performance of the deep cervical flexors, and evaluate the correlation of these outcomes with neck disability and temporomandibular pain. METHODS: In this cross-sectional study, we assessed 57 women (40 with TMDs and 17 without TMDs [controls]). The TMD group was divided into 25 and 15 patients with and without self-reported headache, respectively. We assessed the active and passive upper cervical ROMs using the flexion-rotation test (FRT) and muscle performance using the craniocervical flexion test (CCFT). The neck disability index questionnaire and visual analog scale were used to assess self-reported neck disability and temporomandibular pain, respectively. RESULTS: Compared to controls, all TMD subjects showed reduced cervical mobility on flexion/extension movements, reduced FRT findings and worse performance in CCFT (P < .05 all). Additionally, the CCFT and FRT findings were correlated with temporomandibular pain (r = .4 and .5, respectively) and neck disability (r = .3 and .4, respectively). CONCLUSION: Women with TMDs, regardless of self-reported headaches, showed limited flexion/extension ROM, limited upper cervical spine (C1-C2) mobility and poor deep cervical flexor performance. Neck disability and temporomandibular pain showed a moderate correlation with the functional test findings, that is FRT and CCFT, in subjects with TMDs.

Masseter corticomotor excitability is decreased after intramuscular administration of nerve growth factor.

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.

Contingent electrical stimulation inhibits jaw muscle activity during sleep but not pain intensity or masticatory muscle pressure pain threshold in self-reported bruxers: a pilot study.

OBJECTIVE: This study investigated the effect of contingent electrical stimulation (CES) on present pain intensity (PI), pressure pain threshold (PPT), and electromyographic events per hour of sleep (EMG/h) on probable bruxers with masticatory myofascial pain. STUDY DESIGN: The study enrolled 15 probable bruxers with masticatory myofascial pain in 3 phases: (1) baseline EMG/h recording, (2) biofeedback treatment using a CES paradigm (active group, n = 7) or inactive device (control group, n = 8), and (3) posttreatment EMG/h recording. PI and PPT were assessed after each phase. Analysis of variance models were used to compare results at a 5% significance level. RESULTS: Patients in the active group had 35% lower EMG/h in P2 and 38.4% lower EMG/h in P3, when compared with baseline. There were no differences in PI or PPT levels at any phase. CONCLUSIONS: CES could reduce EMG activity associated with sleep bruxism in patients with masticatory myofascial pain but did not influence perceived pain.

O uso da artrocentese para tratamento do travamento fechado da articulação temporomandibular - relato de caso / The use of arthrocentesis for the treatment of closed lock of the temporomandibular joint - case report

O travamento fechado (TF) da articulação temporomandibular (ATM) tradicionalmente é considerado como consequência de um disco articular deslocado, deformado e irredutível que atua como um obstáculo para a translação condilar. Porém, disco deslocado, fenômeno do disco ancorado ou osteoartrite pode ser a origem intracapsular do TF. Quando o adequado tratamento conservador não resulta em completa solução para a disfunção temporomandibular (DTM) de origem articular, alguns casos selecionados podem ser indicados para intervenções cirúrgicas da ATM. Dentre os tratamentos cirúrgicos utilizados, a artrocentese é o procedimento menos invasivo. O objetivo é relatar um caso de paciente, não responsivo ao tratamento conservador, com limitação de abertura bucal acompanhada de importante sintomatologia dolorosa. Conclui-se que o sucesso da artrocentese está intimamente relacionado com a correta indicação. Deve ser indicada para casos de fenômeno do disco ancorado e pode ser utilizada precocemente em deslocamento de disco sem redução, onde a dor é o principal fator limitante

Closed lock (CL) of the temporomandibular joint (TMJ) is defined as the consequence of a disc displaced, deformed and unyielding that acts as an obstacle to the condylar translation. However, displaced disc or anchored disc phenomenon of osteoarthritis can be the source of intracapsular CL. When the appropriate conservative treatment does not result in complete solution for temporomandibular disorders (TMD), some selected cases may be indicated for surgical management of the TMJ. Among the surgical treatments for TMJ, arthrocentesis is the less invasive one. The objective of this paper was to report a case of a patient, non-responsive to conservative treatment, with limited mouth opening, accompanied by significant TMJ pain. It is concluded that the success of arthrocentesis is closely related to the proper indication. It should be indicated in cases of anchored disc phenomenon and can be used early in disc displacement without reduction, where the pain is the main symptom

Avaliação da influência da alteração dimensional do gesso tipo IV nas moldagens de Implantodontia / Evaluation of type IV gypsum dimensional changes after impression taking for implants

O objetivo deste trabalho foi analisar a alteração dimensional de modelos de gesso obtidos através de 2 técnicas de vazamento. Neste estudo, as mudanças dimensionais ocorridas nos dois grupos de modelos foram avaliadas com o propósito de estabelecer os parâmetros ideais para o procedimento de vazamento. Para isso, foi confeccionado um modelo mestre em aço com 2 réplicas de intermediários para implantes, moldado com silicona de adição e, a partir de 20 moldes, foram obtidos dois grupos de 10 para os procedimentos de vazamento: Grupo 1 - 10 modelos de gesso obtidos com gesso tipo IV na proporção água/pó recomendada pelo fabricante, com espatulação mecânica (grupo controle); Grupo 2 - 10 modelos de gesso obtidos com gesso tipo IV com proporção de água 10% maior que a recomendada pelo fabricante, com manipulação manual, mantendo a mesma medida de pó. Para a leitura dos resultados, foi utilizado um microscópio comparador para medir a distância entre as faces externas e internas das réplicas dos intermediários protéticos. Para a análise estatística, foi aplicado o teste de Tukey, o qual não mostrou diferença significante entre as distâncias externas e internas das réplicas do Grupo 1 (controle) e as do modelo mestre, o que não foi observado entre as do Grupo 2 e as do modelo mestre, isso mostra uma evidência da distorção ocorrida no modelo de trabalho quando não é seguida a correta proporção água/pó para o gesso tipo IV

Conexões entre dentes naturais e implantes / Connections between natural teeth and implants

A união de dentes a implantes, através de próteses parciais fixas, é assunto de controvérsia na Odontologia atual. Com o advento dos implantes, casos mais complexos começaram a ser solucionados, mas casos nos quais a falta de tecido ósseo, a proximidade com o canal mandibular ou seio maxilar ou a perda de implantes impossibilitavam a reabilitação com a utilização de vários implantes, levaram os cirurgiões-dentistas a optarem pela união de dentes remanescentes e implantes numa mesma prótese. Neste trabalho realizou-se uma revisão de literatura e discussão da possibilidade de união de dentes naturais a implantes através de próteses fixas, das alternativas de união, dos aspectos biomecânicos apresentados frente às forças mastigatórias e da possibilidade de intrusão dentária. Conclui-se que, dependendo do tipo e localização da conexão, podem ocorrer intrusões dentárias; que o uso de conexões rígidas é viável dependendo de fatores como a condição periodontal, a seleção do "abutment" e a quantidade de implantes e dentes de suporte; além disso, essas conexões são as que apresentam as maiores vantagens biomecânicas; e que novas pesquisas devem ser realizadas com os novos tipos de implantes e conexões disponíveis no mercado