Manejo das disfunções temporomandibulares. Parte I: tratamento conservador / Management of temporomandibular joint disorders. Part I: conservative treatment

Objetivo: Apresentar as modalidades de tratamentos conservadoras e minimamente invasivas mais usadas disponíveis no arsenal terapêutico das desordens temporomandibulares (DTM). Revisão da literatura: Os objetivos do tratamento invariavelmente incluem redução da dor, diminuição das atividades parafuncionais e restauração da função. Dentre as alternativas conservadoras e minimamente invasivas, podemos citar os dispositivos interoclusais, exercícios terapêuticos, eletrofototermoterapia, agulhamento seco e infiltração de anestésicos locais em pontos gatilho, injeção de sangue autógeno para controle da luxação mandibular, terapia cognitivo comportamental, toxina botulínica, viscossuplementação, controle farmacológico da dor aguda e crônica. As DTMs afetam uma proporção significativa da população. Somente após o fracasso das opções não invasivas é que devem ser iniciados tratamentos mais invasivos e irreversíveis. No entanto, algumas condições, como a anquilose e neoplasias, por exemplo, são essencialmente tratadas cirurgicamente e tentativas de tratamentos conservadores podem trazer piora na qualidade de vida ou risco de morte. Considerações finais: Uma abordagem de equipe multidisciplinar para o manejo é essencial no cuidado fundamental de todos os pacientes com DTM, para que o tratamento possa ser especificamente adaptado às necessidades individuais do paciente.

Aim: To present the most widely used conservative and minimally invasive treatment modalities available in the therapeutic arsenal for temporomandibular disorders (TMD). Literature review: Treatment goals invariably include pain reduction, reduction of parafunctional activities and restoration of function. Among the conservative and minimally invasive alternatives, we can mention interocclusal devices, therapeutic exercises, electrophototherapy, dry needling and infiltration of local anesthetics in trigger points, autogenous blood injection to control mandibular dislocation, cognitive behavioral therapy, botulinum toxin, viscosupplementation, pharmacological control of acute and chronic pain. TMD affects a considerable proportion of the population. Only after non-invasive options have failed should more invasive and irreversible treatments be initiated. However, some conditions, such as ankylosis and neoplasms, for example, are treated surgically and attempts at conservative treatments can lead to worsening quality of life or risk of death. Conclusions: A multidisciplinary team approach to management is essential in the fundamental care of all TMD patients, so that treatment can be specifically tailored to the patient's individual needs.

[Quality Evaluation of Temporomandibular Joint Images from 3 High-resolution Dynamic Sequences].

Objective To compare the image quality of three high-resolution dynamic MRI methods for evaluating the motion of temporomandibular joint disc and condyle. Methods Twenty-five patients with suspected temporomandibular joint disorders were examined by single-shot fast spin-echo (SSFSE),fast imaging employing steady-state acquisition (FIESTA),and spoiled gradient echo (SPGR) on the oblique sagittal position.Two radiologists performed subjective and objective evaluation on the images with double-blind method.The subjective evaluation included the signal intensity of mandibular condyle,articular disc,soft tissue around articular disc,and lateral pterygoid muscle,the contrast between articular disc and condyle,the contrast between articular disc and surrounding soft tissue,condylar motion,and disc movement.The objective evaluation indexes included image signal intensity,signal-to-noise ratio (SNR),and contrast-to-noise ratio (CNR).The subjective and objective indexes of the image quality were compared between the three sequences. Results The SSFSE sequence had lower signal intensity of articular disc and higher signal intensity of condyle and surrounding soft tissue than FIESTA and SPGR sequences (all P<0.001).The SPGR sequence showed higher signal intensity of lateral pterygoid muscle than the SSFSE and FIESTA sequences (P=0.017,P<0.001).Among the three sequences,SSFSE sequence showed the clearest articular disc structure (χ2=41.952,P<0.001),the strongest contrast between articular disc and condyle (χ2=35.379,P<0.001),the strongest contrast between articular disc and surrounding soft tissue (χ2=27.324,P<0.001),and the clearest movement of articular disc (χ2=44.655,P<0.001).SSFSE and FIESTA sequences showed higher proportion of disc displacement and reduction than SPGR sequence (all P<0.001).The CNR (χ2=21.400,P<0.001),SNR (χ2=34.880,P<0.001),and condyle signal intensity (F=337.151,P<0.001) demonstrated differences among SSFSE,FIESTA,and SPGR sequences.The CNR of SSFSE sequence was higher than that of FIESTA sequence (P<0.001),while it had no significant difference between SSFSE and SPGR sequences (P=0.472).In addition,the SSFSE sequence had higher SNR and signal intensity than FIESTA and SPGR sequences (all P<0.001). Conclusion The best image quality can be observed from SSFSE sequence where both the structure and movement of temporomandibular joint are well displayed.Therefore,SSFSE is preferred for the examination of temporomandibular joint movement.

Temporomandibular disorders cases with high-impact pain are more likely to experience short-term pain fluctuations.

Temporomandibular disorders (TMD) patients can present clinically significant jaw pain fluctuations which can be debilitating and lead to poor global health. The Graded Chronic Pain Scale evaluates pain-related disability and its dichotomous grading (high/low impact pain) can determine patient care pathways and in general high-impact pain patients have worse treatment outcomes. Individuals with low-impact TMD pain are thought to have better psychosocial functioning, more favorable disease course, and better ability to control pain, while individuals with high-impact pain can present with higher levels of physical and psychological symptoms. Thereby, there is reason to believe that individuals with low- and high-impact TMD pain could experience different pain trajectories over time. Our primary objective was to determine if short-term jaw pain fluctuations serve as a clinical marker for the impact status of TMD pain. To this end, we estimated the association between high/low impact pain status and jaw pain fluctuations over three visits (≤ 21-day-period) in 30 TMD cases. Secondarily, we measured the association between jaw pain intensity and pressure pain thresholds (PPT) over the face and hand, the latter measurements compared to matched pain-free controls (n = 17). Jaw pain fluctuations were more frequent among high-impact pain cases (n = 15) than low-impact pain cases (n = 15) (OR 5.5; 95% CI 1.2, 26.4; p value = 0.033). Jaw pain ratings were not associated with PPT ratings (p value > 0.220), suggesting different mechanisms for clinical versus experimental pain. Results from this proof-of-concept study suggest that targeted treatments to reduce short-term pain fluctuations in high-impact TMD pain is a potential strategy to achieve improved patient perception of clinical pain management outcomes.

A novel rat model of temporomandibular disorder with improved face and construct validities.

AIMS: Temporomandibular disorders are a cluster of orofacial conditions that are characterized by pain in the temporomandibular joint (TMJ) and surrounding muscles/tissues. Animal models of painful temporomandibular dysfunction (TMD) are valuable tools to investigate the mechanisms responsible for symptomatic temporomandibular joint and associated structures disorders. We tested the hypothesis that a predisposing and a precipitating factor are required to produce painful TMD in rats, using the ratgnawmeter, a device that determines temporomandibular pain based on the time taken for the rat to chew through two obstacles. MATERIALS AND METHODS: Increased time in the ratgnawmeter correlated with nociceptive behaviors produced by TMJ injection of formalin (2.5%), confirming chewing time as an index of painful TMD. Rats exposed only to predisposing factors, carrageenan-induced TMJ inflammation or sustained inhibition of the catechol-O-methyltransferase (COMT) enzyme by OR-486, showed no changes in chewing time. However, when combined with a precipitating event, i.e., exaggerated mouth opening produced by daily 1-h jaw extension for 7 consecutive days, robust function impairment was produced. KEY FINDINGS: These results validate the ratgnawmeter as an efficient method to evaluate functional TMD pain by evaluating chewing time, and this protocol as a model with face and construct validities to investigate symptomatic TMD mechanisms. SIGNIFICANCE: This study suggests that a predisposition factor must be present in order for an insult to the temporomandibular system to produce painful dysfunction. The need for a combined contribution of these factors might explain why not all patients experiencing traumatic events, such as exaggerated mouth opening, develop TMDs.

Ultra-Low Frequency Transcutaneous Electrical Nerve Stimulation on Pain Modulation in a Rat Model with Myogenous Temporomandibular Dysfunction.

Masticatory myofascial pain (MMP) is one of the most common causes of chronic orofacial pain in patients with temporomandibular disorders. To explore the antinociceptive effects of ultra-low frequency transcutaneous electrical nerve stimulation (ULF-TENS) on alterations of pain-related biochemicals, electrophysiology and jaw-opening movement in an animal model with MMP, a total of 40 rats were randomly and equally assigned to four groups; i.e., animals with MMP receiving either ULF-TENS or sham treatment, as well as those with sham-MMP receiving either ULF-TENS or sham treatment. MMP was induced by electrically stimulated repetitive tetanic contraction of masticatory muscle for 14 days. ULF-TENS was then performed at myofascial trigger points of masticatory muscles for seven days. Measurable outcomes included maximum jaw-opening distance, prevalence of endplate noise (EPN), and immunohistochemistry for substance P (SP) and µ-opiate receptors (MOR) in parabrachial nucleus and c-Fos in rostral ventromedial medulla. There were significant improvements in maximum jaw-opening distance and EPN prevalence after ULF-TENS in animals with MMP. ULF-TENS also significantly reduced SP overexpression, increased MOR expression in parabrachial nucleus, and increased c-Fos expression in rostral ventromedial medulla. ULF-TENS may represent a novel and applicable therapeutic approach for improvement of orofacial pain induced by MMP.

Avaliação eletromiográfica da musculatura mastigatória e da coluna cervical com uso de placa oclusal: relato de caso / Electromyographic evaluation of masticatory and cervical musculature with occlusal splint: case report

Objetivo: Avaliar a atividade elétrica de músculos mastigatórios e cervicais e sua inter-relação na estabilização da cadeia crânio cervico umeral com uso da placa oclusal, por meio da avaliação eletromiográfica. Relato de caso: Paciente sexo feminino, 39 anos, queixando-se de dores na cabeça, faciais e cervicais, com prejuízo em suas atividades diárias. Relatou apertar os dentes durante o dia e a noite e ser uma pessoa muito ansiosa. Pratica exercício físico de 5 a 6 vezes por semana. Foi submetida ao tratamento com placa oclusal estabilizadora. O exame eletromiográfico foi realizado nos músculos masseter e trapézio, bilateralmente. A coleta de dados foi realizada antes da instalação da placa e passados 90 dias de uso. Considerações finais: Após o tempo de tratamento, foi relatado redução do comportamento de apertamento noturno e diurno dos dentes, redução do nódulo muscular antes visível na região supraescapular, eliminação das dores e melhor rendimento muscular durante a prática de atividade física.(AU)

Objective: To evaluate the electrical activity of masticatory and cervical muscles and their relationship in the stabilization of the craniocervicohumeral chain using a occlusal splint, through electromyographic evaluation. Case report: Female patient, 39 years old, complaining of headaches, facial and cervical pain, with impairment in her daily activities. She reported teeth clenching during the day and night, and being a very anxious person. She practices physical exercise 5 to 6 times a week. She underwent treatment with a stabilizing occlusal splint. The electromyographic examination was performed on the masseter and trapezius muscles, bilaterally. Data was collected before occlusal splint installation and after 90 days of use. Final considerations: After the treatment period, it was reported a reduction in the behavior of nocturnal and daytime teeth clenching, reduction of the muscle nodule previously visible in the suprascapular region, elimination of pain and better muscle performance during the practice of physical activities.(AU)

Alterações posturais associadas a distúrbios respiratórios e sua correlação com as desordens temporomandibulares: uma revisão de literatura / Postural changes associated with respiratory disorders and their correlation with temporomandibular disorders: a literature review

Objetivo: a presente revisão almeja fornecer à prática clínico-odontológica e ao meio científico uma compreensão atualizada acerca da correlação entre as alterações posturais geradas pela presença de distúrbios respiratórios e as desordens temporomandibulares (DTMs). Revisão de literatura: foi realizada uma busca entre o período de 2005 a 2021 nas seguintes bases de dados: Medline (via PubMed), Portal de Periódicos Capes e Scopus, utilizando-se dos termos "temporomandibular joint; temporomandibular disorders; posture control; postural control; breathing". Como resultado, foram encontrados 4.384 documentos, que foram analisados por títulos, resumos, texto completo e critérios de elegibilidade, até se chegar ao total de 5 estudos a serem incluídos nesta revisão. Considerações finais: os principais fatores observados foram a associação das DTMs com condições como padrão de respiração do tipo bucal, postura anterior da cabeça, hiperatividade de músculos acessórios da respiração, rotação posterior da mandíbula e apneia obstrutiva do sono. Os estudos ressaltaram a necessidade da abordagem completa desses pacientes, visto que os papéis dos distúrbios respiratórios e das alterações posturais podem representar desafios no diagnóstico e no tratamento das DTMs.(AU)

Objective: this review aims to provide to the clinical dental practice and the scientific community an updated understanding of the correlation between postural changes generated by the presence of respiratory disorders and temporomandibular joint disorders (TMD). Literature review: a search was carried out covering the period from 2005 to 2021 in the following databases: Medline (via PubMed), Portal de Periódicos Capes and Scopus using the terms temporomandibular joint; temporomandibular disorders; posture control; postural control; breathing. As a result, 4,384 documents were obtained and shortlisted by title, abstracts, full text and eligibility criteria, resulting in the five studies included in this review. Final considerations: the main factors observed were the association of TMD with conditions as mouth breathing, anterior head posture, hyperactivity of accessory breathing muscles, posterior rotation of the jaw and obstructive sleep apnea. The studies underscored the need for a complete approach to these patients, given that the role of respiratory disorders and postural changes may represent a challenge in the diagnosis and treatment of TMD.(AU)

Mechanisms of Action and Efficacy of Hyaluronic Acid, Corticosteroids and Platelet-Rich Plasma in the Treatment of Temporomandibular Joint Osteoarthritis-A Systematic Review.

Temporomandibular joint osteoarthritis (TMJ OA) is a low-inflammatory disorder with multifactorial etiology. The aim of this review was to present the current state of knowledge regarding the mechanisms of action and the efficacy of hyaluronic acid (HA), corticosteroids (CS) and platelet-rich plasma (PRP) in the treatment of TMJ OA.: The PubMed database was analyzed with the keywords: "(temporomandibular joint) AND ((osteoarthritis) OR (dysfunction) OR (disorders) OR (pain)) AND ((treatment) OR (arthrocentesis) OR (arthroscopy) OR (injection)) AND ((hyaluronic acid) OR (corticosteroid) OR (platelet rich plasma))". After screening of 363 results, 16 studies were included in this review. Arthrocentesis alone effectively reduces pain and improves jaw function in patients diagnosed with TMJ OA. Additional injections of HA, either low-molecular-weight (LMW) HA or high-molecular-weight (HMW) HA, or CS at the end of the arthrocentesis do not improve the final clinical outcomes. CS present several negative effects on the articular cartilage. Results related to additional PRP injections are not consistent and are rather questionable. Further studies should be multicenter, based on a larger group of patients and should answer the question of whether other methods of TMJ OA treatment are more beneficial for the patients than simple arthrocentesis.

Mandibular range of motion in children with juvenile idiopathic arthritis with and without clinically established temporomandibular joint involvement and in healthy children; a cross-sectional study.

BACKGROUND: Recognition of temporomandibular joint (TMJ) involvement in children with juvenile idiopathic arthritis (JIA) has gained increasing attention in the past decade. The clinical assessment of mandibular range of motion characteristics is part of the recommended variables to detect TMJ involvement in children with JIA. The aim of this study was to explore explanatory variables for mandibular range of motion outcomes in children with JIA, with and without clinically established TMJ involvement, and in healthy children. METHODS: This cross-sectional study included children with JIA and healthy children of age 6-18 years. Mandibular range of motion variables included active and passive maximum interincisal opening (AMIO and PMIO), protrusion, laterotrusion, dental midline shift in AMIO and in protrusion. Additionally, the TMJ screening protocol and palpation pain were assessed. Adjusted linear regression analyses of AMIO, PMIO, protrusion, and laterotrusion were performed to evaluate the explanatory factors. Two adjusted models were constructed: model 1 to compare children with JIA and healthy children, and model 2 to compare children with JIA with and without TMJ involvement. RESULTS: A total of 298 children with JIA and 169 healthy children were included. Length was an explanatory variable for the mandibular range of motion excursions. Each centimeter increase in length increased AMIO (0.14 mm), PMIO (0.14 mm), and protrusion (0.02 mm). Male gender increased AMIO by 1.35 mm. Having JIA negatively influenced AMIO (3.57 mm), PMIO (3.71 mm), and protrusion (1.03 mm) compared with healthy children, while the discrepancy between left and right laterotrusion raised 0.68 mm. Children with JIA and TMJ involvement had a 8.27 mm lower AMIO, 7.68 mm lower PMIO and 0.96 mm higher discrepancy in left and right laterotrusion compared to healthy children. CONCLUSION: All mandibular range of motion items were restricted in children with JIA compared with healthy children. In children with JIA and TMJ involvement, AMIO, PMIO and the discrepancy between left and right laterotrusion were impaired more severely. The limitation in protrusion and laterotrusion was hardly clinically relevant. Overall, AMIO is the mandibular range of motion variable with the highest restriction (in millimeters) in children with JIA and clinically established TMJ involvement compared to healthy children.

Neuroimmune interactions in painful TMD: Mechanisms and treatment implications.

The underlying mechanisms and treatment of painful temporomandibular disorders (TMDs) are important but understudied topics in craniofacial research. As a group of musculoskeletal diseases, the onset of painful TMD is proved to be a result of disturbance of multiple systems. Recently, emerging evidence has revealed the involvement of neuroimmune interactions in painful TMD. Inflammatory factors play an important role in peripheral sensitization of temporomandibular joint (TMJ), and neurogenic inflammation in turn enhances TMJs dysfunction in TMD. Furthermore, centralized neuroimmune communications contribute to neuron excitability amplification, leading to pain sensitization, and is also responsible for chronic TMD pain and other CNS symptoms. Therapeutics targeting neuroimmune interactions may shed light on new approaches for treating TMD. In this review, we will discuss the role of neuroimmune interactions in the onset of painful TMD from the peripheral and centralized perspectives, and how understanding this mechanism could provide new treatment options. Insights into the neuroimmune interactions within TMJs and painful TMD would broaden the knowledge of mechanisms and treatments of this multifactorial disease.

An Overview of Anterior Repositioning Splint Therapy for Disc Displacement-related Temporomandibular Disorders.

Anterior repositioning splint (ARS) therapy is considered one of the most effective therapies for treating disc displacement-related temporomandibular disorders (TMDs), which account for a large proportion of TMD cases. Owing to the wide application of this therapy, the exact mechanism of remission has increasingly drawn attention. Given that practitioners have different views on ARS therapy, its indications are broadened, and operating methods diverged. This review attempts to provide an overview of ARS therapy and helps practitioners establish indications and suitable operating methods. Representative views in the past 10 years were summarised, and conclusions were drawn as follows: The mechanism of ARS therapy is mainly attributed to internal derangement correction, improvement of stress distribution and recently reported joint remodeling. It has an evident effect in the short term, and the most prevalent operating methods are protruding the mandible to the edge-to-edge position and wearing the ARS for 24 hours daily for 3-6 months. However, long-term stability is not optimal, and thus indications should be selected carefully. Notably, most of the clinical studies in this field are case analyses with low-quality evidence. Well-designed RCTs are required to further validate relevant theories.

"What if it doesn't unlock?": A qualitative study into the lived experiences of adults with persistent intra-articular temporomandibular disorders.

BACKGROUND: Temporomandibular disorders (TMD) are associated with increased self-reported disability and psychosocial issues, although little is known about those who specifically experience mechanical signs and symptoms such as clicking and locking. Understanding the lived experiences of individuals with persistent intra-articular TMD is an important first step to gaining insight into specific domains of self-reported disability associated with these conditions. This information can be helpful to improve clinical management of this subgroup. OBJECTIVES: To explore the lived experiences of adults with persistent intra-articular TMD, including its impact on activity, participation and psychological wellbeing, and the influence of contextual factors on disability. DESIGN: Qualitative study. METHODS: Semi-structured interviews explored the lived experiences of adults with persistent intra-articular TMD, and data were analysed using thematic analysis. Participants were recruited via convenience sampling from private physiotherapy and dental practices, and the community. RESULTS: Sixteen participants were interviewed. Four themes emerged from the data: i) The challenge of living with intra-articular TMD, ii) Living with uncertainty, iii) Seeking control, and iv) Learning to live with it. Novel findings included the impact of persistent intra-articular TMD on dreams, work, intimacy and socialising; and the role of non-pain symptoms (e.g. locking) in disability. CONCLUSIONS: Persistent intra-articular TMD are associated with numerous activity limitations, participation restrictions and psychological issues. Disability is complex and multi-directional, and influenced by various contextual factors including individuals' thoughts, beliefs and support networks. These findings emphasise the need for biopsychosocial and person-centred care in clinical practice.

Predisposing conditions for condylar sag after intraoral vertical ramus osteotomy.

Intraoral vertical ramus osteotomy (IVRO) is used to treat mandibular prognathism and temporomandibular disorders. However, the improvement of temporomandibular disorders after IVRO is considered to be due to the anterior and downward movement of the mandibular condyle, which may lead to condylar sag, and in the worst case, condylar luxation. In this retrospective cohort study, we examined factors potentially associated with condylar sag. Univariate analysis indicated that condylar sag was significantly associated with the following factors: magnitude of setback (P = 0.001), less than 3 mm setback (P < 0.001), presence of temporomandibular joint (TMJ) symptoms (P = 0.002), Wilkes classification (P = 0.039), occlusal cant correction ≥ 2 mm (P = 0.018), and mandibular condyle deformation (P < 0.001). Setback magnitude (P = 0.032) and TMJ symptoms (P = 0.007) remained significant in the multivariate analysis. In the receiver operating characteristic curve, the setback magnitude cut-off value for condylar sag after IVRO was 3.25 mm. Thus, the incidence of condylar sag after IVRO is increased with a smaller setback magnitude (≤ 3.25 mm) and the presence of TMJ symptoms. These factors should be evaluated by surgeons during treatment planning for IVRO to estimate condylar sag, and it may be possible to predict the risk of condylar luxation.

Association of Oral Behaviors with Anxiety, Depression, and Jaw Function in Patients with Temporomandibular Disorders in China: A Cross-Sectional Study.

BACKGROUND The aim of this study was to investigate the association of oral behaviors (OBs) with anxiety, depression, and jaw function in patients with temporomandibular disorders (TMDs) in China. MATERIAL AND METHODS A total of 537 patients diagnosed with TMD were included in this study (average age, 31.55±12.08 years; 86 men [16.0%] and 451 women [84.0%]). There were 31 cases of masticatory muscle pain, 459 cases of disc displacement, and 13 cases of arthralgia/arthrosis, and 34 cases were uncategorized. Patients were assessed using the Oral Behaviors Checklist (OBC), Jaw Functional Limitation Scale (JFLS), Generalized Anxiety Disorder-7 (GAD-7) scale, and Patient Health Questionnaire-9 (PHQ-9). The relationships between OBC scores and mouth opening, pain scores, JFLS, PHQ-9, and GAD-7 were evaluated with Spearman's correlation analysis. The median TMD symptom duration was 3 (0.5-154) months; men and women did not differ significantly in symptom duration or in the number of episodes of depression and anxiety. RESULTS The following OBs were common in patients with TMDs: "putting pressure on the jaw (52.9%)", "chewing food on 1 side (47.5%)", and "holding teeth together during activities other than eating (33.3%)". The OBC scores were significantly correlated with the JFLS, PHQ-9, and GAD-7 scores (P<0.01). CONCLUSIONS Patients with TMDs exhibit specific OBs, which are associated with depression, anxiety, and jaw function. It is necessary to further investigate the interaction of OBs with depression and anxiety in the development of TMDs.

Vitamin D and Temporomandibular Disorders: What Do We Know So Far?

BACKGROUND AND AIMS: Vitamin D is synthesized in the skin with the aid of ultraviolet-B radiation, playing a variety of roles in the body. Temporomandibular disorders (TMDs) are a group of pathological conditions involving the temporomandibular joints as well as the masticatory muscles and othersurrounding tissues. In the present narrative review, we investigated the potential role of vitamin D in the etiology of temporomandibular disorders in order todetermine whether the current knowledge supports 25-hidroxyvitamin D (25-OHD) supplementation in temporomandibular disorders associated with insufficient or deficient levels of vitamin D. METHODS: A literature research was performed in PubMed, Scopus, Science Direct, and Google Scholar databases, and a total of 10 articles were included for analysis. RESULTS: Among the observational studies published to date, investigating the role for vitamin D in the etiology of TMDs, six of them suggest that there is a connection between the two aspects. In this context, patients suffering from TMD, with deficient levels of vitamin D (<30 ng/mL), are most likely to benefit from supplementation, whereas individuals with vitamin D level >50ng/mL probably have little benefit from supplementation. CONCLUSION: Vitamin D might be a safe, simple, and potentially beneficial way to prevent TMDs or to reduce pain; however, more randomized and placebo-controlled trials are required before any firm conclusions can be drawn.

Three-dimensional finite element analysis of temporomandibular joints in patients with jaw deformity during unilateral molar clenching before and after orthognathic surgery.

ABSTRACT: To analyze the effects of orthognathic surgery on stress distributions in the temporomandibular joint (TMJ) of patients with jaw deformity during unilateral molar clenching (UMC) by using three-dimensional (3D) finite element method.Nine patients with jaw deformity (preoperative group, 26.1 ±â€Š5.6 years old) and 9 asymptomatic subjects (control group, 22.0 ±â€Š6.0 years old) were selected. Furthermore, the patients with jaw deformity were also considered as the postoperative group after undergoing orthognathic surgery. Finite element models for the mandible, articular disc, and maxilla were developed through cone beam computed tomography. Contact was used to simulate the interaction of the articular disc, condyle, fossa, and upper and lower dentition. The muscle forces and boundary conditions corresponding to the UMC were applied on the models.The stresses on both TMJs of the control group were significantly different, whereas there was no significant difference on both sides for the preoperative group. All the stresses of the preoperative group were greater than those of the control and postoperative groups, except the minimum principal stress on the ipsilateral fossa.Orthognathic surgery is beneficial for alleviating the abnormal stress distributions on TMJ.

The Impact of Education and Physical Therapy on Oral Behaviour in Patients with Temporomandibular Disorder: A Preliminary Study.

Patient education is important in the treatment of temporomandibular disorder (TMD), but little is known about its effect on oral behaviors. We aimed to determine the dominant oral behaviours in patients with TMD and assess the impact of education on such behaviours. Between July 2018 and April 2019, 54 patients diagnosed with TMD according to DC/TMD were recruited. They received physical therapy and were provided education on TMD and offered a list of recommendations for improving their oral behaviours. The patient education process usually lasted for 10-20 min. Of these patients, 48 were reexamined at the outpatient clinic, 3-9 months posttreatment. We recorded the Oral Behaviour Checklist (OBC) score, maximum painless mouth opening (mm), visual analogue scale (VAS) score for pain, and Jaw Functional Limitation Scale (JFLS) score pre- and posttreatment. Wilcoxon signed rank test and paired sample t-test were used for statistical analysis. Results showed that the most dominant oral behaviours included "putting pressure on the jaw" (59.3%); "chewing food on one side" (46.3%); "pressing, touching, or holding teeth together at times other than eating" (33.3%); and "eating between meals" (33.3%). Posttreatment, the patients reported a decrease in "chewing gum" (P = 0.002), "leaning with the hand on the jaw" (P = 0.013), "chewing food on one side" (P ≤ 0.001), and "eating between meals" (P = 0.007), but this change was not significant in subgroups with a follow-up interval of 9 months. We also observed a significant improvement in the maximum painless mouth opening (P ≤ 0.001), JFLS score (P ≤ 0.001), and VAS score (P ≤ 0.001) for pain, posttreatment. In conclusion, patient education can facilitate management of oral behaviours and should be targeted towards specific oral behaviours.

Temporomandibular joint dislocation in patients with cleft lip and palate after maxillary distraction osteogenesis: Three case reports.

INTRODUCTION: Distraction osteogenesis (DO) is a widely used for cleft and palate related maxillary hypoplasia. There has been little research on temporomandibular joint (TMJ) dislocation after maxillary DO. We present these 3 cases and analyze the possible causes for reference by other clinicians. PATIENT CONCERNS: In the late stages of maxillary DO, the patients gradually felt a decrease in mandibular mobility and suffered from limited mouth opening. Case 2 and 3 could open their mouth up to 1 and 2 fingers and Case 1 barely able to open her mouth at the completion of distraction. DIAGNOSIS: Case 1 and Case 3 were diagnosed as right TMJ dislocation and Case 2 had a TMJ dislocation on her left side. INTERVENTIONS: Patients with TMJ dislocation were repositioned with manipulation as soon as detected. OUTCOMES: There was no recurrence in all three cases during the postoperative follow-up period. CONCLUSIONS: Maxillary DO can sufficiently advance the maxilla in cleft lip and palate patients. Clinicians should be mindful of the TMJ dislocations that maxillary DO can exert on patients.

Effect of jaw clenching on postural adjustments to a predictable external perturbation.

This study investigated the effect of jaw clenching on anticipatory postural adjustments (APAs) and reactive postural adjustments (RPAs). Eight healthy adults were exposed to predictable external perturbations with and without submaximal jaw clenching. We recorded the three-dimensional body kinematics, ground reaction forces, and electromyography (EMG) of 12 muscles. EMG onset, integrated EMG, and positions of the center-of-mass (COM) and center-of-pressure (COP) during the anticipatory and reactive phases of postural adjustments were computed and compared for the jaw clenching and control conditions. Jaw clenching resulted in an earlier onset of APAs and a greater amplitude of trunk and lower limb EMG activities in the APAs and RPAs. There were no differences in the COM and COP displacements after the perturbation. Jaw clenching is effective for enhancing APAs and RPAs, although it may not increase postural stability following predictable external perturbation in healthy adults.

Imaging of the temporomandibular joint.

Temporomandibular disorders are common, especially in young to middle-aged women, and most settle with supportive treatment. Imaging is indicated for the small percentage of cases that do not respond to conservative management and when the diagnosis is no doubt. The temporomandibular joint (TMJ) is a bilateral synovial articulation between the mandible and skull base. It has an intra-articular disc dividing the joint into superior and inferior compartments and the articular surfaces are lined with fibrocartilage. The normal imaging anatomy of the TMJ is described and illustrated. Different movements occur in each joint compartments: a hinge movement in the inferior joint space and translation or gliding in the superior joint space. Internal derangement is the commonest disorder affecting the TMJ and is most commonly due to disc displacement, followed by osteoarthritis and inflammatory arthritides. The imaging findings, primarily on magnetic resonance imaging (MRI) and computed tomography (CT), of internal derangement and less common disorders of the joint, are reviewed and illustrated. Optimal imaging protocols are discussed with detailed reporting guidelines.