CLINICAL Temporomandibular dysfunction Jonathan Lomas, Taylan Gurgenci, TEMPOROMANDIBULAR DYSFUNCTION (TMD) includes anatomical, pathophysiological Christopher Jackson, Duncan Campbell encompasses a group of disorders of the and psychosocial factors. Successful masticatory system, broadly divided into management of the disorder involves muscular conditions and those affecting identifying and managing these Background the temporomandibular joint (TMJ). TMD predisposing and contributing factors.1 Orofacial pain is a common is a common condition, signs of which Where possible, it is important to presentation in the primary healthcare 1 setting and temporomandibular appear in up to 60–70% of the population. distinguish between myofascial causes dysfunction represents one of the major The peak incidence is seen in adults aged of TMD and intra-articular disorders of causes. Its aetiology is multifactorial, 20–40 years. Women are at least four the joint itself. Myofascial disorders are caused by both masticatory muscle times as likely to suffer from the disorder.1 the result of tension, fatigue or spasm of dysfunction and derangement within Despite signs of TMD being common, the masticatory muscles, whereas intra- the temporomandibular joint. the reported prevalence of symptomatic articular disorder stems from mechanical Objective disease requiring treatment occurs in only or inflammatory disruption of the joint The aim of this article is to provide 5% to 12% of the population.2 Broadly itself. Musculoskeletal dysfunction an overview of temporomandibular speaking, TMD commonly refers to is the most common cause of TMD.5 dysfunction, its management and pain involving the TMJ and surrounding Parafunctional behaviours, such as referral considerations for general structures as well as dysfunction of the bruxism, teeth grinding, clenching and practioners. joint itself. abnormal posture, stress and anxiety, may Discussion all contribute to masticatory muscle pain Temporomandibular joint Anatomy and spasm. Cognitive and psychiatric dysfunction affects a large number disturbance, such as depression and of adults. Conservative management The TMJ is a ginglymoarthrodial joint anxiety, and autoimmune disorders, involving non-pharmacological and and is formed by the insertion of the fibromyalgia and other chronic pain pharmacological therapies is effective mandibular condyle into the glenoid conditions are also frequently associated in the majority of cases. fossa of the temporal bone. It is a complex with TMD6 and may signal that the synovial system composed of two joints symptoms could be a component of a separated by the articular disc. It is the more complex regional pain syndrome. most frequently used joint in the body3 Intra-articular causes of TMD include and permits a wide range of movements internal joint derangement, osteoarthritis, necessary for mastication, swallowing and capsular inflammation, hypermobility communication. The relevant musculature and traumatic injury. Inflammatory involved in TMD are the primary muscles conditions, such as rheumatoid arthritis of mastication, including the masseter, and ankylosing spondylitis, can also lead to temporalis and medial and lateral internal joint derangement. Articular disc pterygoid muscles. Sensory innervation displacement from the normal position is of the TMJ involves branches of the third the most common intra-articular cause of division of the trigeminal nerve, including TMD.7 It is important to note, however, the auriculotemporal and masseteric that disk displacement is a common nerves. Importantly, the auriculotemporal finding in the general population and nerve also provides some sensory the majority of those are asymptomatic. innervation to the temporal region, There is minimal evidence that occlusion external ear and tympanic membrane, abnormalities contribute to TMD. and is highly sensitive to pain responses.4 Differential diagnosis Aetiology It is important to stress that many orofacial The aetiology of TMD is poorly understood and otological conditions can mimic but is likely to be multifactorial and TMD. Conversely, the assumption that 212 | REPRINTED FROM AJGP VOL. 47, NO. 4, APRIL 2018 © The Royal Australian College of General Practitioners 2018 TEMPOROMANDIBULAR DYSFUNCTION CLINICAL TMD is the cause of a patient’s symptoms related to articular surface disruption and is becoming less important as surgical can result in a more sinister pathology may suggest the presence of osteoarthritis. options for treatment diminish. being missed. Box 1 outlines some of the Using a stethoscope to ascultate over the differential diagnoses to consider when TMJ can be a useful adjunct to confirm Management assessing a patient with orofacial pain. the presence of crepitus. A clicking or popping sensation when opening For the majority of patients, a conservative Clinical assessment the mouth may suggest articular disc approach to TMD management should displacement. Malocclusion of the teeth be adopted. Up to 40% of symptomatic TMD is a clinical diagnosis and a thorough should be noted if present; however, this patients have spontaneous resolution of history of the presentation and physical does not contribute to the manifestation their symptoms without any treatment,14 examination should be conducted, of TMD and orthodontic referral is not and 50–90% of patients have relief with paying particular attention to site, onset, recommended for this finding alone. conservative therapy.15 For the general character of pain, radiation, duration and In general terms, tenderness elicited practioner, non-pharmacological and associated symptoms. Typically, patients on palpation of the TMJ, joint clicking pharmacological treatments represent the describe pain within the TMJ or mandible and crepitus are signs of intra-articular main options available. as the predominant symptom. This pain derangement, whereas pain on jaw Non-pharmacological treatments may refer to the scalp or neck, and is often movement, headache and referred pain include patient education and reassurance, exacerbated by mastication, yawning or are suggestive of a muscular problem.12 jaw rest, a soft diet, warm compress over talking for extended periods.4 Difficulty The examination should also include the region of pain and passive stretching opening the mouth, clicking, popping or otoscopy to eliminate otological causes, exercises.8 Stretching and jaw exercises crepitus within the TMJ itself and brief inspection of the oral cavity and palpation locking of the mandible on jaw opening of neck musculature. and closure are also often reported. Box 1. Causes of orofacial pain Orofacial pain not associated with jaw Diagnostic imaging movement may suggest another cause Dental conditions for the patient’s symptoms.8 Headache, Although TMD is largely a clinical • Caries particularly tension type headache, is diagnosis, imaging can be useful, • Tooth abscess a common presentation in the primary particularly when history and examination • Tooth eruption healthcare setting and it is well established findings are unclear. Plain radiography Otological conditions that TMD and primary headache disorder and computed tomography may reveal • Acute otitis media are comorbid diseases;9 the presence of severe degenerative articular disease • Otitis externa (acute or malignant) one may increase the prevalence of the and, importantly, rule out fractures and • Mastoiditis other. Otological symptoms, including dislocations as a cause of the patient’s • Eustachian tube dysfunction otalgia, tinnitus, aural fullness, vertigo symptoms. Panoramic radiography, Headache disorder and subjective hearing impairment, including orthopantomogram, is a • Tension type headache are also frequently reported in patients simple and useful screening tool that • Migraine with TMD.10 These symptoms are more should be used early in the diagnostic • Cluster headache common in patients with myofascial workup to exclude common odontogenic disturbance than in those with intra- causes of facial pain as well as assess Neurogenic conditions articular disc disorder, possibly because of for joint pathology. Ultrasonography is • Trigeminal neuralgia the shared embryonic origin of masticatory not sensitive for the diagnosis of intra- • Postherpetic neuralgia muscles and some middle ear structures.11 articular osteoarthritis, but may be useful • Glossopharyngeal neuralgia Physical examination should include in assessment of disc position in TMJ Inflammatory conditions thorough palpation of the TMJ and disorders.3 Magnetic resonance imaging • Temporal arteritis masticatory muscles, noting any abnormal (MRI) is currently the gold standard for • Rheumatoid arthritis mandibular movement, tenderness and investigation of TMD. The advantage • Systemic lupus erythematosus signs of bruxism. Normal jaw opening of MRI is the ability to assess soft tissue • Parotitis values are 35–45 mm; a value less than structures, articular disc displacement Traumatic 25 mm suggests dysfunction with no and the presence of joint effusion • Mandibular fracture/dislocation translation occurring within the joint. with a high degree of specificity and • Temporal bone fracture Examination of the TMJ can be enhanced sensitivity.13 Given the high cost of MRI, Other by placing one finger in the ear canal and it is predominantly used in the setting of • Atypical facial pain palpating the anterior canal wall while severe, treatment-resistant TMD, as well • Sinusitis the patient opens and closes the mouth. as for pre-operative