Temporomandibular Joint Disorders: A Review

INTRODUCTION

The temporomandibular joint (TMJ) is the joint that is most complex in the body. On Average person opens and closes their jaw up to 2000 times per day to account for a full day’s worth of chewing, talking, breathing, swallowing, yawning, and snoring.¹ The jaw, cervical spine, and alignment of the teeth are integrally related, and dysfunction in one of these regions may cause temporomandibular joint (TMJ) disorder, which is a term used to define clinical disorders resulting in jaw pain or dysfunction.

The etiology of TMJ disorder is usually multifactorial and it may be due to stress, malocclusion, habitual activities including bruxism, postural dysfunction, inflammatory conditions, and trauma.² TMJ disorders more commonly occur in females in comparison to males and the age range from 20-40 years. In general, TMJ disorders are believed to affect anywhere between 5 and 15% of adults in the population[7–10], yet TMD-related symptoms have been reported to be present in up to 50% of adults [11]. Interestingly, there is evidence that the prevalence of TMJ disorders appears to be on the rise in recent years [12–16]. A recent systematic review and meta-analysis in 2021 concluded that the prevalence of TMJ disorders was 11% for children and adolescence and 31% for adults [17].

TMJ disorders represent a significant and complex health problem, with opinions regarding the appropriate course of management often equivocal. In this review, we discuss the current concepts in the etiology and diagnosis of TMJ disorders, followed by an up-to-date management approach from a surgeon’s perspective.

TEMPOROMANDIBULAR JOINT ANATOMY

The temporomandibular joint (TMJ) is a ginglymoarthrodial joint formed by the mandibular fossa and the condyle of the mandible.An articular disk of the TMJ is a thin, oval made up of non-vascular fibrous connective tissue that separates the joint into two synovial cavities with distinctive movement patterns.³ Translatory or gliding movement occurs in the superior joint i.e., between the articular disk and the mandibular fossa. Hinge or rotary movement takes place in the inferior joint i.e., between the articular disk and the condyle.⁴
The muscles present in TMJ disorders are the muscles of the mastication: masseter, temporalis, medial, and lateral pterygoid muscles. Three important ligaments steady the TMJ are the temporomandibular ligament, sphenomandibular ligament, and stylomandibular ligament.
The main blood supply of the TMJ comes from the superficial temporal artery and maxillary branches of the external carotid artery.
Other blood supplies include the anterior tympanic artery, deep auricular artery, and ascending pharyngeal artery. The TMJ receives its sensory innervation from the auriculotemporal branch and the masseteric branch of the mandibular nerve (V3), a branch of the trigeminal nerve.

ETIOLOGY

The etiology of TMJ disorders is moderately understood, but it is concluded to be multifactorial, the proper management of the case need recognizing the predisposing and contributing factors. Myofascial and intraarticular TMJ disorders vary in their etiological factors. As the name signifies, a myofascial disorder means that the masticatory muscles are affected, becoming tense, fatigued, and painful. different factors are linked to muscular dysfunction, including stress, parafunctional habits like bruxism and abnormal posture, psychological conditions like depression and anxiety, and autoimmune diseases.¹⁰

Chronic pain conditions such as fibromyalgia are also often linked to TMJ disorders. Intraarticular disorders refer to inflammatory or mechanical factors which affect the joint, articular disc displacement is the most common. Other intraarticular causes are trauma, capsular inflammation, osteoarthritis, hypermobility, and inflammatory diseases, such as rheumatoid arthritis. it is not yet confirmed that malocclusion contributes to TMD.

DIAGNOSIS OF TMD

Acknowledging the causes of pain and dysfunction related to TMJ disorders is important in making treatment decisions. For instance, different treatment options are often used for the treatment of myogenous versus arthrogenous TMJ disorders. Moreover, those patients who present with TMJ disorders symptoms without a distinct physical cause, who also suffer from psychological co-morbidity, may be best treated by counseling and psychological treatment. The most important part of the diagnosis of TMJ disorders is to differentiate the common diseases from those clinically significant, but unusual conditions, as well as conditions that are more serious for which urgent attention is needed. For example, chondrosarcoma of TMJ is one of the neoplasms that may initially have signs and symptoms as some of the common diagnoses of TMJ disorders, such as pain at the preauricular region and limited mouth opening.⁵ Another example that requires urgent attention is temporal arteritis, which is an inflammatory condition of the temporal vessels with some TMJ disorders-like symptoms, such as headache, pain in the temporal region, and limited mouth opening. However, temporal arteritis is a medical emergency that may cause permanent blindness if not treated promptly.

TREATMENT/MANAGEMENT

Conservative approaches in TMJ disorders reduce symptoms by 50-90 percent and should be applied first. Conservative treatment comprises patient consolation and education, a soft diet, less jaw movement, warm compresses on the painful area, and passive stretching. Occlusal and non-occlusal splints for the management of TMJ disorders remain unclear and not well supported by evidence.

Behavioral Changes

Due to an increase in emotional stress levels, there is an alteration in muscle activity. In treating TMJ disorders, managing a patient’s stress level is very important. Behavioral changes like improving sleep, reducing stress, and treating parafunctional habits can outstandingly improve symptoms. Cognitive-behavioral therapy helps patients with TMJ disorders with short- and long-term treatment.²

Patient Awareness

Educating patients about the association between muscle hyperactivity and stress improves patients’ behavior toward the condition, psychological health, and TMJ disorders.⁶

Restrictive Use

The most common complaint by patients with TMJ disorders is in the TMJ and restricted mandibular movement. The clinician can advise the patient to move the mandible within a difficulty-free range of motion, promoting psychological health and pain management.

Voluntary Avoidance

Patients must try to reduce teeth contact time, but not during mastication, swallowing, and speaking. Clinicians can teach patients how to disocclude the tooth to reduce pain and discomfort. A simple exercise of lip puffing can disengage teeth and enhance patient health.

Physiotherapy

Stretching exercises can improve the range of motion but do not always alleviate the pain. The commonly used manual techniques are soft tissue mobilization, joint mobilization, muscle conditioning, resistance exercises, unassertive stretching of muscle, assisted stretching of muscle, and training of muscle. Thermotherapy, ultrasound, electro galvanic stimulation, and cold laser are other physical therapy modalities that include in physiotherapy.⁶

Pharmacological Treatment

Non-steroidal anti-inflammatory drugs (NSAIDs) are the first line of medicine for treating acute and chronic TMJ disorders. when relaxation management has failed in cases of repetitive masticatory muscle spasms and bruxism, clinicians can give benzodiazepines.⁸ Tricyclic antidepressants may be prescribed as a trial since they improve symptoms of other pain disorders.

Invasive Procedures

Intra-articular long-acting corticosteroids, hyaluronic acid, and botox injections come in this procedure. These treatments are suggested once conservative therapies have failed or in severe acute aggravation.¹⁰

In the acute treatment of osteoarthritis of the TMJ, intra-articular steroids are indicated. Many doses of intra-articular steroids can lead to the destruction of articular cartilage. In treating acute exacerbations there is only less proof regarding the efficacy of hyaluronic acid injection.

Botulinum toxin injections are used to treat painful trigger points and chronic bruxism, but not enough conclusions are found in a recent Cochrane study for myofascial pain.

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