Temporomandibular disorder (TMD) refers to a group of conditions involving the orofacial region divided into those affecting the masticatory (chewing) muscles and those affecting the temporomandibular joint (TMJ). The typical features include pain in the TMJ, restriction of mobility, clicking and clunking sounds of the jaw, locking or dislocation.
TMD can also be the cause of other issues such as ear problems, tinnitus, vestibular issues, headaches etc.
Myofascial and intraarticular TMDs differ in their etiological factors. As the name implies, a myofascial disorder means that the muscles, their fascia and their fascial connections – in this case, the ones involved in mastication - are affected, becoming tensioned, fatigued, and painful. Several factors are linked to muscular dysfunction, including stress, parafunctional habits like bruxism and abnormal posture, psychological conditions like depression and anxiety, and autoimmune diseases. Chronic pain conditions such as fibromyalgia are also often linked to TMD.
Intraarticular disorders refer to inflammatory or mechanical factors that affect the joint itself, articular disc displacement being the most common. Other intraarticular causes include trauma, capsular inflammation, osteoarthritis, hypermobility, malocclusions and inflammatory diseases, like rheumatoid arthritis.
Research says that TMD symptoms can appear at any age, but a peak incidence occurs in adults between 20 to 40 years. Women are more likely to be affected than men, the reason for which is unknown. Even though up to 60 to 70% of the population shows signs of TMJ disorders, only 5% to 12% of people report symptoms and require treatment.
Temporomandibular Joint Disorders
Masticatory Muscle Disorders :Â pain in the masticatory muscles when swallowing, speaking, and chewing, pain increases with palpation and is associated with restricted movement of the jaw.
Derangement of the Condyle-Disc Complex : The derangement of the condyle disc complex arises due to a breakdown in the rotational function of the disc. This condition can result from the lengthening of ligaments and or thinning of the posterior disc border and could be a result of micro or macro trauma.
Disc Dislocation with Reduction : Disc displacement can lead to partial or complete disarticulation of the disc from discal space in condyle–disc assembly. When the mouth is closed, the articular disc is displaced anterior to the condyle head; when the mouth opens, the disc repositions on the condyle head similarly to normal. This on and off disc movement explains the click, snap, or pop sound in the TMJ. This sound does not appear with every movement of the mandible but with some frequency.
A normal range of motion is expected since the articular disc reduces during condylar translation. Jaw deviation while opening the mouth can occur; the interincisal distance of disc reduction during opening is greater than when the disc is dislocated during the closure.
The disc can sometimes fail to reduce with consequent mouth opening limitation. This is known as disc displacement with reduction with intermittent locking.
Disc Dislocation without Reduction : When the articular disc fails to reduce repeatedly, causing a limited mouth opening, the diagnosis of disc displacement without reduction is given.[6]Â The repositioning of the disc can become problematic due to the loss of elasticity in the superior retro-discal lamina. This situation causes forward translation of the condyle forcing the disc in front of the condyle. It presents as a locked jaw during the closure, represented as difficulty in maximum opening. The mandibular opening is around 25 to 30 mm, deflects towards the involved joint, and is associated with pain. The bilateral manipulation technique of loading the joint is painful due to the condyle position in the retro-discal tissues.
Structural Incompatibility with Articular Surfaces :Â The disorder results from changes in the smooth sliding surfaces of the TMJ. The alteration causes friction stickiness and inhibits joint function. Structural incompatibility classifies as a deviation in form, adhesions, subluxation, and spontaneous dislocation.
Deviation in the Form :Â The physiological aging or minor degeneration of the condyle, disc, and fossa can cause deviations and dysfunction, significantly affecting mandibular movements.
Adherences and Adhesions :Â An adherence represents a brief hold of the articular surfaces. Adhesion can happen between the condyle and disc or the disc and fossa. Adhesions result from a fibrous connective tissue or loss of lubrication between the structures. It is characterized by restriction in the normal translation of the condyle movement with no pain. In chronic situations, the patient senses an inability to get the teeth back to occlusion during the closure.
Subluxation :Â It is a non-pathologic condition, a repeatable clinical phenomenon characterized by a sudden forward movement of the condyle past the crest of the articular eminence during the final stages of mouth opening.
Luxation (dislocation) :Â A dislocation happens when the condyle moves in front of the articular eminence and cannot descend back to the normal position.[7] Dislocations result from the TMJ's hyperextension, causing the fixing of the joint in an open position during the opening of the mouth. It can be partial (subluxation) or complete (luxation). It can be acute or chronic (protracted or recurrent), bilateral or unilateral.[7] Anterior teeth are usually separated, and the posterior teeth are closed. The patient will find difficulty closing the mouth and pain.
Inflammatory Disorders of the TMJ :Â The joint disease of inflammatory origin characteristically presents with deep continuous pain commonly accentuated on functional movement. This constant pain can trigger secondary excitatory effects. It expresses as referred pain, sensitivity to touch, protective contraction, or a combination of these problems.
Synovitis/Capsulitis :Â Trauma can cause inflammation of the synovial tissues (synovitis) and the capsular ligament (capsulitis). It presents as continuous pain, tenderness on palpation, and limited mandibular movement.
Retrodiscitis :Â It is caused by trauma or progressive disc displacement and dislocation. The patient complains of pain, which increases with clenching. Limited jaw movement, swelling of retro discal tissues, and acute malocclusion are associated with the disease.
Arthralgia :Â The pain originates in the jaw and is affected by jaw movement, function, or para-function. The pain can be replicated with provocative testing of the TMJ.
Arthritis :Â Pain originates in the joint, and features of inflammation or infection over the affected joint are usually seen, such as edema, erythema, or increased temperature. Further symptoms include dental occlusal changes
Osteoarthritis :Â t is an inflammatory disorder that arises due to an increased joint overload. The increased forces soften the articular surfaces and resorb the subarticular surface. The progressive loading and the subsequent regeneration cause loss of the subchondral layer, bone erosion, and osteoarthritis. The condition characterizes by joint pain that increases with movement. It is also associated with disc dislocation and perforation.
Osteoarthrosis Arthrosis : is the adaptive unaltered arthritic changes of the bone due to decreased bone loading. It occurs after the overloading of the joint, mainly due to parafunctional activity, and is often associated with disc dislocation.
Chronic Mandibular Hypomobility : It is a long-term painless restriction of the mandible. Pain only occurs when using force to attempt opening beyond limitations. Hypomobility can be caused by ankylosis, muscle contracture, or coronoid process impedance.
Growth Disorders :Â Growth disturbances can affect the TMJ bones or muscles. Common growth disturbances of the bones are agenesis (no growth), hypoplasia (insufficient growth), hyperplasia (excessive growth), or neoplasia (uncontrolled, destructive growth). Common growth disturbances of the muscles are hypotrophy (weakened muscle), hypertrophy (increased size and strength of the muscle), and neoplasia (uncontrolled, destructive growth). The growth alterations typically result from trauma.
Temporomandibular joint anatomy
The Temporomandibular joint (TMJ) is a ginglymoarthrodial joint formed by the glenoid fossa of the temporal bone and the mandibular condyle. An articular disc separates the joint into two synovial cavities with distinctive movement patterns. Gliding or translatory movement occurs in the superior joint (between the articular disc and the glenoid fossa). Rotary or hinge movement takes place in the inferior joint (between the articular disc and the condyle).
The most important ligaments that are the (a) stylomandibular ligament between the stylopid process (b) and the mandible(jaw), the temporomandibular ligament (c) in front of the capsule or capsular ligament (d),
the spheno-mandibular ligament (c) on second image and pterygospinous ligament (d) also on second image. The interpterygoid fascia , and important mechanical link, intricately lies between the cranial base, the medial and lateral pterygoid muscles and the spheno-mandibular ligament.
The muscles that are directly involved in temporomandibular disorders and exert the largest forces on the joints are the main muscles of the mastication: temporalis, masseter, medial and lateral pterygoid muscles, but there are numerous other muscles, their fascia and its connections to other fascial tissues that also have a significant effect on the function of the TMJ such as the sterno-cleido-occipital-mastoid muscle (SCOM) with its mandibular band and many of the infra and suprahyoid muscles.
The primary blood supply of the TMJ comes from the superficial temporal and maxillary branches of the external carotid artery.
Other contributing branches include the anterior tympanic, deep auricular, and ascending pharyngeal arteries. The TMJ receives its sensory innervation from the auriculotemporal and masseteric branches of the mandibular nerve (V3), a branch of the trigeminal nerve.
Biomechanics
Other treatments and management of TMD
Conservative treatment reduces symptoms in 50 to 90% of patients and should be adopted first. Conservative methods include patient reassurance and education, a soft diet, jaw rest, warm compresses on the painful area, and passive stretching. Indicating occlusal and non-occlusal splints for TMD treatment remains controversial and not well supported by evidence.
Behavioral Changes
Muscle activity alters due to increased levels of emotional stress. Managing patients' stress is particularly important in treating TMDs. Behavioral changes like improving your sleep reducing stress, and treating parafunctional habits can significantly improve symptoms. Cognitive-behavioral therapy benefits patients with TMD for short- and long-term treatment.
Restrictive Use
In most TMDs, patients complain of pain in the TMJ and restricted mandibular movement. The clinician can instruct the patient to move the mandible within a trouble-free range of motion, promoting psychological health and pain management.
Voluntary Avoidance
The teeth contact can trigger pain in some cases. Patients must try to reduce dental contact time, except during mastication, swallowing, and speaking. Clinicians can teach patients how to disengage the tooth to diminish 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 not always alleviate the pain. The commonly used manual techniques are soft tissue mobilization, joint mobilisation, muscle conditioning, resistance exercises, passive muscle stretching, assisted muscle stretching, and postural training. Other physical therapy modalities include thermotherapy, ultrasound, electro galvanic stimulation, and cold laser.
Pharmacological Treatment
The first-line drugs for treating acute and chronic forms of TMDs are non-steroidal anti- inflammatory drugs (NSAIDs). Benzodiazepines are sometimes used for cases of recurrent masticatory muscle spasms and bruxism when relaxation techniques have failed. Tricyclic antidepressants may be prescribed as a trial since they improve symptoms of other pain disorders.
Invasive Procedures
Invasive strategies include intra-articular long-acting corticosteroid, hyaluronic acid, and Botox injections. These interventions are recommended once conservative therapies have failed or in severe acute exacerbations.
Intra-articular steroids are indicated in the acute treatment of osteoarthritis of the TMJ, but multiple doses can lead to the destruction of articular cartilage.There is only limited evidence regarding the efficacy of hyaluronic acid injections in treating acute exacerbations.
Botulinum toxin injections are used to treat painful trigger points and chronic bruxism, but a recent Cochrane study found inconclusive evidence for myofascial pain.
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Osteopathic SomaTherapy & SomaTraining Treatment
An effective treatment should address the above anatomy at a minimum.
Following an assessment of the joints, my treatment primarily focuses on restoring normal length-tension relationships of all mechanically important links and to normalise movement in the TMJ. This means that each of the above ligaments, joint capsules, fasciae and muscle will be looked at and treated individually. Why? Because they can be either the cause or the consequence (or both) of the problem.
Other anatomy, that may affect the function of the TMJ, will be looked at and addressed, such as your head carriage, the posture of the cervical spine, your scapula placement, your centre of gravity etc. Home care program that follows a manual therapy treatment includes awareness, proprioception and mobilisation exercises as well as stretching and strengthening exercises. The home exercises, in between treatment sessions, are a crucial part of an effective TMJ rehabilitation program.
A gentle home program, in between treatment sessions, can make considerable difference and is a crucial part of an effective TMJ normalisation program.
An effective manual therapy treatment which individually addresses the specific anatomy will bring about neuromuscular normalisation that the nervous system needs to adapt as the new norm. The patient will need to reinforce this norm with the prescribed home exercises.
Ref: Temporomandibular Syndrome - Kushagra Maini, Anterpreet Dua Â