Temporomandibular joint pain and dysfunction (TMJPD) affects people of all ages. The condition presents with either acute or chronic pain in the jaw joints that connect the jaw bone (Mandible) and the skull (Temporal Bone). Normal function of the jaw muscles allows us to chew, speak, and swallow where right and left sides have to move in a coordinated fashion. Movements occurring here are due to the unique shape of the joint surfaces and from a number of specific pairs of muscles acting on the joint, that either open or close the mouth.
There is a cartilage disc that is located within the joint. The joint is enclosed by a capsule that contains synovial fluid, which lubricates the joint. In normal opening and closing, the disc enables more space to be available between the joint's surfaces allowing for effective movement. When opening the mouth, the jaw rotates downward at the same time as it translates forward; this enables a greater bite (S Krohn, 2020).
As the mouth opens, a muscle that attaches to the front of the joint, called the Lateral Pterygoid, pulls the jaw bone and the disc in a forward and slightly downward direction to various degrees depending on how much opening is needed. A series of small ligaments (lateral temporomandibular, sphenomandibular and stylomandibular) assist in guiding movement and position of the joint and disc. When closing the mouth, the jaw performs the reverse action (D Magee 2008). With TMJPD, what can occur is the disc that separates the joint surfaces may become displaced resulting in pain, clicking or clunking upon movement.
The Problem
There are generally two types of termed disc displacement without reduction (disc sits in a forward and inward orientation). In this type, problems with TMJ function are more significant and painful locking can occur (reducing the ability to open the mouth and even lock jaw movement which may require more extensive treatment depending on severity). The other type is disc displacement with reduction in jaw movement that causes some pain or clicking or joint sounds when eating, but the disc tends to go back into where it should normally be (G Klasser 2020). The TMJ disc is largely avascular (without blood) and anural (without nerve tissue in areas where the disc takes load); however, the outer parts of the disc and joint capsule that encase the joint and disc have nerve and vascular structures which tend to be more pain producing when there is a problem, and if there is inflammation (Magee, 2008).
Contributing Factors to Dysfunction and Pain
Muscle imbalance is a major factor leading to TMJ dysfunction. Changes in muscle recruitment patterns increases stress on the joint surfaces causing local pain, headaches, or even toothache type pain can be due to referred pain from fatigued muscles with trigger points (Simons & Travell, 1999). There can be potential damage to the joint resulting in acute or chronic inflammation. Intrinsic factors that can affect the function of the jaw include poor posture, people who experience high levels of stress or anxiety, and also those who clench or grind the teeth. Extrinsic factors include trauma such as a blow to the jaw.
Other conditions that can predispose TMJ dysfunction include Rheumatoid Arthritis, which is an autoimmune disorder that affects multiple joints. Various aspects of mental health, such as anxiety and high stress levels, which contribute to bruxism (grinding) or clenching the teeth (especially chronic in nature), can also lead to temporomandibular disorders (NIH, 2017). Other conditions, such Chronic Fatigue Syndrome (a condition that manifests with severe levels of fatigue and sleep disturbances) and Fibromyalgia (a condition that is associated with multi-region increased pain perception and stiffness in which fatigue and sleep disturbances are also noticed), as well as risk factors like bone diseases or metastasis, respiratory tract or sinus infections, can also increase the likelihood of temporomandibular disorders.
Increased states of anxiety or stress and depression have been shown to be contributing factors to TMJP (L Bonjardim, 2005).
In mouth breathers, the position of the tongue changes slightly and encourages increased use of extra inspiratory muscles (muscles located in the neck and ribs), which are often used when in need of increased breathing. This causes the muscles to become fatigued and tight.
Assessment of Temporomandibular Joint Pain Dysfunction Syndrome
Assessment is performed by a clinician to establish factors associated with initial onset and signs and symptoms, such as radiating jaw and/or facial pain with restricted mandibular movements, how long they have been present for and how severe the patient's problem is. The clinician will gain information about whether pain is associated with closing, which can assist in determining whether there is a problem inside the joint capsule (intracapsular), such as disc displacement or arthritis. If severe pain is associated with opening, this can assist in determining problems outside of the joint capsule such as muscle, ligament or connective tissue involvement (D Magee 2006).
A previous history of a dental procedure or dental-related problems can change chewing mechanics to overuse or compensate with one side more dominantly. This change initially can go unnoticed as it's somewhat natural for the body to do this. Over time, however, this altered mechanical pattern can lead to occlusal factors (changes in the way the teeth, specifically the molar, come into contact with each other). Muscles start to become fatigued, strained and contribute to instability and deceased coordination (S Prater, 2012). The clinician will also gain information about the 24-hour pain pattern, e.g. morning pain from arthritis or fatigue strain in muscles associated with night clenching or bruxism.
Clinical Observations
Once obtaining a history the clinician will aim to get some objective information via feeling the tissue of the TMJ and associated muscles. The clinician will also observe posture alignment and range of mandibular movements, as well as performing the same for other regions of the neck, shoulders and back as these factors are important to include as they can contribute to increased forward head position.
There is evidence that indicates a change of the length tension relationship between the supra and infra hyoid muscles (muscles located below the jaw attaching to the hyoid bone) and other muscles located toward the region just behind the TMJ and upper part of the back of the neck. Imbalances between these muscle groups can contribute to decreased range of motion on either side of the jaw. Additionally, with a forward head position this changes the angle of the jaw, encouraging the mandible bone to sit in a more backward and upward position and increasing the potential for the joint to become compressed (M Mulet, 2007).
Management of Treatment Plan
In the majority of cases, conservative treatments are more effective and recommended prior to more invasive investigation and treatments such as surgical procedures (R Poluha, 2019). During more acute stages of TMJPD, treatment is aimed at reduction in pain and inflammation. In more sub-acute stages, treatment can be progressed. When combined with dental consultation where occlusal splints and other means can be used, advanced soft tissue therapy modalities can be applied to reduce pain in facial muscles or referral patterns from trigger points and promote elongation of restricted muscle and connective tissue.
Additional treatment involves addressing neck, back and shoulder imbalances. A more recent study (Y Gursoy et al 2020) states that manual soft tissue therapy contributed to decreasing jaw pain and improving TMJ movement. Low grade joint mobilisation can be applied to encourage movement and corrective exercises such as gentle stretching of tight TMJ, neck and shoulder muscles. Assisted and resisted movement exercises of the TMJ muscles improve stability and coordination, additionally weaker neck and shoulder muscles are strengthened to improve a forward head position.
Research (N S Mulla, K V Babu, N S kumar et al., 2015) shows that the combined use of low to moderate TMJ mobilisations and specific exercise performed over a two-week trial contributed to increased mouth range of movement. Patient education includes ways to prevent excessive grinding, one-sided dominance when chewing, altering foods while in acute episodes to limit aggravation, as well as providing the patient with relaxation methods such as diaphragmatic breathing practice to reduce overuse of extra inspiratory muscles and reduce tension.
The use of guided self-massage as instructed by the practitioner is also beneficial. Moist heat or ice packs may be used on neck pain and tight shoulder muscles to reduce soreness. Sleeping position can be addressed for e.g. if sleeping on one side predominantly or with the head and neck in poor alignment (Klasser & Epstein 2014).
A multidisciplinary approach "in which multiple professions are involved in a coordinated and effective way, considering together the various approaches as fundamental to improving the outcomes of these patients" (M Garrigos-Pedron, I Elizagaray-Garcia, A A Dominguez-Gordillo et al, 2019) is considered the most effective approach to managing TMJPD.
As there can be many different contributing physical and psychological factors associated with TMJPD, combining dental, medical and psychological interventions with natural therapies, such as physical rehabilitation through physiotherapy and exercise physiology, osteopathic management, as well as manual soft tissue therapies, such as myotherapy or remedial massage and natural medicine as well, is the best way to deal with underlying joint pathology.
References
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