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Temporomandibular Disorders and Orthodontic Treatment – A Review with a Reported Clinical Case

Temporomandibular disorders (TMDs) are musculoskeletal disorders which affect the structures of the stomatognathic system. They include two separate entities of functional disorders: masticatory muscles disorder (tendomyopathy) and temporomandibular joint (TMJ) disorder (anterior disc displacement, osteoarthritis). Their shared symptomatology is pain related to masticatory muscles and/or TMJs, limited mouth opening and pathological noise in the TMJs (clicking, crepitations). In general, TMDs are considered to be multifactorial disorders with pain as the most pronounced symptom and the main reason for patients (from 75 – 90% female) to seek medical help. As the musculoskeletal form of the disorder and due to clinically pronounced pain, TMDs include a biopsychosocial component which is an important factor in creating a clinical picture, wherein the chronic aspect of musculoskeletal pain makes the relatively moderate clinical picture much worse. Therefore, like in many other musculoskeletal disorders in the body, their etiopathology is considered nonspecific, which is to say, they have an idiopathic cause on the level of the patient – individual. Clinical examinations, particularly manual examination techniques, are an integral part of TMD diagnostics and they serve to determine the indication for imaging techniques. Magnetic resonance imaging (MRI) has become the gold standard in diagnopstics and differential diagnostics of TMDs because it shows both hard and soft tissues of the TMJ (primarily of the disc) as well as joint effusion. Since the etiology of TMDs is mostly unknown, the indicated treatment methods are mostly symptomatic, noninvasive and reversible. These methods include the well known occlusal splint, physical therapy, cognitive-behavioral methods, acupuncture in cases of chronic pain and psychological treatment. Masticatory muscles and, especially, TMJs are directly connected to occlusal relations and due to that, TMDs are in correlation with occlusal disorders, ranging from obvious occlusal anomalies, variations of static and dynamic occlusal relations to loss of teeth. The Michigan type of the occlusal splint as the most widely used non-permissive splint serves as reversible initial treatment. Definitive occlusal treatment is not recommended for TMD patients as well as prosthodontic appliances and orthodontic treatments. Namely, orthodontic treatment by itself is not confirmed as a potential etiopathogenic factor of TMDs but it should not be performed in patients with a painful form of TMD. All irreversible and relatively long and expensive occlusal treatments, including orthodontic treatment, are never indicated without prior initial treatments. Manual examination techniques can be used as screening methods for detecting clinical symptoms of TMDs. Although a possibility of TMDs prevention is considered, the orthodontic, prosthodontic or any other form have not been scientifically proven because there is no consensus on the factors which cause TMD. Long-term follow-ups of patients undergoing orthodontic treatments did not show subsequent appearance of TMD and certain occlusal variables (cross bite, Angle class II/1, etc.) do not dominate the overall sample of TMD patients. In the review of literature, there is a clinical case described regarding a 5 year follow-up of a 26-year-old female patient who sought specialist prosthodontic help due to pain in the right TMJ and clicking in the left one with limited mouth opening. From patient history: 7 months ago a general dental practitioner referred her to an orthodontist due to clicking in the same joint and the specialist started treatment with a bimaxillary removable appliance (bionator). Namely, the patient previously had Angle class II/1 (prognate jaw) with a horizontal overlap of 11 mm and non-matching medial line of 1 mm. However, the patient did not realize at first that the pain in the TMJ was not being treated and the orthodontist did not realize that her intention was not to treat the orthodontic anomaly. In the course of orthodontic treatment her right TMJ became painful. The orthodontic appliance fixated the occlusion in an anterior (protrusive) position wherein the posterior teeth were in non-occlusion. A clinical examination confirmed the patient’s symptoms (left with reduction, right without reduction) and the anteriorly displaced disc was identified by MRI in habitual closed mouth position, a protrusive position conditioned by the orthodontic appliance and open mouth position. Besides stopping the orthodontic treatment, the patient initially wore the Michigan splint around 5 months and, after a year, still had pain in the right TMJ, with evident chronic character of pain. TMD treatment continued at home by physical therapy and oral exercises. At a recall 5 years later, the patient did not have pain in the TMJs and only felt discomfort in the right TMJ during wide mouth opening with clinically evidenced minor crepitations. MRI showed no change in the anterior disc displacement bilaterally with osteoarthritic changes in the right joint. Now, she does not have esthetic or functional needs for orthodontic treatment. In conclusion, TMD hinders orthodontic treatment and a prior initial treatment is necessary. Orthodontic treatment does not cause TMD symptoms in previously asymptomatic persons. Occlusal variables as well as anomalies and tooth loss have a limited proven direct connection with TMD appearance.