The temporomandibular joint (TMJ) is a ginglymoarthrodial joint formed by the glenoid fossa of the temporal bone and the mandibular condyle (Lomas et al., 2018). TMJ ankylosis refers to bony or fibrous adhesion of the anatomic joint components, restricting mouth opening and results in difficulties with mastication, speech, and oral hygiene, as well as inadvertently influencing mandibular growth (Sporniak-Tutak et al., 2011). It affects all age groups, but is more prominent in the first decade of life and has been more commonly seen in the Asian subcontinent (Gupta et al., 2012).

TMJ ankylosis has a wide range of presentations, including unilateral, bilateral, fibrous, bony, intraarticular, extraarticular, complete, or partial (Kaban et al., 2009). Trauma to the TMJ can cause extravasation of blood into the joint space, or hemarthrosis, and can lead to calcification and obliteration of the joint space, resulting in intracapsular ankylosis. Local infections, space-occupying lesions, and various types of arthritis are among the other causes of joint ankylosis.

The clinical features usually present as an obvious facial deformity, inability to open the jaw, and/or absent condylar movements on the affected side (Chidzonga, 1999). Common signs and symptoms also include shifting the lower jaw towards the affected side upon mouth opening, flatness and/or crossbite on the affected side, and Class II malocclusion. Radiographically, fusion of the joint may be present, along with loss of joint space, flattening of the condylar head, a prominent antigonial notch, and coronoid hyperplasia (Chidzonga, 1999). The consequences of untreated TMJ ankylosis may include facial growth distortion, nutritional impairment, respiratory disorders, malocclusion, poor oral hygiene, and multiple carious and impacted teeth (Tanrikulu et al., 2005).

The management of TMJ ankylosis involves surgery to mitigate the effects of ankylosis and adjunctive appliance therapy to supplement the results achieved with surgery. A commonly used surgical technique is condylectomy, in which the condylar head is resected and the mandible is released from the cranial base (Zhi et al., 2009). Gap arthroplasty and interpositional gap arthroplasty are also frequently used surgical interventions, in which a wedge of bone is removed to create space between the glenoid fossa and ramus of the mandible (Zhi et al., 2009). This gap can be then filled with an interpositional material that is either synthetic, autogenous, or heterogenous to avoid any chances of re-ankylosis. However, in cases of recurrent joint ankylosis, a total alloplastic joint reconstruction is considered a viable option.

Furthermore, in conjunction with surgery, several devices, appliances, and exercises have also been used to help maintain mobility of the jaw postsurgery, but are rarely documented in the literature. In 1960, Topazian recommended using a space holder between maxilla and mandible postarthroplastic surgery to avoid contact and ankylosis of the articular surfaces and prevent relapse (Topazian, 1964). More recent devices include generic jaw exerciser appliances, such as the Orastretch® press system, E-Z Flex II TMJ Exerciser, TheraBite® Jaw Motion Rehabilitation System™ (TheraBite), TheraPacer™ Jaw Mobilizer, Gentle Jaw®, talk tools, jaw clamps, and mouth props. Traditional orthodontic appliances, such as twin blocks and activators, have also been used in the literature as a retention appliance postsurgery (Behnia et al., 1997). However, while generic devices are readily available, they lack a certain amount of specificity and rely largely on patient compliance and dexterity.

This current systematic review evaluated the body of literature on the various kinds of appliance used for the management of TMJ ankylosis. No previous systematic reviews have examined the scope of literature on this topic. To our knowledge, there is no true consensus on which appliance is best used to manage TMJ ankylosis-related symptoms. Various clinical settings have been known to employ different appliances. The purpose of this systematic review was thus to answer the following research question: does the use of an orthodontic and/or physiotherapy appliance contribute to reductions in ankylosis severity in patients with TMJ ankylosis? The examination of this research topic would not only help gather valuable information on such appliances, but would also give an insight into case-based appliance selection.