Background: There is a wide range of commercial and custom-made devices available for the treatment of trismus (restricted jaw opening). They are used often in conjunction with a prescribed exercise program with the aim of improving maximal inter-incisal opening (MIO). This study compared the efficacy (MIO and patient reported outcome results), adverse events, consumer experience and cost of the different types of devices available.
Methods: Four databases were searched between the years 2001-2021 using the terms 'trismus' and 'device'. Two independent authors assessed each paper for inclusion, then conducted a quality analysis.
Results: Thirty-two studies met the criterion required for inclusion. The majority (n = 27) were in the context of established trismus, where the remaining five used the device preventatively. The trismus device improved MIO in 23 of the rehabilitation programs (pooled mean MIO increased by 9.5 mm in the intervention arm compared to 2.4 mm for controls; p = 0.0001). Improved MIO was not observed in the prevention studies. The Therabite ® was the most common trismus device investigated and with a mean increase in MIO of 10.0 mm and cost of $499AUD. Forces applied by trismus devices were regulated by the perception of pain experienced by the patient, rather than a prescribed force by the treating health professional. Despite this guidance, several adverse events occurred (n = 8), including mandibular and molar fractures. Barriers experienced by consumers included pain, ill-fitting mouthpiece, adverse events, exercise adherence and cost.
Conclusion: Trismus devices which use the application of force to the jaw can improve the MIO of patients with established trismus. However, their role is unproven in the setting of trismus prevention during radiotherapy and several significant barriers such as cost, exercise adherence and safety concerns have been demonstrated for the intervention setting.
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