Evaluation of Treatment Modalities for Radiation Therapy-Induced Trismus, Considering the Timing and Adherence to Progress in Mouth Opening and Oral Health-Related Quality of Life: A Systematic Review.

Abstract

<h4>Purpose</h4>To assess the effectiveness of treatment modalities for radiation-induced trismus in improving mouth opening (MO) and oral health-related quality of life (OHRQoL), with considering of treatment timing and patient adherence.<h4>Methods</h4>Electronic databases (PubMed, Google Scholar, Scopus, EBSCOhost, and ScienceDirect) were searched for studies published between 2015 and 2025 using relevant Medical Subject Headings (MeSH) combined with Boolean operators, including "Treatment OR therapy AND trismus OR limited mouth opening AND radiation therapy OR radiotherapy AND head and neck neoplasm OR head and neck cancer" and "Timing OR starting time AND treatment OR exercise AND trismus OR limited mouth opening OR restricted mouth opening." After duplicate removal, titles, abstracts, and full texts were screened for eligibility.<h4>Results</h4>The initial search identified 472,480 articles, of which 18 met the inclusion criteria after screening titles, abstracts, and full texts. Kruskal-Wallis analysis demonstrated significantly greater improvement in mouth opening when trismus treatment was initiated during or after radiotherapy compared to before radiotherapy (p = 0.020). The greatest improvement was observed with combined laser therapy and Therabite exercises, initiated concurrently with radiotherapy for 3 months with high adherence, resulting in a mean increase of 26.95 mm in MO and an improvement in OHRQoL. The second most effective modality was threaded tapered screw appliance (TTSA) therapy combined with low-level laser therapy (LLLT) administered post-radiotherapy for 6 weeks, yielding a 15 mm improvement with high adherence.<h4>Conclusion</h4>The effectiveness of treatment for radiation-induced trismus is influenced by the therapeutic modality, timing of therapy initiation, and patient adherence, all of which contribute to improvements in MO and OHRQoL. Combination therapy modalities, particularly laser therapy combined with jaw movement devices, initiated during or after radiotherapy and supported by high patient adherence, optimize mouth opening and enhance OHR-QoL.