RESUMEN
OBJECTIVES: Trismus, marked by restricted mouth opening, significantly affects patients with temporomandibular disorder (TMD) and head and neck cancer (HNC). Despite its prevalence, specialized questionnaires for trismus assessment are scarce. This study aims to fill this gap by translating and validating the Gothenburg Trismus Questionnaire version 2 (GTQ-2) into Chinese (C-GTQ-2), enhancing the evaluation of trismus in HNC and TMD patients. MATERIALS AND METHODS: The study involved 78 HNC patients, 75 TMD patients, and a control group of 150 individuals without trismus symptoms. Participants were asked to complete the C-GTQ-2 and other health-related quality of life (HRQL) instruments. A subset of 30 individuals retook the questionnaire within two weeks to assess test-retest reliability. RESULTS: The C-GTQ-2 demonstrated remarkable reliability, with Cronbach's alpha values exceeding 0.70 in three of the four domains, indicating high internal consistency. The instrument also showcased high intra-class correlations in the test-retest, affirming its reliability. Furthermore, it exhibited strong convergent validity, aligning well with other HRQL instruments, and effectively discriminated between patients with and without trismus, establishing its discriminant validity. CONCLUSIONS: The C-GTQ-2 emerges as a valid and reliable tool for assessing trismus in HNC and TMD patients, promising to significantly enhance both clinical and research approaches to managing trismus-related complications in the Chinese-speaking demographic. CLINICAL RELEVANCE: C-GTQ-2 proves effective for trismus assessment in head and neck cancer and temporomandibular disorder patients, offering enhanced clinical and research utility.