Portuguese translation, cultural adaptation and psychometric properties of the temporomandibular joint scale: a cross-sectional study

The temporomandibular joint (TMJ) scale assesses the severity of temporomandibular joint disorders (TMD), yet a European Portuguese translation is lacking.

To translate, cross-culturally adapt and to examine the psychometric properties (construct validity and reliability) of the TMJ scale.

Translation and cultural adaptation were carried out according to international recommendations, including initial translation, evaluation of this translation and cultural adaptation by a panel of experts, and back translation. The final Portuguese version was used to examine the reliability and validity, and participants with TMD were recruited from a Portuguese outpatient clinic. Reliability measures included internal consistency with Cronbach’s alpha and test-retest reliability with the intraclass correlation coefficient (ICC2,1). The Spearman correlation comparing the TMJ scale with the Fonseca and Helkimo indexes was used to assess the construct validity.

A total of 63 participants (23 ± 2 years; 61,9% female) were included. Similar internal consistency was observed between the two moments of application (0.921 and 0.918), and test-retest reliability was excellent, with an ICC2,1 = 0.998 (95%CI: 0.988–0.999). Robust positive correlations (rho 0.554–0.611, p < 0.001) were found between the TMJ scale and Fonseca and Helkimo indexes.

The European Portuguese version of TMJ scale is now available to improve the assessment of severity of TMD in routine clinical practice. This version is also reliable and valid.