Cultural Adaptation and Content Validation of the Persian Version of the Diagnostic Criteria for Temporomandibular Disorders Axis I

Todevelop a Persian version of the diagnostic criteria for temporomandibular disorders (DC/TMD) Axis I and to assess its content validity The present study is a cross-sectional survey. To cross-culturally adapt the instrument, the DC/TMD Axis I was translated using a forward-backward method. Translation quality and cultural adaptation were assessed by a panel of five experts on a scale of 0 to 100. Then, the content validity of the Persian version was quantitatively evaluated by a panel of 10 experts calculating content validity index (CVI) and content validity ratio (CVR). Average values of translation quality were less than 90% in 7 items, which were rephrased. Average values of cultural adaptation of 2 items were less than 90% and they were omitted according to the experts' opinion. CVR values in all items of the questionnaire were between 0.8 - 1 and for the total instrument, the CVR values was obtained to be 0.94. All of the items of the questionnaire in terms of relevancy earned values higher than 0.75. CVI values in terms of clarity for 13 items and in terms of simplicity for 10 items were less than 0.75, which were candidates for revision in the second round. All these items received values higher than 0.75 in the second round. Evaluating contentvalidity of the Persian version of DC/TMD Axis I can be an introduction for assessing other psychometric properties of the questionnaire and will pave the way for including Iran in international studies on TMD.