Investigation of psychometric characteristics of Persian translation of Fonseca index in a sample of Persian-speaking people

Although dental caries, periodontal diseases are the most prevalent conditions of oral health all over the world, it should be pointed out that temporomandibular disorders are the second leading cause of pain after odontogenic pain. Various tools are available for the diagnosis of temporomandibular disorders, including Fonseca questionnaire. The aim of this study was to evaluate the psychometric characteristics of Persian translation of Fonseca index in a sample of Persian-speaking people.
The original English version of the Fonseca questionnaire was translated into Persian by a forward–backward translation method. Then reliability was tested on 400 subjects. Cohen’s kappa, a measure of agreement between observers that includes an adjustment for chance agreement, was likewise calculated.
The reliability coefficient (Cronbach's alpha) of the Fonseca questionnaire was calculated at 0.88, which increased to an acceptable level when each item under study was eliminated. The coefficient of test re-test reliability measured by ICC (Intra-class correlation coefficient) was 0.86 (95% CI: 0.82‒0.91).
The Persian version of Fonseca questionnaire was shown to be valid tool for the evaluation of TMJ disorders by dentists. It should be pointed out that this questionnaire is a screening tool and should be used with clinical and control criteria in the paraclinic for determination of positive and negative cases and for the validity of tests with intervention if necessary.