Development and testing of satisfaction questionnaires for patients with removable dental prostheses

Objective: To develop and test self-administered satisfaction questionnaires for patients with removable dental prostheses (RDPs) in the German language. Method and Materials: A three-phase methodology was used. A pilot questionnaire was developed in phase one. At the end of phase two, the final version of the questionnaires were reached. In phase three, 192 questionnaires were distributed to evaluate the psychometric properties of the final version of the questionnaires. Construct validity, content validity from the patients' perspective, and questionnaire reliability were estimated. Results: At the end of phase two, the final versions of the questionnaires were defined as instruments with good face validity. At the end of phase three, content validity from the patients' perspective was assessed and found to be good. Exploratory factor analysis identified a one-factor model for each questionnaire. Consequently, each questionnaire was summed to create a single index. Internal consistency of the indexes was assessed using Cronbach's a and found to be excellent (a > 0.9). A high repeatability of all the items was identified through a test-retest. Intra-class correlation coefficient (ICC) values ranged from 0.80 to 0.99. Conclusion: The questionnaires and indexes are valid and highly reliable instruments, and can be used to measure patient satisfaction with RDPs.