Three questionnaires to assess the perception of fixed orthodontic therapy before, during and after treatment: validity and reliability.

Background/objective: To assess the validity and reliability of a series of three questionnaires for the quantification of patient perception of fixed appliance orthodontic treatment.

Subjects and methods: The study was carried out at the University of Dundee with content and face validity being assessed using proformas. Initially ten experts (Orthodontic Specialists) assessed content validity with 11 professionals (seven Orthodontic Specialists and four Postgraduates) and 20 patients assessing face validity. Content validity was determined according to the values of item-level content validity index (I-CVI) and scale-level CVI (S-CVI/Ave), while specially designed feedback forms were used for face validation. Internal consistency determined the reliability of the questionnaires according to the value of Cronbach alpha correlation coefficient test. The three questionnaires were then modified according to the recommendations of professionals and patients with seven experts reassessing content validity and ten newly selected patients assessing face validity.

Results: The first round of content validity revealed that around half of the items in the questionnaires were not valid. Therefore, the questionnaires were not valid as a whole (S-CVI/Ave = 0.60). After modifying the questionnaires and removing the non-valid items, the new versions of the Pre-treatment, Orthodontic Experience, and Post-treatment Questionnaires showed high levels of face validity, content validity (S-CVI/Ave: 0.99, 0.97, and 0.99, respectively) and good levels of internal consistency (α = 0.86, 0.78, and 0.88, respectively).

Limitation: The patient sample was collected from a single university clinic and from one city within the UK and this could affect the generalizability of the results.

Conclusion: Three content valid and reliable questionnaires have been developed and validated for the evaluation of patient perception of fixed appliance orthodontic treatment.

Implications: Unlike other tools that assess oral health-related quality of life, this series of three questionnaires assess the perception of fixed appliance orthodontic treatment before, during and after treatment.