Cross-cultural equivalence in translation of the oral health impact profile: how to interpret the final score?

The oral health impact profile (OHIP) is one of the most widely known oral health-related quality of life instruments. In Community Dentistry and Oral Epidemiology, MacEntee and Brondani report the results of a systematic review to identify acceptable methods for translating psychometric instruments for cross-cultural equivalence of the OHIP scale. But in no study has unidimensionality, one aspect of the validity of the internal structure of the scale, been verified, whereas it is a major psychometric step. In the absence of the study of unidimensionality, it is difficult to interpret the final score. The methodology of transcultural validation of the OHIP could be improved, and the study of the unidimensionality is a psychometrically necessary step for the interpretation of the finale score.