Visual Analogue Scale for Dental Fluorosis

Several epidemiological indices have been used to describe the clinical appearance of dental fluorosis (DF) using ordinal scales. However, when correlation between DF severity and other parameters (e.g., fluoride concentration) is necessary, a continuous scale is preferable. Objective: The purpose of this study was to evaluate the validity and reliability of a Visual Analogue Scale (VAS) for DF. Methods: A panel of 23 dentists and 23 non-dentists were asked to grade the amount of discoloration and malformation presented in a set of 22 photographs of teeth varying in levels of DF using a 10cm VAS. These data were used to create a continuous scale for DF severity (DF VAS). The pictures were also graded using the Thylstrup Fejerskov Index (TFI). Results: The Intra-class correlation coefficient (ICC) was used to assess the inter-examiner (ICC=0.79 – “good” agreement) and intra-examiner (ICC= between 0.88 and 0.97 – “excellent agreement) reliability as well as to compare dentists and non-dentists (ICC=0.22 – “fair” agreement). Spearman correlation was used to validate the mean DF VAS of the 46 examiners against the gold standard – TFI (rs = 0.912, p<0.01) as well as of each individual examiner against the gold standard. The Spearman rank-correlation values were above 0.8 (“excellent” correlation) for 24 examiners, between 0.6 and 0.8 (“good” correlation) for 21 examiners and 0.47 (“moderate” correlation) for one examiner. Conclusion: These values confirm the validity and reliability of the DF VAS scale, which will now be tested in areas with endemic DF. This work was supported by the Canadian Institute of Health Research. APGF Vieira was supported by scholarships from the Connaught and Harron Foundations.