Assessment of the validity and consequences of different methods of expressing the severity of dental fluorosis in a subject

The aim was to assess the validity and consequences of different methods of expressing severity of dental fluorosis in a subject. The analyses were ba sed on Ugandan children (n = 481), aged 10-14 years, with lifelong consumpt ion of drinking water with either 0.5 or 2.5 mg fluoride per liter. Fluoros is was assessed using the Thylstrup and Fejerskov (TF) index. All children (n = 219) with 28 teeth and fluorosis on at least 1 tooth pair were selecte d to test methods of expressing fluorosis, e.g. the TF score on the most se verely affected tooth, a maxillary central incisor, the median and the mean scores. A test group (n = 40), the 10 most and the 10 least severely affec ted children in each district, was used to evaluate the methods and a refer ence group (n = 179) to confirm or refute the findings in the test group. T o evaluate consequences of the different methods of expressing severity of fluorosis in a subject, children from the low (n = 130) and the high fluori de (n = 132) districts not included in the test or reference group formed t he community comparison groups. Comparison between the median (gold standar d) and mean scores showed a significant deviation in the reference group on ly. Most of the partial recording methods, such as the score for the most s everely affected tooth, were significantly and systematically higher than t he median. While for all recording methods the median score was zero in bot h communities, the distribution of the subjects according to severity diffe red significantly between the communities.