Changing risk factors for fluorosis among South Australian children

Background: Research in the last decade has shown changing exposure patterns to discretionary fluorides and declining prevalence of fluorosis among South Australian children, raising the question of how risk factors for fluorosis have changed. Objective: To examine and compare risk factors for fluorosis among representative samples of South Australian children in 1992/1993 and 2002/2003. Methods: Similar sampling strategies and data collection methods were employed in the Child Fluoride Study (CFS) Marks 1 (1992/1993) and 2 (2002/2003). Participants in each CFS round were examined for fluorosis using the Thy1strup and Fejerskov (TF) Index. Exposure history was collected for fluoride in water, toothpaste, fluoride supplements and infant formula, allowing for a fluorosis risk assessment analysis. Data were re-weighted to represent the child population at each time. Changes in prevalence of fluorosis, defined as having a TF score of 1+ on maxillary central incisors, fluoride exposure and risk factors between the two rounds were evaluated. Result: A total of 375 and 677 children participated in the 1992/1993 and 2002/2003 rounds respectively. Prevalence of fluorosis declined significantly from 45.3% to 25.9%. Reduced use of fluoride supplements and increased use of 400-550-ppm children F toothpaste were the most substantial fluoride exposure changes. Early toothpaste use, residence in fluoridated areas and fluoride supplement use were the risk factors in 1992/1993. Early toothpaste use and fluoride supplement use were not risk factors, leaving fluoridated water as the only risk factor among the common variables in 2002/2003. In an analysis stratified by the type of fluoridated toothpaste in 2002/2003, the large amount of toothpaste used was a risk factor in those who used 1000-ppm fluoridated toothpaste, and eating/licking toothpaste when toothpaste use started was a risk factor among children who used either 1000-ppm or 400-550-ppm fluoridated toothpaste. Conclusion: Introduction of the 400-550-ppm F toothpaste and use of smaller amount of toothpaste restricted risk associated with early toothpaste use. Less use and possibly a stricter fluoride supplements regimen also restricted fluorosis risk. Periodic monitoring of risk of fluorosis is required to adjust guidelines for fluoride use in caries prevention.