Relationships between daily total fluoride intake and dental fluorosis and dental caries

Objective:To explore the relationships between the dally total intake of fluoride,dental fluorosis and dental caries.Methods:An epidemiological method was used to investigate the daily total intake of fluoride,dental fluorosis,and dental caries among 236 and 290 children aged 8-13 years in a severe endemic area and in a non-fluorosis control area,respectively.The children were divided into eight subgroups according to each child's estimated dally total intake of fluoride.The prevalence of dental fluorosis and dental caries in each group was calculated.Results:As expected,elevated levels of fluoride intake were significantly associated with a higher prevalence of dental fluorosis and an increasing amount of more severe defect dental fhiorosis.When the dally total F intake was 2.78 rag/child/day,the prevalence of dental fluorosis was nearly 100%,with the prevalence of defect dental fluorosis increasing with increasing fluoride intake.There was also a significant negative(inverse) dose-response relationship between the dally total intake of fluoride and the overall preva-lence of dental caries,the prevalence of which decreased when the daily total intake of fluoride increased up to 3.32 mg/child/day.However,at higher levels of daily total intake of fluoride the prevalence of dental caries increased,giving rise to a U-shaped dose-response relationship curve.Conclusion:It is important to monitor total fluoride exposure and protect children from excessive fluoride intake,especially during the years of tooth development.