歯牙フッ素症および尿中フッ素と学童の知能との関連性

Association of Dental Fluorosis and Urinary Fluoride with Intelligence among Schoolchildren.

抄録

フッ化物は水中に天然に存在し、う蝕予防のために世界中で使用されてきた。高フッ化物地域またはフッ素常在地域で実施されたいくつかの研究では、フッ化物が小児の認知機能に悪影響を及ぼすことが報告されているが、いくつかの研究では否定的な所見が得られている。本研究の目的は、飲料水がフッ素化されていない地域に住む学童の尿中フッ化物、歯のフッ素症、および知能の関係を評価することである。この横断研究は、台湾の台中に住む6～12歳の児童562人を対象に実施した。各児童の尿中フッ化物濃度をフッ化物イオン選択電極により測定し、歯のフッ素症の状態をDean's Indexの基準に従って評価した。知能評価にはRaven's Colored Progressive Matrices-ParallelおよびStandard Progressive Matrices-Parallelを用いた．その結果，参加者の尿中フッ化物濃度の平均値（±標準偏差）は0.40±0.27mg/L（0.43±0.23mg/gクレアチニン）であった．歯のフッ素症の有病率は23.67％であった。潜在的交絡因子を広範に評価した結果、歯牙フッ素症および尿中フッ素は、回帰モデルにおいて知能指数（IQ）スコアおよび成績と関連しなかった。結論として、歯のフッ素症および尿中フッ化物濃度は、飲料水フッ化物の少ない地域に住む学童のIQと有意な関連はなかった。

Fluoride is present naturally in water and has been used worldwide for the prevention of caries. Several studies conducted in high water fluoride or endemic fluorosis areas reported that fluoride adversely affected children's cognitive function, but some studies had negative findings. This study aimed to assess the relationship between urinary fluoride, dental fluorosis, and intelligence among schoolchildren living in communities with non-fluoridated drinking water. This cross-sectional study was conducted on 562 children aged 6-12 years in Taichung, Taiwan. Each child's urinary fluoride level was determined by a fluoride-ion-selective electrode, and the dental fluorosis condition was evaluated according to the criteria of Dean's Index. The Raven's Colored Progressive Matrices-Parallel and Standard Progressive Matrices-Parallel were used to assess children's intelligence. The results showed that the mean (±standard deviation) urinary fluoride concentrations were 0.40 ± 0.27 mg/L (0.43 ± 0.23 mg/g creatinine) among participants. The prevalence of dental fluorosis was 23.67%. After extensive evaluation of potential confounders, dental fluorosis and urinary fluoride were not associated with intelligence quotient (IQ) scores or grades in the regression models. In conclusion, dental fluorosis and urinary fluoride levels were not significantly related to the IQ of schoolchildren living in areas with low drinking water fluoride.