Fluoride in Drinking Water A Scientific Review of EPA's Standards (2006) / Chapter Skim
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4 Effects of Fluoride on Teeth
4 Effects of Fluoride on Teeth
Pages 103-130
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From page 103... ...
4 Effects of Fluoride on Teeth In this chapter, the committee reviews research on the occurrence of enamel fluorosis at different concentrations of fluoride in drinking water, with emphasis on severe enamel fluorosis and water fluoride concentrations at or near the current maximum contaminant level goal (MCLG) of 4 mg/L and the secondary maximum contaminant level (SMCL)
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From page 104... ...
. Although it is possible for enamel fluorosis to occur when teeth are exposed during enamel maturation alone, it is unclear whether it will occur if fluoride exposure takes place only at the stage of enamel-matrix secretion.
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From page 105... ...
(2002) showed that rats exposed to fluoride in drinking water at 50 or 100 mg/L had lower total proteinase activity per unit of protein than control rats.
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From page 106... ...
. There appears to be general acceptance in today's dental literature that enamel fluorosis is a toxic effect of fluoride intake that, in its severest forms, can produce adverse effects on dental health, such as tooth function and caries experience.
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From page 107... ...
Finally, with only one category for severe fluorosis, Dean's index does not discriminate between staining and pitting or between discrete and confluent pitting. In fact, Dean revised the index in 1942 to create the version in use today, which combines the original "moderately severe" and "severe" categories.
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From page 108... ...
. The TFI has been shown to be a valid indication of the fluoride content of fluorotic enamel.
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From page 109... ...
EFFECTS OF FLUORIDE ON TEETH 10 TABLE 4-2 Clinical Criteria and Scoring for the Thylstrup and Fejerskov Index (TFI) of Enamel Fluorosis Score Criteria 0 Normal translucency of enamel remains after prolonged air-drying.
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From page 110... ...
110 FLUORIDE IN DRINKING WATER TABLE 4-3 Clinical Criteria and Scoring for the Tooth Surface Index of Fluorosis (TSIF) Score Criteria 0 Enamel shows no evidence of fluorosis.
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From page 111... ...
The ascertainment of severe enamel fluorosis, in contrast, is much more secure. This is especially true in studies of children in communities with relatively high water fluoride concentrations in the United States and similar locales, where there are few if any alternative explanations for dark yellow to brown staining and pitting of the enamel of recently erupted permanent teeth.
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From page 112... ...
This approach is less problematic at comparatively low levels of fluoride intake, where all or almost all of the cases are mild or moderate in severity. At higher intake levels, such as those typically found in communities with water fluoride concentrations at the current MCLG of 4 mg/L or the current SMCL of 2 mg/L, it is more informative to report results for the different levels of fluorosis severity.
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From page 113... ...
Instead, plots of the prevalence estimates in relation to water fluoride concentration were examined for the presence of any clear and obvious patterns or trends. Figure 4-1 shows 94 prevalence estimates from studies in the United States.
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From page 114... ...
The prevalence of severe enamel fluorosis is close to zero in communities at all water fluoride concentrations below 2 mg/L. Above 2 mg/L, the prevalence rises sharply.
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From page 115... ...
Not shown are results for three Ethiopian communities with extremely high water fluoride concentrations of 26, 34 and 36 mg/L and prevalences of 18%, 48% and 25%, respectively (Haimanot et al.
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From page 116... ...
communities with water fluoride concentrations of approximately 4 mg/L have used enamel fluorosis indexes that draw severity distinctions within the "severe" category. In Lowell, Indiana, with a water fluoride concentration of approximately 4 mg/L, 7% of a 1992 sample and 2% of a 1994 sample of children 7-14 years of age had at least one tooth surface assigned the highest possible TSIF score of 7 (Table 4-4)
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From page 117... ...
Community with a Water Fluoride Concentration of 3.8 mg/La 1980 study 1985 study TSIF Age 8-10 Age 13-15 Age 8-10 Age 13-15 Score (n = 59)
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From page 118... ...
These results for New Mexico adults are consistent with the results for children in Indiana and Illinois. A reduction of all water fluoride concentrations to below 2 mg/L would be expected to make severe enamel fluorosis an extreme rarity in the United States, but would not be expected to eliminate it entirely.
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From page 119... ...
and the National Institute of Mental Health to evaluate the issue concluded that "individuals who have suffered impaired dental appearance as a result of moderate and severe fluorosis are probably at increased risk for psychological and behavioral problems or difficulties" (R.E. Kleck, unpublished report, Nov.
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From page 120... ...
For lower water fluoride concentrations, the estimated prevalence ranged from 15% at 1.2 mg/L down to a baseline of 6% at 0.1 mg/L. The committee judges that this analysis produced an overestimation of the prevalence of fluorosis of actual aesthetic concern for two main reasons.
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From page 121... ...
From the standpoint of this committee's charge to consider effects of relatively high levels of water fluoride, the main points to note are that the emphasis of research and discussion on psychological, behavioral, and social effects of enamel fluorosis has been almost entirely on children and on the mild and moderate forms of the condition that are more typical of lower fluoride exposure levels. Research needs to focus specifically on severe enamel fluorosis in those areas in which it occurs with appreciable frequency.
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From page 122... ...
Dental Caries in Relation to Water Fluoride Concentrations of 2 mg/L and Higher Many reports have discussed the inverse relationship between dental caries and water fluoride at concentrations considerably lower than the current MCLG of 4 mg/L and SMCL of 2 mg/L (Dean 1942; PHS 1991; McDonagh et al.
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From page 123... ...
Communities with Water Fluoride Concentrations at or Near the MCLG of 4 mg/L Approximate Water Fluoride Age Number of Concentration Mean Reference (years) Year Community Children (mg/L)
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From page 124... ...
124 FLUORIDE IN DRINKING WATER distribution is inherently unknown, a conservative approach is to compare the children with severe fluorosis at 4 mg/L with children from their own communities with mild to moderate fluorosis. Results for such comparisons are summarized in Table 4-7 for studies reporting the mean number of decayed, missing and filled tooth surfaces (DMFS)
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From page 125... ...
between severe fluorosis and caries frequency. A study of children in a South African community with a water fluoride concentration of 3 mg/L and a 30% prevalence of severe fluorosis reported a positive correlation (P < 0.05)
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From page 126... ...
Dentin continues to grow in terms of overall mass and mineral density as pulp cells deposit more matrix overall and more mineral in the dentin tubules. Several investigators have observed that, like older bone, older dentin is less resistant to fracture and tends to crack more easily (Arola and Reprogel 2005; Imbeni et al.
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From page 127... ...
Severe enamel fluorosis occurs at an appreciable frequency, approximately 10% on average, among children in U.S. communities with water fluoride concentrations at or near the current MCLG of 4 mg/L.
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From page 128... ...
children in communities with drinking water containing fluoride at 4 mg/L would be expected to consume more than the age-specific tolerable upper limits of fluoride intake set by IOM. Results from the Iowa Fluoride Study (Levy 2003)
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From page 129... ...
75th 90th Maximum 3 0.7 0.7 1.1 6.7 12 0.9 0.4 0.7 6.0 24 1.3 0.4 0.6 2.1 36 1.3 0.5 0.7 1.7 aFluoride concentrations in drinking water ranged from <0.3 to 2 mg/L.
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From page 130... ...
reCommendations · Additional studies, including longitudinal studies, of the prevalence and severity of enamel fluorosis should be done in U.S. communities with fluoride concentrations higher than 1 mg/L.
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