Fluoride’s Balancing Act

Dental Hygienists make daily decisions about fluoride for each patient based on the need for prevention. A critical part of this equation, however, is balancing the need for prevention with the risk of fluorosis. Hygienists need to understand the sources of fluoride in their patients’ diets, beyond community fluoridated water and fluoride supplements.

Fluoride is one of the best defenses against dental caries in children and adults. The decline in the prevalence of dental caries over the past 3 decades is due to the widespread use of fluoride.¹ Currently, about 65.8% of the population in the United States is exposed to water fluoridation.¹ Since fluoride’s incorporation into American water supply systems in 1945, a 20% to 40% decrease in dental caries has occurred.¹ Water fluoridation remains the most economical means of delivering fluoride to the general population.

Simultaneously, as researchers have tracked a decline in caries, they have also noted an increase in fluorosis. This result is caused by increased fluoride exposure during tooth development. Fortunately, only a mild form of dental fluorosis has been documented. Mild fluorosis is often not noticed in youth but the white striations become important esthetically with age. The level of fluoride intake between the ages of 15 and 30 months is the most critical for developing dental fluorosis, especially on the maxillary central incisors but the intake of fluoride at younger and older ages can also be of concern.²

FINDING THE SOURCE

Dental fluorosis of permanent teeth can occur if higher than optimal amounts of fluoride are ingested. Optimal amounts are set between .7 ppm and 1.2 ppm in community water systems.³ At these levels, no fluorosis should occur but considering the unpredictable amount of fluoride ingested through different modalities, evidence of a mild form of fluorosis has been seen in recent years.

In 1999, the American Dental Association published a reduction in the infant and children dosage recommendation for fluoride supplements due to the widespread availability of fluoride through other sources. Fluoride can be ingested systemically through water supply systems; prescribed supplements; foods and beverages that contain fluoride, eg, small bony fish, tea, soft drinks, juices; and swallowed dentifrice. Dental hygienists should note these other sources when discussing the need for supplementation. See Table 1 for dosage details.

When infant foods and juices were studied, grape juice—especially white grape juice—contained the highest fluoride levels. White grape juice can have an average of 1.40 ppm fluoride compared to .32 ppm in other juices. Chicken in infant foods contains high amounts of fluoride due to the inclusion of bone particles. Two ounces (about 60 g) per day of the infant chicken food provides approximately 0.5 mg fluoride, about the maximum that infants should be receiving from all sources. Soy-based formula tends to have higher fluoride content than milk-based formula because soy proteins bind some of the fluoride.²

Another source of fluoride is dry infant cereal, which is often processed in different locations across the country. When the cereal is processed, it begins as a slurry made with the water used at the plant and then it is dehydrated, leaving the fluoride in the mix. If the water source varies, the fluoride content level in the cereal varies. A company can also produce all of one size box in a fluoridated area and another size in a nonfluoridated area. An 8 oz box of cereal can have more or less fluoride than a 1 oz box if it is processed with fluoridated water. More diluted mixtures are recommended for young infants and thicker, less diluted mixtures for older infants or toddlers. The result can be a variation in fluoride levels from 0.10 ppm to 0.40 ppm in different types of rice, barley, oatmeal, and mixed cereals. If the caregiver mixes the cereal with fluoridated water, the amount will be even higher.⁴

BOTTLED WATER

Water can create substantially different levels of fluoride in infants and children. Bottled water can introduce fluoride in varying ppm or purposefully as an additive. Evian Natural Spring water has .08 mg/L. Gerber Spring Water with fluoride has .71 mg/L. However, United Valley Bell Valley Pure Drinking water has 1.00 mg/L and Tyler Mountain Water Drinking water has 1.2 mg/L, which is not listed on the label. Dental hygienists must also consider if patients are consuming community or naturally occurring fluoridated water or if bottled water is used for preparing juices from concentrate, soups, or other liquids.⁵ Some bottled water contains very minimal amounts of fluoride. When minimally fluoridated water is used for food and drink preparation and drinking alone, the fluoride levels may be too minimal to meet the recommended amount for caries control. However, using bottled water with fluoride may be another hidden source of ingested fluoride.

Other sources of fluoride are soda and tea drinks. Just as baby food is processed and packaged in different locations causing variations in the amounts of incorporated fluoride, this is also true in the soft drink industry. The fluoride levels in drinks made by Coca-Cola Co, Pepsi Co Inc, Dr Pepper/Seven Up Inc, and others can range from .02 ppm to 1.28 ppm. Heilman et al found that 71% of the carbonated beverages studied contained fluoride levels exceeding 0.60 ppm.⁶ In comparison, water containing the same amount is considered high enough to contraindicate dietary fluoride supplements.⁶ Soda from different sites can also differ in fluoride levels so it is almost impossible to determine the level of fluoride without exact knowledge of the processing location.

Tea drinks provide naturally concentrated levels of fluoride. In order to enhance the tea flavor, the tea is first prepared and then concentrated before water is added back to prepare the bottled tea. In powder mixes, the concentration of fluoride remains high and possibly higher if mixed with fluoridated water.

CULTURAL FACTORS

Beverage consumption in children can vary depending on climate, income, locations, and culture. A study by Pang et al⁵ determined that the daily liquid intake of North Carolina children ranged from 971 ml (33 0z) to 1,243 ml (42 oz). Daily consumption of beverages (including carbonated soft drinks, fruit juices, teas, coffee, and Gatorade) ranged from 585 ml (20 oz) to 756 ml (26 0z). Therefore, children consumed about 40% of their liquid intake from milk and water and about 60% from other beverages. This study showed that the estimated mean daily fluoride ranged from .36 mg for 2-3 year olds to 0.60 mg for 7-10 year olds depending on the drinks consumed. The study further indicated that the majority of the beverages containing fluoride was close to 1.00 ppm.

Fluorosis can come from many hidden sources. Food and beverages prepared in fluoridated areas are continually being brought to nonfluoridated areas. This phenomenon is often referred to as a halo effect. All of these additional sources of fluoride may be sufficient to meet the supplemental needs for caries prevention with the undue esthetic concerns of fluorosis. Dental hygienists should consider individualizing dietary assessment for sources of fluoride to provide a comprehensive recommendation for prevention of dental caries.

REFERENCES

1. Fluorosis Facts. Chicago: American Dental Association; 2005:3.
2. Levy SM. An update on fluorides and fluorosis. J Can Dent Assoc. 2003;69:286-291.
3. Westphal C, Hays R. Not in my water supply. Journal of Practical Hygiene. 2005;14(9)28.
4. Heilman JR. Kiritsy MC, Levy SM, Wefel JS. Fluoride concentration of infant foods. J Am Dent Assoc. 1997;128:857-863.
5. Johnson SA, DeBiase C. Concentration levels of fluoride in bottled drinking water. J Dent Hyg. 2003;77:161-167.
6. Heilman JR, Kiritsy MC, Levy SM, Wefel JS. Assessing fluoride levels of carbonated soft drinks. J Am Dent Assoc. 1999;130:1593-1599.

From Dimensions of Dental Hygiene. May 2006;4(5): 20-21.