Fluoride Facts

Research indicates that dental caries rates are declining, yet dental decay still remains a major public health problem and is still the most common chronic childhood disease.¹ The increased use of fluoride has contributed to the recent decline in caries, especially through community water fluoridation and the use of fluoride products such as toothpastes and mouthrinses.¹ Additionally, a greater interest and awareness of preventive care among consumers have contributed to the declining rates.¹

THE BASICS

Fluoride is an ionic form of fluorine found naturally in water.² A major benefit of fluoride is its effectiveness in remineralizing incipient carious lesions.³ When acids caused by bacteria weaken the enamel on a tooth, the process is called demineralization (a loss of calcium and phosphate minerals salts). Eventually, this process can lead to the clinical appearance of a white or chalky spot on the tooth surface. This occurs because acid lowers the pH at the tooth surface creating a subsurface lesion. If the lesion progresses through further demineralization, a carious lesion occurs.⁴ However, this stage can often be reversed by the topical actions of fluoride.

Fluoride can be delivered to the teeth topically or systemically to aid in the prevention of dental caries.The main exposure to fluoride is in topical applications such as fluoridated toothpaste and community water fluoridation.² However, fluoride is also found in certain processed foods, beverages, mouthrinses, gels, foams, and varnishes.² The intake of water and processed beverages in the United States provides approximately 75% of a person’s fluoride intake.²

Saliva is a major carrier of topical fluoride. Exposure to fluoride-containing products can help increase the concentration of fluoride in saliva, which aids in the process of tooth remineralization.² Remineralization is able to halt the progression of demineralization when saliva acts to neutralize acids and restore the mineral content of calcium and phosphorus to the tooth structure. The role of fluoride is significant because even in low concentrations, it can enhance the remineralization of enamel resulting in a crystal structure, which is more caries resistant. In this dynamic process, caries on the enamel surface can actually be repaired.⁴

ADULT USAGE

Adults today are retaining their teeth longer due to improved oral health and more routine preventive and restorative care. Although studies show tooth retention among older adults has increased, tooth loss continues to be a concern. Tooth decay affects 90% of adults over the age of 40; one fourth of adults over the age of 60 are edentulous.⁵

Studies show there is an increased risk for caries in adults 70 years of age and older. This is largely due to xerostomia caused by the intake of many medications. When older adults develop medication-induced xerostomia, there is a 20% to 40% reduction in salivary flow.⁶ More than 700 medications can cause xerostomia, and 63% of those medications are among the most frequently prescribed in the United States.⁶

Neenan et al found that 67% of men and 61% of women ages 65 to 85+ had root surface lesions.³ As teeth age, more root surfaces are exposed, resulting in increased susceptibility to root caries.³ Establishing good home care techniques along with routine maintenance visits and fluoride treatments can help reduce caries risk in adults.

WATER FLUORIDATION

Oral Health America, a nonprofit organization dedicated to raising awareness of oral health’s importance to total health, reports that dental caries rates among school-aged children has declined since the 1970s.⁷ This can be attributed to the widespread use of a variety of fluoride sources, such as dentifrice, gel, varnish, rinse, fluoride supplements, and community water fluoridation.⁸

According to the Surgeon General’s report, an effective, safe, and ideal public health measure—like community water fluoridation—can benefit people of all ages and socioeconomic status.⁷ Community fluoridation is an effective public health measure for providing fluoride to lower socioeconomic populations that may not have access to fluoride treatments or products such as toothpaste and mouthrinse.⁹ In community water fluoridation, the fluoride concentration of a community’s water supply is adjusted to the level necessary for optimal health.

Many children and adults still do not benefit from effective preventive methods known to combat oral diseases. In one study, the incidence of root caries was approximately 50% less in lifelong residents who had lived in a community with a fluoridated water supply.⁴ Even though community water fluoridation is one of the most cost-effective methods of protecting teeth, studies show that more than 100 million Americans still have no access to an appropriate amount of fluoridated water.⁵ The per capita cost of water fluoridation over a person’s lifetime is less than the cost of one dental filling.⁵ Jenkins et al reported that the mean annual per capita cost of community water fluoridation on an annual basis was calculated at $0.68 for a population over 50,000 and $0.98 for a population between 10,000 and 50,000.¹⁰
An objective of Healthy People 2010, a National Health Initiative, is to provide fluoridated water to 75% of the United States population’s public water system.⁷ The American Dental Association (ADA) also considers community water fluoridation safe, beneficial, and cost-effective for preventing dental caries in children and adults.¹¹ Optimal levels of community water fluoridation range from 0.7 ppm-1.² ppm for protection against tooth decay depending on the average maximum daily air temperature of the area. Lower fluoride concentrations are appropriate for residents in warmer climates due to the assumption that people tend to drink more water. However, this assumption has become questionable with the increased use of air conditioners.² To obtain information on the specific concentration of fluoride in a community’s water supply, residents can contact the water supplier or the local public health department.

The ADA also reports that fluoridated water reduces decay in children by 18%-40% and in adults by nearly 35%.¹² However, there is concern about the overall health effects of fluoride. Opponents of water fluoridation are concerned about dental fluorosis and the impact of fluoride on human health.

Fluorosis occurs when teeth are exposed to excessive amounts of fluoride during enamel formation. Too much fluoride can create defects in the enamel, causing it to be pitted and rough with white specks or streaks. Young children may be at risk for fluorosis when they live in areas where the drinking water has higher than optimum levels of naturally occurring fluoride, by ingesting or swallowing fluoride toothpaste, or by taking inappropriately prescribed fluoride supplements.³

ADDITIONAL SOURCES

In the United States, various sources of fluorides are available both systemically and topically. Reports show that some countries that may have less centralized water systems use salt fluoridation to prevent dental caries, while other countries have begun to use milk fluoridation in some school-based fluoride delivery programs.³ However, in some United States communities, water fluoridation is still not available or may not be desirable for various reasons. School-based fluoride rinse programs are alternatives to providing a cost-effective means of fluoride benefits to children. While children attend school during the day, a time is set aside for them to receive the fluoride rinse. The children rinse for 60 seconds with 10 ml of a 2% sodium fluoride solution and then expectorate into a cup.

School-based programs are normally located at the school site and require parental permission and supervision by a licensed dentist. It is common for a registered dental hygienist or certified dental assistant to also be involved in such community-based outreach programs. There are other effective methods of fluoride delivery to prevent dental caries in children and adults. See Table 1 for information on fluoride sources.

A recent study noted that in comparing various fluoride sources, varnishes were approximately 14% more effective than topical fluoride gels.¹³ Most varnishes cause a temporary yellow discoloration on the surface for about 24-48 hours. Some dental professionals prefer the yellowish tint because it helps them see where the varnish has been applied. However, a white varnish* is now available that does not cause the yellow discoloration, which may be more attractive to patients.¹³ A fluoride varnish** is also on the market that can be used as a cavity liner and desensitizing agent.¹⁴

CONCLUSION

Combining healthy foods and good oral hygiene increases the overall effectiveness of fluoride use. Although fluoride is well-documented as safe and beneficial for preventing caries in children and adults, only small amounts are necessary for maximum benefits. Young children should be carefully monitored and supervised to prevent any potential overdose or the appearance of spots on developing teeth. Parents may want to consider fluoride varnish as a topical fluoride choice due to its reported advantages—easy application, proven effectiveness, safety, and efficacy.¹⁴

Fluoride is especially advantageous for children and adults at risk for tooth decay and those in underserved areas. When considering primary preventive efforts and the goals of 2010, greater assessment and educational strategies must be made for implementing community fluoridation where needed and increasing school-based or community-based fluoride rinse and fluoride varnish programs.

REFERENCES

1. Harris NO.Introduction to primary preventive dentistry.In: Primary Preventive Dentistry. 6th ed.Upper Saddle River, NJ: Pearson Education Inc; 2004:2-3.
2. Adair SM, Bowen WH, Burt BA, et al.Recommendations for using fluoride to prevent and control dental caries in the United States. MMWR Recommendations and Reports. 2001;50(RR14):1-42.
3. Neenan ME, Easley M, Ruiz M. Water fluoridation. In: Primary Preventive Dentistry. 6th ed. Upper Saddle River, NJ: Pearson Education Inc; 2004:1888-18191.
4. Mattana DJ.Fluorides. In: Wilkins EM. Clinical Practice of the Dental Hygienist. 9th ed. Boston: Lippincott, Williams & Wilkins; 2005:543-563.
5. Preventing Cavities, Gum Disease, and Tooth Loss, 2007. Available at: www.cdc.gov/nccdphp/publications/aag/pdf/oh.pdf.Accessed June 27, 2007.
6. Zunt S. The importance of saliva. Dimensions of Dental Hygiene. 2006;4(1):26.
7. Oral Health in America: A Report of the Surgeon General-Executive Summary. Rockville, Md: United States Depart of Health and Human Services. National Institute of Dental and Craniofacial Research. National Institutes of Health, 2000.
8. Centers for Disease Control. Oral Health in America: 2010 Objectives.Available at: www.healthypeople.gov/document/pdf.volume2/21oral.pdf.Accessed June 27, 2007.
9. Young DA, Featherstone JDB. Fluoride and the reversal of dental caries. In: Daniel SJ, Harfst SA, eds. Mosby’s Dental Hygiene: Concepts, Cases and Competencies. St Louis: Mosby; 2004:393-402.
10. Jenkins
11. ADA Statement of Fluoride in Drinking Water: A Scientific Review of EPA’s Standards.Available at: www.ada.org/public/media/releases/0603_release02.asp. Accessed June 27, 2007.
12. American Dental Association. Centers for Disease Control. Water Water Fluoridation: Nature’s Way to Prevent Tooth Decay.Available at: www.ada.org/goto/fluoride. Accessed June 27, 2007.
13. Stookey GK. Fighting dental decay: past, present and future. Access. 2006;20(2):12-16.
14. Harris NO, Segura A. The developing carious lesion.In: Primary Preventive Dentistry. 6th ed.Upper Saddle River, NJ: Pearson Education Inc; 2004:64-65.

From Dimensions of Dental Hygiene. July 2007;5(7): 28-30.