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Fighting Tooth Decay

Howard Pollick, BDS, MPH, discusses the benefits, risks, and alternatives of community-based fluoridation.

[ Click here to read Part 1 ]

Q. When did communities begin fluoridating the water supply and has it been effective in reducing the incidence of caries?

A. In 1945, the first series of community water fluoridation trials began to reduce the burden of tooth decay, primarily in children.1-4 The trials were initiated due to evidence showing that children living in communities with about 1 ppm of naturally-occurring fluoride in their drinking water experienced only one-third of the tooth decay compared to those living in communities with a negligible concentration of fluoride in the water. The children also had much less dental mottling or fluorosis (only 10%-15%) than comparable children in communities with more than 2 ppm fluoride. A systematic review of published studies, conducted on behalf of the Task Force on Community Preventive Services by a team of experts, found that community water fluoridation was effective in reducing tooth decay among populations. Based on strong evidence of effectiveness, the Task Force recommends that community water fluoridation be part of a comprehensive population-based strategy to prevent or control tooth decay in communities.5

Q. What are the effects of excessive fluoride exposure on children beyond their dentition?

A. While we are always concerned about the ingestion of too much fluoride, extensive research shows that fluoridated water has no other effects on the body other than on teeth and bone. The science has been reviewed, corroborated, and confirmed by numerous scientific bodies such as the International Programme on Chemical Safety, World Health Organization;6,7 the Agency for Toxic Substances and Disease Registry, the US Public Health Service;8,9 the National Research Council;10 the Centers for Disease Control and Prevention;11 the Institute of Medicine;12 the University of York, United Kingdom;13 and the Medical Research Council, United Kingdom.14 In addition to its proven safety in humans, water fluoridation is also safe for the environment.15

Even though increased amounts of fluoride may be picked up by bone in fluoridated areas, it does not manifest in any changes of character in the bone or development. However, excessive intake of fluoride naturally occurring in water supplies and cooking methods in parts of China and India can lead to skeletal fluorosis.16 This often affects rural populations when high levels of fluoride intake are combined with malnutrition, which exacerbates the effects of fluoride. Skeletal fluorosis is characterized by excessively calcified bone and is rarely seen in the United States. The US Environmental Protection Agency has set the maximum amount of naturally occurring fluoride in public water at 4 ppm to protect against skeletal fluorosis. Remember that fluoride-deficient water is fluoridated between 0.7 and 1.2 ppm.

FLUOROSIS

Q. Does fluorosis cause denser bone?

A. A distinction needs to be made between dental fluorosis and skeletal fluorosis. Dental fluorosis can vary in extent, from questionable to very mild, mild, moderate, or severe. Ten to 15% of dental fluorosis of the very mild or mild type may come from fluoridated water. The major causes of dental fluorosis are from swallowing fluoride toothpaste while the teeth are developing (less than 6 years old)—particularly between the ages of 18 months and 3 years—and from taking too many fluoride supplements during the same time period. Skeletal fluorosis, on the other hand, is not associated with fluoridated water or dental products.

Q. Are there other effects on bone, such as an increased risk of hip fracture?

A. Water fluoridation doesn’t affect hip fractures. Some studies of hip fractures showed that a high level of fluoride is protective while others demonstrated that a high level of fluoride increases hip fractures. Some studies have shown no difference.17 The consensus is that basically every study has some flaws or biases because of the sample selection process and the method of estimating fluoride intake. The conclusion is that fluoride products and fluoridated water have no effect on the development of hip fracture.13

Q. In communities without water fluoridation, what is the best strategy for reducing tooth decay?

A. In communities without water fluoridation, fluoride supplementation is recommended. The American Academy of Pediatrics, the American Academy of Pediatric Dentistry, and the ADA recommend prescription fluoride supplements for children from the age of 6 months to 16 years on a daily basis where the fluoride concentration of the water is below 0.6 ppm (see Table 1). Compliance with this schedule is not very good. As children get older, compliance drops to less than 5%, so it’s not an effective public health program.

 

Table 1. Dietary Fluoride Supplement Schedule
Fluoride ion level in drinking water (ppm)*
Age Less than 0.3 ppm 0.3 – 0.6 ppm Greater than 0.6 ppm
Birth – 6 months None None None
6 months – 3 years 0.25 mg/day** None None
3 – 6 years 0.50 mg/day 0.25 mg/day None
6 – 16 years 1.0 mg/day 0.50 mg/day None

* 1 ppm = 1 mg/L

** 2.2 mg sodium fluoride contains 1 mg fluoride ion.

From Centers for Disease Control and Prevention. Dietary fluoride supplement schedule. Available at: http://www.cdc.gov/OralHealth/waterfluoridation/other/spplmnt_schdl.htm. Accessed January 24, 2006.

 

Q. Is it a community-based decision on whether the water is fluoridated in a geographic area?

A. Yes, but the definition of local can vary. Local can encompass a very small community or an entire water district with jurisdiction over several cities. There is public consent to water fluoridation by a vote of representative body or of the people. There is no other public health program that we vote on as a community.

Other community programs, like school-based programs for fluorides, are effective at reducing tooth decay. In these programs a 0.2% sodium fluoride rinse is distributed in the school every week. The rinse is swished around the mouth for a minute or so and spit out so it’s not ingested. Rinses are not given to those under 6 because young children may not be able to spit out.

Q. How long should we advise our patients to brush in order to gain the maximum benefits of fluoride exposure?

A. The longer the time period, the more effective the fluoride is. However, people rarely brush longer than a minute and brushing with fluoride toothpaste is more effective when done more than once a day.18 High-risk individuals over the age of 6 should use a product that has 5,000 ppm of fluoride in their toothpaste, which is only available through prescription. Over-the-counter fluoride rinses, which have about 230 ppm of fluoride, are also effective.


REFERENCES

  1. Arnold FA Jr, Likins RC, Russell AL, Scott DB. Fifteenth year of the Grand Rapids Fluoridation Study. J Am Dent Assoc. 1962;65:780-785.
  2. Ast DB, Fitzgerald B. Effectiveness of water fluoridation. J Am Dent Assoc . 1962;65:581-587.
  3. Blayney JR, Hill IN. Fluorine and dental caries. J Am Dent Assoc . 1967;74:225-302.
  4. Hutton WL, Linscott BW, Williams DB. Final report of local studies on water fluoridation in Brantford. Can J Public Health . 1956;47:89-92.
  5. Truman BI, Gooch BF, Sulemana I, et al. Reviews of evidence on interventions to prevent dental caries, oral and pharyngeal cancers, and sports-related craniofacial injuries. Am J Prev Med . 2002;23(1 Suppl):21-54.
  6. International Programme on Chemical Safety Task Group on Environmental Health Criteria for Fluorine and Fluorides. Environmental Health Criteria 36. Fluorine and Fluorides. Available at: www.inchem.org/documents/ehc/ehc/ehc36.htm. Accessed January 24, 2006.
  7. World Health Organization. Report of a WHO Expert Committee on Oral Health Status and Fluoride Use. Geneva, Switzerland: World Health Organization; 1994.
  8. Report of the Ad Hoc Subcommittee on Fluoride of the Committee to Coordinate Environmental Health and Related Programs. Review of fluoride: benefits and risks. Available at: www.health.gov/environment/ReviewofFluoride/default.htm. Accessed January 24, 2005.
  9. Agency for Toxic Substances and Disease Registry. 2003. Public Health Statement for Fluorides, Hydrogen Fluoride, and Fluorine. Available at: www.atsdr.cdc.gov/toxprofiles/phs11.html. Accessed January 24, 2006.
  10. National Academies Press. Health Effects of Ingested Fluoride. Available at: http://stills.nap.edu/books/030904975X/html. Accessed January 24, 2006.
  11. Centers for Disease Control and Prevention. MMWR. Achievements in public health, 1900- 1999: fluoridation of drinking water to prevent dental caries. Available at: www.cdc.gov/mmwr/preview/mmwrhtml/mm4841a1.htm. Accessed January 24, 2006.
  12. National Academies Press. Dietary reference intakes for calcium, phosphorus, magnesium, vitamin D, and fluoride. Available at: http://books.nap.edu/books/0309063507/html/288.html#pagetop. Accessed January 24, 2006.
  13. Centre for Reviews and Dissemination. A Systematic Review of Public Water Fluoridation 2000. Available at: www.york.ac.uk/inst/crd/fluores.htm. Accessed January 24, 2006.
  14. Medical Research Council. MRC working group report: water fluoridation and health. Available at: www.mrc.ac.uk/prn/index/public-interest/publicnews/public-fluoridation_report-2.htm. Accessed January 24, 2006.
  15. Pollick HF. Water fluoridation and the environment: current perspective in the United States. Int J Occup Environ Health . 2004;10:343-350.
  16. World Health Organization. Water-related diseases. Available at: www.who.int/water_sanitation_health/diseases/fluorosis/en/. Accessed January 26, 2006.
  17. Hillier S, Cooper C, Kellingray S, Russell G, Hughes H, Coggon D. Fluoride in drinking water and risk of hip fracture in the UK: a case-control study. Lancet . 2000;22;355:265-269.
  18. Davies RM, Davies GM, Ellwood RP. Prevention. Part 4: Toothbrushing: what advice should be given to patients? Br Dent J . 2003;195:135-141.

From Dimensions of Dental Hygiene. February 2006;4(2):22-23.

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