Aspects of oral health in Tasmanian children with varying experience of fluoride

Caries experience among children in fluoridated Townsville and unfluoridated Brisbane

Fluoridation of community water supplies constitutes the main public health strategy for prevention of dental caries in Australia. In recent years questions have been raised about the effectiveness of water fluoridation. The aim of this paper was to examine differences in caries experience of children aged 5 to 12 years who were lifetime residents either of Brisbane (the unfluoridated Queensland capital) or Townsville (fluoridated since 1965). Children from each city were sampled from patients of the school dental service. Dental therapists and dentists from the school dental service recorded data describing dental caries experience and parents were asked to complete a questionnaire about their children's residential history and exposure to other fluorides. Of the 18,348 children sampled, 10,195 (55.6 per cent) provided completed questionnaires, and 4588 were lifetime residents of their respective cities. Caries rates were significantly lower (P < 0.01) among children in Townsville than in Brisbane, both in the deciduous dentition (according to age 32 to 55 per cent fewer tooth surfaces affected) and permanent dentition (20 to 65 per cent fewer tooth surfaces affected). Significantly lower rates in Townsville persisted (P < 0.01) in multivariate analyses that controlled for oral hygiene practices, exposure to fluoride supplements and household income. Water fluoridation appears to provide a substantial public health benefit for children in Townsville.

Associations between exposure to fluoridated drinking water and dental caries experience among children in two Australian states

OBJECTIVES

This study assessed associations between exposure to fluoride in water and dental caries experience among children in two Australian states.

METHODS

Cross-sectional data were obtained from 9,690 South Australian children aged 5-15 years and 10,195 Queensland children aged 5-12 years. School dental service practitioners recorded DMFS and dmfs data. A questionnaire to parents gained information about residential history that was used to calculate children's percent of lifetime exposed to fluoridated water.

RESULTS

Greater exposure to fluoride in water was associated with lower dmfs and DMFS in both states (P < .01), although in South Australia the effect for DMFS was statistically significant only after controlling for extent of unknown fluoridation exposure and for fluoride supplements. Caries-fluoridation associations were stronger for dmfs compared with DMFS and for Queensland (5% of population fluoridated) compared with South Australia (70% of population fluoridated). Effects for DMFS persisted after controlling for socioeconomic factors.

CONCLUSIONS

Fluoridation was associated with lower caries experience. The weaker association with DMFS in South Australia may be due to less caries and more fissure sealants in that state, and is consistent with a "diffusion" effect, whereby a high proportion of the population exposed to fluoridation diminishes differences among exposure groups.

The effect of fluoride consumption and social class on dental caries in 8-year-old children

School dental service data indicate that whilst Melbourne eight-year-old children had worse dental health than similar children in the Geelong area in 1979, the situation in 1985 was the reverse. In order to investigate this, and determine the effects of socio-economic level (SEL), residential history, and fluoride history on dental caries status, 208 eight-year-old children in the Melbourne area and 209 eight-year-old children in the Geelong area were examined for dental caries. A questionnaire was administered to gain details of subjects' exposure to water and supplement fluorides. The SEL of the subjects' school was used in place of individual SEL. A high proportion (46 per cent) of Geelong subjects used a fluoride supplement at some stage, but few continued this for most of their life. Residential history was important, with 2.4 per cent of the Melbourne subjects living most of their life in a nonfluoridated area and 3.4 per cent of Geelong subjects living most of their life in a fluoridated area. There was a significant difference between the dmft in Melbourne and Geelong when only children who had lived all their life in the city in which they were examined and did not use a fluoride supplement were included. A large part of this difference is attributed to water fluoridation in Melbourne. A substantial number of children would benefit from fluoridation of the reticulated water supply in Geelong, particularly those in the lower social classes.

Effectiveness of water fluoridation

The efficacy of communal water fluoridation in reducing dental caries has been reviewed based on surveys conducted in the last decade of caries prevalence in fluoridated and nonfluoridated communities in the United States as well as in Australia, Britain, Canada, Ireland, and New Zealand. The efficacy is greatest for the deciduous dentition, with a range of 30-60 percent less caries in fluoridated communities. In the mixed dentition (ages 8 to 12), the efficacy is more variable, about 20-40 percent less caries. In adolescents (ages 14-17), it is about 15-35 percent less caries. Current data on caries prevalence in adults and seniors are extremely limited and include several populations living in communities with higher than optimal fluoride levels. For these adults and seniors, a range of 15-35 percent less caries would also apply. Viewed in toto, the current data for children, adolescents, adults and seniors show a consistently and substantially lower caries prevalence in fluoridated communities. For an accurate measurement of the efficacy of water fluoridation in reducing dental caries, it is essential that only persons with a record of continuous or long-term residency in fluoridated versus nonfluoridated areas be included in such assessments. Because of the high geographic mobility in our society and the widespread use of fluoride dentifrices, supplements, and other topical fluoride agents, such comparisons are becoming more difficult to conduct. Accordingly, the effectiveness (rather than the efficacy) of water fluoridation has decreased as the benefits of other forms of fluoride have spread to communities lacking optimal water fluoridation.