A review of water fluoridation implementation strategy in England 2002-2005

Do missing teeth cause early-onset cognitive impairment? Re-examining the evidence using a quasi-natural experiment

PURPOSE

Multiple studies have reported a positive association between missing teeth and cognitive impairment. While some authors have postulated causal mechanisms, existing designs preclude assessing this.

METHODS

We sought evidence of a causal effect of missing teeth on early-onset cognitive impairment in a natural experiment, using differential exposure to fluoridated water during critical childhood years (ages 5-20 years) in England as the instrument. We coded missing teeth from 0 (≤ 12 missing) to 3 (all missing) and measured the association with cognitive impairment in the English Longitudinal Study of Ageing data (2014-5), covering 4958 persons aged 50-70 years.

RESULTS

We first replicated previous evidence of the strongly positive association of missing teeth with cognitive impairment (β = 0.25 [0.11, 0.39]), after adjusting for socio-demographic covariates, such as age, gender, education, and wealth. Using an instrumental variable design, we found that childhood exposure to water fluoridation was strongly associated with fewer missing teeth, with being exposed to fluoridated water during childhood (16 years) associated with a 0.96 reduction in the missing teeth scale (β = - 0.06 [- 0.10, - 0.02]). However, when using the instrumented measure of missing teeth, predicted by probability of fluoride exposure, we found that missing teeth no longer had an association with cognitive impairment (β = 1.48 [- 1.22, 4.17]), suggesting that previous oral health-cognitive impairment associations had unobserved confounding.

CONCLUSIONS

Our findings are consistent with the possibility that unobserved confounding leads to the oft-observed association between missing teeth and early-onset cognitive impairment, suggesting that the relationship is spurious rather than causal.

Anticaries activity of GERM CLEAN in Streptococcus mutans and Candida albicans dual-species biofilm

OBJECTIVE

To evaluate the antimicrobial effects of a peptide containing novel oral spray GERM CLEAN on dual-species biofilm formed by Streptococcus mutans and Candida albicans and to investigate whether GERM CLEAN inhibits the demineralization procedure of bovine enamel in vitro.

METHODS

The antimicrobial effects of GERM CLEAN on dual-species biofilm were analyzed by initial adherence rate calculation, water-insoluble exopolysaccharides quantification, total biomass quantification, and colony-forming units (CFUs) counting. Scanning electron microscopy and confocal laser scanning microscopy were applied to evaluate the impacts of GERM CLEAN on the biofilm structure. Further, the effects of GERM CLEAN on acidogenicity of dual-species were appraised via glycolytic pH drop analysis and hydroxyapatite dissolution measurement. The percentage of Surface Microhardness Reduction (%SMHR) evaluation, Atomic Force Micrograph (AFM) examination, and Transverse Microradiography (TMR) analysis after pH cycling were used to determine whether GERM CLEAN inhibited the demineralization of bovine enamel.

RESULTS

GERM CLEAN decreased the adherence rate, water-insoluble EPS production, biofilm formation, and acidogenicity of the dual-species. Moreover, GERM CLEAN significantly inhibited the demineralization status of bovine enamels.

CONCLUSION

This peptide containing novel oral spray GERM CLEAN has antimicrobial potential toward the dual-species. GERM CLEAN can also impede the demineralization procedure of enamel.

Causal Effect of Tooth Loss on Functional Capacity in Older Adults in England: A Natural Experiment

BACKGROUND/OBJECTIVES

Tooth loss is associated with reduced functional capacity, but so far, there is no relevant causal evidence reported. We investigated the causal effect of tooth loss on the instrumental activities of daily living (IADL) among older adults in England.

DESIGN

Natural experiment study with instrumental variable analysis.

SETTING

The English Longitudinal Study of Aging (ELSA) combined with the participants' childhood exposure to water fluoride due to the community water fluoridation.

PARTICIPANTS

Five thousand six hundred and thirty one adults in England born in 1945-1965 participated in the ELSA wave seven survey (conducted in 2014-2015; average age: 61.0 years, 44.6% men).

MEASUREMENTS

The number of natural teeth predicted by the exogenous geographical and historical variation in exposure to water fluoride from age 5 to 20 years old (instrumental variable) was used as an exposure variable. The outcome, having any limitations in IADL (preparing a hot meal, shopping for groceries, making telephone calls, taking medications, doing work around the house or garden, or managing money), was assessed by self-reported questionnaires.

RESULTS

Linear probability model with Two-Stage Least Squares estimation was fitted. Being exposed to fluoridated water was associated with having more natural teeth in later life (coefficient: 0.726; 95% confidence interval (CI) = 0.311, 1.142; F = 11.749). Retaining one more natural tooth reduced the probability of having a limitation in IADL by 3.1 percentage points (coefficient: -0.031; 95% CI = -0.060, -0.002).

CONCLUSION

Preventing tooth loss maintains functional capacity among older adults in England. Given the high prevalence of tooth loss, this effect is considerable. Further research on the mechanism of the observed causal relationship is needed.