Economic evaluation of a water fluoridation scheme in Cumbria, UK

OBJECTIVES

The addition of fluoride to community drinking water supplies has been a long-standing public health intervention to improve dental health. However, the evidence of cost-effectiveness in the UK currently lacks a contemporary focus, being limited to a period with higher incidence of caries. A water fluoridation scheme in West Cumbria, United Kingdom, provided a unique opportunity to study the contemporary impact of water fluoridation. This study evaluates the cost-effectiveness of water fluoridation over a 5-6 years follow-up period in two distinct cohorts: children exposed to water fluoridation in utero and those exposed from the age of 5.

METHODS

Cost-effectiveness was summarized employing incremental cost-effectiveness ratios (ICER, cost per quality adjusted life year (QALY) gained). Costs included those from the National Health Service (NHS) and local authority perspective, encompassing capital and running costs of water fluoridation, as well as NHS dental activity. The measure of health benefit was the QALY, with utility determined using the Child Health Utility 9-Dimension questionnaire. To account for uncertainty, estimates of net cost and outcomes were bootstrapped (10 000 bootstraps) to generate cost-effectiveness acceptability curves and sensitivity analysis performed with alternative specifications.

RESULTS

There were 306 participants in the birth cohort (189 and 117 in the non-fluoridated and fluoridated groups, respectively) and 271 in the older school cohort (159 and 112, respectively). In both cohorts, there was evidence of small gains in QALYs for the fluoridated group compared to the non-fluoridated group and reductions in NHS dental service cost that exceeded the cost of fluoridation. For both cohorts and across all sensitivity analyses, there were high probabilities (>62%) of water fluoridation being cost-effective with a willingness to pay threshold of £20 000 per QALY.

CONCLUSIONS

This analysis provides current economic evidence that water fluoridation is likely to be cost-effective. The findings contribute valuable contemporary evidence in support of the economic viability of water fluoridation scheme.

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.

Esthetic and Functional Rehabilitation of an Adolescent Patient with Severe Dental Fluorosis: A Clinical Report

Dental fluorosis is a developmental defect affecting amelogenesis. It presents clinically in different forms depending on the concentration, duration, and time of exposure to fluoride. Several therapeutic modalities have been described to manage mild and moderate forms of dental fluorosis; however, limited literature is available on the restorative management of severe forms of dental fluorosis, specifically in young individuals. This clinical report describes a complete prosthodontic rehabilitation of an adolescent patient with severe dental fluorosis affecting his permanent dentition. The patient was treated with a combination of monolithic, minimally-veneered zirconia crowns and direct composite resins. At the 1-year follow-up appointment, there were no complications, and both the patient's oral health and the integrity of the restorations remained stable.

A cost-effectiveness analysis of community water fluoridation for schoolchildren

BACKGROUND

Community water fluoridation (CWF), the controlled addition of fluoride to the water supply for the prevention of dental caries (tooth decay), is considered a safe and effective public health intervention. The Republic of Ireland (Ireland) is the only country in Europe with a legislative mandate for the fluoridation of the public water supply, a key component of its oral health policy. However, more recently, there has been an increase in public concern around the relevance of the intervention given the current environment of multiple fluoride sources and a reported increase in the prevalence of enamel fluorosis. The aim of this economic analysis is to provide evidence to inform policy decisions on whether the continued public investment in community water fluoridation remains justified under these altered circumstances.

METHODS

Following traditional methods of economic evaluation and using epidemiological data from a representative sample of 5-, 8-, and 12-year-old schoolchildren, this cost-effectiveness analysis, conducted from the health-payer perspective, compared the incremental costs and consequences associated with the CWF intervention to no intervention for schoolchildren living in Ireland in 2017. A probabilistic model was developed to simulate the potential lifetime treatment savings associated with the schoolchildren's exposure to the intervention for one year.

RESULTS

In 2017, approximately 71% of people living in Ireland had access to a publicly provided fluoridated water supply at an average per capita cost to the state of €2.15. The total cost of CWF provision to 5-, 8-, and 12-year-old schoolchildren (n = 148,910) was estimated at €320,664, and the incremental cost per decayed, missing, or filled tooth (d3vcmft/D3vcMFT) prevented was calculated at €14.09. The potential annual lifetime treatment savings associated with caries prevented for this cohort was estimated at €2.95 million. When the potential treatment savings were included in the analysis, the incremental cost per d3vcmft/D3vcMFT prevented was -€115.67, representing a cost-saving to the health-payer and a positive return on investment. The results of the analysis were robust to both deterministic and probability sensitivity analyses.

CONCLUSION

Despite current access to numerous fluoride sources and a reported increase in the prevalence of enamel fluorosis, CWF remains a cost-effective public health intervention for Irish schoolchildren.

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.

Drinking Water in the United States: Implications of Water Safety, Access, and Consumption

Recent water quality crises in the United States, and recognition of the health importance of drinking water in lieu of sugar-sweetened beverages, have raised interest in water safety, access, and consumption. This review uses a socioecological lens to examine these topics across the life course. We review water intakes in the United States relative to requirements, including variation by age and race/ethnicity. We describe US regulations that seek to ensure that drinking water is safe to consume for most Americans and discuss strategies to reduce drinking water exposure to lead, a high-profile regulated drinking water contaminant. We discuss programs, policies, and environmental interventions that foster effective drinking water access, a concept that encompasses key elements needed to improve water intake. We conclude with recommendations for research, policies, regulations, and practices needed to ensure optimal water intake by all in the United States and elsewhere.

Area-level deprivation, childhood dental ambulatory sensitive hospitalizations and community water fluoridation: evidence from New Zealand

Background

We examined the association between area-level deprivation and dental ambulatory sensitive hospitalizations (ASH) and considered the moderating effect of community water fluoridation (CWF). The hypothesis was that higher levels of deprivation are associated with higher dental ASH rates and that CWF will moderate this association such that children living in the most deprived areas have greater health gain from CWF.

Methods

Dental ASH conditions (dental caries and diseases of pulp/periapical tissues), age, gender and home address identifier (meshblock) were extracted from pooled cross-sectional data (Q3, 2011 to Q2, 2017) on children aged 0–4 and 5–12 years from the National Minimum Dataset, New Zealand (NZ) Ministry of Health. CWF was obtained for 2011 and 2016 from the NZ Institute of Environmental Science and Research. Dental ASH rates for children aged 0–4 and 5–12 years (/1000) were calculated for census area units (CAUs). Multilevel negative binomial models investigated associations between area-level deprivation, dental ASH rate and moderation by CWF status.

Results

Relative to CWF (2011 and 2016), no CWF (2011 and 2016) was associated with increased dental ASH rates in children aged 0–4 [incidence rate ratio (IRR) = 1.171 (95% confidence interval 1.064, 1.288)] and aged 5–12 years [IRR = 1.181 (1.084, 1.286)]. An interaction between area-level deprivation and CWF showed that the association between CWF and dental ASH rates was greatest within the most deprived quintile of children aged 0–4 years [IRR = 1.316 (1.052, 1.645)].

Conclusions

CWF was associated with a reduced dental ASH rate for children aged 0–4 and 5–12 years. Children living in the most deprived areas showed the greatest effect of CWF on dental ASH rates, indicating that the greater health gain from CWF occurred for those with the highest socio-economic disadvantage. Variation in CWF contributes to structural inequities in oral-health outcomes for children.

Fluoride exposure alters Ca2+ signaling and mitochondrial function in enamel cells

Fluoride ions are highly reactive, and their incorporation in forming dental enamel at low concentrations promotes mineralization. In contrast, excessive fluoride intake causes dental fluorosis, visually recognizable enamel defects that can increase the risk of caries. To investigate the molecular bases of dental fluorosis, we analyzed the effects of fluoride exposure in enamel cells to assess its impact on Ca2+ signaling. Primary enamel cells and an enamel cell line (LS8) exposed to fluoride showed decreased internal Ca2+ stores and store-operated Ca2+ entry (SOCE). RNA-sequencing analysis revealed changes in gene expression suggestive of endoplasmic reticulum (ER) stress in fluoride-treated LS8 cells. Fluoride exposure did not alter Ca2+ homeostasis or increase the expression of ER stress-associated genes in HEK-293 cells. In enamel cells, fluoride exposure affected the functioning of the ER-localized Ca2+ channel IP3R and the activity of the sarco-endoplasmic reticulum Ca2+-ATPase (SERCA) pump during Ca2+ refilling of the ER. Fluoride negatively affected mitochondrial respiration, elicited mitochondrial membrane depolarization, and disrupted mitochondrial morphology. Together, these data provide a potential mechanism underlying dental fluorosis.

Public Sense of Water Fluoridation as Reflected on Twitter 2009-2017

Though controversial, water fluoridation has been hailed as one of the top-ten public-health achievements of the 20th century in the United States of America. In this article, we aim to investigate the public sense of water fluoridation as reflected on Twitter, using data from 2009 to 2017. To this end, tweets related to water fluoridation were collected using queries such as "fluoridated water or fluoride water," "water fluoridation or fluoridation of water," and hashtags related to water fluoridation. The collected tweets (n = 218,748) were examined through informetric, linguistic (word sentiment, word frequency, and word network analyses), and issue tweet analyses. We found that Twitter users who tweeted about water fluoridation in English between 2009 and 2017 constituted about <0.01% of all users including non-English users. In their tweets, words such as "poison" and "waste" were the strong negative sentiment words most often used. Of the top 30 words most frequently used, words related to information sources on water fluoridation and the safety of water fluoridation appeared more often than words related to its efficacy. Additionally, the words related to information sources on water fluoridation and the safety of water fluoridation were found to be core terms in the sentences of tweet mentions. Our linguistic analyses indicate that Twitter users responded sensitively to words that emphasize negative aspects of fluoridation. This is clearly shown in our issue tweet analysis, where tweet mentions expressing negative opinions about water fluoridation accounted for at least 59.2% of all mentions. By contrast, <15% of tweet mentions were found to be positive. These findings suggest that professionals need to reevaluate the current state of online information about water fluoridation, and improve it in a way so that the public can easily access reliable information sources.

Dental caries experience in children of a remote Australian Indigenous community following passive and active preventive interventions

Objectives

To report on changes in dental caries experience in children of a remote Indigenous community following 6 years of passive preventive intervention (PPI) and 2 years of active preventive intervention (API).

Methods

Five consecutive cross‐sectional surveys were conducted on 4‐ to 15‐year‐old school going children between 2004 and 2017 following phases of Community Water Fluoridation (CWF), post‐cessation of CWF and API. Following treatment of any cavities present, API included selective placement of fissure sealants (FS) and an annual application of povidone‐iodine (PI) and fluoride varnish (FV). The World Health Organization's (WHO) “Oral Health Surveys – Basic Methods (4th Edition)” methodology was used in the first two and the International Caries Detection and Assessment System (ICDAS‐II) in the latter three surveys. ICDAS‐II codes of 3‐6, representing advanced caries, were combined to allow comparison to the decayed component of the DMF caries index.

Results

Age‐weighted mean dmft decreased by 37.7% in the deciduous (DD) and DMFT by 35% in the permanent (PD) dentitions between the pre‐ and post‐CWF surveys, followed by increases of 25% and 7.7%, respectively, between the 1‐year and 4‐year post‐CWF surveys. After 2 years of API, mean dmft decreased by 14.3% and DMFT by 7.1%. Untreated dental caries however remained a concern in the DD and PD during both phases of PPI and of API. The decline in caries experience for both dentitions following 2 years of API exceeded that for the 6‐year period of PPI.

Conclusions

The annual reductions in caries experience of 7.2% (DD) and 8% (PD) during the phase of API exceeded annual decreases of 4.7% (DD) and 4.6% (PD) during the phase of PPI. Due to remoteness, cost and logistics in ensuring long‐term viability of API programmes, CWF remains necessary in this type of community.