Hotter Years, More Cavities? Understanding Link Between Climate and Dental Health

The researchers describe dehydration and changes in saliva production as possible routes through which heat could affect oral health, with changes in daily habits and access to dental services offering other possible connections.

A hotter year might seem likely to bring more dental problems, especially if dehydration affects the mouth's natural protection or extreme heat makes getting care harder. A study covering all 27 European Union countries found no clear evidence that yearly changes in temperature tracked changes in tooth decay, gum disease or unmet dental needs.

Published in Frontiers in Public Health, the research by Cassandra Lupita and colleagues, titled 'Climate risk or healthcare investment? Explaining oral health outcomes across European Union member states,' examined national data from 2016 to 2023. The findings describe what researchers could detect across eight years of country-level records, leaving important questions about personal exposure and longer-term effects open.

Why researchers looked for a link between heat and teeth

Saliva helps protect teeth by neutralising acids, controlling bacteria and supplying minerals that support enamel repair. The researchers describe dehydration and changes in saliva production as possible routes through which heat could affect oral health, with changes in daily habits and access to dental services offering other possible connections.

Those explanations were part of the study's background, rather than processes measured in the people represented by the data. The team had no comparable information across the EU on dry mouth, saliva flow or individual heat exposure.

Europe offered a useful setting because its countries differ considerably in climate, public spending and dental-care arrangements. Understanding whether oral health changes as a country experiences hotter years requires separating those yearly changes from persistent differences between countries, including their diets, economic conditions and health services.

What eight years of European records showed

The researchers assembled 216 country-year observations for most measures and 215 for unmet dental care, bringing together weather records, disease estimates and information about access to services.

Their methods describe using Open-Meteo temperature data from each country's geographic centre to calculate annual average temperatures and the number of days exceeding 30°C. This gave every country a consistent weather measure, with limited ability to represent the conditions experienced by people living across different regions.

Estimates from the Global Burden of Disease 2023 dataset covered untreated decay in permanent teeth and periodontal disease, which affects the tissues supporting teeth. Eurostat supplied the percentage of people aged 16 or older who reported being unable to obtain a needed dental examination because of cost, distance or waiting lists.

According to the paper's main descriptive table, untreated tooth decay averaged approximately 37.5% across the country-year records, age-standardised periodontal disease prevalence averaged 11.2%, and unmet dental needs averaged 3.5%. These figures summarise the records analysed; they are not population-weighted estimates for the EU as a whole.

The differences were substantial: untreated decay ranged from about 22.1% to 47.7%, and unmet dental needs ranged from 0.1% to 14.2%. Disease estimates changed relatively little within individual countries during the study period, giving researchers a narrower range of annual changes to examine.

The main analysis found no clear temperature or spending link

The central analysis compared each country with itself over time, accounting for stable national characteristics and shared influences affecting countries in the same year. Neither average annual temperature nor the number of extreme heat days showed a statistically significant association with any of the three oral-health outcomes at the conventional 5% threshold.

Comparisons that combined countries and years showed geographical patterns linking temperature with tooth decay and periodontal disease. Those patterns did not hold up in the analysis of changes within countries, suggesting that differences in geography, social conditions or healthcare arrangements could help explain the initial relationships.

Additional checks tested whether the relationship curved as temperatures increased or differed according to government health spending. No statistically significant pattern emerged. A resampling check using 999 repetitions, chosen to improve statistical assessment with only 27 countries, supported the main findings.

The changing climate and spending measures explained only a small share of the remaining outcome variation after country and year effects were accounted for: approximately 5.6% for tooth decay, 3.2% for periodontal disease and 4.4% for unmet dental needs.

Government health expenditure, measured as a percentage of gross domestic product, showed no statistically significant association with any outcome at the 5% threshold. The analysis offered no evidence that this spending measure reduced a climate-related oral-health risk.

That result cannot tell readers whether investment in dental services works, because the spending measure covered government healthcare broadly and did not identify money allocated to dental treatment, prevention or coverage. Its value could change through movements in either health spending or the size of the economy.

What the findings leave unanswered

Eight years of national data may miss dental problems that develop slowly, happen during short heatwaves or affect certain communities. Temperatures measured at each country's geographic centre cannot show everyone's exposure, and national averages can hide local differences, vulnerable groups and how people cope with heat.

The disease figures were estimates, and no individual patients were followed, so the study cannot prove that heat causes problems with teeth or gums. The small number of countries, limited yearly changes, repeated statistical comparisons and unexplained patterns across years and countries made the results less precise.

The paper contains conflicting heat thresholds, figures and statements about health spending. This article uses its main data table and detailed statistical results. Longer studies need local and individual heat measurements, saliva tests, and information on dental spending, coverage and service use to understand delayed effects and risks that national averages may miss.