Association between climate change and oral health outcomes: a systematic review of time-series studies

This Systematic review aimed to assess the association between short term environment exposures and oral health outcomes using evidence from time-series studies.

The protocol was registered with PROSPERO (International Prospective Register of Systematic Reviews). A comprehensive search of PubMed, Embase, Scopus, Web of Science and Google Scholar were conducted to identify relevant studies. Records were imported to Rayyan AI for multistage screening by two independent reviewers, and any conflicting views were resolved with the third reviewer. Data extraction followed the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) guidelines, and findings were summarized narratively and in tabular form.

Seven time-series studies involving over 4 million epidemiological observations were included. Summarized evidence suggested association between change in climate and oral health outcomes. Lower air temperature was associated with 75% risk of periodontal diseases over a lag of 1 to 7 days. Every 10 µg/m³ increase in NO₂ was associated with a 30% increase in outpatient visits for periodontitis over 0-4 lag days particularly on warmer days, whereas consistent exposure above threshold limits was associated with 12% risk of oral cancer over 3 years lag (at 95% CI: 10%, 13%). Furthermore, a unit increase in concentration level of pollutants such as PM_2.5 and CO, was associated with increased risk of pulpitis by 2.4%, 5%, and 9.1%, respectively. Similarly, mean temperature 12.5 °C and air pollution was associated with higher risk of dental caries. Demographic characteristics appear to modify risk and O₃ acts as a protective factor against periodontitis [RR = 0.99 at 95% C.I. (0.991, 0.995)].

Environmental exposures, particularly air pollution and temperature, may influence the outcome of oral health. Further well-designed studies are needed to clarify causal pathways and strengthen evidence base.