Affordability of fluoride toothpaste and national prevalence of untreated dental caries in low- and middle-income countries: an ecological cross-sectional study

Background Dental caries disproportionately affects low- and middle-income countries (LMICs), where access to fluoride toothpaste is often limited by poor affordability. This study aimed to assess the affordability of ≥ 950 parts per million of fluoride (ppm F) toothpaste for the general population in LMICs and its association with the prevalence of untreated dental caries. Methods A cross‑sectional ecological survey was conducted between January and March 2023. Key-informants—medical professionals with extensive experience in LMICs—reported brand, fluoride concentration, pack size, and price for commonly used toothpastes. Prices were converted to United States dollars using average 2023 exchange-rates, product volumes were standardised to grams, and annual consumption assumed 3 g/day (twice daily brushing). Affordability was defined as the proportion of 2023 median annual income required to purchase a 1‑year supply per person. National prevalence of untreated caries (ages ≥ 5 years), per capita refined sugar availability (2019), gross domestic product (GDP) per capita (PPP), and Gini index were assembled from international databases. Multiple linear regression assessed associations between caries prevalence and affordability, adjusting for GDP, Gini, and sugar; log‑transformations were applied except for Gini. Results Data were obtained for 45 LMICs across Asia, Africa, Oceania, Latin America, and the Middle East. The mean annual cost of fluoride toothpaste was USD 30.87 (SD 18.74; range 4.91–87.26). The mean affordability ratio was 0.48% (SD 0.49%; range 0.09–2.33%). In regression analyses, only affordability showed a significant positive association with untreated caries prevalence (coefficient 0.08; 95% CI 0.01–0.16; p = 0.03); GDP per capita, Gini index, and sugar availability were not significant. Conclusions Affordability of ≥ 950 ppm F toothpaste varies substantially across LMICs and is significantly associated with the national prevalence of untreated dental caries.