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

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 toothpaste containing ≥ 950 parts per million fluoride (ppm F) for the general population in LMICs and its association with the prevalence of untreated dental caries. 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 was estimated assuming 3 g/day (twice daily brushing). Affordability was defined as the proportion of 2023 country-specific median annual income required to purchase a 1‑year supply per person. National prevalence of untreated caries (ages ≥ 5 years), per capita sugar availability, gross domestic product (GDP) per capita based on purchasing power parity (PPP), and Gini index were assembled from international databases. Multiple linear regression assessed associations between log-transformed untreated caries prevalence and affordability, adjusting for GDP, Gini, and sugar availability. Affordability, GDP per capita, and sugar availability were log-transformed, whereas the Gini index was not. Data were obtained for 44 LMICs across Asia, Africa, Oceania, Latin America, and the Middle East. A total of 165 fluoride toothpaste products with verified fluoride concentrations of ≥ 950 ppm F were included in the analyses. The mean annual cost of fluoride toothpaste was USD 31.28 (SD 18.75; 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 0.082; 95% CI 0.004–0.159; p = 0.040); GDP per capita, Gini index, and sugar availability were not significantly associated with untreated caries prevalence. Affordability of ≥ 950 ppm F toothpaste varies substantially across LMICs and is significantly associated with the national prevalence of untreated dental caries.