The guideline "WHO guideline on environmentally friendly and less invasive oral health care for preventing and managing dental caries" provides evidence-based recommendations for preventing and treating dental caries using mercury-free, minimally invasive and environmentally sustainable approaches. Developed by WHO with support from UNEP, it responds to the global transition away from dental amalgam under the Minamata Convention on Mercury. The guideline assesses the clinical effectiveness, cost-effectiveness, safety and environmental impact of products including fluoride varnish, silver diamine fluoride, fissure sealants, glass ionomer cements and resin-based composites, while also addressing patient safety, occupational exposure, waste management, sustainable procurement and implementation within health systems.
Key Insights
Dental caries affects approximately 2.7 billion people worldwide and disproportionately affects marginalized populations with limited access to essential oral health care.
Dental amalgam contains approximately 50% mercury by weight, and WHO promotes a transition toward mercury-free alternatives in line with the Minamata Convention on Mercury and the Global Oral Health Action Plan 2023–2030.
The guideline contains eight evidence-based recommendations and two best-practice statements covering prevention, nonrestorative care, restorative treatment and risk mitigation.
WHO strongly recommends applying 5% sodium fluoride varnish twice a year as a population-wide preventive intervention against dental caries in both primary and permanent teeth.
WHO conditionally recommends 38% silver diamine fluoride applied twice a year for population-wide caries prevention and strongly recommends it for non-invasive management of selected cavitated lesions without pulp involvement.
Pit and fissure sealants are strongly recommended for preventing dental caries in the first permanent molars of children at high risk of caries.
Fluoride varnish is strongly recommended as a non-invasive treatment for initial, non-cavitated carious lesions in both primary and permanent teeth.
WHO suggests glass ionomer cements and resin-based composites as mercury-free direct restorative materials, while stressing that material choice should reflect dental, oral and patient-related factors.
For children, adolescents, pregnant women and breastfeeding women, WHO suggests limiting resin-based fissure sealants and composites containing bisphenol A derivatives because of potential endocrine effects, although the certainty of evidence is very low.
WHO also recommends caution when using resin-based composites in people with allergic conditions because methacrylate monomers can cause sensitization and allergic reactions.
Best-practice measures for resin-based composites include good ventilation, high-volume suction, appropriate protective equipment, no-touch handling, effective isolation, thorough curing and proper surface finishing or polishing.
The guideline places prevention first, alongside sugar reduction, optimal fluoride use, early and minimally invasive care, shared decision-making and the precautionary principle.
Implementation requires supportive procurement and reimbursement policies, professional training, resilient mercury-free product supply chains, appropriate waste management systems and stronger collaboration between health and environmental authorities.
WHO identifies important research gaps concerning the long-term effectiveness, cost-effectiveness, occupational safety and full life-cycle environmental impacts of mercury-free dental products, including microplastic and nanoparticle waste.
