Overview
EN ISO 3990:2023 (ISO 3990:2023) specifies standardized in vitro test methods to evaluate claimed antibacterial activity of dental restorative materials, luting materials, fissure sealants and orthodontic bonding or luting materials. Developed by ISO/TC 106 in collaboration with CEN/TC 55, the standard defines a testing scheme (rather than a single test) to select appropriate methods based on material type and intended use.
Note: the standard excludes pulp‑capping materials, endodontic filling materials, dental implants/implant systems, nightguards and additive‑manufactured (3D‑printed) materials. It does not cover sterilization or disinfection effectiveness and cannot be used to demonstrate absence of microbial contamination.
Key topics and requirements
- Two main test categories
- Extract tests - assess antibacterial effects of substances leaching from the material.
- Direct contact tests - assess effects from leachables and/or surface interactions when bacteria contact the material.
- Stepwise approach
- Tests are recommended first on planktonic bacterial cultures and, if positive, then on bacterial biofilms.
- Sample preparation
- Guidance for specimen form, sterility, and special requirements for light‑curing, chemically setting and CAD/CAM/subtractive materials.
- Procedures for preparing liquid extracts, including extraction vehicle, conditions and consecutive elution cycles.
- Test organisms and media
- Recommended bacterial strains and nutrient broths; culture preparation protocols.
- Endpoints and measurement methods
- Primary measurement: reduction of bacterial ability to replicate (e.g., CFU assay).
- Additional evaluations: bacterial membrane damage (e.g., flow cytometry) and metabolic activity reduction (e.g., MTT assay).
- Reporting
- Requirements for assessment of results and content of the final test report for comparability and regulatory use.
Applications and users
Who uses EN ISO 3990:2023:
- Dental materials manufacturers validating antibacterial claims for product development and labeling.
- Research laboratories and academic investigators studying antimicrobial properties of dental materials.
- Independent testing laboratories performing standardized in vitro evaluations for quality assurance or third‑party certification.
- Regulatory bodies and notified bodies assessing preclinical data supporting safety and performance claims.
Practical applications:
- Support for R&D decisions on antimicrobial additives/coatings.
- Comparative testing between formulations or suppliers.
- Generating standardized data for regulatory submissions and marketing claims (with attention to the standard’s stated limits).
Related standards
- EN ISO 3990:2023 is part of the broader portfolio of ISO/CEN dentistry standards (ISO/TC 106, CEN/TC 55). For full conformity and device assessment, use together with other relevant dental materials standards and national regulatory guidance.
Keywords: EN ISO 3990:2023, ISO 3990:2023, antibacterial activity, dental restorative materials, luting materials, fissure sealants, orthodontic bonding, extract test, direct contact test, biofilms, CFU assay, flow cytometry, MTT assay, dental materials testing, CEN.