Overview
ISO 23317:2014 - "Implants for surgery - In vitro evaluation for apatite-forming ability of implant materials" specifies a standardized laboratory method to detect apatite formation on implant surfaces using simulated body fluid (SBF). The test is intended for implant surfaces designed to come into direct bone contact and provides an in vitro evaluation of a material’s potential to bond with living bone (a measure of bioactivity).
Key topics and requirements
- Purpose: Detect formation of an apatite layer on material surfaces after immersion in SBF as an indicator of bone-bonding potential.
- Test media (SBF): An acellular, protein-free inorganic solution with ion concentrations close to human blood plasma. Example ion values in the standard include Na ~142, K ~5, Mg ~1.5, Ca ~2.5, Cl ~147.8, HCO3 ~4.2, HPO4 ~1.0, SO4 ~0.5 (values given in the document).
- Apparatus and materials: Analytical-grade reagents, water complying with ISO 3696, temperature-controlled water bath (≈36.5 °C), pH meter, balance, and clean plastic containers (glass is avoided to prevent nucleation).
- Specimen preparation: Any implant-derived geometry may be used, but disc or rectangular plate specimens are recommended. Specific machining and handling rules apply (e.g., avoid aqueous machining for water-soluble glasses).
- Procedure controls: Careful, ordered reagent addition, temperature and pH control, and prevention of homogeneous precipitation during SBF preparation.
- Detection methods: Thin-film X-ray diffraction (TF‑XRD) and scanning electron microscopy (SEM) are the specified techniques to confirm apatite layers and microstructure.
- Reporting: The standard requires documentation of the induction period (time to first detectable apatite), test conditions, specimen prep, and analytical findings.
Practical applications
- Screening new biomaterials and surface treatments for bone-bonding potential prior to animal or clinical studies.
- Comparative evaluation of coatings, bioactive glasses, ceramics, and treated metals (e.g., alkali-heat-treated titanium).
- Quality control and research in biomedical R&D labs developing orthopedic and dental implants.
- Supporting regulatory submissions by providing standardized in vitro bioactivity data.
Who should use this standard
- Biomaterials scientists and engineers
- Implant manufacturers and surface-treatment developers
- Preclinical testing laboratories
- Regulatory and quality assurance professionals in medical device development
Related standards
- ISO 14630 - Non-active surgical implants - General requirements (terms and definitions referenced)
- ISO 3696 - Water for analytical laboratory use - Specification and test methods (water quality for SBF)
Keywords: ISO 23317, apatite-forming ability, simulated body fluid, SBF, in vitro evaluation, implant materials, bioactivity testing, TF‑XRD, SEM, bone-bonding, implant surface testing.