ISO 23317:2025

International
Standard
ISO 23317
Fourth edition
Implants for surgery — Materials
2025-06
— Simulated body fluid (SBF)
preparation procedure and test
method to detect apatite formation
in SBF for initial screening of bone-
contacting implant materials
Implants chirurgicaux — Matériaux — Mode opératoire de
préparation de fluide corporel simulé (FCS) et méthode d’essai
pour détecter la formation d’apatite dans le FCS pour l’étude
préliminaire de matériaux d’implant en contact avec l’os
Reference number
© ISO 2025
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ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Apparatus and materials . 2
5 Test specimen . 3
5.1 Test specimen shape and dimensions .3
5.2 Test specimen preparation .3
5.3 Test specimen characterization .3
6 Simulated body fluid . 4
6.1 General .4
6.2 Reagents for SBF .4
6.3 Preparation of SBF .5
6.3.1 General .5
6.3.2 Step 1 .5
6.3.3 Step 2 .5
6.3.4 Step 3 .5
6.3.5 Step 4 .6
6.3.6 Step 5 .6
6.3.7 Step 6 .6
6.3.8 Step 7 .6
6.3.9 Step 8 .6
6.3.10 Step 9 .6
6.3.11 Step 10 .6
6.3.12 Step 11 .6
6.4 Evaluation of SBF .7
6.5 Preservation of SBF .7
7 Procedure of the SBF test . . 7
8 Test report .10
Annex A (informative) Apparatus for preparing SBF .12
Annex B (informative) Preparation of reference glasses .13
Bibliography . 14

iii
Foreword
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This document was prepared by Technical Committee ISO/TC 150, Implants or surgery, Subcommittee SC 1,
Materials.
This fourth edition cancels and replaces the third edition (ISO 23317:2014), which has been editorially
revised. The main changes are:
— the title, Introduction and scope have been revised to clarify the significance and limitations of the SBF test;
— the terms and definitions clause has been rearranged and revised for better understanding;
— the list of apparatus and materials has been enriched and detailed;
— the test specimen preparation has been revised, and test specimen characterization has been added;
— the preparation of SBF has been revised and described in more detail;
— a description of test specimens with lower density than SBF has been added;
— the arrangement of the test specimen in the SBF test has been revised and explained depending on the
specimen’s shape and density;
— the necessity of visual inspection of SBF has been added;
— the soaking period of seven days in the SBF test has been specified;
— the criteria for judging the specimen’s apatite-forming ability in the SBF test have been clarified;
— the test report has been detailed according to the revised SBF test procedure;
— the bibliography has been revised and each bibliographical entry has been cited at the relevant point in
this document.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

iv
Introduction
The mechanism of action of bone-contacting implant materials is based upon a complex series of reactions
in the body that can be influenced by the surface properties of the implant material in contact with bone. In
some cases on synthetic bone-contacting implant materials such as Bioglass, Cerabone® A-W, Ceravital®-
1)
type glass-ceramic and sintered hydroxyapatite (Ca (PO ) (OH) ), a layer of an avascular, non-cellular
10 4 6 2
apatite-like mineral phase is found on the implant surface, at the bone-implant interface, and is said to
promote the bone-bonding behaviour. It has been shown that in vivo apatite formation can be initially
modelled in vitro using a number of different aqueous solutions, including an acellular simulated body fluid
[1]-[3]
(SBF) with inorganic ion concentrations nearly equal to those found in human blood plasma .
The apatite formed in an SBF test can indicate if an implant material's physicochemical surface features
warrant further evaluation and testing, including cell culture studies and animal studies, to demonstrate
[4],[5]
safety and efficacy of the implant material .
SBF described in this document is highly supersaturated with respect to apatite and several other calcium
phosphates and is similar in pH and inorganic ion concentrations to human blood plasma. SBF can retain
its metastable state without inducing calcium phosphate precipitation for four weeks under certain, well-
controlled conditions described in this document. SBF has been shown to produce a crystalline calcium
phosphate (apatite-like) layer that is chemically and crystallographically similar to bone mineral. Thus, SBF
can be used as a test solution for initial screening of the formation of calcium phosphate and apatite-like
mineral at the surface of a synthetic bone-contacting implant material.
Since SBF can be prepared easily from ultrapure water and ordinary chemical reagents (inorganic salts and
a buffer), and the proposed SBF test is a simple and low-cost method available in almost every laboratory,
SBF has been used worldwide over the past few decades to evaluate inorganic chemical reactions at the
implant surface exposed to the solution. These worldwide tests using SBF have been used to understand
biomineralization processes in humans and to be used as a screening tool to predict the potential for in vivo
apatite formation on an implant surface. However, SBF is an acellular, biomolecule-free pseudo-physiological
solution for mimicking in vivo inorganic chemical reactions only and
...