ISO-23317-2007.pdf

Reference number ISO 23317:2007(E) © ISO 2007 INTERNATIONAL STANDARD ISO 23317 First edition 2007-06-15 Implants for surgery In vitro evaluation for apatite-forming ability of implant materials Implants chirurgicaux Évaluation in vitro de la capacité de formation d'apatite des matériaux d'implants Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=IHS Employees/1111111001, User=DAWSON, DAVIS Not for Resale, 07/03/2007 02:02:59 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 23317:2007(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat accepts no liability in this area. Adobe is a trademark of Adobe Systems Incorporated. Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below. COPYRIGHT PROTECTED DOCUMENT © ISO 2007 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISO's member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii © ISO 2007 All rights reserved Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=IHS Employees/1111111001, User=DAWSON, DAVIS Not for Resale, 07/03/2007 02:02:59 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 23317:2007(E) © ISO 2007 All rights reserved iii Contents Page Foreword iv Introduction v 1 Scope . 1 2 Normative references. 1 3 Terms and definitions. 1 4 Apparatus 2 5 Test specimen. 2 5.1 Specimen configuration and size 2 5.2 Specimen preparation 3 6 Simulated body fluid. 3 6.1 General. 3 6.2 Reagents for SBF 3 6.3 Ion concentrations and pH of SBF 3 6.4 Preparation of SBF . 4 6.5 Confirmation of ion concentration of SBF. 6 6.6 Preservation of SBF 6 7 Procedure 6 8 Test report . 8 Annex A (informative) Apparatus for preparing SBF 9 Annex B (informative) Preparation of standard glasses for evaluating apatite-forming ability. 10 Bibliography. 12 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=IHS Employees/1111111001, User=DAWSON, DAVIS Not for Resale, 07/03/2007 02:02:59 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 23317:2007(E) iv © ISO 2007 All rights reserved Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 23317 was prepared by Technical Committee ISO/TC 150, Implants for surgery, Subcommittee SC 1, Materials. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=IHS Employees/1111111001, User=DAWSON, DAVIS Not for Resale, 07/03/2007 02:02:59 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 23317:2007(E) © ISO 2007 All rights reserved v Introduction It has been revealed that materials of various kinds bind to living bone through a layer of apatite. It has been shown that this apatite layer can be reproduced on their surfaces in an acellular and protein-free simulated body fluid (SBF) with ion concentrations nearly equal to those of human blood plasma, and that apatite thus formed is very similar to the bone mineral in its composition and structure. This evaluation of apatite-forming ability on implant material in SBF is useful for evaluating its in vivo bone- bonding ability preliminary to animal experiments. When a bioactive material is implanted in a living body, a thin layer rich in Ca and P forms on its surface. The material then connects to the living tissue through this apatite layer without a distinct boundary. It has been shown that this apatite layer can be reproduced on the surfaces of materials in SBF as well, and that apatite thus formed is very similar to bone mineral in its composition and structure. As bioactivity increases, apatite forms on the material surface in a shorter time in proportion to this increase. The formation of apatite layers can be detected by thin film X-ray diffraction spectrometry and/or scanning electron microscopy. NOTE 1 The material which forms apatite on its surface in vivo can bond to living bone, since this apatite is biologically active. Their in vivo apatite deposition can be reproduced on their surfaces even in vitro in SBF. For example, in vivo calcification on surfaces of Bioglass®, CaO-SiO2 glasses, Na2O-CaO-SiO2 glasses, Cerabone®A-W, Ceravital®-type glass-ceramic, sintered hydroxyapatite and alkali-heat-treated titanium metal, are correlated with in vitro calcification in SBF. However, this does not exclude the possibility that materials, which do not form apatite on their surfaces in vivo, bond to living bone. For example, it is reported that such resorbable materials as beta-tricalcium phosphate (Ca3(PO4)2) and calcium carbonate bond to living bone without forming an apatite layer on their surfaces. NOTE 2 It has been reported that glasses with different compositions in the system Na2O-CaO-SiO2 show a correlation between bone-forming ability of materials implanted into a bone defect of a rabbit and apatite-forming ability on its surface in SBF. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=IHS Employees/1111111001, User=DAWSON, DAVIS Not for Resale, 07/03/2007 02:02:59 MDTNo reproduction or networking permitted without license from IHS -,-,- Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=IHS Employees/1111111001, User=DAWSON, DAVIS Not for Resale, 07/03/2007 02:02:59 MDTNo reproduction or networking permitted without license from IHS -,-,- INTERNATIONAL STANDARD ISO 23317:2007(E) © ISO 2007 All rights reserved 1 Implants for surgery In vitro evaluation for apatite-forming ability of implant materials 1 Scope This International Standard describes the method for detecting apatite formed on a surface of a material in simulated body fluid (SBF). 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 3696:1987, Water for analytical laboratory use Specification and test methods ISO 14630:2005, Non-active surgical implants General requirements 3 Terms and definitions For the purposes of this document, the terms and definitions given in ISO 14630 and the following apply. 3.1 apatite group of calcium-phosphates including bone mineral and the main inorganic constituent of bones and teeth similar to hydroxyapatite, which has the composition Ca10(PO4)6(OH)2 NOTE Bone mineral also contains ions such as CO32, F, Na+ and Mg2+. 3.2 apatite-forming ability capability to develop apatite on the surface 3.3 bioactivity property that elicits a specific biological response at the interface of the material, which results in the formation of a bond between tissue and material 3.4 induction period time to detect apatite formation on a surface of a specimen after soaking the specimen in simulated body fluid 3.5 simulated body fluid SBF inorganic solution having a similar composition to human plasma without organic components Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=IHS Employees/1111111001, User=DAWSON, DAVIS Not for Resale, 07/03/2007 02:02:59 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 23317:2007(E) 2 © ISO 2007 All rights reserved 3.6 standard glass for evaluating apatite-forming ability class of standard glasses with certain chemical compositions showing given apatite-forming abilities in SBF and when implanted in an animal body 3.7 thin film X-ray diffraction spectrometry TF-XRD method for detecting minerals in a thin layer at the surface of a material from a diffraction pattern obtained by X-ray with small glancing angle against the surface of the sample 4 Apparatus 4.1 Electric balance, capable of measuring a mass with an accuracy of ± 1 mg. 4.2 Water bath equipped with magnetic stirrer, to maintain temperature of the solution within the range 36,0 °C to 40,0 °C. 4.3 pH meter, capable of measuring the pH of a solution with an accuracy of ± 0,01. 4.4 Thin film X-ray diffraction spectrometer, capable of detecting apatite formed in a thin layer at the surface of a material. 4.5 Scanning electron microscope, capable of observing apatite grains and/or layers formed on a plain surface of a material with a magnification up to × 10 000. 5 Test specimen 5.1 Specimen configuration and size This International Standard allows specimens of any configuration and size derived from implant parts and devices to be used. However, a disc or rectangular plate specimen is highly recommended, because bioactivity of a material is evaluated by confirmation of apatite formed on the surface of the material using TF-XRD and/or SEM. Recommended specimen dimensions are shown in Figure 1. Dimensions in millimetres a) b) Figure 1 Recommended specimen dimensions for (a) disc specimen and (b) rectangular specimen Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=IHS Employees/1111111001, User=DAWSON, DAVIS Not for Resale, 07/03/2007 02:02:59 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 23317:2007(E) © ISO 2007 All rights reserved 3 5.2 Specimen preparation 5.2.1 General This International Standard allows several options for specimen preparation. The specimens should be machined, if necessary, to alter the configurations of original implants. 5.2.2 Basic machining procedure In the case of a rectangular thin plate specimen as shown in Figure 1 b), the following procedure shall be used. Specimens shall be ground using a diamond wheel of grit size between 120 and 400. Conditions such as depth of cut per pass, wheel speed and others depend on the ground material. Water soluble materials, such as bioactive standard glasses, shall be machined under non-aqueous conditions. Where a customary machining procedure has been developed that is completely satisfactory for apatite- forming ability testing, this customary procedure can be used. 6 Simulated body fluid 6.1 General Simulated body fluid (SBF) as defined in Table 1 shall be used. NOTE 1 For SBF as defined in Table 1, a correlation was observed between in vivo bone ingrowth and in vitro apatite-forming ability. NOTE 2 Other kinds of SBFs have been proposed in the literature. 6.2 Reagents for SBF The following powder reagent grade chemicals shall be stored in a desiccator. Water in accordance with ISO 3696:1987, grade 2, shall be used for the preparation of SBFs. a) sodium chloride (NaCl) b) sodium hydrogen carbonate (NaHCO3) c) potassium chloride (KCl) d) di-potassium hydrogen phosphate trihydrate (K2HPO4.3H2O) e) magnesium chloride hexahydrate (MgCl2.6H2O) f) calcium chloride (CaCl2) g) sodium sulfate (Na2SO4) h) tris-hydroxymethyl aminomethane (TRIS): (HOCH2)3CNH2) i) hydrochloric acid solution, c(HCl) = 1 mol/l. j) pH standard solutions, (pH 4, 7 and 9) 6.3 Ion concentrations and pH of SBF The ion concentrations and pH of SBF are shown in Table 1. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=IHS Employees/1111111001, User=DAWSON, DAVIS Not for Resale, 07/03/2007 02:02:59 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 23317:2007(E) 4 © ISO 2007 All rights reserved Table 1 Ion concentrations of SBF and human blood plasma Concentration (10 3 mol) in Ion SBF (pH 7,40) Blood plasma (pH 7,2 to 7,4) Na+ 142,0 142,0 K+ 5,0 5,0 Mg2+ 1,5 1,5 Ca2+ 2,5 2,5 Cl 147,8 103,0 HCO3 4,2 27,0 HPO42 1,0 1,0 SO42 0,5 0,5 6.4 Preparation of SBF 6.4.1 General Since SBF is supersaturated with respect to apatite, an inappropriate preparation method can lead to the homogeneous precipitation of apatite in the solution. During its preparation the solution shall remain colourless, transparent and without deposit on the surface of the bottle. If any precipitation occurs, stop preparing SBF, abandon the solution and restart by washing the apparatus. In Table 2, the reagents for the preparation of 1 l of SBF are given in the required order of dissolution. Table 2 Order, amount, weighing container, purity and formula weights of reagents for preparing 1 l of SBF Order Reagen