1、PD ISO/TS 20746:2016 Dentistry Determination of the strength of dental amalgam by the Hertzian indentation strength (HIT) method BSI Standards Publication WB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06PD ISO/TS 20746:2016 BRITISH STANDARD National foreword This British Standard is the UK i
2、mplementation of ISO/TS 20746:2016. The UK participation in its preparation was entrusted to Technical Committee CH/106/1, Dental restorative and orthodontic materials. A list of organizations represented on this committee can be obtained on request to its secretary. This publication does not purpor
3、t to include all the necessary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2016. Published by BSI Standards Limited 2016 ISBN 978 0 580 91396 9 ICS 11.060.10 Compliance with a British Standard cannot confer immunity from legal obliga
4、tions. This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 December 2016. Amendments/corrigenda issued since publication Date T e x t a f f e c t e dPD ISO/TS 20746:2016 ISO 2016 Dentistry Determination of the strength of dental amalgam by the
5、 Hertzian indentation strength (HIT) method Mdicine bucco-dentaire Dtermination de la rsistance des amalgames dentaire par lindentation hertzienne (HIT) mthode TECHNICAL SPECIFICATION ISO/TS 20746 Reference number ISO/TS 20746:2016(E) First edition 2016-12-15PD ISO/TS 20746:2016ISO/TS 20746:2016(E)i
6、i ISO 2016 All rights reserved COPYRIGHT PROTECTED DOCUMENT ISO 2016, Published in Switzerland All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or postin
7、g on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Ch. de Blandonnet 8 CP 401 CH-1214 Vernier, Geneva, Switzerland Tel. +41 22 749 01 11 Fax +41
8、 22 749 09 47 copyrightiso.org www.iso.orgPD ISO/TS 20746:2016ISO/TS 20746:2016(E)Foreword iv Introduction v 1 Scope . 1 2 Normative references 1 3 T erms and definitions . 1 4 Hertzian indentation strength test (HIT) applied to dental amalgam .2 5 Apparatus for the production of test-pieces 3 5.1 E
9、quipment . 3 5.2 Specifications for the mould 4 6 Sampling 4 7 Preparation of dental amalgam test-pieces . 4 7.1 Mixing the dental amalgam 4 7.2 Test-piece production . 5 7.2.1 Packing the mould, removal of the test-piece and inspection for surface defects 5 7.3 Measurement of the test-piece and sto
10、rage prior to testing . 5 7.3.1 Equipment . 5 7.3.2 General 6 8 Test procedure 6 8.1 Apparatus 6 8.2 Mechanical testing . 6 9 Treatment of data and reporting of results 7 Bibliography 8 ISO 2016 All rights reserved iii Contents PagePD ISO/TS 20746:2016ISO/TS 20746:2016(E) Foreword ISO (the Internati
11、onal 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
12、 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 standa
13、rdization. The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordan
14、ce with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives). 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. Details o
15、f any patent rights identified during the development of the document will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents). Any trade name used in this document is information given for the convenience of users and does not constitute an endors
16、ement. For an explanation on the meaning of ISO specific terms and expressions related to conformit y assessment, as well as information about ISOs adherence to the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following URL: www.iso.org/iso/foreword.html
17、. The committee responsible for this document is ISO/TC 106, Dentistry, Subcommittee SC 1, Filling and restorative materials.iv ISO 2016 All rights reservedPD ISO/TS 20746:2016ISO/TS 20746:2016(E) Introduction This document gives the practical details of the test method for the measurement of the st
18、rength of a dental amalgam by the Hertzian indentation (HIT) method. In this test, the specimen geometry and the localized application of force leads to radial crack formation at the surface opposite the one to which the force is applied and under the point at which it is applied. This protocol prod
19、uces a loading condition similar to that encountered during normal oral function. When a requirement is agreed, it is the intention of ISO/TC 106/SC 1 to consider the inclusion of this test procedure in the ISO standards for dental amalgam. This method for measuring the strength of a brittle materia
20、l (and materials that have very low plasticity) can be applied to other dental restorative materials. ISO 2016 All rights reserved vPD ISO/TS 20746:2016PD ISO/TS 20746:2016Dentistry Determination of the strength of dental amalgam by the Hertzian indentation strength (HIT) method 1 Scope This documen
21、t gives the practical details of the test method for the measurement of the strength of a dental amalgam by the Hertzian indentation strength test (HIT) method. It is applicable to dental amalgam formed from products that are within the scope of ISO 24234 and ISO 20749. 2 Normative references The fo
22、llowing documents are referred to in the text in such a way that some or all of their content constitutes requirements 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
23、 6344-1, Coated abrasives Grain size analysis Part 1: Grain size distribution test ISO 7488, Dental amalgamators ISO 13565-2, Geometrical Product Specifications (GPS) Surface texture: Profile method; Surfaces having stratified functional properties Part 2: Height characterization using the linear ma
24、terial ratio curve ISO 13897, Dentistry Amalgam capsules ISO 24234, Dentistry Dental amalgam 3 T erms a nd definiti ons For the purposes of this document, the terms and definitions given in ISO 1942 and the following apply. ISO and IEC maintain terminological databases for use in standardization at
25、the following addresses: IEC Electropedia: available at http:/ /www.electropedia.org/ ISO Online browsing platform: available at http:/ /www.iso.org/obp 3.1 dental amalgam alloy alloy in fine particles, composed mainly of silver, tin and copper, which, when mixed with dental mercury (3.2), produces
26、a dental amalgam 3.2 dental mercury mercury supplied for use in the preparation of dental amalgam TECHNICAL SPECIFICATION ISO/TS 20746:2016(E) ISO 2016 All rights reserved 1PD ISO/TS 20746:2016ISO/TS 20746:2016(E) 3.3 pre-capsulated dental amalgam product dental amalgam product supplied in a sealed
27、capsule that contains measured amounts of dental amalgam alloy (3.1) powder and dental mercury (3.2) with masses that are appropriate for the production of a mass of dental amalgam that is considered to be suitable for a single small or medium size restoration in a single tooth Note 1 to entry: The
28、dental amalgam alloy powder and dental mercury are separated by a barrier that is broken immediately prior to mixing to allow their contact. The capsule remains sealed until mixing has been completed. 3.4 dental amalgam alloy tablet dental amalgam alloy (3.1) powder that has been compressed to form
29、a single entity for the purpose of providing a pre-dosed quantity of the alloy that, when mixed with an appropriate mass of dental mercury (3.2), produces a mass of dental amalgam that is considered to be suitable for a single small or medium size restoration in a single tooth Note 1 to entry: Durin
30、g mixing, the tablet is intended to break apart, forming a fine powder. 3.5 dental mercury sachet measured quantity of dental mercury (3.2) supplied in a sachet (for use in a reusable mixing capsule) in a mass that, when mixed with an appropriate mass of dental amalgam alloy (3.1), produces a mass o
31、f dental amalgam that is considered to be suitable for a single small or medium size restoration in a single tooth Note 1 to entry: The sachet is intended to rupture during mixing to allow the dental mercury to come into contact with the dental amalgam alloy. 3.6 top surface of the test-piece surfac
32、e of the disc shaped test-piece that has been produced by carving back unset amalgam that is above the level of the mould until the surface of the test-piece is flat and level with that mould surface 3.7 test surface of the test-piece surface of the disc-shaped test-piece that has been produced by c
33、ontact with the polished glass plate when the mixed amalgam is packed into the mould 3.8 radial cracking fracture pattern of Hertzian indentation test-piece disc in which (more or less) planar cracks form along radii, normal to the face of the disc, thus dissecting it into two or more sectors EXAMPL
34、E Some radial fracture patterns in disc shaped test-pieces are illustrated here. Note 1 to entry: Such radial cracks initiate on the test surface of the test-piece and propagate through the disc to produce approximately equiangular dissection in most cases. 4 Hertzian indentation strength test (HIT)
35、 applied to dental amalgam This test utilizes a disc-shaped test-piece to which a linearly increasing force is applied through a hard steel ball sited at the centre of one of the flat faces of the disc. The other face of the disc is in contact with a smooth substrate that is also disc shaped and thi
36、cker than the test-piece. The substrate has a Youngs modulus value that is of the same order as that of dentine. Fracture is produced by radial cracks initiating at the surface in contact with the substrate. By having close control of the test-piece, the 2 ISO 2016 All rights reservedPD ISO/TS 20746
37、:2016ISO/TS 20746:2016(E) resistance to fracture is quantified by the fracture force. Dental amalgam products are compared using the values of the fracture force. A vertical section through the apparatus required for testing is shown in Figure 1. Dimensions in millimetres Key 1 universal mechanical
38、testing machine upper compression platen 2 chrome steel bearing ball 3 dental amalgam test-piece (see Figure 2 for the dimensions and dimensional tolerances for this) 4 30 % glass-filled polyamide disc 5 universal mechanical testing machine lower compression platen Figure 1 Loading arrangement for t
39、he Hertzian indentation strength test (HIT) 5 Apparatus for the production of test-pieces 5.1 Equipment 5.1.1 Mould, as shown in Figure 2. 5.1.2 Flat square scratch-free polished glass plate with an edge length greater than 30 mm. 5.1.3 Glass microscope slide to provide a straight edge to carve back
40、 the dental amalgam. 5.1.4 Hand-instrument for dental amalgam packing. 5.1.5 Dental amalgam mechanical mixer. ISO 2016 All rights reserved 3PD ISO/TS 20746:2016ISO/TS 20746:2016(E) 5.2 Specifications for t he mould The mould shall be made of hardened tool steel or hardened stainless steel. The upper
41、 and lower surfaces shall be flat and parallel and have a core roughness depth (R k ) not greater than 6,3 m when tested in accordance with ISO 13565-2. The hole shall have a taper of (7 2) to allow the amalgam disc to be ejected without undue force when this is applied to the face that has the smal
42、ler diameter for the hole. The tapered surface shall be smooth enough not to impede the ejection of the test-piece. For example, it may be honed to a core roughness depth (R k ) of 6,3 m (when tested in accordance with ISO 13565-2). NOTE 1 For convenience, to distinguish between the two surfaces dur
43、ing test-piece production, a small engraved mark (set away from the hole) can be made on one of the mould faces. NOTE 2 The angle of the taper, (7 2), is the included angle. The wall of the mould is at an angle of (3,5 1,0) with the centre line. Dimensions in millimetres Figure 2 Mould to produce te
44、st-pieces for the Hertzian indentation strength test (HIT) 6 Sampling Procure sufficient dental amalgam alloy and dental mercury from single lots that have been produced for retail. The required mass of dental amalgam alloy will depend upon the dental amalgam alloy: dental mercury mixing ratio. Depe
45、nding on the product, a total of the order 3,2 g of mixed amalgam will be required for each test-piece. 7 Preparation of dental amalgam test-pieces 7.1 Mixing the dental amalgam Prepare test-pieces at (23 2) C.4 ISO 2016 All rights reservedPD ISO/TS 20746:2016ISO/TS 20746:2016(E) For a dental amalga
46、m alloy product supplied either as tablets or as a free-flowing powder in bulk, the ratio by mass of the dental amalgam alloy to that of the dental mercury shall be the ratio recommended by the manufacturer. Use dental mercury sachets that comply with ISO 24234. Use a capsule (with a pestle, if need
47、ed) that complies with Type 2 of ISO 13897. Use any other mixing accessory that is required, as recommended by the manufacturer. If more than one mix is required to make the test- piece, produce these mixes simultaneously using equipment of the same type for each mix. However, if the last mix can be
48、 produced within the working time of the first mix, mixing these masses sequentially on a single piece of equipment is allowed. For pre-capsulated products, use as many capsules as needed. Mix the contents of the capsules either simultaneously using the same number of pieces of equipment of the same
49、 type, or sequentially on a single piece of equipment. (The latter is allowed, provided the mixing of the last capsule is completed before the end of the working time of the first.) If necessary, use only a portion of the dental amalgam mix from one of these capsules. Use a mechanical mixing machine for dental amalgam that complies with ISO 7488 and that is recommended for mixing the dental amalgam alloy product with dental mercury or mixing the pre- capsulated product. Use the dental amalgam mechanical mi
