1、BRITISH STANDARD BS 5612:1978 Specification for Dental porcelains for jacket crowns UDC 616.314089.28033.62BS5612:1978 This British Standard, having been prepared under the directionof the Dental StandardsCommittee, waspublished under the authorityof the Executive Boardon 31 October 1978 BSI 04-2000
2、 The following BSI references relate to the work on this standard: Committee reference DNS/1 Draft for comment 73/62382DC ISBN 058010297 1 Cooperating organizations The Dental Standards Committee, under whose direction this British Standard was prepared, consists of representatives from the followin
3、g Government departments and scientific and industrial organizations Association of Dental Hospitals of Great Britain and Northern Ireland British Dental Association* British Dental Trade Association* British Society for the Study of Prosthetic Dentistry* Dental Education Advisory Council Dental Mat
4、erials Panel Department of Health and Social Security* Department of Industry (Laboratory of the Government Chemist)* Department of Industry (National Engineering Laboratory) Department of Industry (National Physical Laboratory) Federation Dentaire Internationale Institute of Dental Surgery* Ministr
5、y of Defence* Royal Society of Medicine Scottish Health Services The organizations marked with an asterisk in the above list, together with the following, were directly represented on the committee entrusted with the preparation of this British Standard; British Ceramic Research Association British
6、Institute of Surgical Technicians British Society for the Study of Orthodontics British Steel Corporation Dental Laboratories Association Limited General Dental Practitioners Association Institute of Metallurgists London Dental Study Club Amendments issued since publication Amd. No. Date of issue Co
7、mmentsBS5612:1978 BSI 04-2000 i Contents Page Cooperating organizations Inside front cover Foreword ii 1 Scope 1 2 References 1 3 Definitions 1 4 Classification 1 5 Requirements 1 6 Sampling 2 7 Inspection 2 8 Test methods 2 9 Marking and packing 8 Appendix A Examples of the method of calculation an
8、d expression of results for the test procedures described in 8.9, 8.10 and 8.11 9 Figure 1 Mould vibrator assembly 10 Figure 2 Mould 25 mm 6 mm 3 mm for use in the preparationofspecimensfor determination of firing shrinkageandflexuralstrength and thermal expansion test 11 Figure 3 Mould 16 mm 1.6 mm
9、 for the preparation ofspecimensforuseinfired porosity and chemical solubility tests 11 Figure 4 Mould 6.0 mm 4.0 mm for use in pyroplasticity test 12 Table 1 Physical requirements for porcelain specimens 8 Table 2 Example results after preliminary firing and grinding 9 Table 3 Example of results af
10、ter refiring and regrinding (cycle 1) 9 Table 4 Example of results after refiring and regrinding (cycle 2) 9 Table 5 Example of results after refiring and regrinding (cycle 3) 10 Publications referred to Inside back coverBS5612:1978 ii BSI 04-2000 Foreword This British Standard was prepared under th
11、e direction of the Dental Standards Committee. Dental porcelain presents particular difficulties in testing because its properties are probably more dependent on the expertise and handling technique used than those of any other dental material. An extensive and detailed research programme undertaken
12、 by the British Ceramic Research Association, under the auspices of the Department of Industry, provided much of the technical data on which the specification was prepared. Because the testing of dental porcelains for standards purposes is a completely new field, particular attention has been paid t
13、o the details and overall coverage of this specification. The adequacy of, and need for, such details will be kept under review, and if experience, backed by technical data, indicates the need for amendment, this will be considered by the responsible BSI committee. A British Standard does not purpor
14、t to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cov
15、er, pagesi andii, pages1 to12, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS5612:1978 BSI 04-2000 1 1 Scope This British Standard specifie
16、s the characteristics of dental porcelains used for jacket crown restorations made entirely of porcelain. The standard specifies limits and methods of test for mechanical, thermal, optical and other general properties of the materials. 2 References The titles of the standards publications referred t
17、o in this standard are listed on the inside back cover. 3 Definitions For the purposes of this British Standard the following definitions apply. 3.1 aluminous porcelains dental porcelains significantly strengthened by the addition of crystalline !-alumina 3.2 condensation any process by which the ap
18、parent powder density (as defined in BS 2955) of unfired dental porcelain is intentionally increased 3.3 core porcelains opaque dental porcelains that provide a mechanically strong, optically uniform basis for a jacket crown restoration 3.4 dental porcelains ceramic materials that may be fabricated
19、into shapes simulating the form and function of a natural tooth 3.5 dentine/body porcelains translucent, pigmented dental porcelains used to give the overall shape and colour to a jacket crown restoration 3.6 degrees of fusion a) High biscuit: the state achieved when firing shrinkage is just complet
20、e. b) Medium glaze: the state of glaze that is clinically and aesthetically acceptable. 3.7 enamel porcelains translucent, lightly pigmented dental porcelains used as an outer covering of a jacket crown restoration to simulate the translucency of natural teeth 3.8 modelling fluid a liquid, other tha
21、n water, with which a dental porcelain may be mixed prior to condensation 3.9 pyroplasticity plastic deformation by gravitational and/or surface tension forces at elevated temperatures 3.10 vacuum firing porcelain a dental porcelain intended to be fired at a reduced pressure 4 Classification Dental
22、porcelains may be classified as follows: a) vacuum (reduced pressure) firing or air (atmospheric pressure) firing porcelains; b) aluminous or non-aluminous porcelains; c) core-, dentine/body- or enamel-porcelains; d) according to fusion range: 5 Requirements 5.1 Powder. The dental porcelain shall be
23、 supplied as a powder free from extraneous matter. The powder shall be of such a composition that no adverse chemical reactions occur during the production of a jacket crown restoration that has been made according to the manufacturers instructions. 5.1.1 Types and their identification. Dental porce
24、lains shall be divided into types according to their intended use and, if a colour coding system is used to identify the type of powder, the appropriate colour given below shall be used. Colour coding shall not involve the addition to the powder of more than 0.01% (m/m) of organic material. Low-fusi
25、ng 800 C to 1050 C Medium-fusing 1050 C to 1200 C High-fusing 1200 C to 1400 C Type Colour Core porcelains Yellow or none Dentine/body porcelains Pink Enamel porcelains Blue Neck material Green Transparent material None Concentrate material None Add-on material None Glaze material NoneBS5612:1978 2
26、BSI 04-2000 5.1.2 Pigments, dyes and fluorescing agents. Both the metal oxide pigments used to obtain the fired colour of dental porcelain and the dyes used for identification shall be uniformly dispersed throughout the dental porcelain powder. No segregation of the pigments or separation of the dye
27、s from the porcelain shall take place when it is mixed in accordance with 8.1. Deliberate additions of radioactive substances for the purpose of producing fluorescence shall not bemade to dental porcelains manufactured after30June 1978. 5.1.3 Particle size. The particle size shall be such that, when
28、 the powder is tested in the manner described in 8.2, not more than 0.5 % (m/m) is retained on a 75 4m test sieve and not more than5.0% (m/m) is retained on a 53 4m test sieve. Test sieves that comply with the requirements of BS410 shall be used. 5.2 Dental porcelain paste. When mixed in the correct
29、 proportion with water or a suitable modelling fluid, the dental porcelain powder shall not form lumps or granules. The paste formed shall be suitable for the hand-building of a jacket crown restoration by conventional dental laboratory techniques. 5.3 Condensed porcelain. The condensed dental porce
30、lain powder shall not crack or crumble during the drying cycle recommended by the manufacturer. 5.4 Freedom from irritants or toxic ingredients. The dental porcelain shall not contain ingredients in sufficient concentration to cause prolonged local irritation or any systemic toxic reaction when used
31、 in accordance with the manufacturers instructions. 5.5 Physical and chemical properties. Specimens prepared and tested in accordance with the relevant methods in clause 8 shall comply with the requirements specified in Table 1. 5.6 Resistance to staining. When tested as described in 8.12, the “as f
32、ired” outer surfaces of the specimens, and the fractured, glazed or ground surfaces shall show no visible staining. 5.7 Manufacturers instructions. The instructions supplied by the manufacturer shall include the following information: a) a time-temperature cycle for drying the condensed porcelain po
33、wder; b) a time-temperature cycle for the firing schedule including the rate of heating, the final temperature (in C/min) and the time it should be held; c) the glazing temperature; d) if applicable, the level and duration of vacuum; e) details of the coefficient of linear expansion and upper transf
34、ormation temperature (as defined in BS3447) under the conditions of test detailed in8.6. 6 Sampling The following samples shall be obtained. a) Where there are four or more shades in a type of dental porcelain (see 5.1.2), take one 50 g sample of each shade. b) Where there are two or three shades of
35、 a type of dental porcelain, take two 50 g samples of each shade. c) Where there is only one shade of a type of dental porcelain, take three 50 g samples. Sufficient quantities of essential modelling fluids should be obtained, if their use is recommended by the manufacturer. If the shades of a type
36、of porcelain comply with the requirements 5.1, 5.2 and 5.3, form a “pool” of powder of that type by taking samples of equal mass from each shade using the grid type sample divider principle as described in BS 3406-1. The total mass of the pool of powder shall be 100g. 7 Inspection Visual inspection,
37、 without magnification, shall be used to determine compliance with the requirements specified in 5.1.1, 5.1.2, 5.1.3, 5.2 and5.3. 8 Test methods 8.1 Preparation of test specimens 8.1.1 General. The apparatus described in 8.1.4 and8.1.6, and the conditions of mixing, condensation and firing apply to
38、all the test methods unless it is stated otherwise. 8.1.2 Ambient conditions. All mixing of the porcelain pastes in preparing test specimens and all testing shall be carried out at a temperature of 23 2 C. No special precautions need to be taken to control the humidity. 8.1.3 Components. Unless stat
39、ed otherwise, tests shall be carried out on specimens prepared from the “pool” of powder specified in clause 6, with water or the modelling fluid recommended by the manufacturer. NOTE8.9, 8.10 and 8.11 require material of specific shades. The powder shall be taken from the “pool” using the grid-type
40、 sample divider referred to in clause 6 and all water used in the test procedures shall comply with BS 3978.BS5612:1978 BSI 04-2000 3 8.1.4 Apparatus for mixing. The following apparatus shall be used for mixing dental porcelain powder with water or a modelling fluid: a) glass slab or mixing palette;
41、 b) spatula made from a material, other than metal, which is not abraded by the dental porcelain powder. Glass is recommended. All apparatus used for mixing shall be clean, dry and free from particles of hardened porcelain paste. 8.1.5 Method of mixing. Add water or modelling fluid to the porcelain
42、powder. Avoid vigorous mixing which will tend to incorporate air bubbles with the paste. Excess liquid may be removed by blotting with an absorbent tissue. Examine the paste for signs of the segregation as mentioned in 5.1.2. 8.1.6 Condensation. Condense the porcelain paste used for making the test
43、specimens by a “vibration and absorption” technique in an open multipart mould from which the condensed specimen may be removed without distortion. A suitable vibration system consists of: a) a variable amplitude sine-wave generator operating at 50 Hz to 60 Hz; b) an amplifier; c) a vibrator (see Fi
44、gure 1); d) a mould-carrier (see Figure 1), which is pivoted at one end and spring-loaded so that the mould is subjected to an impact in each cycle of vibration. The output of the system shall be of sufficient amplitude to give the required 50 Hz to 60 Hz impacting vibration. Overfill the mould, fir
45、mly attached to the mould carrier, with dental porcelain paste and vibrate until excess liquid appears at the free surface of the specimen. Remove the excess liquid continually by absorption into a paper tissue or similarly absorbent material resting on the free surface of the specimen. Replace the
46、tissue when it becomes saturated with liquid. Continue the vibration and absorption until no further liquid can be removed. Level the free surface of the condensed specimen using a suitable sharp instrument. A bevelled glass microscope slide is ideal. After removal from the mould, place the specimen
47、 on a firing tray to await firing. Clean, dry and re-assemble the mould. 8.1.7 Firing. Fire the porcelain specimens in accordance with the porcelain manufacturers recommended firing schedule unless otherwise specified. Position the specimens in the furnace so that they will be uniformly fired, using
48、 a rigid substrate to which they will not adhere and from which there will be no material pick-up. Lightly sintered !-alumina sheet is recommended. 8.2 Determination of residue on sieving 8.2.1 Apparatus. The following apparatus is required: a) two fine-mesh sieves, one of 75 4m and the other 53 4m
49、nominal width aperture, complying with the requirements of BS 410; b) an oven or drying cabinet capable of maintaining a temperature of 40 2 C. 8.2.2 Procedure. Add 10 g of porcelain powder to150ml of water in a 250 ml conical flask. Stopper the flask and shake for 2 min. Transfer the suspension to the 75 4m sieve nested on the 53 4m sieve and wash with water until the washings are clear. When the washings from the 75 4m sieve are clear, the sieves may be separated to facilitate washing the residues on the 53 4m sieve. Dry t
