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1、BRITISH STANDARD BS 5612:1978 Specification for Dental porcelains for jacket crowns UDC 616.314 089.28 033.62 Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 13:49:33 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5612:1978 This British Standard, having been prepared under the direction of the
2、 Dental Standards Committee, was published under the authority of the Executive Board on 31 October 1978 BSI 04-2000 The following BSI references relate to the work on this standard: Committee reference DNS/1 Draft for comment 73/62382 DC ISBN 0 580 10297 1 Cooperating organizations The Dental Stand
3、ards Committee, under whose direction this British Standard was prepared, consists of representatives from the following Government departments and scientific and industrial organizations Association of Dental Hospitals of Great Britain and Northern Ireland British Dental Association* British Dental
4、 Trade Association* British Society for the Study of Prosthetic Dentistry* Dental Education Advisory Council Dental Materials Panel Department of Health and Social Security* Department of Industry (Laboratory of the Government Chemist)* Department of Industry (National Engineering Laboratory) Depart
5、ment of Industry (National Physical Laboratory) Federation Dentaire Internationale Institute of Dental Surgery* Ministry 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
6、on the committee entrusted with the preparation of this British Standard; British Ceramic Research Association British Institute of Surgical Technicians British Society for the Study of Orthodontics British Steel Corporation Dental Laboratories Association Limited General Dental Practitioners Associ
7、ation Institute of Metallurgists London Dental Study Club Amendments issued since publication Amd. No.Date of issueComments Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 13:49:33 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5612:1978 BSI 04-2000i Contents Page Cooperating organizationsInsi
8、de front cover Forewordii 1Scope1 2References1 3Definitions1 4Classification1 5Requirements1 6Sampling2 7Inspection2 8Test methods2 9Marking and packing8 Appendix A Examples of the method of calculation and expression of results for the test procedures described in 8.9, 8.10 and 8.119 Figure 1 Mould
9、 vibrator assembly10 Figure 2 Mould 25 mm 6 mm 3 mm for use in the preparation of specimens for determination of firing shrinkage and flexural strength and thermal expansion test11 Figure 3 Mould 16 mm 1.6 mm for the preparation of specimens for use in fired porosity and chemical solubility tests11
10、Figure 4 Mould 6.0 mm 4.0 mm for use in pyroplasticity test12 Table 1 Physical requirements for porcelain specimens8 Table 2 Example results after preliminary firing and grinding9 Table 3 Example of results after refiring and regrinding (cycle 1)9 Table 4 Example of results after refiring and regrin
11、ding (cycle 2)9 Table 5 Example of results after refiring and regrinding (cycle 3)10 Publications referred toInside back cover Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 13:49:33 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5612:1978 ii BSI 04-2000 Foreword This British Standard was pre
12、pared under the 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 progra
13、mme undertaken 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 h
14、as been paid to 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 d
15、oes not purport 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 in
16、side front cover, pages i and ii, pages 1 to 12, 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. Licensed Copy: sheffieldun sheffieldun, na, F
17、ri Dec 01 13:49:33 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5612:1978 BSI 04-20001 1 Scope This British Standard specifies the characteristics of dental porcelains used for jacket crown restorations made entirely of porcelain. The standard specifies limits and methods of test for mechanical, th
18、ermal, optical and other general properties of the materials. 2 References The titles of the standards publications referred to 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 dent
19、al porcelains significantly strengthened by the addition of crystalline !-alumina 3.2 condensation any process by which the apparent 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
20、strong, optically uniform basis for a jacket crown restoration 3.4 dental porcelains ceramic materials that may be fabricated 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
21、 to a jacket crown restoration 3.6 degrees of fusion a) High biscuit: the state achieved when firing shrinkage is just complete. 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 oute
22、r covering of a jacket crown restoration to simulate the translucency of natural teeth 3.8 modelling fluid a liquid, other than 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 te
23、mperatures 3.10 vacuum firing porcelain a dental porcelain intended to be fired at a reduced pressure 4 Classification Dental porcelains may be classified as follows: a) vacuum (reduced pressure) firing or air (atmospheric pressure) firing porcelains; b) aluminous or non-aluminous porcelains; c) cor
24、e-, dentine/body- or enamel-porcelains; d) according to fusion range: 5 Requirements 5.1 Powder. The dental porcelain shall be 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
25、restoration that has been made according to the manufacturers instructions. 5.1.1 Types and their identification. Dental porcelains 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 sh
26、all be used. Colour coding shall not involve the addition to the powder of more than 0.01 % (m/m) of organic material. Low-fusing800 C to 1 050 C Medium-fusing1 050 C to 1 200 C High-fusing1 200 C to 1 400 C TypeColour Core porcelainsYellow or none Dentine/body porcelainsPink Enamel porcelainsBlue N
27、eck materialGreen Transparent materialNone Concentrate materialNone Add-on materialNone Glaze materialNone Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 13:49:33 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5612:1978 2 BSI 04-2000 5.1.2 Pigments, dyes and fluorescing agents. Both the metal
28、 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 dyes from the porcelain shall take place when it is mixed in accordance wi
29、th 8.1. Deliberate additions of radioactive substances for the purpose of producing fluorescence shall not be made to dental porcelains manufactured after 30 June 1978. 5.1.3 Particle size. The particle size shall be such that, when the powder is tested in the manner described in 8.2, not more than
30、0.5 % (m/m) is retained on a 75 4m test sieve and not more than 5.0 % (m/m) is retained on a 53 4m test sieve. Test sieves that comply with the requirements of BS 410 shall be used. 5.2 Dental porcelain paste. When mixed in the correct proportion with water or a suitable modelling fluid, the dental
31、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 porcelain powder shall not crack or crumble during the drying cycle re
32、commended 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 in accordance with the manufacturers instructions. 5.5 Physical
33、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 fired” outer surfaces of the specimens, and the fractured, glazed
34、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 powder; b) a time-temperature cycle for the firing schedule includi
35、ng 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 transformation temperature (as defined in BS 3447) under the conditions
36、 of test detailed in 8.6. 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 a type of dental porcelain, take two 50 g samples of each shad
37、e. 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 of porcelain comply with the requirements 5.1, 5.2 and 5.3, for
38、m 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 100 g. 7 Inspection Visual inspection, without magnification, shall be used to determine compliance
39、with the requirements specified in 5.1.1, 5.1.2, 5.1.3, 5.2 and 5.3. 8 Test methods 8.1 Preparation of test specimens 8.1.1 General. The apparatus described in 8.1.4 and 8.1.6, and the conditions of mixing, condensation and firing apply to all the test methods unless it is stated otherwise. 8.1.2 Am
40、bient 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 stated otherwise, tests shall be carried out on specimens prepar
41、ed 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 sample divider referred to in clause 6 and all water used i
42、n the test procedures shall comply with BS 3978. Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 13:49:33 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5612:1978 BSI 04-20003 8.1.4 Apparatus for mixing. The following apparatus shall be used for mixing dental porcelain powder with water or a m
43、odelling fluid: a) glass slab or mixing palette; 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
44、. Add water or modelling fluid to the porcelain 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. Conden
45、se the porcelain paste used for making the test 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
46、to 60 Hz; b) an amplifier; c) a vibrator (see Figure 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
47、 Hz impacting vibration. Overfill the mould, firmly 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 o
48、n the free surface of the specimen. Replace the 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.
49、After removal from the mould, place the specimen 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 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.