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1、ADA Specification No. 18: 1992 Dental alginate impression material 1 Scope This lnternational Standard applies to dental alginate impression materials used in dentistry to take impressions of teeth and tissues of the oral cavity. It specifies reqrirements for dental materials containing an alginate
2、as essential gel-forming in- gredient, which. aner mixing with water in accord- ance with the manufacturers instrtrctions, is capable of reacting to form a material suitable for taking impressions. 2 Normative reference The following standard contains provisions which. through reference in this text
3、, constitute provisions of this lnternational Standard. At the time of publi- cation, the edition indicated was valid. All standards are subject to revision, and parties to agreements based on this lnternational Standard are encour- aged Lo investigate the possibility of applying the most recent edi
4、tion of the standard indicated below. Members of IEC and IS0 maintain registers of cur- rently valid lnternational Standards. IS0 6873:1983, Dental gypsum products 3 Definitions For the purposes of this lnternational Standard, the following definitions apply. 3.1 mixing time: That part of the total
5、working time specified or required in order to obtain a satisfactory mix. 3.2 total working time: That period of time between the start of mixing and the commencement of set- ting. 3.3 setting time: That period of time between the start of mixing and the achievement of the neces- sary elasticity to
6、remove the impression. 4 Requirements 4.1 Powder The powder shall be uniform and free from foreign materials (matter). Compliance with this requirement shall be deter- mined in accordance with 6.2. 4.2 Biocompatibility See the introduction (p.v) for guidance on biocompatibility. 4.3 Mixed material T
7、he material, mixed in accordance with the manu- facturers instructions, shall be homogeneous and free from lumps and granules and shall have a smooth surface; it shall form a smooth plastic mass. Compliance with this requirement shall be deter- mined in accordance with 6 2. 4.4 Mixing time The mixin
8、g time, stated by the manufacturer, shall not be more than 60 s (1 min). 4.5 Total working time When determined in accordance with 6.3, the aver- age penetration value achieved shall not exceed 0.25 mm at the end of the total working time stated by the manufacturer. 4.6 Compatibility with gypsum and
9、 reproduction of detail The impression material shall impart a smooth sur- face to, and separate cleanly from. a gypsum cast made from a recommended brand of gypsum prod- uct; this cast poured against the impression shall reproduce the 50 pm-line see fignre3a)l without ISO 1563:1990(E) interruption
10、when the test specified in 6.4 is carried out. 4.7 Recovery from deformation When determined in accordance with 6.5, the recov- er-y from deformation shall be at least 95 %. 4.8 Strain in compression When determined in accordance with 6.6, the strain in compression shall be neither less than 5 % nor
11、 more than 20 %. 49 . Compressive strength When determined in accordance with 6.7, the compressive strength shall be at least 0,35 MPa. 5 Sampling Representative samples from a Single manufactur- ing batch, including all necessary manufacturers instructions and devices, shall be obtained. The amount
12、 of material and deionized or distilled water to be obtained shall be sufficient to produce approximately 750 g of impression material to com- plete all the tests. 6 Test methods 6.1 General The alginate powder in the closed original Container and the test equipment (except for the smaller items use
13、d for mixing and specimen formation) shall be conditioned for not less than IO h at 23 C + 2 OC and (50 k 10) % relative humidity. The sialler items may be used after 30 min storage in the pre- scribed environment. Unless otherwise stated, all tests shall be carried out under these conditions. Disti
14、lled or deionized mixing water shall be used at the temperature as stated by the manufacturer or otherwise at 23 “C + 1 “C. - The proportions of powder and water shall be in ac- cordante with the manufacturers instructions and shall be achieved by weighing the components. The specimen shall be prepa
15、red by mixing the alginate powder with water using the ratio and the method of mixing specified in the manufacturers instructions. 6.2 Visual inspection Compliance with the requirements laid down in 4.1, 4.3, clause 7 and, as far as applicable, clause 8 shall be determined by visual inspection. 6.3
16、Total working time 6.3.1 Apparatus 6.3.1.1 Penetrometer, equipped with a cylindrical penetrator and a dial indicator Q, graduated in 0,Ol mm intervals, with a spindle having a travel of at least 25 mm (see figure 1). The penetrator shall have a total mass of 50 g + 1 g and shall be positioned with i
17、ts longi- tudinal axis perpendicular to the base of the instru- ment. The penetrometer shall have a mechanical or magnetic locking device so that the penetrator tan be fixed in any vertical Position. 6.3.1.2 Rigid ring mould, made of brass or stainless steel, at the discretion of the manufacturer (s
18、ee fig- ure 2). NOTE 1 If brass is used, the internal surface of the ring should be covered with a thin film of a non-reactive grease. 6.3.1.3 Smooth flat glass plate, large enough to support the ring mould (6.3.1.2). 6.3.2 Procedure Place the glass plate (6.3.1.3) on the base of the penetrometer (6
19、.3.1.1). Allow the penetrator to come into contact with the plate, take a fiducial reading (reading a) and then raise and fix the penetrator so that the tip is well above the upper end of the ring mould (6.3.1.2). Place the ring mould on the plate centrally under the penetrator and fill it with mixe
20、d material. Level the upper surface. Place the penetrator in contact with the upper surface of the material and fix it in that Position. Five seconds (5 s) before the end of the total working time stated by the manufacturer, release the penetrator, with the spindle held in the “up” Position. Ten sec
21、- onds (IO s) after release, fix the penetrator in the released (lowered) Position. The lower the spindle until contact is made and take a second reading (reading h). 6.3.3 Expression of results Calcu late the differente between readings a and h in mil limetres. Record the average of three tests as
22、the result. 2 ISO 1563:1990(E) 6.4 Compatibility with gypsum and reproduction of detail 6.4.1 Apparatus 6.4.1.1 Ruled test block, made of cast or wrought austenitic stainless steel see figure 3a). 6.4.1.2 Ring mould figure 3b). 6.4.1.3 Split mould, such that gypsum cast tan he removed without darnag
23、e see figure 3c). 6.4.1.4 Smooth flat metal or glass plate, large enough to be a base for the ring mould (6.4.1.2). 6.4.1.5 Mass, 1 kg. 6.4.1.6 Water bath, capable of being maintained at 35 OC + 1 OC. -. 6.4.2 Procedure Place the ring mould (6.4.1.2) on the plate (6.4.1-4) and slightly overfili with
24、 mixed alginate material. Twenty seconds (20 s) before the end of the working time stated by the manufacturer, centre the clean test block (6.4.1.1) above the mould and press it down into the mass of alginate. Immediately place the assembly in the water bath (6.4.1.6), maintained at 35 OC + 1 YZ, an
25、d load with the 1 kg mass (6.4.1.5) conditioned at 35 OC + 1 OC. Three minutes (3 min) after the stated settinctime, remove the as- sembly from the water bath and separate the ring mould, toqether with the plate, from the test block. L Immediately prepare a gypsum mix, using a gypsum brand type 3 or
26、 4 in accordance with ISO 6873, as recommended by the manufacturer see (clause 7i). Rinse the alginate surface with water, or treat in any other way described in the manufac- turers instructions (e.g. with fixative Solution), and Shake off the excess fluid. Place the Split mould (6.4.1.3) on the rin
27、g mould and gently fill with the gypsum product mix, using mechanical Vibration in such a way that the gypsum product displaces any moisture adhering to the surface of the alginate. Al- low the gypsum product mix to harden for 30 min in excess of the setting time. Separate the Split mould containing
28、 the gypsum cast from the ring mould containing the alginate. 6.4.3 Test Observation Examine the gypsum cast under low-angle illumi- nation, at a magnification of x4 to 12, and record whether the 50 Pm-line line a in figure 3a) is com- pletely reproduced over the full length of 25 mm be- tween the i
29、ntersection lines. NOTES 2 lf the alginate impression material tends to stick to the surface of the ruled test block, it is recommended that this surface be painted immediately before the alginate is rnixed with a suitable separating agent- 3 To check that the gypsum product has not deteri- orated,
30、it is recommended that the setting time be deter- mined in accordance with ISO 6873; the setting time should be within + 20 O/o of the time stated by the manu- facturer. 6.4.4 Expression of results Record whether the 50 Pm-line line a in figure 3a) is fully reproduced by at least two casts, resultin
31、g from three tests. 6.5 Recovery from deformation 6.5.1 Apparatus 6.5.1.1 Deformation apparatus, with sufficient forte to deform the specimen height by 20 % and capable of measuring the height with an accuracy of 0,Ol mm, without the specimen being displaced (see figure 4). The forte exerted by the
32、spindle of the dial indicator shall be 0,6 N + 0,l N. - The material of the apparatus in figure4 shall be cast or wrought austenitic stainless steel. Ottie f- aPP aratus with equal accuracy and perform- ante maY be used. 6.5.1.2 Split mould, with fixation ring, made of stainless steel or brass alloy
33、 (see figure 5). 6.5.1.3 Two flat glass plates, approximately 50 mm x 50 mm and at least 3 mm thick. 6.5.1.4 Flat glass plate, approximately 15 mm x 15 mm and 2 mm thick. 6.5.1.5 Water bath, capable of being maintained at 35 OC + 1 “C. - 6.5.1.6 C-clamps, having a throat capacity of at least 30 mm.
34、6.5.2 Preparation of the test specimen Place the fixation ring (6.5.1.2) on one of the glass plates (6.5.1.3) and fill it slightly more than one-half full with atginate material, mixed in accordance with the manufacturers instructions. Press the Split mould in the ring until the bottom of the mould
35、touches the plate and alginate extrudes above the top of the mould. Then press the second plate (6.5.1.3) over the mould to forte away the excess alginate material and to form the upper surface of the specimen. ISO 1563:1990(E) Thirty seconds (30 s) after the end of mixing, place the mould and its a
36、ccompanying plates, fixed by the C-clamp (6.5.1.6) in the water bath (6.5.1.5), main- tained at 35 OC + 1 “C. At the stated setting time, remove the asseibly from the water bath. After re- moving the flash, separate the specimen from the Split mould. Centre the flat plate (6.5.1.4) on top of the spe
37、cimen. Place the specimen on the table of the deformation apparatus (6.5.1.1). 6,6.1.2 Other apparatus, as described in 6.5.1.2 to 6.5.1.6. 6.6.2 Preparation of test specimen Prepare the test specimens as described in 6.5.2. 6.6.3 Procedure Carry out the test in accordance with the following time sc
38、hedule (where t is the manufacturers stated setting time): 6.5.3 Procedure Carry out the test in accordance with the following time schedule (where t is the manufacturers stated setting time): a) t + 60 s: place the specimen on the table of the compression device (6.6.1.1) and subject it to a load o
39、f 125 g + 10 g, thereby producing a stress of approximately 0,Ol N/mm*; a) t i- 45 s: gently lower the spindle of the dial in- dicator so that it Comes into contact with the plate on the specimen; b) t -t- 90 s: read the dial indicator and record the value as reading a; b) t -t- 55 s: read the diat
40、indicator, record the value as reading a and fix the spindle in the “up” pos- ition; c) t + 120 s: increase the load to 1250 g + 10 g within 10 s thereby producing a total stress of 0,l mm2; c) t i- 60 s: deform the specimen to a height of 16 mm + 0,l mm within 1 s, maintain this defor- - mation for
41、 5 s + 0,5 s, then release the defor- mation forte; d) t -t 150 s: read the dial indicator and record the value as reading 6. NOTE 5 Before star ,ting the te st procedure the dial in- dicator should be in a zero posi t i on lower than h. d) t -t- 90 s: gently lower the spindle of the dial in- dicato
42、r so that it Comes into contact with the plate on the specimen; 6.6.4 Expression of results e) t t- 100 s: read the dial indicator and record the value as reading b. Calculate the strain in compression, as a percent- age, using the following formula: 1oox(*) NOTE 4 Before starting the test procedure
43、 the dial in- dicator should be in a zero Position lower than h. where 20 is the length of the mould, in millimetres. 6.5.4 Expression of results Record the average strain in specimens as the test result. compression of three Calculate the recovery from deformation, as a per- centage, using the foll
44、owing formula: 6.7 Compressive strength IOOX I-Jg ( 6.7.1 Apparatus where 20 is the length of the mould, Record the average recovery from three specimens as the test result. 6.6 Strain in compression 6.6.1 Apparatus 6.63 .l Compression device, having in millimetres. deformation of AnY compressive-st
45、rength-testing apparatus capable of applying a load at a rate of 100 N/min and of recording the forte with an accuracy of 1 N in ac- cordante with 6.7.3. 6.7.2 Preparation of test specimens Prepare the test specimens as described 6.5.2. a dial indicator, 6.7.3 Procedure graduated in 0,Ol mm interval
46、s, and a measuring forte of 0,6 N + 0,l N (see figure 6). The device shall be capable of-applying the forces required for the test as outlined in 6.6.3. Sixty seconds (60 s) after the manufacturers stated setting time, place the specimen, covered at both ends with a piece of bond Paper, between the
47、anvils ISO 1563:1990(E) of the compressive-strength-testing apparatus (6.7.1). Load the specimen continuously and as uni- formly as possible to give an average rate of loading of 100 min + 20 N/min, until the first fracture is clearly showi on the graph. NOTE 6 This fracture is indicated by a (spont
48、aneous) med iately after cleaning so that the most accu- rate result s are obtained; i) identification of at least one type-3 and one type-4 gypsum products, which are assumed to meet the requirements of ISO 6873 and which are compatible with the alginate impression ma- terial; decrease of about 10
49、O/o or more of the actuai load. Record the forte at fracture to the nearest 1 N. 6.7.4 Expression of results Calculate the compressive strength, K, megapascals, using the following formula: 417; lc E- nd* j) information that the material shall be stored in a tightly closed Container. in 8 Packaging and marking 8.1 Packaging The material shall be supplied in Containers which neither contaminate nor permit contamination of the contents. where F is the forte at fracture, in newtons; d is the diameter of the test specimen (equal to the inside diameter of the