BS EN ISO 3107:2011 pdf download – Dentistry — Zinc oxide/eugenol cements and zinc oxide/ non-eugenol cements (ISO 3107:2011)
126.96.36.199 Cabinet, as specified in 188.8.131.52.
184.108.40.206 Micrometer or similar measuring device, accurate to 1 μm.
220.127.116.11 Mechanical tester, capable of being operated at a cross-head speed of (0,75 ? 0,30) mm/min or at a loading rate of (50 16) N/min.
7.3.2 Preparation of test specimens
Condition the moulds (18.104.22.168), screw clamps (22.214.171.124) and top and bottom plates (126.96.36.199) at (23 ? 1) °C.
After mixing in accordance with the manufacturer’s instructions, pack the cement, to a slight excess, into the split moulds within 1 min of the completion of mixing. In order to consolidate the cement and to avoid trapping air, it is advisable to convey the largest convenient portions of mixed cement to the mould and apply to one side with a suitable instrument. Fill the mould to excess in this manner and then place the mould on the bottom plate and pack the cement, such that the excess is expressed.
To facilitate the removal of the hardened cement specimen, the internal surface of the mould may be evenly coated, prior to filling, with a 3 % solution of micro-crystalline or paraffin wax in pure toluene. Alternatively, a thin film of silicone grease or polytetrafluoroethylene (PTFE) dry film lubricant may be used. Remove any extruded cement, place the top metal plate in position and squeeze together. Put the mould and plates in the clamp (188.8.131.52) and screw tightly together. Not later than 2 min after completion of mixing, transfer the whole assembly to the cabinet (184.108.40.206), maintained at (37 ? 1) °C.
One hour after completion of mixing, remove the plates, and prepare the surface of the ends of the specimen plane, at right angles to its long axis, using a small amount of 45 μm silicon carbide powder or similar abrasive, mixed with water (ISO 3696, grade 2) on a flat glass plate. Keep the specimen wet during preparation. Alternatively, use an equivalent grade of abrasive coated paper and water (ISO 3696, grade 2). Keep the ends of the specimen flat by rotating the specimen one quarter turn every few strokes. Remove the specimen from the mould immediately after surfacing and examine for air voids or chipped edges.
Discard any specimens with these defects. Immerse each specimen in distilled or deionized water (ISO 3696, grade 2) and maintain at (37 ? 1) °C for 24 h, after which condition in distilled or deionized water at (23 1) °C for (15 ? 1) min prior to testing. Then, measure the diameter of the cylinder with the micrometer (220.127.116.11) to the nearest micrometre. Proceed immediately to testing. The testing procedure requires five specimens.
Immediately after the end of the conditioning period, place the specimen with the flat ends between the platens of the mechanical testing apparatus (18.104.22.168) so that the load is applied in the long axis of the specimen. Use a cross head speed of (0,75 ? 0,30) mm/min or a loading rate of (50 ? 16) N/min until fracture. Record the maximum force applied when the specimen fractures.
Test five specimens.
Calculate the compressive strength, k , in megapascals, using the following equation:
k = 4F/?d 2
F is the maximum applied force, in newtons (N);
d is the measured mean diameter of the specimen, in millimetres (mm).
7.3.4 Treatment of results
a) If at least four of the values are no less, or for type I materials for compressive strength no greater, than the limit specified in Table 1, the material is deemed to have complied with the requirement of 5.1.
b) If three or more of the values are less, or for type I materials for compressive strength are greater, than the limit specified in Table 1, the material is deemed to have failed without the need for further testing.
c) If only three of the values are no less, or for type I materials for compressive strength no greater, than the limit specified in Table 1, repeat the whole test. If any values are lower, or for type I for compressive strength greater, than the limit in Table 1, the material is deemed to have failed the test.