BS EN ISO 28399:2021 pdf free download – Dentistry – External tooth bleaching products.
B.1 Principle
The depth of erosion of enamel and dentine caused by external tooth bleaching products is determined using a light microscope.
Test summary: sound enamel and dentine slabs of approximately 4 mm x 4 mm x 1,4 mm are cut from caries and erosion free molars or incisors of human or bovine tooth. These slabs are mounted on a plastic rod and the natural surface of the slab is removed by sanding to expose fresh enamel or dentine. The surface is protected with fingernail polish leaving a 1,0 mm unprotected stripe down the centre of the fresh enamel or dentine surfaces. The specimens are exposed to the potentially erosive solution/ gel following the manufacturer’s instructions for use or for standard solutions, for 1 h while stirring. The specimens are rinsed with distilled water (D-H20), cleansed in mild detergent solution, rinsed with ethanol, and rinsed again with D-H20 and visually inspected to ensure that all product residues have been removed. The specimens are then sliced perpendicular to the exposed stripe to yield 3 or 4 cross-section slices from each specimen slab. The cross-section slices are mounted on a glass slide, and a digital image is obtained under microscope. A digital image of a reference scale such as a grid or millimetre ruler is also obtained at the same magnification. The reference scale and the cross-section can be in the same digital image. The digital image for each cross-section is evaluated for surface loss using software capable of assessing the gray scale values of pixels1). The surface loss for each crosssection from a specimen slab is averaged to give the erosion loss for each specimen.
B.2 Test condition
Perform the test at (23 ± 2) °C, i.e. ambient temperature.
B.3 Apparatus and materials
B.3.1 Apparatus
B.3.1.1 Stereo microscope with digital camera, see Figure B.1 b).
B.3..1.2 Slow speed saw, see Figure BL1 a).
B.3.1.3 Sandpaper, 600 carbide grit (1 200 grit EU standards).
B.3.1.4 Disposable beakers, 50 ml.
B.3.1.5 Glass beakers, 100 ml.
1) Image software methods are described in B.10 as an example. ImageJ software is freely available and in the public domain and downloadable from https://imagej.nih.gov/ij/. lmageJ bundled with Java 1.8.0_112 (64-bit Java) is available for Windows system and ImageJ bundled with Java 1.8.0_172 is available for Mac OS X and follow the installation instructions. This information is given for the convenience of users of this document and does not constitute endorsement by ISO of this product.
B.3.1.6 Volumetric flask, 100 ml, in accordance with Iso 1042, Class A.
B.3.17 Magnetic stir plate and magnetic stir bars.
B.3.1.8 Plastic rods (poly methyl methacrylate), 6 mm diameter x 15 cm length.
B.3.1.9 Grid, of known dimensions or mm scale to 0,5 mm.
B.3.1.1O pH/mV electrometer (pH meter), with a sensitivity of +0,1 mV.
B.3.2 Materials
B.3.2.1 Citric acid monohyd rate (C6H807.H20).
B.3.2.2 Sodium citrate dihyd rate (Na3C6H5O7•2H20).
B.3.2.3 Distilled water, in accordance with ISO 3696, Grade 2.
B.3.2.4 Potassium hydroxide (KOH) at 0,1 mol/l.
B.3.2.5 Hydrochloric acid (H Cl) at 0,1 mol/l.
B.3.2.6 Ethanol.
B.3.2.7 Teeth (human or bovine; erupted only or unerupted only, if known) with caries free and erosion free surfaces, sufficient amounts of teeth for collecting six 4 mm x 4 mm x 1,4 mm specimens for each group, disinfected in storage solution.
B.3.2.8 Fingernail polish, pigmented.
B3.2.9 Fingernail polish, clear.
B.3.2.1O Cyanoacrylate glue.
B.3.2.11 Detergent solution, e.g. 1 % sodium lauryl sulfate solution.