Analysis of YY/T 0631-2008 dental material color stability test method

Scope: This standard specifies a method for determining the color stability of dental materials after being irradiated with water immersion light. Test device: Xenon lamp with medium pressure of luminous source, the color temperature is between 5000K and 10000K. Measured according to GB16422.2, the illuminance on the sample should reach 150000lx±15000lx. Other luminous sources equivalent to xenon lamps can also be used. After the xenon lamp and ultraviolet filter are used for 1500h, their luminous intensity will change due to aging, so they should be replaced in time. Use a suitable illuminance meter to measure the illuminance and adjust the illuminance accordingly. The ultraviolet filter is made of optical glass (borosilicate glass). The transmittance of light waves below 300nm should be less than 1%, and the transmittance of light waves above 270nm should be greater than 90%. Distilled or deionized water in a circulating water bath in the testing-equipment' target='_blank'>test chamber, the temperature is maintained at (37±5) ℃, the water surface is (10±5) mm on the sample, and the sample is placed in parallel at the bottom of the test chamber. The specimen holder is made of opaque material, preferably metal, and can be used to hold specimens up to 50mm in diameter. Figure 1 shows a suitable sample holder. Test procedure: ①Sample preparation The size, sample preparation method and conditions of each dental material standard control sample, and the products of the control sample are all stipulated. These standards should be used in conjunction with this standard. ② Half of the irradiated test sample is clamped with a sample holder (see detailed standards), or wrapped with tin or aluminum foil. For dental specimens, wrap half of the dental vestibule with tin or aluminum foil parallel to the long axis of the tooth. Install the ultraviolet filter, put the sample in a water bath, and irradiate the sample with a xenon lamp (24±1) h. Take care to avoid shadows on the specimen. Evaluation-color comparison: three examiners with normal color vision will observe the half of the irradiated sample and the half of the unirradiated sample, and any difference in the color of the sample with the unirradiated sample. Examiners with normal color vision should be checked and verified by a doctor or other suitable specially trained person. Colorless vision correction glasses can be worn. The comparison should be made under bright diffuse sunlight under north-facing non-direct sunlight, or under a xenon lamp with an illuminance of 1000 lx to 2000 lx or an equivalent lamp conforming to CIED65 without any obvious color reflection. The disc-shaped sample is placed on a diffuse white background with a reflectivity of about 90%. The background is the same size as the disc, surrounded by a diffuse gray background with a reflectivity of (30±5)%. For the tooth-shaped specimen, use a diffuse gray background with a reflectivity of (30±5)%. Let three observers observe at a distance of 200 mm to 300 mm from the specimen for no more than 2 s. Record the comparison results of the three observers respectively. If the observation conclusion is controversial, the majority result shall prevail.
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