ASTM E2466-06(2011)

The light reflected from the facial anterior teeth can be used to calculate color coordinates. Monitored over time, changes in color can be observed. These data reveal information about the efficacy of a product, treatment study, or epidemiology of tooth color. For example, clinical studies of consumer tooth whitening systems evaluate the efficacy of manufacturers’ products.

The change in color of the facial surfaces of anterior teeth can be used to optimize the efficacy of tooth whitening systems. For example, the data can provide the answer the question: “What is the optimum percentage of whitening agent in a consumer tooth whitening system?”

This procedure is suitable for use in research and development, marketing studies, comparative product analyses, and clinical trials.

Prior research shows that a popular visual assessment method of determining tooth color, changes in tooth color, and whiteness among clinicians yields less than desirable results (1-4). These assessment tools are designated “shade guides.” They consist of tooth-shaped, synthetic objects in the form of teeth all of slightly different colors or different shades from one another. A “shade” is generally regarded as a color slightly different from a reference color (on a comparative basis). The colors of the synthetic teeth in these “shade guides” do not progress linearly as observed visually or logically in a CIE colorimetric coordinate system, and they are metameric to real teeth.

Translucency—Human teeth are translucent and the degree of translucency varies widely between subjects. However, translucency does not vary over the short term and is not therefore a consideration in this test method.

1.1 This test method covers the procedure, instrumental requirements, standardization procedures, material standards, measurement procedures, and parameters necessary to make precise measurements of in-vivo tooth color and tooth whiteness. In particular it is meant to measure the color of teeth in selected human subjects.

1.2 Digital images are used to evaluate tooth color of both posterior and anterior dentition (teeth). All other non-relevant parts, such as gums, spaces, etc., must be separated from the measurement and the analysis. All localized discoloration; such as stains, inclusions, etc., may be separated from the measurement and the analysis.

1.3 The broadband reflectance factors of teeth are measured. The colorimetric measurement is performed with a digital still camera while using an illuminator(s) that provides controlled illumination on the teeth. The measured data from a digital image are captured using a DSC. This test method is particularly useful for the gamut of tooth color which is:

1.3.1 CIE L* from 55 to 95,

1.3.2 CIE a* from 3 to 12,

1.3.3 CIE b* from 8 to 25 units.

1.4 The wavelengths for this test method include that portion of the visible spectrum from 400 to 700 nm.

1.5 Data acquired using this test method is for comparative purposes used during clinical trials or other types of research.

1.6 This test method is designed to encompass natural teeth, artificial teeth, restorations, and shade guides.

Note 1—This procedure may not be applicable for all types of dental work.

1.7 The apparatus, measurement procedure, data analysis technique are generic, so that a specific apparatus, measurement procedure, or data analysis technique may not be excluded.

1.8 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.

1.9 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and to determine the applicability of regulatory limitations prior to use.