1、Designation: E 2670 09Standard Test Method forObjective Quantification of Dental Plaque Using Digital StillCameras1This standard is issued under the fixed designation E 2670; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year
2、 of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.INTRODUCTIONDental plaque is a biofilm, which grows on teeth and surrounding tissue. In many cases, dentalplaque is the underl
3、ying cause of many oral diseases, that is, cavities and gum diseases. Thus,controlling dental plaque through its removal and inhibition of re-growth is essential to maintaininggood oral health. Today, there are hundreds of products produced to control dental plaque. Examplesare; toothbrushes, toothp
4、astes, floss, rinses, gums and routine dental cleanings. One universal designobjective maximizes plaque control through enhanced cleaning ability or chemistry which inhibitsplaque growth; that is, anti-bacterial agents. Often, the effectiveness of a product or procedure ismeasured in a clinical tria
5、l with traditional methods of estimating plaque coverage. For example, themodified Turesky index is often used. This index is an integer scale ranging from 0 (no plaque) to 5(complete plaque coverage). The clinical examiner estimates the numerical value or score based onvisual observation of the pla
6、que. Unfortunately, there are drawbacks to this approach. First, the scaleis non-linear with respect to plaque area coverage. Second, the application of the scale is subjectiveby nature. Therefore, an objective method of measuring the amount of plaque on teeth represents asignificant improvement in
7、the science of plaque measurement.1. Scope1.1 This method covers the procedure, instrumental require-ments, standardization procedures, material standards, mea-surement procedures, and parameters necessary to make pre-cise measurements of dental plaque on the teeth revealed byfluorescence. In partic
8、ular it is meant to measure the amount ofplaque and plaque coverage on human teeth.1.2 Digital images are used to measure the coverage ofdental plaque on the teeth using discrimination analysis. Alllocalized discoloration, such as stains, inclusions, pigmenta-tions, etc., may be separated from the m
9、easurement and theanalysis. All other non-relevant parts, such as teeth, tongue,spaces, dental restorations or prostheses, etc., must be sepa-rated from the measurement and the analysis.NOTE 1This procedure may not be applicable for all types of dentalwork.1.3 The broadband reflectance factors of th
10、e teeth andsurrounding tissue are measured. The colorimetric measure-ment is performed using an illuminator system that providescontrolled illumination on the teeth and surrounding tissue. ADigital Still Camera (DSC) is used to capture the digital image.1.4 Data acquired using this method may be use
11、d to assesspersonal plaque coverage for the purposes of identifyingoverall health status, health status at specific sites in the mouth,or to track changes in personal health status for individualsover time. Pooled data may be used to assess plaque coverage,health, disease among populations in epidem
12、iological surveys,evaluation of comparative product efficacy, or safety andtreatment response in clinical trials involving plaque coverageor disease.1.5 The apparatus, measurement procedure, and analysistechnique described herein are generic. The intent is not toexclude a specific apparatus, measure
13、ment procedure, or analy-sis technique.1This test method is under the jurisdiction of ASTM Committee E12 on Colorand Appearance and is the direct responsibility of Subcommittee E12.06 on ImageBased Color Measurement.Current edition approved Feb. 1, 2009. Published June 2009.1Copyright ASTM Internati
14、onal, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.1.6 The values stated in SI units are to be regarded asstandard. The values in parenthesis are for information only.1.7 This standard does not purport to address all of thesafety concerns, if any, associated wi
15、th its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E 179 Guide for Selection of Geometric Conditions forMeasurement o
16、f Reflection and Transmission Properties ofMaterialsE 284 Terminology of AppearanceE 1345 Practice for Reducing the Effect of Variability ofColor Measurement by Use of Multiple MeasurementsE 1767 Practice for Specifying the Geometries of Observa-tion and Measurement to Characterize the Appearance of
17、Materials2.2 ISO Publications:3ISO 17321-1 Colour characterization of digital still cameras(DSCs) Part 1: stimuli, metrology, and test proceduresISO/IEC 15444-1:2000JPEG2000 Information technology JPEG 2000 image coding system Part 1: Corecoding system, commonly known as JPEG 2000 jp2 fileformat2.3
18、ISCC Publications:4Technical Report 2003-1 Guide to Material and Their Use inColor Measurement3. Terminology3.1 Terms and definitions in Terminology E 284 are appli-cable to this test method.3.2 Definitions: Terms included in this section that arepeculiar to this standard.3.2.1 angle of incidence, n
19、u1and u2optional, the polarangle between the central ray of the illuminator(s), I1and I2,and the Z axis, which is the optical axis of the camera.3.2.1.1 DiscussionThese are shown in Fig. A1.1.3.2.2 anterior teeth, nanterior teeth are the six upper andsix lower front teeth; the anterior teeth consist
20、 of incisors andcuspids (canines).3.2.3 bit depth, nthe number of digital bits used to storeinformation contained in each color channel of each pixel.3.2.3.1 DiscussionThe bit depth determines the maximumnumber of colors that may be encoded by the system. Forexample, a 24 bit system comprising 8 bit
21、s per channel canencode 283 283 28or about 17 million colors; far more thanare distinguishable by the human observer.3.2.4 biofilm, na complex aggregation of microorganisms.3.2.4.1 DiscussionBiofilms have been implicated in theformulation of dental plaque and gingivitis.3.2.5 canine, nthe third toot
22、h from the center of themouth towards the back of the mouth; these are the front teeththat have one rounded or pointed edge used for biting.3.2.6 dental plaque, na biofilm consisting of bacteria inan intrabacterial matrix, which adheres to teeth.3.2.7 disclosing agent, na dye which binds to, adsorbs
23、 toor is physically retained in the plaque matrix.3.2.7.1 DiscussionCommon disclosing agents are fluores-cein, erythrosine, fast green, and methlyene blue.3.2.8 facial surfaces, nthe surfaces of teeth and gingivathat are oriented outward toward the lips (labial) and cheeks(buccal), and facing away f
24、rom the tongue or roof of themouth.3.2.9 in-vivo, adjwithin a living body.3.2.9.1 DiscussionPertaining to measurements made in aliving body.3.2.10 NIR cutoff filter, nan optical filter that does notpass wavelengths longer than 700 nm.3.2.11 posterior teeth, nthe large teeth in the back of themouth.4
25、. Summary of Test Method4.1 This method describes the procedures for in-vivo broadband reflectometry of the subjectsteeth, plaque, and surround-ing tissue.4.2 This method describes the standardization of the mea-surement instrumentation used to measure a subjects teeth.4.3 The DSC captures and store
26、s the RGB values of theimages. The data from the reflectance measurements areanalyzed to discriminate between plaque, teeth, and surround-ing tissue.4.4 Discrimination analysis allows one to calculate percent-age of plaque coverage on teeth.4.5 Guidelines are given for disclosing of plaque.5. Signif
27、icance and Use5.1 The light reflected from the teeth and emitted from theplaque on the teeth is captured by a DSC. Digital data extractedfrom the images can be used to discriminate and classifypixels. Monitored over time, changes in plaque coverage canbe observed. An example is a clinical study of t
28、he efficacy oftooth brushes to remove dental plaque.5.2 Assessing the quantity and coverage of dental plaque onteeth can be used to optimize the design of products andprocedures intended to reduce dental plaque coverage.5.3 Clinical assessment, for example, the modified TureskyPlaque Index,5,6is a s
29、ubjective, non- linear, integer based scalethat may require extensive examiner training and recertifica-tion. The method described here provides increased precision,repeatability, and reproducibility in comparison to other meth-ods.2For referenced ASTM standards, visit the ASTM website, www.astm.org
30、, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from International Imaging Industry Association (13A), 701Westchester Ave., Suite 317W, White Plains, NY 10064, www.13
31、A.org.4Available from ISCC, Inter-Society Color Council, 11491 Sunset Hills Rd.,Reston, VA 20190, www.iscc.org.5Turesky S., Gilmore, N. D., Glickman I., “Reduced plaque formation by thechloromethyl analogue of Vitamin C,” Journal of Periodontology, Vol. 41, 1970,pp. 41-43.6QuigleyG.A., and Hein J. W
32、., “Comparative cleansing efficiency of manual andpower brushing,” Journal of the American Dental Association, Vol. 65, 1962, pp.26-29.E26700925.4 This procedure is suitable for use in research anddevelopment, marketing claims and advertising, comparativeproduct analysis, and clinical trials.6. Inte
33、rferences6.1 The interferences identified below may be eliminatedand problems avoided by controlling and regulating each factorwithin the constraints of the allowable experimental error. Thevalues and limits for these factors are typically determinedexperimentally. If the standard laboratory conditi
34、ons listedbelow change during the test or from test to test by anappreciable amount these conditions may cause interferences,and the accuracy and precision requirements of this test methodmay not be achieved. In some cases these effects may only beobserved during the performance of the test.6.1.1 Fa
35、ctors Affecting Test ResultsThe following factorsare known to affect the test results.6.1.1.1 Extraneous RadiationLight including near infra-red from sources other than the illuminator(s) must be shieldedfrom the test apparatus.6.1.1.2 VibrationsMechanical oscillations that causecomponents of the ap
36、paratus to move relative to one anothermay cause errors in test results.6.1.1.3 Thermal ChangesTemperature changes occurringduring a test or differences in temperature between testinglocations may affect the reflectance factor of the standardiza-tion, calibration, and verification plaques, and the a
37、pparatusspectral response function.6.1.1.4 Power Input FluctuationsLarge changes in theline frequency or supply voltage may cause the apparatus toreport erroneous results.6.1.2 RetractorsThe surface finish of the retractors affectsthe experimental test results. It has been determined that aglossy fi
38、nish on the surface of the retractors may introduce abias into the test results.6.2 StandardizationThe system must allow for successfulstandardization. If the system cannot be standardized, a seriesof checks must be performed (lighting, camera, etc.) to identifythe reason. The component of the syste
39、m in error will beadjusted or replaced to bring the system back into calibration.7. Apparatus7.1 GeneralThe components described in this section aredescribed generically. The intention is not to exclude anycomponent from being used, or to exclude any type ofinstrument that may be available commercia
40、lly. Between 4 and6 different components or component assemblies are requiredto accomplish the measurement.7.2 GeometryThe geometry of the system is 45:0 asrecommended in Practice E 1767. The DSC System Geometry(Coordinate System) and Angular Convention are shown inFig. A1.1, included in Annex A1.7.
41、3 ComponentsA block diagram of component assem-blies is shown in Fig. A1.2, included in Annex A1.7.3.1 Source Illumination AssemblyContains the illumi-nation source and associated optics to produce irradiance, E,onthe sample over a specified spot area, designated A. A diagramof the components of a t
42、ypical illumination system is shown inFig. A1.3, included in Annex A1.7.3.2 Spectral Power DistributionThe exact spectral na-ture of the illuminator is immaterial for the measurement. Thesource must be stable with time and have adequate energy atthe wavelengths of interest. The illumination must exc
43、ite thedisclosing agent. Commonly used light sources include incan-descent lamps, either operated without filters or filtered tosimulate standard illuminants, flashed or continuous-wavexenon-arc lamps, and discrete monochromatic or polychro-matic sources, such as light emitting diodes (LEDs).7.3.3 S
44、ample Plane HolderThe sample plane holder pro-vides a secure mount so that it positions the subjects incisorsnormal to the Z axis and centered along the X and Y axes. Thismust be done so that the teeth are presented to the DSC in arepeatable and reproducible manner. The sample mount mustbe kept unob
45、trusive so that it is “friendly” and not intimidatingto the subjects.Achin rest can be used to precisely position theFIG. 1 Subject Positioned in Chin RestFIG. 2 Chin RestFIG. 3 Matte Lip RetractorsE2670093subjects relative to the instrumentation (Fig. 1). The subjectplaces their chin on a chin rest
46、 which is a quartercup shapedrig, as shown in Fig. 2, chin rest.7.3.4 Lip Retractors7(Fig. 3) are used to expose themajority of the subjects teeth to the DSC. The subject holdsthe head straight, join the tips of the upper and lower incisorstogether, and places the tongue against the top of the mouth
47、.The facial surface of the central incisors should be aligned witha line marked on the chin rest indicating the center along the Xaxis.7.3.5 Detector Optical Elements:7.3.5.1 The typical detector optical elements are shown inFig. A1.4, included in Annex A1.7.3.6 Digital Still CameraThe DSC must have
48、 severalperformance characteristics.7.3.6.1 Depth of FocusThe depth of focus of the cameraand lens combination must be sufficient to accommodatedifferences in positioning, teeth geometry, and natural varia-tions between subjects.7.3.6.2 DetectorsEither a 3 chip RGB DSC or a singlechip RGB DSC will p
49、erform adequately in this application.7.3.6.3 Field of ViewThe field of view of the DSC andlens combination must be sufficient to accommodate differ-ences in positioning, teeth geometry, and natural variationsbetween subjects. This geometry is shown in Fig. A1.6,included in Annex A1. There can be no exception to thisrequirement.7.3.6.4 Bit DepthThe bit depth must be 8 bits or greaterper channel to accommodate accurate conversion of the digitalsignals into CIE Color Spaces. A bit depth of 8 bits iscommonly available.7.3.6.5 Acceptance Apertu
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