ASTM E2545-07(2012)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: E2545 − 07 (Reapproved 2012)
Standard Test Method for
Objective Measurement of Gingival Color Using Digital Still
Cameras
This standard is issued under the fixed designation E2545; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
The color of gingiva is an important parameter used to ascertain certain medical and esthetic
information. RGB color values for gingiva are derived from the native signals generated by a digital
stillcamera,DSC,bybroadbandmeasurementofthereflectanceofgingiva.ThisTestMethod,E2545,
specifies the procedure used for the color measurement of gingival color at 45° relative to the sample
plane containing the gingiva under a nearly equal energy illuminating at 45° and viewing at 0°. This
method is appropriate for evaluating the color of facial gingiva.
1. Scope surveys, evaluation of comparative product efficacy, or safety
and treatment response in clinical trials involving gingival
1.1 This test method covers the procedure, instrumental
health or disease.
requirements, standardization procedures, material standards,
1.4 The apparatus, measurement procedure, and data analy-
measurement procedures, and parameters necessary to make
sistechniquearegeneric,sothataspecificapparatus,measure-
precise measurements of gingival color. In particular it is
ment procedure, or data analysis technique may not be ex-
meant to measure the color of gingiva in human subjects.
cluded.
1.2 Digitalimagesareusedtoevaluategingivalcoloronthe
1.5 The values stated in SI units are to be regarded as the
facial labial or buccal surfaces of the gingiva. The marginal
standard. The values given in parentheses are for information
gingival tissue adjacent to natural teeth may be of particular
only.
interestforanalysis.Allothernon-relevantparts;suchasteeth,
1.6 This standard does not purport to address all of the
tongue, spaces, dental restorations or prostheses, etc., must be
safety concerns, if any, associated with its use. It is the
separatedfromthemeasurementandtheanalysis.Alllocalized
responsibility of the user of this standard to establish appro-
discoloration; such as stains, inclusions, pigmentations, etc.,
priate safety and health practices and determine the applica-
may be separated from the measurement and the analysis.
bility of regulatory limitations prior to use.
1.2.1 The broadband reflectance factors of gingiva and the
surrounding tissue are measured. The colorimetric measure-
2. Referenced Documents
ment is performed using an illuminator(s) that provides con-
2.1 ASTM Standards:
trolled illumination on the gingiva using a digital still camera
E179Guide for Selection of Geometric Conditions for
to capture the digital image.
Measurement of Reflection and Transmission Properties
1.3 Data acquired using this test method may be used to of Materials
E284Terminology of Appearance
assess personal gingival color for the purposes of identifying
E308PracticeforComputingtheColorsofObjectsbyUsing
overallhealthstatus,healthstatusatspecificsitesinthemouth,
or to track changes in personal health status for individuals the CIE System
E1345Practice for Reducing the Effect of Variability of
over time. Pooled data may be used to assess gingival color,
health and disease among populations in epidemiological Color Measurement by Use of Multiple Measurements
E1767Practice for Specifying the Geometries of Observa-
tion and Measurement to Characterize the Appearance of
Materials
This test method is under the jurisdiction of ASTM Committee E12 on Color
andAppearanceandisthedirectresponsibilityofSubcommitteeE12.06onDisplay,
Imaging and Imaging Colorimetry. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Feb. 1, 2012. Published February 2012. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 2007. Last previous edition approved in 2007 as E2545–07. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/E2545-07R12. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E2545 − 07 (2012)
2.2 ISO Publications: RGBvaluesoftheseimagesarereadandstored.Theresultsare
ISO 17321–1Colour characterization of digital still cameras reported as RGB values and can be converted to other
(DSCs) — Part 1: Stimuli, metrology, and test procedures colorimetric coordinates such as CIELAB. Procedures for
ISO/IEC 1544–1:2000 – JPEG2000Information technology converting the RGB camera values to component CIELAB
– JPEG 2000 image coding system – Part 1: Core coding values are also presented.
system, commonly known as JPEG 2000 jp2 file format
5. Significance and Use
2.3 ISCC Publications:
Technical Report 2003–1Guide to Material Standards and 5.1 Thecolorofgingivaorchangesingingivalcolorcanbe
Their Use in Color Measurement
observed. The light reflected from the facial surfaces of the
2.4 Other Publications: gingiva can be used to calculate color coordinates. These data
TIFFTagged Image File Format reveal information about the efficacy of a product, treatment
studied, or epidemiology of anti-gingivitis treatments. For
3. Terminology
example,clinicalstudiesofgingivitistreatmentsystemsevalu-
ate the efficacy of manufacturers’ products.
3.1 Terms and definitions in Terminology E284 are appli-
cable to this test method.
5.2 The change in color of the facial surface gingiva can be
used to determine and optimize the efficacy of anti-gingivitis
3.2 Definitions: Terms included in this section are peculiar
treatments.Forexample,thedatacanprovidetheanswertothe
to this standard.
question:“What product or system is the most efficacious in
3.2.1 angle of incidence, n—θ and optional θ , the polar
1 2
the treatment of gingivitis?”
angle between the central ray of the illuminator(s), I and I ,
1 2
and the Z axis which is the optical axis of the camera.
5.3 Chronic inflammatory disease of the gingiva and peri-
3.2.1.1 Discussion—These are shown in Fig. A1.1.
odontium results in destruction of gingival connective tissue,
3.2.2 bit depth, n—the number of digital bits used to store periodontal ligament, and alveolar bone. Clinically, inflamma-
tion is seen as redness, swelling, and bleeding observed upon
information contained in each color channel of each pixel.
3.2.2.1 Discussion—Thebitdepthdeterminesthemaximum probing.
number of colors that may be encoded by the system. For
5.4 This procedure is suitable for use in diagnosis and
example, a 24 bit system comprising 8 bits per channel can
monitoring, research and development, epidemiological or
8 8 8
encode2 by2 by2 orabout17million;colorsfarmorethan
other surveys, marketing studies, comparative product
are distinguishable by the human observer.
analysis, and clinical trials.
3.2.3 facial surfaces, n—the surfaces of teeth and gingiva
5.5 Popular methods assess gingival inflammation via re-
that are oriented outward toward the lips (labial) and cheeks
6,7
peated clinical examination of the gingival tissues. These
(buccal), and facing away from the tongue or roof of the
methods typically quantify gingival color, which are used to
mouth.
assess gingival health or disease, at multiple intraoral sites on
3.2.4 gingivitis, n—inflammation of the marginal gingiva in
the gingiva using a simple non-linear scoring system or index.
response to dental plaque accumulation on adjacent tooth
Assessment of gingival color is an important component of
surfaces.
health status for mild-to-severe gingival disease. These tech-
niquesaretime-consuming,subjective,andofteninvasive,and
3.2.5 in-vivo—adj, or adv, within a living body.
for archival purposes, separate intraoral photographs must be
3.2.5.1 Discussion—Used to describe measurements made
collectedtodocumentgingivalcolorandappearance.Variation
in a living body.
between and among examiners may contribute to appreciable
3.2.6 polarization, n—the process by which vibrations of
differences in measurement.
lightaregivenadefiniteorientation;alsothestateproducedby
that process.
6. Interferences
3.2.7 polarizing filter, n—a component that blocks one of
6.1 The interferences identified below may be eliminated
the two planes of vibration of an electromagnetic wave, thus
andproblemsavoidedbycontrollingandregulatingeachfactor
producing linearly polarized light.
within the constraints of the allowable experimental error. The
values and limits for these factors are typically determined
4. Summary of Test Method
experimentally. If the standard laboratory conditions listed
4.1 Thistestmethoddescribestheproceduresforbroadband
below change during the test or from test to test by an
reflectometry of gingival tissue. The standardization of the
appreciable amount, these conditions may cause interferences,
instrumentusedtomeasurethetissueisdefined.Theimagesof
artifact standards and samples are captured with a DSC. The
Loe H., and Silness, J., “Prevalence and Severity,” Journal Peridontal Disease
in Pregnancy,I, Acta Odontologica Scand, 1963, 21:533-551.
3 7
Available from International Imaging Industry Association (13A), 701 Lobene,R.R.,Weatherford,T.,Ross,N.M.,Lamm,R.A.,andMenaker,L.,“A
Westchester Avenue, Suite 317W, White Plains NY 10604, www.13a.org. modified gingival index for use in clinical trials,” Clinical Prevention Dentistry,
Available from ISSC, Inter-Society Color Council, 11491 Sunset Hills Rd., 1986, 8:3–6.
Reston, VA 20190, www.iscc.org. McClanahan, S. F., Bartizek, R. D., and Biesbrock, A. R., “Identification and
TIFF, Tagged Image File Format,Adobe Systems Incorporated, San Jose, CA, consequences of distinct Loe-Silness gingival index examiner styles for the clinical
http://www.adobe.com. assessment of gingivitis,” Journal of Periodontology, 2001, 72:383–92.
E2545 − 07 (2012)
andtheaccuracyandprecisionrequirementsofthistestmethod
may not be achieved. In some cases these effects may only be
observed during the performance of the test.
6.1.1 Factors Affecting Test Results—The following envi-
ronmental factors are known to affect the test results.
6.1.1.1 Extraneous Radiation—Light including near infra-
redfromsourcesotherthantheilluminator(s)mustbeshielded
from the test apparatus.
6.1.1.2 Vibrations—Mechanicaloscillationsthatcausecom-
ponents of the apparatus to move relative to one and another
may cause errors in test results.
6.1.1.3 Thermal Changes—Temperature changes occurring
during a test or differences in temperature between testing
locations may affect the reflectance factor of the
standardization, calibration, and verification plaques, and the
apparatus spectral response function.
FIG. 1 Subject Positioned in Instrumentation
6.1.1.4 Power Input Fluctuations—Large changes in the
line frequency or supply voltage may cause the apparatus to
report erroneous results.
6.1.2 Retractors—Thesurfacefinishoftheretractorsaffects
the experimental test results. It has been determined that a
glossy finish on the surface of the retractors may introduce a
bias into the test results.
6.2 Thesystemmustallowforsuccessfulstandardization.If
the system cannot be standardized, a series of checks must be
performed (lighting, camera, etc.) to identify the reason. The
component of the system in error will be adjusted or replaced
to bring the system back into calibration.
7. Apparatus
7.1 General—The components described in this section are
described generically. The intention is not to exclude any
FIG. 2 Chin Rest
component from being used, or to exclude any type of
instrumentthatmaybeavailablecommercially.Between4and
6 different components or component assemblies are required
to accomplish the measurement.
7.2 Geometry—The geometry of the system is 45:0 as
described in Practice E1767. The DSC System Geometry
(Coordinate System) and Angular Convention are shown in
Fig. A1.1 included in Annex A1.
7.3 Components—A block diagram of these component
assembliesisshowndiagrammaticallyinFig.A1.2,includedin
Annex A1.
7.3.1 Source IlluminationAssembly—Containsthesourceof
illumination and associated optics to produce irradiance, E,on
thesampleoveraspecifiedspotarea,designated A.Thesource
is broadband and continuous in nature.Adiagrammatic repre-
sentation of the components of a typical source illumination
assembly Unit is shown in Fig. A1.3, included in Annex A1.
7.3.2 Spectral Power Distribution—The light source should
FIG. 3 Picture of Matte Lip Retractor
be spatially uniform over the area of interest, and have a
spectrum that approximates CIE Illuminant D50 over the
spectral range of the DSC, a choice that is customary and 7.3.3 Polarizer—The linear polarizer provides and controls
achieves the uniformity of practice. Commonly used light thepolarizationstateoftheincidentlight.Thispolarizeronthe
sources include incandescent lamps with filters to simulate a illuminators plus a cross polarizing filter on the lens system of
standard illuminant, flash xenon with filters, or white-LED the DSC eliminates glare caused by reflection of the subject’s
lamps to realize the approximate color temperature of 5000K. gingiva tissue during imaging. Wavelength range, extinction
E2545 − 07 (2012)
ratio, transmittance, and beam deviation are important param- 7.5.4 AcceptanceAperture—Theapertureofthelenssystem
eters of the components and must be selected. must be sufficient to accommodate the angular subtense of the
7.3.4 Heat Rejection Filters—These filters remove unde- sample and illuminate the detector chip.
sired near infrared (IR) radiation including heat that adversely
7.6 Computer Interface:
affects the subject, and provide spectral shaping of the spectral
7.6.1 The DSC must be interfaced and controlled by a
power distribution of the source illumination
computer.
7.3.5 Selective Blue Filters—These filters condition the
7.6.1.1 White Balance and Black Balance must be adjust-
spectral power distribution of the illumination so that the
able by the computer through the interface.
spectral power distribution is similar to Illuminant D50.
7.6.1.2 Exposure control must be settable and reproducible
7.3.6 Sample Plane Holder—The sample plane holder pro-
by the computer.
vides a secure mount so that it positions the subject’s incisors
7.6.1.3 Gaincontrolshouldbeselectableandsettablebythe
normaltotheZaxis,andcenteredalongtheXandYaxes.This
computer.
mustbedonesothatthegingivaltissueispresentedtotheDSC
7.6.2 Itisdesirabletohavealivevideooutputforvalidating
...