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Organizing color in dentistry
E S T H E T I C
D E N T I S T R Y
Organizing color in dentistry
Lloyd M iller, DMD
Although esthetic dentistry techniques have grown more sophisticated, the fabrication and control of color in dentistry can be improved. An organized and precise system is necessary to combine artistic and scientific approaches. For this, a color order system, based on Munsell’s notations and spectrophotometric re search on the color space of natural teeth, would provide restorations of excellent color. he visual im pact o f tooth colors, both artificial and natural, exerts an ex traordinary influence on dentists, patients, and laboratory technicians. As the ability to m ake artificial restorations to m atch p a tient needs im proves, there is undeniable pressu re to achieve even higher levels of perfection. Although oral health needs and treatm en ts are largely determ ined by the dentist, elective esthetic im provem ents are b est suggested by the patient. The person paying for the restoration com m ands the ac ce p ta n ce or rejection o f resto ratio n s. This aspect puts m ore pressure on m anu factu rers, dentists, and laboratory techni cians to keep im proving visible resto ra tions. In esthetic dentistry, the patient has clout. Significant im provem ents have occurred in esthetic dentistry, but the control, fabri cation, and com m unication o f color in den tistry rem ains disorganized and archaic. C urrent com m unication typically is based on the traditional one-dim ensional shade guide sy stem , w hich w as developed to m ake attractive teeth for com plete den tu res. W ith this system there is little regard for m atching specific natural teeth closely. Scientific colorim etry is not used and o r
T
26-E ■ JADA (Special Issue) December 1987
ganization is extraordinarily meager. A lthough the human eye is the final arbi trator, success in color construction and com m unication is best achieved by com b in in g tr a d itio n a l a r tis tic te c h n iq u e s (largely subjective) with the science o f col orim etry. The A m erican D ental A ssocia tion has addressed this problem , and the Council on D ental M aterials, Instrum ents, and Equipm ent has established guidelines on su b m issio n o f d e n ta l sh a d e g u id es (copies are available from the council).
Communication The habitual use of a particular shade guide generates a certain visual picture in the m ind’s eye. To some extent, this fam iliarity produces some skill in selecting and com m unicating color; currently, it is far too narrow a system . A m ore useful com m uni cation system uses two approaches. F irst, the system relates to know n and easily recognized natural phenom ena. A rainbow is produced when the su n ’s rays are absorbed, reflected, and dispersed by falling rain or mist. W hen Isaac N ew ton in 1666 passed daylight through a prism , he produced a band of consecutive colors that w hen fused together produce daylight (Fig 1). T hese colors vary from the long red w aves of about 760 nm to the violet w aves o f 380 nm. The science of colorim etry m ea sures these pure hues and designates pre cise w avelengths that are constant and ir refutable. This is the foundation and stan dard for all color and m ust be incorporated in color organization in dentistry. S econd, the system uses specific tech nique and method for color m easurem ent. The o bservation, recording, and com m uni cation o f color may be divided into two
areas, artistic (traditional) and scientific. The artistic approach norm ally requires many years o f intense study and practice, even for the gifted. F u rth er, the naming of colors in the traditional m anner is not accu rate enough to be applied to m odern den tistry. R ather, a scientific, precise, and or ganized system is needed.
M unsell system o f color notation This system starts with the visible light spectrum o f red to violet and develops the n atu ral p h en o m en a into a visible co m m unication system for color (Fig 2-5). In 1905, M unsell1 described the entire question o f color and its three dim ensions in a logical m anner that organizes a clear and definite m ental concept of all color ex pression. In sim plistic term s they are: — Hue, the name o f the color; the quality by w hich one color family is identified from another, such as red from yellow. In scien tific term s, the identification is designated by specific w avelengths. — Value, the lightness o f a color; this quality identifies a light color from a dark one. Brightness is often used to describe this dim ension. It is incorrect to say it is the am ount o f gray in a color. H ow ever, value is m easured on a scale of black to w hite with gradations of grays. A black-andw hite photograph of colored o bjects is ach rom atic and all form s are show n in term s of value differences. — C hrom a, the strength of a color; the quality by w hich a w eak color from a strong one is defined. The intensity o r purity o f a color also designates chrom a. The notations are expressed as a simple th ree -d im en sio n al fo rm u la— hue v alu e/ chrom a, or H V/C— and always in that se-
E S T H E T I C
D E N T I S T R Y
Fig 1 ■ The passage o f a narro w beam o f daylight through a prism bends and refracts the light into a band of visible colors from red to violet. M acbeth, Division of K ollm organ C orp.
Fig 2 ■ Schematic of refracted daylight shows total visible color spectrum from the shortest violet wavelengths to the longest red wavelengths.
Fig 3 ■ In the M unsell System , the tw o ends of the visible spectrum are closed to form a circle (hue). An achrom atic vertical colum n represents value from black (1 to 10). Any degree of brightness o r reflectance can be represented by th is dimension. The th ird dimension o f chrom a is represented by the radius o f the circle— from the weakest in the center to the strongest a t th e periphery.W hen the M unsell Color Wheel is expanded to a solid, it encom passes the entire color spectrum in the three dimensions H V/C.
M UNSELL HUE VALUE/CHROM A CHART W hife
Fig 4 ■ The th re e dimensions of the M unsell System sepa
Fig 5 ■ E xternal view of the corrected M unsell C olor
rated . The hues o f visible light have been sep arated into ten
Solid shows different hues have varying m axim um
equal spaces. A hue of 5 represents a p u re hue for th a t color.
chrom as, which give it this shape (M unsell Color Co).
Each hue is divided into ten p arts (M unsell C olor Co).
Miller: ORGANIZING COLOR IN DENTISTRY ■ 27-E
E S T H E T I C
D E N T I S T R Y
STANDARD ILLU M IN A N T
GRATING
Fig 6 ■ Schematic for spectrophotometer. A known light source shines on an object (apple), and is transmit ted, absorbed, and reflected. The reflected light passes through a grating mechanism that divides the light and passes it on to a sensor that measures each color. This is then recorded.
FOR SPECTROPHOTOMETER
Fig 7 ■ Above, three-dimensional schematic of Munsell Color Solid indicates how the two charts are developed (fan and rectangle). Note that the fan has been expanded to spread the data. Right, cross section of a tooth indicates varying thicknesses of pulp, dentin, and enamel, which tends to produce scattering of data for spectrophotometric readings.
Fig 8 ■ Hue/chroma (H/C) graph of Hayashi6 data on 68 adult teeth. Bunching of data is result of the method of using graded samples of colored paper. The patients were selected as the most representative of normal tooth color.
28-E ■ JADA (Special Issue) December 1987
E S T H E T I C
NATURAL
TEETH
D E N T I S T R Y
t. h a y a s h i
8 .0 /
7 .5 /
7 .0 / VALUE 6 .5 /
6 .0 /
5 .5 /
/I
/2
•*— —
/3
/4
CHROMA —
/5 — ►
Fig 10 ■ H/C chart of data by Sproull7 using 37 extracted teeth. Notice the strong distribution into YR.
Fig 9 ■ Value/chroma (V/C) graph of teeth in Figure 8. Color values of teeth from Japanese adults are lower in value in this limited study than in other recorded research.
quence. A typical claret red could be desig nated: R5 3/4: hue = red 5, value = 3, chrom a = 4. T hus, all colors can be located precisely and rationally.1-4 O ther exam ples are show n in Table 1. Table 1 ■ Color formulas. Traditional name
Ivory Tan Orange
Hue lY—5Y 3YR—10YR 10R -6Y R
Munsell notation
Value 7 / — 9/ 4 .5 / — 6 .5 / 5 .5 / — 7 /
Chroma /1-/4 / 1 - / 4 .5
/ 10 — /
14
The large spread for traditional nam es o f colors prohibits their use for unam biguous color identification. M unsell’s notations o f H V/C apply num bers in a system atic fash ion to the subjective analysis o f color. Such a system bridges the gap betw een the tradi tional artistic color nam es and scientific m ethod, the spectrophotom eter.
Spectrophotometer T his d ev ice m easu res and reco rd s the am ount o f radiant energy for each hue in the entire visible spectrum (Fig 6). The quality o f lightness/darkness for each hue
also is m easured. The data can be trans lated into M unsell’s notations by com pu ter. Teeth and dental porcelain are inter fused by a fourth dim ension o f translucency. This com plicates tooth and porce lain m easurem ent because three system s of color mixing are present: additive, subtrac tive, and optical. T he analysis of opaque colorants is far more reliable because of the lack of translucency. Although the spectrophotom eter is cur ren tly to o com p lex and ex p e n siv e for routine use in the dental office or labora to ry , it has trem endous potential for use in population sam ples, m anufacture o f porce lain, and developm ent o f shade guides.
Population samples We need to know hue, value, and chrom a for large numbers of teeth both in vitro and in situ. With a large data base, porcelain can be designed to fill the color space of natural teeth in a reasonable m anner. H o w ev er, sp e c tro p h o to m e tric m ea surem ent of natural teeth is difficult and significant in situ data are not yet available. C urrently, the main disadvantage to this system is that teeth m ust be extracted and placed w ithin the m achine. M o reo v er, color and translucency changes o ccur if teeth are not m easured soon after extrac
tio n . It is assu m ed th a t in v itro m e a surem ents lack the red filtration o f pulp cham ber and gingival tissue but this has not yet been quantified. T he sp ectrophotom eter is so sensitive that the highly reflective and translucent to o th p ro d u c e s c h a n g in g d a ta a s th e m easuring point m oves from one area to another (Fig 7). A special spectro p h o to m e ter is being developed w ith a fiber-optic w and and integrating tip to m easure small averages in situ. If successful, th is may be the breakthrough needed to provide a large data base o f natural teeth in situ.
Manufactured porcelain In general, m anufacturers are not accu s tom ed to w arrant that: — Porcelain pow ders are the sam e from batch to batch (invalid color tolerances not based on specific standards o f deviation). — P o rc e la in p o w d e rs, w h en fu se d , m atch the shade guides. — Specific shades can be routinely pro duced following m a n u factu rers’ in stru c tions. — Porcelain pow ders and shade guide sam ples are the sam e m aterial. — S tan d a rd s o f tran slu ce n cy /o p a city have been developed and follow ed. — A lterations in hue, value, and chrom a
Miller: ORGANIZING COLOR IN DENTISTRY ■ 29-E
E S T H E T I C
NATURAL
D E N T I S T R Y
TEETH 8.5
Fig 12 ■ H/C chart of d a ta on 231 n a tu ra l teeth studied by J. M. Ney Co (86 patients).8 7. 0 VALUE 6. 5
N ATU R AL TE E TH (M u n s e ll N o ta tio n s ) 6 0 ADULT
TEETH
(J a p a n e s e )
1
2
3
4
------------------- C ROMA
Fig 14 ■ H/C chart of H ayashi stu d y 6 with blue tracing to demon strate data layout.
R . Sprouli
Fig 11 ■ V/C chart of Sprouli7 data on natural teeth.
NATURAL
TEETH
M u n s e ll N o ta tio n s
J.M. NEY 1974
8 .0 /
-
’ T*
;;L £ y •
7 .5 /
. 7 .0 /
i- -m: ...
.
can be predictably accom plished. It seems most of the foregoing problem s could be improved or corrected if a spec trophotom eter was used to define H V /C for fused porcelain and a standard of devia tion was adopted by industry.
NATURAL
TEETH
T. HAYASHI
VALUE 6 .5 /
Shade guides
.1* 6 .0 /
5 .5 /
■-nv- %
■j ; /I
/2
/3
/4
-«---------- - CHROMA------231 Plots, 86 Pts.
Fig 13 ■ V/C chart of Ney8 data.
30-E ■ JADA (Special Issue) December 1987
Q u ality c o n tro l by s p e c tro p h o to m e try could be used to establish that: — shade guides fall within the color space o f natural teeth and m eet those needs with reasonable distribution: — like shades be the same in all three d im e n sio n s, from o n e sh a d e g u id e to another; — shade guides be organized according to a logical system using M unsell’s nota tions o r a sim ilar system ; and — any shade guide system perm it logi cal m ovem ent in hue, value/chrom a within the color space o f natural teeth. S p e c tro p h o to m e tric m e a su re m e n t o f translucent dental porcelain poses som e of the same problem s as tooth analysis, viz, background influence and the interplay of light betw een the various layers. Standards should be developed. The com plete color sp ace o f natural teeth in term s of H V /C has not been deter-
Fig 15 ■ V/C chart for Hayashi study6 with author’s blue tracing to illustrate data coverage.
E S T H E T I C
D E N T I S T R Y
NATURAL TEETH
jL
HUE — IO Y R
,Y
NATURAL TEE TH
?Y
5 CHROM A 4
Fig 16 ■ H/C chart for Sprouli study7 with au thor’s brown tracing to illustrate data coverage.
3
1 r
; §
\
®5 bl¿5
3 ”
6.0
5.5
Fig 18 ■ H/C chart for Ney study with author’s green tracing to illus trate data coverage. Fig 17 ■ V/C chart for Sprouli study’ with author’s brown tracing to illustrate data coverage.
NATURAL
TEETH
— HUE — IOYR
5 CHROMA 4
Fig 20 ■ H/C overlay of the three studies (author’s interpretation).
Fig 19 ■ V/C chart for Ney study with author’s green trac ing to illustrate data coverage.
Miller: ORGANIZING COLOR IN DENTISTRY ■ 31-E
E S T H E T I C
D E N T I S T R Y
B IO F O R M
SHADES
— HUE —
NATURAL TEETH 8.5
7.0 VALUE 6.5
Fig 22 ■ H/C graph of Trubyte Bioform Shade Guide analyzed by Sprouli,7 1973. Fig 21 ■ V/C overlay of the three studies (author’s interpre tation).
BIOFORM SHADES
M unsell N o ta tio n s
( H v/ c )
T R U B Y T E B IO F O R M S H A D E G U ID E
8.0
(2 4 PLOTS)
7.5
7.0 VALUE 6.5
6.0
5.5
CHROMA
R. S proaii
Fig 23 ■ H/C graph of Trubyte Bioform Shade Guide, 1979. Compare with Figure 22.
Fig 24 ■ V/C graph of Trubyte Bioform Shade Guide, 1979. Compare with Figure 23.
mined. T he prim ary reason for this void is th a t cu rren t sp ectrophotom eter system s require that ex tracted teeth be used. A short review o f the data available is pro vided.
trophotom eter to m easure the color space o f 37 extracted teeth (Fig 10,11). The visual im pact of tooth colors in three dim ensions o f hue, value, and chrom a stirred a great deal o f interest. The sp ectro p h o to m eter becam e the preferred instrum ent for exam ining and recording tooth and porcelain colors. In 1974, the J. M. N ey C o8 studied natu ral teeth. A to talo f2 3 1 teeth extracted from 86 p a tie n ts w e re e x a m in e d b y sp e c -
Natural tooth color space In 1931, C lark2-5 published in vivo data on the problem s o f color and the matching of tooth colors w ith artificial m aterials. H e 32-E ■ JADA (Special Issue) December 1987
observed and recorded H V/C for 6,000 natural teeth from 1,000 patients, and pro duced a custom shade guide. In 1966, in Japan, H ayashi6 investigated 81 teeth in vivo, 68 from adults and 13 from c h ild re n (p rim ary sam p le s). C a re fu lly graded sam ples o f opaque paper in three dim ensions w ere used to m easure H V/C by visual com parison (Fig 8, 9). Such com parison is difficult. In 1 9 7 3 , S p r o u l i 7 u s e d a s p e c
E S T H E T I C
D E N T I S T R Y
VITA S H A D E S — HUE1Y ÎO Y R ^ —- T
9Y3 ^ 8YFv ^
2Y
3Y
\
\
\
'
V -T
/
^ v 4 Y
/ ' 5 / / p "-/
/ /
X / / 4
CHROMA
® /
-&L /
/
/
3
®ay / / z
\ \ \ f
w
%
Fig 26 ■ H/C chart of Vita Shade Guide (1972), analyzed by Sproull.7
VITA S H A D E S Fig 25 ■ V/C graph of Trubyte Bioform Shade Guide, 1979. Compare with Figure 24.
- - HUE 1Y
2Y
3Y
10 YR 5Y
VITA SHADES
;.........
4Y
80
• *
'
> ,4
LA
...... ...; ____ _
I
■
.Ä Ä I
5 „
m
I7]
CHROMA
7.5
4
7.0 VALUE 6.5
60
5.5
CHROMA
Fig 27 ■ V/C chart of Vita Shade Guide (1973), analyzed by Sproull.7
Fig 28 ■ H/C chart of Vita Shade Guide (1979). Compare with Figure 26.
trophotom etry (Fig 12, 13). (Data supplied by H em m endinger Color L aboratory with perm ission o f J. M. N ey Co.) T o c o m p a re d a ta fro m th e s e th re e studies, color tracings w ere placed to show data coverage (Fig 14-19). These colored tracings then w ere overlaid on each other to show how the three sets of d ata com pare (Fig 20, 21).
Commercial shade guide data The traditional method o f color com m uni cation in d en tistry is the m anufactured shade guide. All three dim ensions o f H V/C
are represented by a single letter, num ber, or com bination. T he organizations, ori gins, and rationales for the m yriad o f avail able shade guides are obscure. M ost guides w ere apparently designed years ago when com plete dentures and color m atching to natural teeth was a low priority. D entists are usually advised to send the particular shade guide tab selected to the laboratory as shade guides are not expected to be reli able, and laboratory technicians develop th eir ow n te ch n iq u es to mimic the tab supplied. In 1973, Sproull7 m easured th ree popular sh a d e g u id e s a n d fo u n d th e y la c k e d
Miller: ORGANIZING COLOR IN DENTISTRY ■ 33-E
E S T H E T I C
D E N T I S T R Y
IV O C L A R M u ris e li N o ta tio n s
H
v/c
S H A D E G U ID E
(M u ris e li N o ta tio n s ) 1984
VITA L U M IN S H A D E GUIDE
Williams Gold U.S.A.
0 6 PLOTS
b ___ © Í
.
©
8 .0 /
KtL
%
7,5/ © ©
• A 3.5
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VALUE
6.5/ :
6 .0 /
t
5.5/ ■
/2
/3
/4
/5
ÎT 30! Fig 30 ■ H/C chart of Ivoclar Shade Guide, 1984.
ft Fig 29 ■ V/C chart of Vita Shade Guide (1979). Compare with Figure 27.
IV O C L A R
S H A D E G U ID E
1984 W illia m s G old USA
M u n s e !/ N o ta tio n s
n
é
i 5'f
6C
-
7 .5 / ^
I A *
2C
7 .0 /
$
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S
. 0
®
6 .5 /
I
6.0 /
▼
5 .5 /
/I 21 Shades
/2
/3
/4
!
VALUE
/5
C H R O M A --------
Fig 31 ■ V/C chart of Ivoclar Shade Guide, 1984.
34-E ■ JADA (Special Issue) December 1987
Fig 32 ■ H/C chart of Crystar Shade Guide, 1982.
adequate distribution and logical arrange ment. My analysis in 1979 (Fig 22-29) for two o f the same shade guides indicates serious alteratio n s have o ccurred since Sproull’s research (Fig 22-29). O ther system s do not show great im provem ent over the stated problem s (Fig 30-36). C om bining all the shade guides tested does not com e close to covering the color space o f natural teeth. If all three dim ensions o f a given tooth m atch the H V/C o f a particular shade tab , a near perfect m atch can occur. Clinical ob servation show s this achievem ent is rare. R ather, currently available shade guides have been designed to em brace only the
average population cen ter and is an in adequate system . As Sproull reported, log ical arrangem ent and adequate distribution are lacking. M oreover, predictable altera tion in any direction o f H V/C is not avail able.
Fused porcelain samples Because o f the m any problem s posed by the traditional m ultilayered com m ercial shade guide, ceram ists often devise custom shade tabs to verify color control. There are three key difficulties to these. First, the ceram ist is required to make a thin piece o f porcelain (0.8 to 1.5 mm) to
E S T H E T I C
D E N T I S T R Y
BIODENT SHADE GUIDE (Munsell Notations) MARCH 1984
CHROMA
19 SHADES
Fig 34 ■ H/C chart of Biodent Shade Guide, 1984.
Fig 33 ■ V/C chart of Crystar Shade Guide, 1982.
BIODENT SHADE GUIDE MARCH 1984
Munsell N otations
8.0 /
•«
1 •
7 .5 /
7|K
70/
VALUE
•
•
6 .5 /
6 ,0 /
5 .5 /
/! 19
/2
/3
/4
/5
■*------------- CHROMA------------*■ SHADES
Fig 35 ■ V/C chart of Biodent Shade Guide, 1984.
□B
match a shade guide several millimeters thick. Second, batch variations of the pow dered porcelain produce fused porcelain colors that do not m atch the shade guide c o n s iste n tly . T h ird , ex c e p t by artistic judgm ent, it is difficult to predict the final co lo r o f the ty p ical lay ered v e n e e r o f opaque, m odifier, dentin, and enamel. To correct some of these problem s, sam ple tabs o f m ost porcelain system s were formed and exam ined by spectrophotom e ter. Data were translated into M unsell’s notations o f H V/C (Fig 36). Only parts of tw o system s are provided. Many others have been exam ined. Initially the Jelenko Shade Mold was used to form the rectangu lar tabs (approxim ately 4 x 8 mm). With in tr o d u c tio n o f a la y e r e d s h a d e ta b form er,9 an accurate thickness of porcelain c o u ld be m a d e a n d a tr u e p o r c e la in sandw ich, with layers o f controlled thick ness, could be produced in one firing (Fig 37-40). The three difficulties m entioned previously could then be solved. All sam ples w ere m easured with a spec trophotom eter, using an illumination slit of 2 x 6 mm. The background w as a light gray m astic w ith a reflectance of about 65% (M unsell value of about 8.35). Illumination cam e from daylight source C (H. Hemm e n d in g e r, p e rso n a l co m m u n ic atio n ). C om paring d ata from shade guides and fused porcelain sam ples with the limited inform ation on natural teeth indicates sev eral problem s. First, the co lo rsp ace o f shade guides and porcelain is severely deficient in orange (YR) (Fig 41). A lso, clinical experience at
tests to the futility o f trying to m atch H V/C of the tooth with a one-dim ensional shade guide. It is difficult enough if the teeth and m aterials were opaque, but translucency com plicates the p rocedures trem endously, which is particularly difficult in the dim en sion o f value (brightness). Finally, the term inology used by the shade guides could be greatly im proved in accuracy and proper nom enclature. The system should follow natural phenom ena (ra in b o w ), s c ie n tif ic te rm in o lo g y (w av elen g th ), a rtis tic (tra d itio n al) la n guage, and subject nom enclature (Munsell’s notations). A nalyzing the ch arts indi cates how to solve some of the obstacles (Fig 42-45).
Altering hue T he limited studies on natural teeth seem to in d icate su fficie n t yellow in p o rcelain w ithout any further additions. M odifica tion o f hue to the Y R side is feasible.
Improving orange (YR) deficiency In Figure 41, the large gray area to the left o f the shade num bers indicates the need for hue m odification o f the shade guide to m atch the many teeth in that color space. A logical approach is to add an orange m od ifier (dentin) to shift the hue tow ard the YR for the A group. F o r the V ita system , a reasonably pure orange (neither red nor yellow) is obtained by mixing tw o parts of no. 568 (rose) to one part no. 566 (yellow). N o. 568 rose H V/C = 8.5 R 6.6/S.4. N o.
Miller: ORGANIZING COLOR IN DENTISTRY ■ 35-E
E S T H E T I C
D E N T I S T R Y
CERAMCO II OC T. 1986 •
OPAQUE M O D IF IE R S ¡61 BODY M O D IF IE R S 161 IN C IS A L 191
/4 CHROMA
Fig 36 ■ H/C chart of Ceramco II body shades, 1986.
H/C chart for Ceramco II modifier and incisal shades, 1986.
Value comparison of Ceramco II opaque/body. A value difference of 0.2 to 0.3 is easily recognized by most viewers. The higher readings for the translucent body may be related to the background value of 8.3.
H/C chart of Vita sample tabs of dentin and enamel, 1979.
CERAMCO II OCT. 1988
CERAMCO II
INCISAL 19! O BODY MODIFIERS I8l • OPAQUE MODIFIERS iei
OCT, 1986
M u n s e tl N o ta tio n s VITA
V M K -6 S
H v/ c
S A M P L E TABS
BODY/DENTIN ¡16)
20 PL0TS D E N TIN E ( ENAM EL •
0 w "" %
8.0 7.5
$ .A3.5-.2 Fe *
©
7,5
ft
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8.0
© ©
7.0
© ©
7.0 VALUE
•
8 .0 /
m ® 7.5/
•
m •
SB
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7.0/ VALUE
6.5
VALUE
6 .5/
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6.5
,,
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60
»
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6 .0 /
5 .5 / / 2 /I
/ 2
— -----------------
/3 CHROMA
i4
/' 3 CHROMA
/ 4
/ 5
%
----------- ----- ►
_____ _______ __-..— _____ _______ V/C chart of Ceramco II body shades, 1986.
36-E ■ JADA (Special Issue) December 1987
V/C chart of Ceramco II modifier and incisal shades, 1986.
V/C chart of Vita sample tabs, 1979.
E S T H E T I C
D E N T I S T R Y
Fig 37 ■ The precision shade tab former is assembled in two pieces. The center piston is screwed up and down inside the housing. A micrometer type gauge on the outside permits precise positioning to .1 mm.
Fig 38 ■ A precise layer of opaque and dentin is con densed and the piston is backed off for each layer. The piston surface has greater adhesion than the side walls, permitting lowering of condensed porcelain for the next layer.
Fig 39 ■ Organic dyes distinguish the three condensed layers of enamel (blue), dentin (pink), and opaque (yel low) ready for firing.
Miller: ORGANIZING COLOR IN DENTISTRY ■ 37-E
E S T H E T I C
D E N T I S T R Y
Fig 40 ■ The fused three-layer custom tab of porcelain showing the enamel, dentin, and opaque. Each layer can be made to a precise thickness.
566 yellow H V/C = 6.8 YR 6.3/8.S. A m ixture 2 parts 568 rose and 1 part 566 yellow = 4.4 YR 6.3/5.6 (Fig 44, 45). Increm ental additions o f this modifier m ixture to the A and D shades of dentin 1/30, 1/20, 1/10, 1/5, produces the predict able hue shifts seen in Figure 43. F abricat ing custom shade tabs with a precision shade tab form er simplifies the selection of the co rrect ratio for orange m odification. An interesting and useful secondary fea ture o f the foregoing m ixtures is that the values a re below th a t o f th e “ p r e tty ” high-value porcelain veneers, a problem com m on in m etal ceram ics. V alues are 38-E ■ JADA (Special Issue) December 1987
low ered w ithout graying o u t the porcelain (Fig 44-46).
Altering value T he addition o f black o r low -value gray to pigm ents of lower brightness is com m on to many color industries. V alue changes in ceram ics are far m ore sensitive to deal with than either hue or chrom a. O bservable dif ferences easily o ccur for the m etal-ceram ic restoration according to: type of metal; thickness and value o f the opaque; am ount and value o f the m o d ifiers; th ic k n e ss, value, and translucency of the dentin and
Fig 42 ■ V/C chart of the author’s overlays of natural teeth (gray is a composite of Figure 24). Compare with the Vita shade guide and their overlays of the four groups.
E S T H E T I C
D E N T I S T R Y
CHANGING HUE VITA V M K - 6 8 P O R C E L A I N
M u tis e li N o ta tio n s
H v/c
VITA V M K - S 3 P O R C E L A IN S A M P L E TABS
Oixaque .Modifiers {4)0
HUE
> n tin e M odifiers { 1 0 5 #
R
Fig 43 ■ Incremental addition of orange modifier, 4.4 YR 6.3/5.6, produces predictable shifting of A l, A2, A3, D3, and D3 toward YR. The brown overlay of natural teeth is from Figure 16.
M a n s e // N o ta tio n s V/TA
V M K - 6 8 P O R C E L A IN
O p o q u e M o d ifie rs (4 3
H
v/ c
Fig 44 ■ H/C location of Vita opaque and dentin modifiers. The white circled green dot represents the special orange modifier used in Figure 43.
S A M P L E TABS
•
D en tin e M o d ifie rs (*0) • S p e c ia l M o d ifie rs (O R ) i / 2
5 6 6 /5 6 8
% 9.5
H U E -V A L U E M O D IF IC A T IO N S
9.0 8.5
8.0 7.5
YELLO W
HUE
ORANGE
7 0 6.5 VALUE 5.5 5.0
ORANGE MODIFIER ADDITIONS (D E N T IN )
4.5 4 .0 3.5 3.0
GREY
2.5 4 -
5 6 7 CHROMA —
MODIFIER
ENAM ELS
ADDITIONS (D E N T IN )
Fig 45 ■ V/C location of Vita opaque and dentin modifiers. The white circled green dot represents the special orange modifier. Most of the modifiers are lower in value than the brown color space of natural teeth (Fig 17).
en am el; am o u n t and v alu e o f su rfa c e stains; and firing tem perature and num ber of firings (thermal history), that is, alm ost any stage of the m etal-ceram ic construc tion.
Raising value W hite o r high-value gray pigm ents can be used to raise the value but with a reduction
Fig 46 ■ Hue/value modifications. Adding orange shifts hue and lowers value. Gray dentin modifier (Fig 47) and elective use of enamels (Fig 36, lower right, ) may be used to decrease value.
in translu cen cy — som etim es a desirable feature o f the incisal portion o f some natu ral teeth.
Lowering value M ost often the m etal-ceram ic restoration appears too bright and high in value. Com mon causes o f this problem are the use of opacifiers in the dentin to control translu
cency and the in d u stry 's use of opaques higher in value than dentin. One approach to reducing the value is to add gray dentin m odifier (Fig 47). U nfortu n a te ly , th e se p ro c e d u re s g ray o u t th e p o rc e la in an d p ro d u c e an u n d e sira b le esthetic feature for m ost patients. M od ifiers and low value opaques are often used to low er brightness (value) (Fig 45). Surface colorants (stains) are a useful
Miller: ORGANIZING COLOR IN DENTISTRY ■ 39-E
E S T H E T I C
M u n s e ll N o ta tio n s
WW
H v/ c
D E N T I S T R Y
C H R O M -L
VITA
STAIN S
C H R O M -L
S T A IN S 9 .5
CHANGING VALUE VITA VMK 6 8 PORCELAIN MODE - A DO! TION INCREMEN TS GRAY BODY MODIFIER
9 .0
SHADES
8.5
8.0 7 .5 7 .0 6 .5 VALU VALUE
5.5
6,5/
5.0
6. 0/
4.0
4.5
3.5
5,5/
3 .0 2 .5 /I
/2
/3
/«
I
/5
................ CHROMA------------ --
Fig 47 ■ Incremental additions of gray dentin modifier no. Fig 48 ■ H/C location of Vita Chrom L Stains. 570 (Vita) to dentin. The powders are mixed before firing. Compare with the brown natural teeth overlay in Figure 17.
w ay to fine-tune H V/C (Fig 48, 49). H ow ever, they are sem iopaque filter system s, and excessive use reduces optical quality o f th e translucent layers beneath.
Altering chroma This dim ension of color is probably the easiest to m anipulate in porcelain. Increas ing chrom a is achieved by addition of the dom inant hue. If modifiers designated with accurate hues and values w ere available, then simple increm ental addition could be used. Surface stains are often used to en h a n c e c h r o m a . R e d u c in g c h r o m a is achieved by diluting the colorants—usually w ith enam el or translucent porcelain. M ix ing com plem entary colors also reduces chrom a, but precise alterations should not be expected. A ddition o f blue and violet surface stains as com plem entary colors to yellow and yellow-red fused dentin porce lain may appear to reduce value. H ow ever, this is m ore logically related to the effect of filtration. Blue and violet surface stains are
40-E ■ JADA (Special Issue) December 1987
2
3
4
5
6
7
8
9
10 II
12
-------------- C H R O M A ----------- -
low in value and filter out the brightness of the porcelain beneath (Fig 49).
Conclusions The organization of color for dental pur poses can be greatly im proved. N o logical or practical system is used to com m unicate color in three dim ensions. T he fourth di m ension o f o p acity/translucency should also be addressed by industry. T he infor m a tio n d isp la y e d h ere re in fo rc e s th e guidelines available from the ADA Council on D ental M aterials, In stru m en ts, and E quipm ent. Q uality control by the m anufacturers, further research on the color space of natu ral teeth, and a color order system based on M unsell’s notations will greatly enhance ou r ability to provide superior restorations to patients. T h e a u th o r th anks Jane and R obert U llrich, Arri B racco n ier, an d E llen T ucker for graphics and photog rap h y ; D r. H en ry H em m endingerforspectrophotom et-
Fig 49 ■ V/C location of Vita Chrom L Stains (Fig 48). Compare with the location of natural teeth from Figure 17.
ric m e a su re m e n ts; G nathos D ental L a b o ra to ry for porcelain sam ples; and teachers R obert Sproull, S teve B ergen, Jack P reston, and R obert Berger. Dr. M iller is clinical professor, graduate and post g raduate prosthodontics, Tufts U niversity School of D ental M edicine. A ddress requests for reprints to the au th o r, 65 C olpitts Rd, W eston, MA 02193. 1. M unsell, A .H . A color notation. B altim ore, M un sell C olor C o, 1981. 2. C lark, E .B . An analysis o f tooth color. JA D A 18(11):2093-2103, 1931. 3. S proull, R .C . C olor m atching in dentistry. The three-dim ensional n atu re o f color. J P ro sth e t D ent 29(4):416-424, 1973. 4 . C la r k e , F . C o lo u r a n d f lu o r e s c e n c e m e a surem ents on hum an teeth and dental porcelain. B ritish C eram ic R esearch A ssociation, 1974. 5. C la rk , E .B . T o o th c o lo r s e le c tio n . JA D A 20(6): 1065-1073, 1933. 6. H ayashi, T. M edical color standard tooth crow n. T okyo, Japan R esearch Institute, 1967. 7. Sproull, R .C . C olor m atching in dentistry. P racti cal applications o f the organization of color. J Prosthet Dent 29(5):556-566, 1973. 8. L em ire, P .A ., and Bir, B. C olor in dentistry. H artfo rd , C T, J. M. N ey C o, 1975. 9. M iller, Lloyd L. Precision shade-tab form er, p a te n t no . 4,617,159.
D E N T I S T R Y
Organizing color in dentistry
Lloyd M iller, DMD
Although esthetic dentistry techniques have grown more sophisticated, the fabrication and control of color in dentistry can be improved. An organized and precise system is necessary to combine artistic and scientific approaches. For this, a color order system, based on Munsell’s notations and spectrophotometric re search on the color space of natural teeth, would provide restorations of excellent color. he visual im pact o f tooth colors, both artificial and natural, exerts an ex traordinary influence on dentists, patients, and laboratory technicians. As the ability to m ake artificial restorations to m atch p a tient needs im proves, there is undeniable pressu re to achieve even higher levels of perfection. Although oral health needs and treatm en ts are largely determ ined by the dentist, elective esthetic im provem ents are b est suggested by the patient. The person paying for the restoration com m ands the ac ce p ta n ce or rejection o f resto ratio n s. This aspect puts m ore pressure on m anu factu rers, dentists, and laboratory techni cians to keep im proving visible resto ra tions. In esthetic dentistry, the patient has clout. Significant im provem ents have occurred in esthetic dentistry, but the control, fabri cation, and com m unication o f color in den tistry rem ains disorganized and archaic. C urrent com m unication typically is based on the traditional one-dim ensional shade guide sy stem , w hich w as developed to m ake attractive teeth for com plete den tu res. W ith this system there is little regard for m atching specific natural teeth closely. Scientific colorim etry is not used and o r
T
26-E ■ JADA (Special Issue) December 1987
ganization is extraordinarily meager. A lthough the human eye is the final arbi trator, success in color construction and com m unication is best achieved by com b in in g tr a d itio n a l a r tis tic te c h n iq u e s (largely subjective) with the science o f col orim etry. The A m erican D ental A ssocia tion has addressed this problem , and the Council on D ental M aterials, Instrum ents, and Equipm ent has established guidelines on su b m issio n o f d e n ta l sh a d e g u id es (copies are available from the council).
Communication The habitual use of a particular shade guide generates a certain visual picture in the m ind’s eye. To some extent, this fam iliarity produces some skill in selecting and com m unicating color; currently, it is far too narrow a system . A m ore useful com m uni cation system uses two approaches. F irst, the system relates to know n and easily recognized natural phenom ena. A rainbow is produced when the su n ’s rays are absorbed, reflected, and dispersed by falling rain or mist. W hen Isaac N ew ton in 1666 passed daylight through a prism , he produced a band of consecutive colors that w hen fused together produce daylight (Fig 1). T hese colors vary from the long red w aves of about 760 nm to the violet w aves o f 380 nm. The science of colorim etry m ea sures these pure hues and designates pre cise w avelengths that are constant and ir refutable. This is the foundation and stan dard for all color and m ust be incorporated in color organization in dentistry. S econd, the system uses specific tech nique and method for color m easurem ent. The o bservation, recording, and com m uni cation o f color may be divided into two
areas, artistic (traditional) and scientific. The artistic approach norm ally requires many years o f intense study and practice, even for the gifted. F u rth er, the naming of colors in the traditional m anner is not accu rate enough to be applied to m odern den tistry. R ather, a scientific, precise, and or ganized system is needed.
M unsell system o f color notation This system starts with the visible light spectrum o f red to violet and develops the n atu ral p h en o m en a into a visible co m m unication system for color (Fig 2-5). In 1905, M unsell1 described the entire question o f color and its three dim ensions in a logical m anner that organizes a clear and definite m ental concept of all color ex pression. In sim plistic term s they are: — Hue, the name o f the color; the quality by w hich one color family is identified from another, such as red from yellow. In scien tific term s, the identification is designated by specific w avelengths. — Value, the lightness o f a color; this quality identifies a light color from a dark one. Brightness is often used to describe this dim ension. It is incorrect to say it is the am ount o f gray in a color. H ow ever, value is m easured on a scale of black to w hite with gradations of grays. A black-andw hite photograph of colored o bjects is ach rom atic and all form s are show n in term s of value differences. — C hrom a, the strength of a color; the quality by w hich a w eak color from a strong one is defined. The intensity o r purity o f a color also designates chrom a. The notations are expressed as a simple th ree -d im en sio n al fo rm u la— hue v alu e/ chrom a, or H V/C— and always in that se-
E S T H E T I C
D E N T I S T R Y
Fig 1 ■ The passage o f a narro w beam o f daylight through a prism bends and refracts the light into a band of visible colors from red to violet. M acbeth, Division of K ollm organ C orp.
Fig 2 ■ Schematic of refracted daylight shows total visible color spectrum from the shortest violet wavelengths to the longest red wavelengths.
Fig 3 ■ In the M unsell System , the tw o ends of the visible spectrum are closed to form a circle (hue). An achrom atic vertical colum n represents value from black (1 to 10). Any degree of brightness o r reflectance can be represented by th is dimension. The th ird dimension o f chrom a is represented by the radius o f the circle— from the weakest in the center to the strongest a t th e periphery.W hen the M unsell Color Wheel is expanded to a solid, it encom passes the entire color spectrum in the three dimensions H V/C.
M UNSELL HUE VALUE/CHROM A CHART W hife
Fig 4 ■ The th re e dimensions of the M unsell System sepa
Fig 5 ■ E xternal view of the corrected M unsell C olor
rated . The hues o f visible light have been sep arated into ten
Solid shows different hues have varying m axim um
equal spaces. A hue of 5 represents a p u re hue for th a t color.
chrom as, which give it this shape (M unsell Color Co).
Each hue is divided into ten p arts (M unsell C olor Co).
Miller: ORGANIZING COLOR IN DENTISTRY ■ 27-E
E S T H E T I C
D E N T I S T R Y
STANDARD ILLU M IN A N T
GRATING
Fig 6 ■ Schematic for spectrophotometer. A known light source shines on an object (apple), and is transmit ted, absorbed, and reflected. The reflected light passes through a grating mechanism that divides the light and passes it on to a sensor that measures each color. This is then recorded.
FOR SPECTROPHOTOMETER
Fig 7 ■ Above, three-dimensional schematic of Munsell Color Solid indicates how the two charts are developed (fan and rectangle). Note that the fan has been expanded to spread the data. Right, cross section of a tooth indicates varying thicknesses of pulp, dentin, and enamel, which tends to produce scattering of data for spectrophotometric readings.
Fig 8 ■ Hue/chroma (H/C) graph of Hayashi6 data on 68 adult teeth. Bunching of data is result of the method of using graded samples of colored paper. The patients were selected as the most representative of normal tooth color.
28-E ■ JADA (Special Issue) December 1987
E S T H E T I C
NATURAL
TEETH
D E N T I S T R Y
t. h a y a s h i
8 .0 /
7 .5 /
7 .0 / VALUE 6 .5 /
6 .0 /
5 .5 /
/I
/2
•*— —
/3
/4
CHROMA —
/5 — ►
Fig 10 ■ H/C chart of data by Sproull7 using 37 extracted teeth. Notice the strong distribution into YR.
Fig 9 ■ Value/chroma (V/C) graph of teeth in Figure 8. Color values of teeth from Japanese adults are lower in value in this limited study than in other recorded research.
quence. A typical claret red could be desig nated: R5 3/4: hue = red 5, value = 3, chrom a = 4. T hus, all colors can be located precisely and rationally.1-4 O ther exam ples are show n in Table 1. Table 1 ■ Color formulas. Traditional name
Ivory Tan Orange
Hue lY—5Y 3YR—10YR 10R -6Y R
Munsell notation
Value 7 / — 9/ 4 .5 / — 6 .5 / 5 .5 / — 7 /
Chroma /1-/4 / 1 - / 4 .5
/ 10 — /
14
The large spread for traditional nam es o f colors prohibits their use for unam biguous color identification. M unsell’s notations o f H V/C apply num bers in a system atic fash ion to the subjective analysis o f color. Such a system bridges the gap betw een the tradi tional artistic color nam es and scientific m ethod, the spectrophotom eter.
Spectrophotometer T his d ev ice m easu res and reco rd s the am ount o f radiant energy for each hue in the entire visible spectrum (Fig 6). The quality o f lightness/darkness for each hue
also is m easured. The data can be trans lated into M unsell’s notations by com pu ter. Teeth and dental porcelain are inter fused by a fourth dim ension o f translucency. This com plicates tooth and porce lain m easurem ent because three system s of color mixing are present: additive, subtrac tive, and optical. T he analysis of opaque colorants is far more reliable because of the lack of translucency. Although the spectrophotom eter is cur ren tly to o com p lex and ex p e n siv e for routine use in the dental office or labora to ry , it has trem endous potential for use in population sam ples, m anufacture o f porce lain, and developm ent o f shade guides.
Population samples We need to know hue, value, and chrom a for large numbers of teeth both in vitro and in situ. With a large data base, porcelain can be designed to fill the color space of natural teeth in a reasonable m anner. H o w ev er, sp e c tro p h o to m e tric m ea surem ent of natural teeth is difficult and significant in situ data are not yet available. C urrently, the main disadvantage to this system is that teeth m ust be extracted and placed w ithin the m achine. M o reo v er, color and translucency changes o ccur if teeth are not m easured soon after extrac
tio n . It is assu m ed th a t in v itro m e a surem ents lack the red filtration o f pulp cham ber and gingival tissue but this has not yet been quantified. T he sp ectrophotom eter is so sensitive that the highly reflective and translucent to o th p ro d u c e s c h a n g in g d a ta a s th e m easuring point m oves from one area to another (Fig 7). A special spectro p h o to m e ter is being developed w ith a fiber-optic w and and integrating tip to m easure small averages in situ. If successful, th is may be the breakthrough needed to provide a large data base o f natural teeth in situ.
Manufactured porcelain In general, m anufacturers are not accu s tom ed to w arrant that: — Porcelain pow ders are the sam e from batch to batch (invalid color tolerances not based on specific standards o f deviation). — P o rc e la in p o w d e rs, w h en fu se d , m atch the shade guides. — Specific shades can be routinely pro duced following m a n u factu rers’ in stru c tions. — Porcelain pow ders and shade guide sam ples are the sam e m aterial. — S tan d a rd s o f tran slu ce n cy /o p a city have been developed and follow ed. — A lterations in hue, value, and chrom a
Miller: ORGANIZING COLOR IN DENTISTRY ■ 29-E
E S T H E T I C
NATURAL
D E N T I S T R Y
TEETH 8.5
Fig 12 ■ H/C chart of d a ta on 231 n a tu ra l teeth studied by J. M. Ney Co (86 patients).8 7. 0 VALUE 6. 5
N ATU R AL TE E TH (M u n s e ll N o ta tio n s ) 6 0 ADULT
TEETH
(J a p a n e s e )
1
2
3
4
------------------- C ROMA
Fig 14 ■ H/C chart of H ayashi stu d y 6 with blue tracing to demon strate data layout.
R . Sprouli
Fig 11 ■ V/C chart of Sprouli7 data on natural teeth.
NATURAL
TEETH
M u n s e ll N o ta tio n s
J.M. NEY 1974
8 .0 /
-
’ T*
;;L £ y •
7 .5 /
. 7 .0 /
i- -m: ...
.
can be predictably accom plished. It seems most of the foregoing problem s could be improved or corrected if a spec trophotom eter was used to define H V /C for fused porcelain and a standard of devia tion was adopted by industry.
NATURAL
TEETH
T. HAYASHI
VALUE 6 .5 /
Shade guides
.1* 6 .0 /
5 .5 /
■-nv- %
■j ; /I
/2
/3
/4
-«---------- - CHROMA------231 Plots, 86 Pts.
Fig 13 ■ V/C chart of Ney8 data.
30-E ■ JADA (Special Issue) December 1987
Q u ality c o n tro l by s p e c tro p h o to m e try could be used to establish that: — shade guides fall within the color space o f natural teeth and m eet those needs with reasonable distribution: — like shades be the same in all three d im e n sio n s, from o n e sh a d e g u id e to another; — shade guides be organized according to a logical system using M unsell’s nota tions o r a sim ilar system ; and — any shade guide system perm it logi cal m ovem ent in hue, value/chrom a within the color space o f natural teeth. S p e c tro p h o to m e tric m e a su re m e n t o f translucent dental porcelain poses som e of the same problem s as tooth analysis, viz, background influence and the interplay of light betw een the various layers. Standards should be developed. The com plete color sp ace o f natural teeth in term s of H V /C has not been deter-
Fig 15 ■ V/C chart for Hayashi study6 with author’s blue tracing to illustrate data coverage.
E S T H E T I C
D E N T I S T R Y
NATURAL TEETH
jL
HUE — IO Y R
,Y
NATURAL TEE TH
?Y
5 CHROM A 4
Fig 16 ■ H/C chart for Sprouli study7 with au thor’s brown tracing to illustrate data coverage.
3
1 r
; §
\
®5 bl¿5
3 ”
6.0
5.5
Fig 18 ■ H/C chart for Ney study with author’s green tracing to illus trate data coverage. Fig 17 ■ V/C chart for Sprouli study’ with author’s brown tracing to illustrate data coverage.
NATURAL
TEETH
— HUE — IOYR
5 CHROMA 4
Fig 20 ■ H/C overlay of the three studies (author’s interpretation).
Fig 19 ■ V/C chart for Ney study with author’s green trac ing to illustrate data coverage.
Miller: ORGANIZING COLOR IN DENTISTRY ■ 31-E
E S T H E T I C
D E N T I S T R Y
B IO F O R M
SHADES
— HUE —
NATURAL TEETH 8.5
7.0 VALUE 6.5
Fig 22 ■ H/C graph of Trubyte Bioform Shade Guide analyzed by Sprouli,7 1973. Fig 21 ■ V/C overlay of the three studies (author’s interpre tation).
BIOFORM SHADES
M unsell N o ta tio n s
( H v/ c )
T R U B Y T E B IO F O R M S H A D E G U ID E
8.0
(2 4 PLOTS)
7.5
7.0 VALUE 6.5
6.0
5.5
CHROMA
R. S proaii
Fig 23 ■ H/C graph of Trubyte Bioform Shade Guide, 1979. Compare with Figure 22.
Fig 24 ■ V/C graph of Trubyte Bioform Shade Guide, 1979. Compare with Figure 23.
mined. T he prim ary reason for this void is th a t cu rren t sp ectrophotom eter system s require that ex tracted teeth be used. A short review o f the data available is pro vided.
trophotom eter to m easure the color space o f 37 extracted teeth (Fig 10,11). The visual im pact of tooth colors in three dim ensions o f hue, value, and chrom a stirred a great deal o f interest. The sp ectro p h o to m eter becam e the preferred instrum ent for exam ining and recording tooth and porcelain colors. In 1974, the J. M. N ey C o8 studied natu ral teeth. A to talo f2 3 1 teeth extracted from 86 p a tie n ts w e re e x a m in e d b y sp e c -
Natural tooth color space In 1931, C lark2-5 published in vivo data on the problem s o f color and the matching of tooth colors w ith artificial m aterials. H e 32-E ■ JADA (Special Issue) December 1987
observed and recorded H V/C for 6,000 natural teeth from 1,000 patients, and pro duced a custom shade guide. In 1966, in Japan, H ayashi6 investigated 81 teeth in vivo, 68 from adults and 13 from c h ild re n (p rim ary sam p le s). C a re fu lly graded sam ples o f opaque paper in three dim ensions w ere used to m easure H V/C by visual com parison (Fig 8, 9). Such com parison is difficult. In 1 9 7 3 , S p r o u l i 7 u s e d a s p e c
E S T H E T I C
D E N T I S T R Y
VITA S H A D E S — HUE1Y ÎO Y R ^ —- T
9Y3 ^ 8YFv ^
2Y
3Y
\
\
\
'
V -T
/
^ v 4 Y
/ ' 5 / / p "-/
/ /
X / / 4
CHROMA
® /
-&L /
/
/
3
®ay / / z
\ \ \ f
w
%
Fig 26 ■ H/C chart of Vita Shade Guide (1972), analyzed by Sproull.7
VITA S H A D E S Fig 25 ■ V/C graph of Trubyte Bioform Shade Guide, 1979. Compare with Figure 24.
- - HUE 1Y
2Y
3Y
10 YR 5Y
VITA SHADES
;.........
4Y
80
• *
'
> ,4
LA
...... ...; ____ _
I
■
.Ä Ä I
5 „
m
I7]
CHROMA
7.5
4
7.0 VALUE 6.5
60
5.5
CHROMA
Fig 27 ■ V/C chart of Vita Shade Guide (1973), analyzed by Sproull.7
Fig 28 ■ H/C chart of Vita Shade Guide (1979). Compare with Figure 26.
trophotom etry (Fig 12, 13). (Data supplied by H em m endinger Color L aboratory with perm ission o f J. M. N ey Co.) T o c o m p a re d a ta fro m th e s e th re e studies, color tracings w ere placed to show data coverage (Fig 14-19). These colored tracings then w ere overlaid on each other to show how the three sets of d ata com pare (Fig 20, 21).
Commercial shade guide data The traditional method o f color com m uni cation in d en tistry is the m anufactured shade guide. All three dim ensions o f H V/C
are represented by a single letter, num ber, or com bination. T he organizations, ori gins, and rationales for the m yriad o f avail able shade guides are obscure. M ost guides w ere apparently designed years ago when com plete dentures and color m atching to natural teeth was a low priority. D entists are usually advised to send the particular shade guide tab selected to the laboratory as shade guides are not expected to be reli able, and laboratory technicians develop th eir ow n te ch n iq u es to mimic the tab supplied. In 1973, Sproull7 m easured th ree popular sh a d e g u id e s a n d fo u n d th e y la c k e d
Miller: ORGANIZING COLOR IN DENTISTRY ■ 33-E
E S T H E T I C
D E N T I S T R Y
IV O C L A R M u ris e li N o ta tio n s
H
v/c
S H A D E G U ID E
(M u ris e li N o ta tio n s ) 1984
VITA L U M IN S H A D E GUIDE
Williams Gold U.S.A.
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ÎT 30! Fig 30 ■ H/C chart of Ivoclar Shade Guide, 1984.
ft Fig 29 ■ V/C chart of Vita Shade Guide (1979). Compare with Figure 27.
IV O C L A R
S H A D E G U ID E
1984 W illia m s G old USA
M u n s e !/ N o ta tio n s
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C H R O M A --------
Fig 31 ■ V/C chart of Ivoclar Shade Guide, 1984.
34-E ■ JADA (Special Issue) December 1987
Fig 32 ■ H/C chart of Crystar Shade Guide, 1982.
adequate distribution and logical arrange ment. My analysis in 1979 (Fig 22-29) for two o f the same shade guides indicates serious alteratio n s have o ccurred since Sproull’s research (Fig 22-29). O ther system s do not show great im provem ent over the stated problem s (Fig 30-36). C om bining all the shade guides tested does not com e close to covering the color space o f natural teeth. If all three dim ensions o f a given tooth m atch the H V/C o f a particular shade tab , a near perfect m atch can occur. Clinical ob servation show s this achievem ent is rare. R ather, currently available shade guides have been designed to em brace only the
average population cen ter and is an in adequate system . As Sproull reported, log ical arrangem ent and adequate distribution are lacking. M oreover, predictable altera tion in any direction o f H V/C is not avail able.
Fused porcelain samples Because o f the m any problem s posed by the traditional m ultilayered com m ercial shade guide, ceram ists often devise custom shade tabs to verify color control. There are three key difficulties to these. First, the ceram ist is required to make a thin piece o f porcelain (0.8 to 1.5 mm) to
E S T H E T I C
D E N T I S T R Y
BIODENT SHADE GUIDE (Munsell Notations) MARCH 1984
CHROMA
19 SHADES
Fig 34 ■ H/C chart of Biodent Shade Guide, 1984.
Fig 33 ■ V/C chart of Crystar Shade Guide, 1982.
BIODENT SHADE GUIDE MARCH 1984
Munsell N otations
8.0 /
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1 •
7 .5 /
7|K
70/
VALUE
•
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6 .5 /
6 ,0 /
5 .5 /
/! 19
/2
/3
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/5
■*------------- CHROMA------------*■ SHADES
Fig 35 ■ V/C chart of Biodent Shade Guide, 1984.
□B
match a shade guide several millimeters thick. Second, batch variations of the pow dered porcelain produce fused porcelain colors that do not m atch the shade guide c o n s iste n tly . T h ird , ex c e p t by artistic judgm ent, it is difficult to predict the final co lo r o f the ty p ical lay ered v e n e e r o f opaque, m odifier, dentin, and enamel. To correct some of these problem s, sam ple tabs o f m ost porcelain system s were formed and exam ined by spectrophotom e ter. Data were translated into M unsell’s notations o f H V/C (Fig 36). Only parts of tw o system s are provided. Many others have been exam ined. Initially the Jelenko Shade Mold was used to form the rectangu lar tabs (approxim ately 4 x 8 mm). With in tr o d u c tio n o f a la y e r e d s h a d e ta b form er,9 an accurate thickness of porcelain c o u ld be m a d e a n d a tr u e p o r c e la in sandw ich, with layers o f controlled thick ness, could be produced in one firing (Fig 37-40). The three difficulties m entioned previously could then be solved. All sam ples w ere m easured with a spec trophotom eter, using an illumination slit of 2 x 6 mm. The background w as a light gray m astic w ith a reflectance of about 65% (M unsell value of about 8.35). Illumination cam e from daylight source C (H. Hemm e n d in g e r, p e rso n a l co m m u n ic atio n ). C om paring d ata from shade guides and fused porcelain sam ples with the limited inform ation on natural teeth indicates sev eral problem s. First, the co lo rsp ace o f shade guides and porcelain is severely deficient in orange (YR) (Fig 41). A lso, clinical experience at
tests to the futility o f trying to m atch H V/C of the tooth with a one-dim ensional shade guide. It is difficult enough if the teeth and m aterials were opaque, but translucency com plicates the p rocedures trem endously, which is particularly difficult in the dim en sion o f value (brightness). Finally, the term inology used by the shade guides could be greatly im proved in accuracy and proper nom enclature. The system should follow natural phenom ena (ra in b o w ), s c ie n tif ic te rm in o lo g y (w av elen g th ), a rtis tic (tra d itio n al) la n guage, and subject nom enclature (Munsell’s notations). A nalyzing the ch arts indi cates how to solve some of the obstacles (Fig 42-45).
Altering hue T he limited studies on natural teeth seem to in d icate su fficie n t yellow in p o rcelain w ithout any further additions. M odifica tion o f hue to the Y R side is feasible.
Improving orange (YR) deficiency In Figure 41, the large gray area to the left o f the shade num bers indicates the need for hue m odification o f the shade guide to m atch the many teeth in that color space. A logical approach is to add an orange m od ifier (dentin) to shift the hue tow ard the YR for the A group. F o r the V ita system , a reasonably pure orange (neither red nor yellow) is obtained by mixing tw o parts of no. 568 (rose) to one part no. 566 (yellow). N o. 568 rose H V/C = 8.5 R 6.6/S.4. N o.
Miller: ORGANIZING COLOR IN DENTISTRY ■ 35-E
E S T H E T I C
D E N T I S T R Y
CERAMCO II OC T. 1986 •
OPAQUE M O D IF IE R S ¡61 BODY M O D IF IE R S 161 IN C IS A L 191
/4 CHROMA
Fig 36 ■ H/C chart of Ceramco II body shades, 1986.
H/C chart for Ceramco II modifier and incisal shades, 1986.
Value comparison of Ceramco II opaque/body. A value difference of 0.2 to 0.3 is easily recognized by most viewers. The higher readings for the translucent body may be related to the background value of 8.3.
H/C chart of Vita sample tabs of dentin and enamel, 1979.
CERAMCO II OCT. 1988
CERAMCO II
INCISAL 19! O BODY MODIFIERS I8l • OPAQUE MODIFIERS iei
OCT, 1986
M u n s e tl N o ta tio n s VITA
V M K -6 S
H v/ c
S A M P L E TABS
BODY/DENTIN ¡16)
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_____ _______ __-..— _____ _______ V/C chart of Ceramco II body shades, 1986.
36-E ■ JADA (Special Issue) December 1987
V/C chart of Ceramco II modifier and incisal shades, 1986.
V/C chart of Vita sample tabs, 1979.
E S T H E T I C
D E N T I S T R Y
Fig 37 ■ The precision shade tab former is assembled in two pieces. The center piston is screwed up and down inside the housing. A micrometer type gauge on the outside permits precise positioning to .1 mm.
Fig 38 ■ A precise layer of opaque and dentin is con densed and the piston is backed off for each layer. The piston surface has greater adhesion than the side walls, permitting lowering of condensed porcelain for the next layer.
Fig 39 ■ Organic dyes distinguish the three condensed layers of enamel (blue), dentin (pink), and opaque (yel low) ready for firing.
Miller: ORGANIZING COLOR IN DENTISTRY ■ 37-E
E S T H E T I C
D E N T I S T R Y
Fig 40 ■ The fused three-layer custom tab of porcelain showing the enamel, dentin, and opaque. Each layer can be made to a precise thickness.
566 yellow H V/C = 6.8 YR 6.3/8.S. A m ixture 2 parts 568 rose and 1 part 566 yellow = 4.4 YR 6.3/5.6 (Fig 44, 45). Increm ental additions o f this modifier m ixture to the A and D shades of dentin 1/30, 1/20, 1/10, 1/5, produces the predict able hue shifts seen in Figure 43. F abricat ing custom shade tabs with a precision shade tab form er simplifies the selection of the co rrect ratio for orange m odification. An interesting and useful secondary fea ture o f the foregoing m ixtures is that the values a re below th a t o f th e “ p r e tty ” high-value porcelain veneers, a problem com m on in m etal ceram ics. V alues are 38-E ■ JADA (Special Issue) December 1987
low ered w ithout graying o u t the porcelain (Fig 44-46).
Altering value T he addition o f black o r low -value gray to pigm ents of lower brightness is com m on to many color industries. V alue changes in ceram ics are far m ore sensitive to deal with than either hue or chrom a. O bservable dif ferences easily o ccur for the m etal-ceram ic restoration according to: type of metal; thickness and value o f the opaque; am ount and value o f the m o d ifiers; th ic k n e ss, value, and translucency of the dentin and
Fig 42 ■ V/C chart of the author’s overlays of natural teeth (gray is a composite of Figure 24). Compare with the Vita shade guide and their overlays of the four groups.
E S T H E T I C
D E N T I S T R Y
CHANGING HUE VITA V M K - 6 8 P O R C E L A I N
M u tis e li N o ta tio n s
H v/c
VITA V M K - S 3 P O R C E L A IN S A M P L E TABS
Oixaque .Modifiers {4)0
HUE
> n tin e M odifiers { 1 0 5 #
R
Fig 43 ■ Incremental addition of orange modifier, 4.4 YR 6.3/5.6, produces predictable shifting of A l, A2, A3, D3, and D3 toward YR. The brown overlay of natural teeth is from Figure 16.
M a n s e // N o ta tio n s V/TA
V M K - 6 8 P O R C E L A IN
O p o q u e M o d ifie rs (4 3
H
v/ c
Fig 44 ■ H/C location of Vita opaque and dentin modifiers. The white circled green dot represents the special orange modifier used in Figure 43.
S A M P L E TABS
•
D en tin e M o d ifie rs (*0) • S p e c ia l M o d ifie rs (O R ) i / 2
5 6 6 /5 6 8
% 9.5
H U E -V A L U E M O D IF IC A T IO N S
9.0 8.5
8.0 7.5
YELLO W
HUE
ORANGE
7 0 6.5 VALUE 5.5 5.0
ORANGE MODIFIER ADDITIONS (D E N T IN )
4.5 4 .0 3.5 3.0
GREY
2.5 4 -
5 6 7 CHROMA —
MODIFIER
ENAM ELS
ADDITIONS (D E N T IN )
Fig 45 ■ V/C location of Vita opaque and dentin modifiers. The white circled green dot represents the special orange modifier. Most of the modifiers are lower in value than the brown color space of natural teeth (Fig 17).
en am el; am o u n t and v alu e o f su rfa c e stains; and firing tem perature and num ber of firings (thermal history), that is, alm ost any stage of the m etal-ceram ic construc tion.
Raising value W hite o r high-value gray pigm ents can be used to raise the value but with a reduction
Fig 46 ■ Hue/value modifications. Adding orange shifts hue and lowers value. Gray dentin modifier (Fig 47) and elective use of enamels (Fig 36, lower right, ) may be used to decrease value.
in translu cen cy — som etim es a desirable feature o f the incisal portion o f some natu ral teeth.
Lowering value M ost often the m etal-ceram ic restoration appears too bright and high in value. Com mon causes o f this problem are the use of opacifiers in the dentin to control translu
cency and the in d u stry 's use of opaques higher in value than dentin. One approach to reducing the value is to add gray dentin m odifier (Fig 47). U nfortu n a te ly , th e se p ro c e d u re s g ray o u t th e p o rc e la in an d p ro d u c e an u n d e sira b le esthetic feature for m ost patients. M od ifiers and low value opaques are often used to low er brightness (value) (Fig 45). Surface colorants (stains) are a useful
Miller: ORGANIZING COLOR IN DENTISTRY ■ 39-E
E S T H E T I C
M u n s e ll N o ta tio n s
WW
H v/ c
D E N T I S T R Y
C H R O M -L
VITA
STAIN S
C H R O M -L
S T A IN S 9 .5
CHANGING VALUE VITA VMK 6 8 PORCELAIN MODE - A DO! TION INCREMEN TS GRAY BODY MODIFIER
9 .0
SHADES
8.5
8.0 7 .5 7 .0 6 .5 VALU VALUE
5.5
6,5/
5.0
6. 0/
4.0
4.5
3.5
5,5/
3 .0 2 .5 /I
/2
/3
/«
I
/5
................ CHROMA------------ --
Fig 47 ■ Incremental additions of gray dentin modifier no. Fig 48 ■ H/C location of Vita Chrom L Stains. 570 (Vita) to dentin. The powders are mixed before firing. Compare with the brown natural teeth overlay in Figure 17.
w ay to fine-tune H V/C (Fig 48, 49). H ow ever, they are sem iopaque filter system s, and excessive use reduces optical quality o f th e translucent layers beneath.
Altering chroma This dim ension of color is probably the easiest to m anipulate in porcelain. Increas ing chrom a is achieved by addition of the dom inant hue. If modifiers designated with accurate hues and values w ere available, then simple increm ental addition could be used. Surface stains are often used to en h a n c e c h r o m a . R e d u c in g c h r o m a is achieved by diluting the colorants—usually w ith enam el or translucent porcelain. M ix ing com plem entary colors also reduces chrom a, but precise alterations should not be expected. A ddition o f blue and violet surface stains as com plem entary colors to yellow and yellow-red fused dentin porce lain may appear to reduce value. H ow ever, this is m ore logically related to the effect of filtration. Blue and violet surface stains are
40-E ■ JADA (Special Issue) December 1987
2
3
4
5
6
7
8
9
10 II
12
-------------- C H R O M A ----------- -
low in value and filter out the brightness of the porcelain beneath (Fig 49).
Conclusions The organization of color for dental pur poses can be greatly im proved. N o logical or practical system is used to com m unicate color in three dim ensions. T he fourth di m ension o f o p acity/translucency should also be addressed by industry. T he infor m a tio n d isp la y e d h ere re in fo rc e s th e guidelines available from the ADA Council on D ental M aterials, In stru m en ts, and E quipm ent. Q uality control by the m anufacturers, further research on the color space of natu ral teeth, and a color order system based on M unsell’s notations will greatly enhance ou r ability to provide superior restorations to patients. T h e a u th o r th anks Jane and R obert U llrich, Arri B racco n ier, an d E llen T ucker for graphics and photog rap h y ; D r. H en ry H em m endingerforspectrophotom et-
Fig 49 ■ V/C location of Vita Chrom L Stains (Fig 48). Compare with the location of natural teeth from Figure 17.
ric m e a su re m e n ts; G nathos D ental L a b o ra to ry for porcelain sam ples; and teachers R obert Sproull, S teve B ergen, Jack P reston, and R obert Berger. Dr. M iller is clinical professor, graduate and post g raduate prosthodontics, Tufts U niversity School of D ental M edicine. A ddress requests for reprints to the au th o r, 65 C olpitts Rd, W eston, MA 02193. 1. M unsell, A .H . A color notation. B altim ore, M un sell C olor C o, 1981. 2. C lark, E .B . An analysis o f tooth color. JA D A 18(11):2093-2103, 1931. 3. S proull, R .C . C olor m atching in dentistry. The three-dim ensional n atu re o f color. J P ro sth e t D ent 29(4):416-424, 1973. 4 . C la r k e , F . C o lo u r a n d f lu o r e s c e n c e m e a surem ents on hum an teeth and dental porcelain. B ritish C eram ic R esearch A ssociation, 1974. 5. C la rk , E .B . T o o th c o lo r s e le c tio n . JA D A 20(6): 1065-1073, 1933. 6. H ayashi, T. M edical color standard tooth crow n. T okyo, Japan R esearch Institute, 1967. 7. Sproull, R .C . C olor m atching in dentistry. P racti cal applications o f the organization of color. J Prosthet Dent 29(5):556-566, 1973. 8. L em ire, P .A ., and Bir, B. C olor in dentistry. H artfo rd , C T, J. M. N ey C o, 1975. 9. M iller, Lloyd L. Precision shade-tab form er, p a te n t no . 4,617,159.