25.tooth shade selection - seminar
TRANSCRIPT
-
8/13/2019 25.Tooth Shade Selection - Seminar
1/44
TOOTH SHADE SELECTION
CONTENTS
Introduction: Light and Color
Color has Quantity and Quality.
Color Atlases
Atlases based on Subtractive or Additive Color Mixture
Perceptually Unior!ly Spaced Color Atlases
Color Matching and Colori!etry
Measure!ent and Matching o "u!an #eeth
Color Matching o $ental Prosthetic Materials
Methods o Colori!etry
#he %le!ents o %sthetics&Application o Color Science
#he %le!ents o %sthetics
'ptical %le!ents
"ue
(alue
Chro!a )saturation*
Color 'rdering
Shade +uide Use
Surace #exture
Controlled %nviron!ent
Clinical Procedures
Color Modiications
'ther 'pti!al Properties
,hat lies Ahead-
Su!!ation o #echniue
/
-
8/13/2019 25.Tooth Shade Selection - Seminar
2/44
INTRODUCTION:
LIGHT AND COLOR
Light is an electro!agnetic radiation in the optical region that is
capable o sti!ulating the eye0 the range o 1avelengths being 234 n! to
564 n!. ,hen light sti!ulates the eye0 a pattern o physiological
perception is aroused. #he perceptions are related to the distribution o
light in the retinal i!age in ter!s o space0 ti!e0 and spectral po1er
distribution. #he light co!ing ro! an ob7ect !ust thereore be treated as
co!ing ro! a unior! ele!ent o area and as constant in respect ti!e.
"o1ever0 1hen tooth 1hich has an a181ard three&di!ensional shape0
1ith texture or !ar8ing and dierences in gloss or si9e0 it is diicult or
any hu!an observers & dentists are no exception & to !atch color. In such
a situation even photoelectric instru!ents !ay not be capable o giving a
valid color speciication.
COLOR HAS QUANTITY AND QUALITY.
#he co!!on units used in photo!etry are the lu!en or lu!inous
lux0 the lux )lu!en per s !* or lu!inance on a surace0 and the candela
-
8/13/2019 25.Tooth Shade Selection - Seminar
3/44
-
8/13/2019 25.Tooth Shade Selection - Seminar
4/44
to !a8e a syste!atic color solid has been !uch !ore popular than the
one described irst0 and or!s the basis o !ost types o color atlas.
COLOR ATLASES
A color atlas is a syste!atic arrange!ent o a large range o
colored sa!ples0 usually surace colors0 as described above0 but 1ith an
i!portant additional eature: the colors have been spaced out regularly
according to so!e stated criterion or reuire!ent. ;ecause o the three
di!ensional nature o color space0 all color atlases consist o a collection
o charts0 each to represent a t1o&di!ensional section through the color
space. #he particular color solid represented by the sa!ples in a color
=
-
8/13/2019 25.Tooth Shade Selection - Seminar
5/44
atlas is a color order syste!. It is i!portant to reali9e that the color
ga!ut that can be covered depends on the glossiness o the sa!ples: the
higher the gloss the !ore saturated or dar8 a sa!ple can be. >urther0 the
value o an atlas depends on the per!anence o its speci!ens.
In the criterion o color spacing bet1een sa!ples and the
unior!ity 1ith 1hich the sa!pling actually ollo1s0 spacing is
i!portant. #here are three basic 1ays o spacing the sa!ples in ter!s o
color dierence in a color atlas: i* by colorant !ixture variation0 ii* by
additive !ixture variations and iii* by sa!pling to obtain perceptual
unior!ity o color spacing.
ATLASES BASED ON SUBTRACTIVE OR ADDITIVE COLOR
MIXTURE
Colorant !ixture spaced atlases have been !ade to de!onstrate the
coloration produced by syste!atic ad!ixture o certain base colorants0
or exa!ple0 using subtractive color !ixture. #hese are o value to dyers
and users o pig!ents in paint0 plastics0 printing etc. #he ?u&"ue custo!
Color Syste! has /0444 !atte painted cards developed ro! a 1hite0 a
blac80 and six chro!atic single&pig!ent paints. #he Colori9er )/@=5* has
/02 !atte painted chips developed ro! a 1hite0 a gray0 a blac80 and
-
8/13/2019 25.Tooth Shade Selection - Seminar
6/44
t1elve chro!atic base paints. #he Plochere Color Syste! )/@=3* is
another exa!ple0 1ith /0=3 !atte painted cards.
#he Pantone Matching Syste! )/@620 revised /@5=* uses a 1hite0 a
blac80 and eight chro!atic base pig!ents to give 35 sa!ples printed in
both a glossy and a !atte series. #he color range is extended by 6
additional saturated colors or!ed by !a8ing use o an extra seven
saturated base pig!ents. #he syste! is 1idely used as an aid to
speciying and or!ulating printed colors.
#he ICI Color Atlas )/@6@* has /025@ opaue sa!ples !ade
1ithout using blac8. #he ICI Color Atlas thus gives the closest gradations
bet1een neighboring colors o any atlas0 and they are close enough or all
co!!ercial dyeing purposes. Additive color !ixture spaced atlases sho1
the seuences o colors that can be produced by additive color !ixture.
#he original conception in /@/5 1as that o 'st1ald )/@24*0 1ho devised
a color syste! 1ith a central gray scale and radial sections containing
colors o nearly the sa!e hue. #he original atlases o 'st1ald had so!e
deects and are not available or practical use0 but in !odern ti!es a
!uch better version called the Color "ar!ony Manual 1as produced.
6
-
8/13/2019 25.Tooth Shade Selection - Seminar
7/44
#here are t1o notable color atlases that are partly based on
subtractive color !ixture o colorants and partly on additive color
!ixture. #hese are based on screen plate printing color !ixture0 and are
o particular value to the printing industry.
PERCEPTUALLY UNIFORMLY SPACED COLOR ATLASES
#he inal class o color atlas is based on grading the color spacing
o the sa!ples to produce sub7ectively unior! spacing 1ith perceptually
eual dierences bet1een successive sa!ples in a seuence. Such
syste!s are i!portant in psychological0 aesthetic0 and design
applications. #he !ost a!ous color atlas and syste! o this type is the
Munsell. #his 1as originally produced as the Munsell ;oo8 Color using
a central vertical gray scale and =4 radial sections0 each 1ith colors o a
given hue. #he three perceptual attributes o light na!ely lightness0 hue0
and saturation are represented by scales o value0 hue and chro!a0
respectively.
5
-
8/13/2019 25.Tooth Shade Selection - Seminar
8/44
#here is another perceptually unior!ly spaced color atlas and
syste!0 the $I? 6/6= Color Syste! 1hich 1as produced originally as
tinted transparent gelatine ilters in arrays0 1ith surace color versions
beco!ing available later. In the $I? 6/6= Syste! there are three
variables: arbton )hue* #0 sattigung )saturation* S and dun8elstue
)dar8ness* $. As 1ith the Munsell syste!0 the hues o the $I? syste!
are perceptually unior!ly spaced round the co!plete ga!ut o hues. #he
$I? 6/6= colors have been speciied in ter!s o the Munsell and CI%
colori!etric syste!s.
A very recent color atlas0 the ?atural Color Syste!0 described by
"ard )/@54*0 uses perceptual 7udg!ent to subdivide color space in ter!s
o hue0 saturation0 and blac8ness0 1ith sa!ples o a given hue being
arranged in a triangular array 1ith lines o eual saturation and eual
blac8ness sa!ples. A !a7or deect is that the nu!ber o hue steps
bet1een the perceptually BpureB red0 yello10 green0 and blue hues 1as
orced to be eual )i!plying that these particular hues !ust be arranged
at @4to each other in the space*0 1ith the result the si9es o unit steps are
not eual in the our uadrants o the circle o hues.
3
-
8/13/2019 25.Tooth Shade Selection - Seminar
9/44
In dentistry0 the principle o color !atching and !easure!ent by
reerence to a suitable color atlas has !uch to co!!end it. "o1ever0 the
general&purpose color atlases described above0 are not able to !eet the
needs o dentists or color !atching and !easure!ent0 though they could
be applied to the aesthetic ield. )such has !atching gu! colors in
poly!er. * #he colors o teeth cover a very restricted region o color
space0 and a special&purpose color atlas containing perhaps 44 or 244
sa!ples 1ould enable neighboring sa!ples to be never !ore than three
7ust noticeable dierences apart and usually about t1o.
@
-
8/13/2019 25.Tooth Shade Selection - Seminar
10/44
COLOR MATCHING AND COLORIMETRY - COLOR MATCHING
PROPERTIES OF REAL OBSERVERS
#he three la1s o +rass!ann and that o Abney or! the basis o
colori!etry. #he !ost i!portant corollary o these la1s is: increasing or
decreasing the a!ounts o t1o lights o the sa!e color by the sa!e
actor0 8eeping the relative spectral co!positions o each unchanged0 1ill
not destroy the color !atch. #he above state!ents provide the basis o
the additive )additivity* concept in colori!etry0 1hich is o unda!ental
i!portance in allo1ing prediction o color !atches and color
speciications0 is per!itting data in ter!s o any triad o !atching sti!uli
to be transor!ed to values in ter!s o any other triad o !atching or
reerence sti!uli. #he la1s o colori!etry and photo!etry stated above
are valid over !ost o the operating range o the eye0 and under all
co!!on conditions. #he la1s apply to light entering the eye0 1hether it
/4
-
8/13/2019 25.Tooth Shade Selection - Seminar
11/44
is directly or! a pri!ary source )an illu!inant* or 1hether it co!es
indirectly ro! such a source via a secondary source )a surace color*.
#he concept o metamerism can be extended to hu!an observers
as 1ell. In this case it is ter!ed observer !eta!eris!0 and it arises
because o the variation in color !atching ound a!ong the nor!al
trichro!atic observers !a8ing up the bul8 o the population. 'bserver
!eta!eris! !eans that 1hat is a color !atch or one observer is not
exactly so or another. #hus i there is !eta!eric color !atch bet1een
t1o suraces o dierent spectral relectance proile0 then or the Standard
observer they 1ill !atch under a stated illu!inant. >or any other
illu!inant or 1ith that illu!inant or those real observers 1ho dier ro!
the Standard 'bserver0 there 1ill probably be so!e degree o !is!atch.
So!e !eta!eric !atched surace colors have spectral dierences such
that they happen to !atch under t1o or even three illu!inants but not
under other illu!inants.
MEASUREMENT AND MATCHING OF HUMAN TEETH
$entistry is an occupation 1here aesthetics is o considerable
i!portance0 especially 1hen patients are stage or public igures.
"o1ever it is interesting to note that color science has not so ar been
applied very successully in dental shade !atching to give uantitative
//
-
8/13/2019 25.Tooth Shade Selection - Seminar
12/44
ans1ers to the proble!s. #here are very good reasons or this0 1hich are
discussed belo1.
#he needs0 ho1ever0 are clear enough and !ay be stated as the
selection0 coloring0 and processing o the right dental prosthetic !aterials
so as to produce a convincing !atch in appearance to the natural teeth o
the patient. #his is a !uch harder proble! than those !et 1ith by the
color production industries0 such as textiles paints0 and plastics0 or
reasons0 1hich 1ill no1 be explained.
TEETH AS COLORIMETRIC SAMPLES
#he properties o sa!ples presented or !easure!ent 1ith
colori!eters and spectro&photo!eters that give rise to diiculties and
syste!atic errors have been !entioned in previous sections: luorescence0
!eta!eris!0 non&unior!ity across the surace0 inho!ogeneous internal
structure in layers0 translucency0 s!all si9e0 irregular shape0 and
surrounding pro7ections 1hich 1ould prevent their close presentation
against the instru!ent !easuring port. #he reasons 1hy teeth !ust be
7ust about the only ob7ects to have all the properties at once and in
abundant !easure.
#he luorescence is readily seen by illu!inating 1ith near&
ultraviolet light and its e!ission is a pale bluish&1hite in color. As the
/
-
8/13/2019 25.Tooth Shade Selection - Seminar
13/44
near ultraviolet is present in natural daylight0 it is li8ely that luorescence
inluences the color o teeth 1hen illu!inated by daylight.
Meta!eris! is inevitable 1hen synthetic !aterials such as colored
dental porcelains0 ce!ents0 and poly!ers are !atched against natural
teeth. "o1ever0 it is the geo!etrical properties in the above list o
a181ard sa!ple properties that !a8e instru!ental colori!etry unli8ely
to be ully successul.
A cross§ion through a hu!an tooth is sho1n in plate 30 1hich
sho1s the three principal layers 1ithin it: ena!el0 dentine0 and nutritional
pulp. #hese layers have dierent scattering coeicients0 and hence
dierent opacity and translucency properties. #he spectral absorption
property o the pulp is !ar8edly dierent ro! that o the ena!el and
dentine0 giving it the pin8y red color. #he ena!el and dentine are a
yello1ish 1hite0 but the ena!el 1ith about @5 hydroxyapatite content
is !ore translucent than the dentine0 1hich has about 54 hydroxyapatite
content. So!e teeth that are very translucent see! al!ost bluish&1hite in
parts. #his is probably due to the bluish rays light scattering o s!all sub&
1avelength particles0 seen against the yello1ish 1hite o the !ore
densely scattering parts 1here the short 1ave absorption and natural
yello1ish color predo!inate.
/2
-
8/13/2019 25.Tooth Shade Selection - Seminar
14/44
>ro! the preceding inor!ation it is clear that teeth are translucent
and inho!ogeneous in several dierent 1ays. #his0 co!bined 1ith the
s!all si9e and the geo!etrically co!plicated shape o a tooth and o its
neighboring teeth and gu! tissue0 !eans that a dierent raction o an
incident ray o illu!inating light 1ill be scattered bac8 as relected light
or al!ost every angle o illu!ination0 and 1ith each given angle o
illu!ination or al!ost every portion o a tooth illu!inated. #he only
1ay to try to even out the selective local and angular eects 1ould be to
use he!ispherical0 or nearly he!ispherical0 diuse illu!ination o a tooth
as 1ell as its ad7oining teeth and gu! tissues.
In vie1 o 1hat has been !entioned earlier0 it is clear that the
general&purpose co!!ercial colori!etric instru!ents do not oer the
possibility o !easuring teeth in vivo satisactorily. #he !ain
reuire!ent thereore0 is that the 1hole !outh should be diusely and
unior!ly illu!inated 1ith only a s!all area vie1ed0 o perhaps 2 or =
!! across. #his i!plies a large integrating sphere and hence a lo1
overall optical eiciency0 so that a high po1er la!p or la!ps 1ould be
needed. #here are instru!ents that can be applied locally to a tooth
surace. So!e colori!eters )photoelectric and visual* have a ibre&optic
lexible !easuring head 1ith =D4or 4D= illu!inating and vie1ing
geo!etry.
/=
-
8/13/2019 25.Tooth Shade Selection - Seminar
15/44
A eature o teeth that urther co!plicates the issue is local
staining0 oten conined to crac8s or supericial issures. ,hereas the
hu!an observer can ignore this and concentrate on the !ain tooth body
color0 photoelectric instru!ents cannot do anything but !easure the
average color 1ithin the sa!pled area. A dentist needs to !atch the !ain
body color o the natural teeth and can apply artistically si!ulated stain
!ar8ings ater 1ards to the selected prosthetic cro1n !aterial. A
unior! !aterial o the average color o the natural teeth 1ould not loo8
right0 i the teeth have stain !ar8ings0 a point discussed by McLean
)/@5@* and Preston and ;ergen )/@34*.
Measuree!"s #! Tee"$ a" "$e Na"%#!a& P$'s%(a& La)#ra"#r'
In order to support a progra!!e o 1or8 at ;ritish Cera!ic
Eesearch Association on dental porcelains0 the ?ational Physical
Laboratory !ade an investigation o the color and luorescence o teeth
and o so!e dental porcelain. %xtracted teeth preserved in or!alin
solution 1ere observed to be unnaturally dar8 and bro1nish0 due to their
being 1aterlogged because o the correct os!otic balance no longer being
!aintained. Atte!pts at drying the! led to the !easured color being
progressively lighter and lighter 1ith no stable endpoint. Ater a 1hile
they loo8ed unnaturally light and started to cra9e0 eventually alling to
pieces. ;ecause o this it 1as decided that no credible colori!etry could
/
-
8/13/2019 25.Tooth Shade Selection - Seminar
16/44
be carried out on extracted teeth0 even 1hen stored under ideali9ed
conditions0 and that !easure!ents in vivo 1ere necessary.
#he i!plication o this 1or8 is that dental prosthetic !aterials
should not only !atch the natural teeth in the visible region o the
spectru!0 but their luorescence should roughly !atch as 1ell. In the
case o sho1&business and other patients 1ho are public igures0 the
luorescence needs to !atch uite 1ell0 to cover public appearances in
discos0 theatres0 or other places 1ith orna!ental ultraviolet illu!ination.
C#r Ma"($%!* #+ De!"a& Pr#s"$e"%( a"er%a&s
#he 1idely used general&purpose colori!etric instru!ents are
unsuitable or dental proble!s0 due to si9e o the !easured area0 and that
the special&purpose instru!ents 1ith s!all !easured areas have
co!pletely unsuitable !eans o illu!inating the 1hole !outh )or at least
part o the !outh to include the tooth and all neighboring structures and
tissues*. In the absence o this special dental spectrophoto!eter0 visual
!ethods 1ill have to be relied on or so!e ti!e to co!e. "o1ever0 the
proble! is that dental prosthetic !aterials are not nor!ally available to
the dentist in the right or!. #hey should be abricated as tooth shaped
sa!ples or!ing a dental color atlas0 that is0 a shade guide constructed to
sho1 the three&di!ensional variation o color ound in natural teeth0 1ith
the variations being syste!atic and unior!ly graded according to so!e
/6
-
8/13/2019 25.Tooth Shade Selection - Seminar
17/44
stated criteria. #he !aterials should be selected to give !ini!al
!eta!eris! 1ith natural teeth0 this is also applying to the luorescence
seen under near&ultraviolet irradiation. #he second step is to deine a
a!ily o spectrophoto!etric curves to avoid proble!s o !eta!eris!
and luorescence. I leave it to the dental proession to suggest the
re!aining steps in such an endeavor.
Me"$#,s #+ C#r%e"r'
#here are three basic !ethods o colori!etry:
Matching the test sa!ple against standardi9ed and inely graded
reerence sa!ples organi9ed as in a color atlas and interpolating to
ind the best esti!ate o the color speciicationF
Measuring the color speciication directly by !eans o a tristi!ulus
colori!eterF and
Measuring the spectrophoto!etric characteristic o the sa!ple and
calculating the tristi!ulus values.
In principle0 all these three !ethods could be i!ple!ented by
visual or by photoelectric !eans. #he use o a color atlas is too slo1 and
inaccurate or nor!al industrial use. Inaccuracies arise !ainly ro!
/5
-
8/13/2019 25.Tooth Shade Selection - Seminar
18/44
!eta!eris!0 o 8eeping the reerence sa!ples clean0 unda!aged0 and
1ithin calibration. (isual tristi!ulus colori!etry is slo1er and less
precise than photoelectric !ethods0 but is reliable. #he !ost 1idely used
types o visual colori!eter are !ade by the #into!eter Ltd and it !a8es
use o sets o graded colored glass trans!ission standards as described.
Se("r#$#e"r%( C#r%e"r'
Spectrophoto!eters are instru!ents that !easure0 1avelength by
1avelength0 the spectral variation o trans!ittance or relectance o a
sa!ple.
FOUR GREAT PROBLEMS IN COLORIMETRY
F&u#res(e!" Sa&es
Certain substances exhibit the pheno!enon o photolu!inescence0
1hereby radiant energy is absorbed in one part o the spectru! and re&
e!itted in another part o the spectru!. I the e!ission appears to be
si!ultaneous 1ith the absorption0 the eect is co!!only called
luorescence0 although strictly spea8ing those e!issions occurring ater
intervals longer than 10-8 secshould be called phosphorescence. Most
luorescent substances including all organic ones0 have their e!ission
spectra overlapping 1ith their excitation spectra0 but in all cases the
!axi!u! region o e!ission is at a longer 1avelength than the
/3
-
8/13/2019 25.Tooth Shade Selection - Seminar
19/44
!axi!u! region o excitation. #his is because energy is lost in the
optical transition0 and the energy o a photon. An opaue luorescent
sa!ple seen by relected light has its apparent diuse relectance actor
!ade up o to1 parts0 the true relective co!ponent 1here a raction o
the incident light at each 1avelength is scattered bac8 1ithout change o
1avelength and the luorescent co!ponent 1here a raction o the light
incident at 1avelengths in the excitation region is re&e!itted in a
1aveband centered at a longer 1avelength. ?or!al colori!etric
instru!ents or surace colors are capable o handling correctly the
ordinary relected co!ponent o light0 but not the luorescent co!ponent.
#he luorescent co!ponent o the total radiance actor o a sa!ple is0
ho1ever0 dependent on the relative spectral po1er distribution o the
incident light0 as sho1n.
METAMERISM
,hen t1o suraces !atch or nearly !atch or color under so!e
illu!ination0 but !is!atch under one or !ore other illu!inants0 they are
said to be !eta!eric0 and their spectral relection proiles 1ill be ound
to be dierent or any color. #here are0 in general0 !any possible spectral
distributions0 a act that ollo1s ro! the trivariance o hu!an color
vision. Any color0 regardless o spectral distribution0 can be !atched by a
suitable !ixture o any or !any dierent possible sets o !atching
/@
-
8/13/2019 25.Tooth Shade Selection - Seminar
20/44
sti!uli. Meta!eris! arises to so!e extent 1henever a target color
sa!ple is !atched using dierent colorants0 substrates0 or 8inds o
!aterial. It is never possible to duplicate exactly the target colors o
spectral relection proile 1hen such changes o !aterials are involved.
THE ELEMENTS OF ESTHETICS-APPLICATION OF COLOR
SCIENCE
"istory has recorded !an8indGs interest in his personal appearance
and the eect that sel i!age has on conidence0 peror!ance0 and social
inter course. $ental esthetic has igured pro!inently in this role o sel&
i!age and various ethnic groups have adorned and altered their dentitions
in diverse !anners. Si!ilarly0 any treatise on esthetics is sub7ect to
individual interpretation. #he dentist !ust0 thereore0 atte!pt to use the
technical and conceptual ability to develop or the patient a restoration
that best !eets the patientGs psychological and biological needs and
desires. %sthetic excellence is largely an art 1ith pri!arily sub7ective
interpretation0 though not enough has been done to eectively analy9e
and or!ulate it. Although a consideration o color and shade !atching
1ill receive !a7or e!phasis0 the relative role o this ele!ent !ust be
placed in the right context.
4
-
8/13/2019 25.Tooth Shade Selection - Seminar
21/44
THE ELEMENTS OF ESTHETICS
%sthetic ele!ents can be approached ro! a nu!ber o dierent
vie1points and any approach to taxono!y or grouping results in so!e
redundancy and inadeuacy. #he ele!ents o esthetics 1ithin the
headings o or!0 texture and color. >or 1ant o a better syste! I shall
herein approach the dissection o co!ponents o esthetics into BspatialB0
BopticalB0 and BbiologicalB considerations.
SPATIAL
Spatial co!ponents are those actors0 1hich apply to
tridi!ensional or! and the relation o the teeth to one another as 1ell as
to the approxi!ating or enclosing ele!ents. #here are also perceptual
ele!ents0 1hich include linear har!ony0 perspective vie10 and
orientation to the sot tissue. #hese ele!ents individually and in concert
deliver the greatest i!pact to the vie1er. Additionally0 the actual and
inite !ay not be as i!portant as the eect perceived. Illusion is a !ost
signiicant entity.
OPTICALAnyone 1ho has tried to !atch teeth 1ith a restorative !aterial
recogni9es that the procedure is co!plex. #he optical appearance is not
/
-
8/13/2019 25.Tooth Shade Selection - Seminar
22/44
!erely one o BcolorB as great a concern as that pheno!enon is0 but also
involves light and shado10 surace texture0 translucency0 and opacity.
BIOLOGIC
#he biologic ele!ents include those vital actors0 1hich separate
the dyna!ic and physiologic ro! the static and lieless.
ANALYTICAL PROBLEMS
,hen all o these considerations are expanded into their
subordinate co!ponents it is little 1onder that obtaining esthetic
excellence has presented so!e analytical proble!s. #his !ay be si!ply
stated by noting that the dentist !ust )a* understand 1hat the patient
1ants )psychologic*0 )b* 1hat the patient needs )physiologic*0 and )c* o
1hat dental science0 especially as expressed by the dental tea! rendering
the speciic service0 is capable )technical*. Unless the psychologic
physiologic0 and technical ele!ents can be brought into consonance0
therapy should not be initiated.
PLANNING
%ssential to the planning o a restoration or prosthesis is an
adeuate set o diagnostic casts that reproduce the patientGs sot and hard
tissues 1ith idelity. It is advisable to !a8e a duplicate set o casts to
provide a baseline record that 1ill have both therapeutic and legal value.
-
8/13/2019 25.Tooth Shade Selection - Seminar
23/44
Such casts should usually be !ounted0 although si!pler procedures can
be acco!plished on un!ounted casts.
DIAGNOSTIC AXING
Modiication to !eet both esthetic and unctional needs can best be
planned or through the use o a diagnostic 1axing procedure. Although
the diagnostic 1axing procedure is li!ited by the inani!ate properties o
the cast0 it nonetheless can reveal !any o the eatures that !ay indicate
or li!it success. #ogether 1ith clinical 7udg!ent developed ro!
observing the lip lines0 phonetics0 and inor!ation gleaned ro! the
patient intervie10 a precursor o the inal restoration can be developed.
#his incorporation o the patientGs desires enhances acceptance and
greatly reduces the possibility o dissatisaction or disappoint!ent at the
ti!e o place!ent o the co!pleted restoration. It is essential to ascertain
the desired esthetic result or !etal cera!ic units in advance in order to
allo1 1axing0 a ra!e 1or8 that provides proper !etal support0 yet does
not interere 1ith translucency and color nor inringe upon the ad7acent
tissues.
Porcelain is a !aterial that has intrinsic li!itations that !ust be
recogni9ed. #he !arriage o !etal to porcelain in the !etal cera!ic
restoration is an atte!pt to ta8e advantage o the strength o !etal and the
beauty o porcelain. Si!ilarly0 all the cera!ic restoration e!ploying an
2
-
8/13/2019 25.Tooth Shade Selection - Seminar
24/44
alu!inous core is a procedure that enhances success through dispersion
and strengthening. Porcelain ails in either syste! 1hen there is excess
bul8 or0 to phase it in the negative0 inadeuate support. #hereore0 the
strengthening support syste! )either !etal or alu!ina* !ust be
developed to allo1 as little o the esthetic veneering glass as possible )to
allo1 or strength* yet leave suicient bul8 to cover the substructure and
develop the esthetic optical properties desired. Such an acco!plish!ent
reuires 8no1ledge and planning. #he desired result !ust be pre&
established i both opti!u! strength and esthetic excellence are to be
obtained.
IMPLIED GENDER
Anthropologically0 there is no sexual di!orphis! o hu!an teeth.
,hereas it has been convenient to consider the !ale or! as one that is
!ore cuboidal )robust* and the e!inine as being !ore rounded )gracile*0
atte!pts to veriy this have ailed. As the dentition 1ears as a result o
unction or para&unction0 the !ore 7uvenile incisal edge contours are lost0
and the rounded or! evolves into one that is !ore angular. #hus0 it
appears that 1ear and aging have been translated into B!asculineB0 1hile
the !ore youthul or unaltered or! is as Be!inineB.
=
-
8/13/2019 25.Tooth Shade Selection - Seminar
25/44
EMBRASURES
All o the our e!brasure spaces )incisal0 cervical0 labial0 and
lingual* are i!portant0 but oten the irst perception o or! is the
silhouette o the teeth against the dar8 bac8ground o the oral cavity.
#his silhouette is generated by the incisal e!brasures and the connecting
incisal edges. #here is0 obviously0 an interace bet1een the incisal and
cervical e!brasures0 1hich or!s the inciso&gingival contact area.
OPTICAL ELEMENTS
#here are !any voids in the 8no1ledge o esthetic or!ulation0 but
so!e o these are slo1ly being illed. #he study o color in dentistry
!ust include translucency0 opacity0 and the eect o light and shado1.
Indeed0 it !ust be recogni9ed that color and light are a single entity 1ith
dierent !aniestations. 'ne cannot study color 1ithout studying light0
As $r. ;ruce Clar8 noted al!ost 4 years ago Bcolor&li8e or! has three
di!ensionsB. #hese three di!ensions or! the cornerstone o the logical
approach to clinical shade !atching. Color is a co!plex pheno!enon
and its recognition involves a physical sti!ulus0 a psycho&physical inter
change bet1een the receptor cells o the eye0 and the sub7ective response
by the brain to the inor!ation trans!itted ro! the receptor organ.
Hust as dental esthetics !ust be dissected into its co!ponent parts
to be co!prehended0 so BcolorB !ust be dissected into its three di!ensions
-
8/13/2019 25.Tooth Shade Selection - Seminar
26/44
i it is to be BseenB and shade co!parisons !ade. ,hen a shade guide and
a tooth do not !atch0 it is not enough to note that a B!atchB is lac8ing0 but
deviations in each o the three di!ensions !ust be noted. #his reuires a
basic and clear understanding o those three di!ensions.
HUE
#he irst di!ension0 hue0 is usually deined as Bthe na!e o the
colorB. #his is an inadeuate deinition because it ails to recogni9e that
hue na!es are very i!precise. #here are !any dierent reds0 oranges0
greens0 etc. "ue is generated by the 1avelength o the sti!ulus. (isible
light is co!posed o 1aves o bet1een 234 ad 564 nano!eters. #he
shortest 1aves are seen as violet0 1hile the longest are red. #he physical
seuence0 dictated by 1avelength0 is violet0 blue0 green0 yello10 orange0
and red. It !ay0 then0 be said0 Bhue is the uality o color designated by a
convenient a!ily na!e0 and deter!ined by the 1avelength o the
sti!ulus.
VALUE
#he second di!ension0 value0 is !erely the uality o blac8ness or
1hiteness. It is the euation o the color to a gray scale. "ue and value
are independent0 or value can exist 1ithout hue )the converse is not true*.
#hese are !erely one&di!ensional renditions. ;ecause the hu!an
6
-
8/13/2019 25.Tooth Shade Selection - Seminar
27/44
observer is so very sensitive to slight dierences in value0 it is this
di!ension that is !ost i!portant in dentistry.
CHROMA /SATURATION0
Although value exists in the absence o hue0 chro!a is only present
1hen there is hue. Chro!a is !erely the intensity0 concentration0 or
strength o the hue. Any one o the three di!ensions !ay be varied
independent o the others0 but in dentistry this rarely happens.
COLOR ORDERING
Many syste!s have been devised to interrelate the various colors
possible by changing hue0 value0 and chro!a. So!e are best suited to
!easure!ent by colori!eters or spectrophoto!eters. Munsell !erely
related hue0 value0 and chro!a in the sa!e !anner that length0 1idth0 and
depth are related. #he hues 1ere !ade a continuu! by ta8ing advantage
o the act that the shortest 1avelengths )violet* contained visual ele!ents
o the next shorter )blue* and the longest )red*. #hereore0 a visual circle
could be !ade 1ith violet as the connecting lin8. Using the six hues
previously na!ed0 this circle 1ould read Bviolet0 blue0 green0 yello10
orange0 red0 violet0 blue0 etc.B Munsell then established a value scale o 4
5
-
8/13/2019 25.Tooth Shade Selection - Seminar
28/44
)blac8* to /4 )1hite*. "ues can be related to values !uch the sa!e 1ay a
1heel is related to an axle. "ues o a lo1 value appear dull0 those o high
value0 bright.
Chroma0 the third di!ension0 1ould be analogous to the spo8es o
a 1heel and represents the intensity o the color at any hue or value. #his
ordered color syste! !a8es possible the expression o all colors in ter!s
o hue0 value0 and chro!a. Color !atching can be done ro! a standard
and interpolation bet1een available color chips can be !ade in hue0
value0 and chro!a. Contrast to this ordered logic 1ith the procedures is
no1 used in dentistry. ?o shading syste! has both logical order and
adeuate distribution. ,or8 done by Clar80 )/@2/*0 Sproull )/@52*0
Le!ire and ;ur8 )/@5*0 and Miller )/@3/* has docu!ented the lac8 o
correlation bet1een the hue0 value0 and chro!a o natural teeth and that
o available shade guides.
+enerally0 shade guides do not include enough lo1 value and
higher chro!a sa!ples. A conservative esti!ate had been !ade that les
than ity percent o the population !ay be satisactorily !atched by
dental shade guides. Should one be ortunate enough to ind a shade tab
that apparently satisies the patientsG needs0 the proble! is not solved.
Meta!eris! is a continually perplexing actor0 since the spectral curves
3
-
8/13/2019 25.Tooth Shade Selection - Seminar
29/44
o porcelain do not !atch those o natural teeth. As a result0 the B!atchB
that is apparent in the clinical environ!ent !ay not be present in other
areas o illu!ination.
Meta!eris! in shade !atching has evolved ro! !ore areas than
7ust the discrepancy o spectral curves o natural teeth and porcelain )or
resins*. #here are only a very or shade guides that are used or porcelain
!atching although !any co!panies !anuacture porcelain syste!s that
are based on these guides. 'paue and body porcelains0 sho1n by the
1or8 recently done by Miller and "e!!en $inger0 have uite dierent
hue0 value0 and chro!a plots. #his !eans that the opaue is applied to
!as8 the !etal and then the body porcelain !ust be applied in a uantity
great enough to !as8 the opaue.
,hen this co!plex series o inaccuracies is considered0 the
recurring proble! o !is!atched shades is not surprising. Acceptance o
a shade is an individual actor and no absolute para!eters are deinable.
#hus the restoration o a single central incisor continues to be the greatest
challenge or the less co!pensation.
@
-
8/13/2019 25.Tooth Shade Selection - Seminar
30/44
IMPOSING LOGIC ON AN ILLOGICAL SYSTEM
,hen co!parison bet1een the teeth to be !atched and the shade
guide is !ade then an assess!ent o BdierenceB or Bno dierenceB is then
necessary. I the dierence exceeds the acceptable level0 a description o
that dierence is needed so that !odiication !ay be !ade to correct the
deviation. #hree uestions 1ill !a8e that description possible.
Is the shade guide yello1er than or redder than the tooth being
!atched-B #his uestion deals 1ith the di!ension o hue and
ac8no1ledges that since teeth are only in the yello1&to&yello1 red range0
no other hue error can be present.
BIs the shade guide hue !ore saturated or less saturated than that o
the tooth being !atched-B Again0 this !ay be diicult to separate hue
ro! value0 and either value saturation0 or both deviations !ay be
present.
24
-
8/13/2019 25.Tooth Shade Selection - Seminar
31/44
#hese three uestions 1ill help deine the dierence bet1een a
shade guide tooth and the tooth to be replicated. I no satisactory !atch
is available0 a guide tooth that is higher in value and lo1er in chro!a
should be selected. A higher value shade can be rather easily lo1ered
1ithout loss o translucency by the use o the co!ple!entary color
externally or gray or co!ple!entary !odiiers internally. ,hen the ten
hues Munsell na!ed 1ere given0 nothing 1as said o Bbro1n0B or bro1n
is not a hue0 it is a color. ;ro1n is a lo1 value o several hues0 but or
our purposes in dentistry0 the bro1ns are lo1 value yello1 reds.
SHADE GUIDE USE
It is helpul or the dentist 1ho oers porcelain restorations to
patients to have 8no1ledge o ho1 such units are abricated. %ven though
there in no intention o actually doing oneGs o1n laboratory 1or80 the
8no1ledge can greatly i!prove.
Suice it to say that porcelain is built up in layers using opaue0
body0 and incisal porcelains. %ach o these contributes to the inal optical
eect and each !ay be !odiied 1ith colorants to create the desired
eects. Shade guides reuently have characteri9ed areas that !ay or !ay
not be appropriate to the teeth being !atched. >or this reason0 at least
three o each o the shade guides used should be available to the dentist.
2/
-
8/13/2019 25.Tooth Shade Selection - Seminar
32/44
#he irst is an un!odiied guide. #his guide !ay )and probably
does* have a cervical or that is dierent ro! the standard body shade.
#he second guide should have this cervical section0 co!posed o Bspecial
eectB porcelain0 re!oved. #he third guide should have the gla9e
re!oved )1ith stones0 discs0 or abrasive spray* or !odiication 1ith
cera!ic colorants. A ourth guide 1ith both cervical and incisal areas
re!oved !ay be desirable.
#he overlay o the ena!el portion on the body !ay be done in
dierent uantities and at dierent angles and !ay not be at all li8e the
standard guide. #he BopticalB ele!ents o translucency and opacity can be
as i!portant as BcolorB in developing an esthetically acceptable
restoration0 but tangible !eans o !easuring or co!!unicating the! are
largely lac8ing. Most porcelain syste!s have a series o dierent incisal
porcelains that !ay be used0 though !ost dentists are una1are o their
i!portance.
#he shade guide tab should be occupied by the restoration being
abricated. #his is easier to do or a pontics than or a cro1n. #he
gingival area o the shade guide should approxi!ate the gingival portion
o the tooth being !atched0 and the incisal edge o the guide should be in
2
-
8/13/2019 25.Tooth Shade Selection - Seminar
33/44
the sa!e position as that o the natural tooth. #he goal is to have the light
to be incident on the guide the sa!e 1ay the intended restoration 1ill
receive and relect light. >reuently the re!aining teeth 1ill exhibit
dierent shades and the goal !ust be not to !atch any particular one but
to achieve an acceptable blend.
#he position o teeth in the arch alters light relection and
so!eti!es acco!!odations !ust be !ade. >or exa!ple0 i the tooth that
is !ore pro!inent is !ore li8ely to reuire restoration )because it is !ore
sub7ect to trau!atic da!age*. ,hen the restoration is planned0 a shade
that is slightly lo1er in value !ight be selected in order to blend 1ith the
ad7acent central incisor.
SURFACE TEXTURE
Since color is entirely a result o light0 the !anner in 1hich the
light is relected is i!portant. #he surace topography o both the shade
guide and the tooth !ay alter the uantity and uality o light. #he
replication o surace !orphology is i!portant in order to eectively
produce natural tooth appearances. #his is done by proper carving o the
surace and obtaining the correct degree o gla9e. ?ot only does surace
texture eect the apparent value o a restoration0 but there are indications
that it also aects hue.
22
-
8/13/2019 25.Tooth Shade Selection - Seminar
34/44
CONTROLLED ENVIRONMENT
It has been repeatedly stated that the light incident to and relected
ro! an ob7ect entirely control color. #he ob7ect has the ability to absorb
or relect certain spectra o light. I it absorbs all light0 it is seen as blac8F
i it relects all light0 it is seen as 1hite0 provided a ull spectral light is
incident upon it. ,hen the ob7ect relects so!e rays and absorbs others0
the nature o the relected rays deter!ines the sti!ulus to the eye to
receive and the brain to perceive BcolorB. I the dental shade !atching
procedure is to be controlled0 then the incident light !ust also be
controlled.
#here are three areas that reuire attention i environ!ental control
is to be eective. >irst0 the light radiated !ust be co!plete spectru!
lighting0 at least co!plete as is reasonably possible. $aylight changes
hour&to&hour0 day&to&day0 and season&to&season. It varies in intensity and
in uality. #o ensure that the tubes selected are acceptable0 three criteria
should be !et. First,the tube should have a correlated color te!perature
si!ilar to that o standard daylight. )Standard daylight is deined in the
U.S as that light available in ,shington0 $.C. during the !onth o Hune
bet1een the hours o /:44 ad /:44 oGcloc80 1ith a slightly overcast s8y*.
#his te!perature is approxi!ately 044 Jelvin. Second, the spectral
curve o the light source should be si!ilar to that o this sa!e Bstandard
2=
-
8/13/2019 25.Tooth Shade Selection - Seminar
35/44
daylightB. >inally0 the illu!inant should have a Color Eendering Index
)C.E.I.* o @4 or greater.
#he uantity o light reuired is !ediated by !any actors0 once
the uantity and uality o light have been achieved. Attention !ust be
given to several actors to preserve both. In order to !aintain the spectral
uality and brightness0 no intense colors or dar8 suraces should be used
in the roo!. Ee!e!ber that 1hen light hits a body0 so!e rays are
absorbed and so!e are relected. #he dar8er that body0 the !ore the hue
1ill be relected. #he dar8er that body0 the e1er are the rays relected.
#he !ore highly colored the body0 the !ore hue 1ill be relected and the
less spectrally pure 1ill be the light in the environ!ent. %very colored
ob7ect alters the light that is incident upon it. #hereore0 the larger the
surace )such as 1alls or cabinet ronts* or the closer it is to the critical
color !atching area&the patientGs !outh )or exa!ple*. A third factor0
ater the light source and relecting suraces0 is the acuity o the vision o
the observer !a8ing the evaluation. #his acuity can be di!inished by
sustained vie1ing0 and the evaluation period should be li!ited to ive
seconds. Ater the shade guide&tooth co!parison0 the vie1er should avoid
hue adaptation by loo8ing at a !ediu! blue or grapy card (this writer
prefers the ble!beore !a8ing another co!parison. #he control o light
2
-
8/13/2019 25.Tooth Shade Selection - Seminar
36/44
source0 roo! eatures0 and vie1er perception is essential to eective
color !atching.
CLINICAL PROCEDURES
,hen a restoration is received ro! the laboratory0 it !ay be either
in a gla9ed or ungla9ed condition0 although !etal cera!ic porcelains are
al1ays carried to !aturity )gla9ed* and then shaped prior to inal gla9ing.
At the try&in o the restoration0 the !odiications o or! are !ade irst.
#he principles or this procedure have been discussed at length
previously. ?ext0 the proper surace texture is achieved using dia!ond
stones0 dis8s0 or other instru!ents. In the process o reshaping0 the gla9e
!ay be re!oved in so!e areas and not in others. #he gla9e should be
re!oved ro! all suraces 1ith the possible exception o tissue suraces
o pontics or non&visible areas such as the lingual aspect. #he gla9e is
best re!oved 1ith an abrasive spray0 but i this is not possible e!ery
dis8s or ine dia!ond stones !ay be used. Ee!oving the gla9e ro! all
suraces allo1s ho!ogenous regla9ing rather than having suraces 1ith
dierent degrees o gla9e on various areas o the restoration. I colorants
are to be added to the suraces0 they 1ill be ired at the sa!e ti!e the
restoration is regla9ed.
26
-
8/13/2019 25.Tooth Shade Selection - Seminar
37/44
-
8/13/2019 25.Tooth Shade Selection - Seminar
38/44
23
-
8/13/2019 25.Tooth Shade Selection - Seminar
39/44
COLOR MODIFICATIONS
,hen any shade other than a basic shade guide color is indicated0
the color !odiication !ay be either intrinsic0 i.e.0 added into the
porcelain at the ti!e o abrication0 or extrinsic i.e.0 applied to the surace
ater iring. ;oth procedures have advantages and disadvantages. Intrinsic
additions oer the broadest range o shade alteration. Internal
!odiication0 ho1ever0 reuires s8ill0 and is reversible only by re!oval
o the porcelain itsel0 and cannot be previe1ed prior to iring. "o1ever0
surace colorants are easily applied or re!oved0 loo8 very !uch the sa!e
beore iring as ater0 and do oer a si!ple !anner o !a8ing inal shade
corrections and adding characteri9ations.
>or !ore intense eects0 the !ore concentrated colors called
BstainsB can be added to either the basic porcelain or !odiiers. #hese
stains are !etal oxides in a luxed porcelain base. Metal oxides are
opaue and !ust be dispersed through the glass !atrix to give the desired
optical eect. #he opaue porcelain po1ers !ay be !ore intensely
colored 1ithout any detri!ental eects0 since they are0 by necessity0
already opaue. Conversely0 surace !odiications are li!ited in the
degree o saturation possible0 since the translucency o the restoration
!ay be lost as concentration increases.
2@
-
8/13/2019 25.Tooth Shade Selection - Seminar
40/44
EXTRINSIC MODIFICATION
#o understand the eect o !odiiers on porcelain color it is
necessary to recogni9e the !any ele!ents that enter into the generation o
color in a restoration.
Since extrinsic colors )stains* are applied to the surace0 they
produce their eect dierently than do intrinsic color !odiiers. Much o
the eect is the result o spectral relectance. #he !ore heavily the
surace stain is applied0 the greater 1ill be the spectral relectance and the
less 1ill the color be generated ro! 1ith in. #he cause o this is
t1oold. First0 less incident light 1ill pass through the surace !odiiers0
since they are opaue0 and 1ill be directly relected ro! the!. Second0
so!e o the light that did pass through the surace layer to the underlying
porcelain 1ill be relected ro! the undersurace o the extrinsic stains
bac8 into the restoration.
In spite o the li!itations o extrinsic !odiication0 the procedure
has !any applications that can enhance the esthetic acceptability o a
restoration and should be in the ar!a!entariu! o every restorative
dentist. An essential prereuisite to eective extrinsic !odiication is the
!ixing o the colorant po1ers 1ith the liuid !ediu! to achieve a
suitable consistency. (arious !edia are used0 but all have a higher
viscosity than 1ater to reduce lo1. Prophylene glycol is oten used.
=4
-
8/13/2019 25.Tooth Shade Selection - Seminar
41/44
I the !odiications are to be !ade at chair&side0 the colorants
should be !ixed and applied to the restoration ater it has been placed in
the !outh. 'nce the proper eect has been achieved the !outh be
cleaned. #his !ay be done !ost eectively 1ith stea!0 but this acility is
rarely available in a dental oice. %ither distilled 1ater in an ultrasonic
cleaner or vigorous brushing 1ith a clean brush under running 1ater 1ill
suice. #he restoration is then dried and the colorants reapplied. #he
need or this apparently repetitious procedure is to obviate conta!ination
ro! saliva0 cervicular luid0 or debris. 'nce the desired colorants have
been !ixed and the eect visuali9ed0 it is a si!ple !atter to reproduce
the eect in the second application.
'ne o the si!plest shade !odiication procedures is increasing
chro!a. I the inal restoration is lo1 in chro!a0 the properly hued
colorant is chosen. $ecreasing value is si!ilarly si!ple. #he perception
is oten expressed as a need or B!ore grayB. +ray stain0 ho1ever0 is not
the colorant o choice. I the value decrease is to give the i!pression o
greater translucency or neutrali9e hue0 violet is the proper colorant. #his
use o a co!ple!entary color to achieve a lo1er value is one o the !ost
co!!on applications o extrinsic colorants.
=/
-
8/13/2019 25.Tooth Shade Selection - Seminar
42/44
#he dental colorants do not !eet the reuire!ents o the
subtractive color syste!. Instead o cyan )pri!ary* and green
)secondary*0 yello1 and red0 !agenta and blue0 cyan is o!itted and
orange is added. >or this reason0 violet 1or8s or nearly all shades 1hen
an increase in apparent translucency is needed or value needs to be
lo1ered !oderately. ;ro1n is !ost eective or !ore signiicant value
decreases 1hen chro!a is being raised conco!itantly. ,hen bro1n is
!ixed 1ith the colorant being used to increase chro!a0 the value
lo1ering eect is !uch greater than 1hen violet is used.
FLUORESCENCE
Another actor that has been the sub7ect o great concern and
reuent consternation to those !anuacturing dental porcelain is that o
luorescence. >luorescence is a or! o lu!inescence 1herein a sti!ulus
belo1 the visible spectru! )ultraviolet* causes a body to e!it light 1ithin
the visible spectru!. ,hen ultra violet )blac8 light* is the pri!ary source0
the dierence bet1een natural teeth and !ost restorations is gross. So!e
recent luorescence or!ulas have been innovatively successul in
achieving excitation e!ission properties si!ilar to natural teeth0 yet so!e
porcelains lac8 any signiicant luorescence.
=
-
8/13/2019 25.Tooth Shade Selection - Seminar
43/44
OTHER OPTIMAL PROPERTIES
#he replication o ano!alous teeth 1ith porcelain can still be
rustrating. Color is not the only variable that reuires ad7ust!ent0 since
relative translucency and opacity !ust also be considered. So!e teeth
actually !ay be seen to beco!e !ore opaue as they dry0 and each shade
co!parison is dierent. Much o the inal success co!es only 1ith
patience and s8illed artistry0 and so!eti!es success is si!ply not
obtained to the degree desired.
HAT LIES AHEAD1
#he advent o an era in dentistry 1hen porcelain is the ocus o so
!uch attention should not be perceived as an indication that this is the
ulti!ate !aterial. Porcelain has excellent esthetic properties and the
abrication procedures0 1hile not entirely si!ple0 allo1 the production o
a signiicant percentage o the restorative !aterials in use. Porcelain by
itsel lac8s tensile strength and ailures are not unco!!on. ,hen bonded
to !etal to achieve greater strength0 a hostile environ!ent or the
ra!e1or8 is established. #he abrasiveness o porcelain against natural
teeth creates a rather destructive occlusal proble! in so!e situations.
#he iring te!peratures preclude the use o organic pig!ents li!iting the
procedures available or color control. Eesin poly!ers can be bonded to
!etal oxides 7ust as glass poly!ers can. +rating procedures see! to
=2
-
8/13/2019 25.Tooth Shade Selection - Seminar
44/44
!a8e virtually any property possible. It see!s probable that resins
1ithout !etal support can be developed or dental use. >or the present0
ho1ever0 so!e interesting !odiications o current techniues are at
hand.
SUMMATION OF TECHNIQUE
I there is one 1ord that holds the best advice or i!proved
esthetics it 1ould be BobserveB. It is the natural0 pleasing dental
co!position 1e see8 to e!ulate and it is the hu!an dentition and its
associated tissues that beco!e the textboo8 o study.
A second 1ord or success is BplanB. #he result should be
envisioned beore deinitive therapy is initiated. #his anticipated BresultB
!ust be the sa!e in the !ind o the patient as it is in the !ind o the
dentist0 i dissatisaction and esthetic ailure are to be avoided.
==