Esthetic Dentistry: A Clinical Approach to Techniques and Materials pdf

Assistant Clinical Professor, Department of Dentistry Mount Sinai School of Dental Medicine of New York University Assistant Attending Dentist, The Mount Sinai HospitalNew York, New York

Assistant Clinical Professor, Department of Dentistry Mount Sinai School of Dental Medicine of New York University Assistant Attending Dentist, The Mount Sinai Hospital

New York, New York Private Practice Englewood, New Jersey

SECOND EDITION

With 975 illustrations

A Harcourt Health Sciences Company

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SECOND EDITION

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Library of Congress Cataloging in Publication Data

Esthetic dentistry : a clinical approach to techniques and materials / [edited by] Kenneth

W Aschheim, Barry G Dale.-2nd ed.

p ; cm.

Includes bibliographical references and index.

ISBN 0-323-00162-9 (hard cover)

1 Dentistry-Aesthetic aspects I Aschheim, Kenneth W II Dale, Barry G.

[ DNLM: 1 Esthetics, Dental 2 Dental Materials 3 Dental Restoration, Permanent.

WU 100 E79 2000]

RK54 E88 2000

01 02 03 04 05 OW / KPT 9 8 7 6 5 4 3 2 1

Former Associate Administrator

Nursing Hospital of University of

Department of Restorative andProsthodontic SciencesNew York UniversityCollege of DentistryNew York, New YorkVincent Celenza, DMDDiplomate

American Board of ProsthodonticsPrivate Practice

Manhattan, New YorkCharles 1 Citron, DDS, MScDDirector of Pediatric DentistryDental Department

New York Hospital Medical Center

of QueensQueens, New YorkDavid R Federick,DMD, MScDAdjunct Associate ProfessorDepartment of Fixed ProsthodonticsUniversity of Texas

School of DentistryHouston, TexasAdjunct Clinical Assistant ProfessorDepartment of Restorative DentalSciences

Boston University, Goldman School

of Dental MedicineBoston, Massachusetts

Richard J Lazzara,DMD, MScDAssistant Professor

Department of Periodontics and

I mplant RegenerationUniversity of MarylandBaltimore, MarylandEnrique Lenchewski, DDSAssistant Clinical ProfessorDepartment of Implant DentistryNew York University

New York, New YorkAssistant AttendingDepartment of DentistryMount Sinai Medical CenterNew York, New YorkCharles Andrew Lennon, DMDAssistant Attending Dentist(Prosthodontict)

Oral and MaxillofacialReconstructive DepartmentNew York Hospital

New York, New York

New York, New York

Co-Chief, Orthodontic Division

Department of Surgery (Dental)

Lenox Hill Hospital

New York, New York

Senior Attending Staff

Dental Clinic

Greenwich Hospital

Greenwich, Connecticut

Richard D Miller,DDS, FICD

Former Associate Clinical Professor

Division of Restorative and

Professor and Head

Division of Restorative and

Prosthodontic Sciences

New York University

New York, New York

Professor and Chairman

Department of Prosthodontics and

Graduate School of Arts andSciences

New York UniversityNew York, New YorkBurton R Pollack,DDS, MPH, JDDean and Professor

School of Dental MedicineSUNY at Stony BrookStony Brook, New YorkStephan S Porter, DDS, MSD, MSDirector of Clinical Dentistry

I mplant InnovationsPalm Beach Gardens, FloridaGregory E Rauscher,MDProfessor

Department of Plastic SurgeryHackensack University MedicalCenter

Hackensack, New JerseyProfessor

Department of Plastic SurgeryUniversity of Medicine and Den-tistry of New Jersey

University HospitalNewark, New JerseyEdwin S Rosenberg, BDS, H.Dip.Dent., DMD

ProfessorDepartment of Implant DentistryNew York University

School of Dental MedicineNew York, New YorkBruce A Singer, BS, DDSClinical Assistant ProfessorDepartment of General RestorativeDentistry

University of PennsylvaniaSchool of Dental MedicinePhiladelphia, PennsylvaniaAlbert Einstein Medical Center,North Division

Jenkintown, PennsylvaniaRobert A Strauss, DDSAssociate Professor and Chief, Resi-dency Training Program

Department of Oral andMaxillofacial SurgeryMedical College of VirginiaVirginia Commonwealth UniversityRichmond, Virginia

Van P Thompson, DDS, PhDAssociate Dean for ResearchDepartment of Prosthodontics andBiomaterials

University of Medicine and tistry of New Jersey

Den-Newark, New JerseyJames Torosian, DMDAssistant ProfessorDepartment of PeriodonticsTemple University

School of DentistryPhiladelphia, PennsylvaniaRichard D Trushkowsky, DDS, FAGD, FADM

Director of Operative DentistryDental Department

Staten Island University HospitalStaten Island, New York

Michel G Venot, DCD, DDS, MScD, FICD

Adjunct Associate ProfessorDepartment of RestorativeDentistry

Case Western Reserve UniversitySchool of Dentistry

Cleveland, OhioStaff Maxillofacial ProsthodontistDepartment of Dental ServiceVeteran Administration MedicalCenter

Cleveland, OhioMorton Wood,DDS, MEdChairman

Department of RestorativeDentistry

University of MarylandDental School

Baltimore, MarylandIra D Zinner, DDS, MSDDiplomate, American Board ofProsthodontics

Fellow, American College ofProsthodontists

Clinical ProfessorDivision of Restorative andProsthodontic SciencesNew York UniversityCollege of DentistryNew York, New York

these elective procedures If dentists wait for patients to

GORDON J CHRISTENSEN, DDS, MSD, PhD

In memory of my parents, David and Edith Aschheim; together they pointed me in the right direction And to my wife, Susan, her parents, Herb and Edith Margulis, and my children, Sara and Joshua, without whom I could not continue to find the way KWA

To my parents, Jack and Frances Dale, who built a strong foundation, and to my wife, Ellen, my son, Adam, and my daughter, Chelsea,

who assure me the stars. BGD

cally since the education of most practitioners, or the

in-formation was simply unavailable during their formal

dental training In fact, the myriad choices of techniques

and materials available initially may appear

overwhelm-ing In reality, when properly organized, this body of

knowledge is easily managed This, then, was the

chal-lenge in preparing this book: to create a definitive, all

en-compassing, single source of information presented in a

clinically relevant, easy-to-use format

Resolution of a cosmetic dental problem requires the

practitioner to determine a diagnosis, formulate a

treat-ment plan, and select the appropriate instrutreat-ments and

materials Treatment must then be performed in an

or-derly fashion with an understanding of proper clinical

technique and specific material manipulations The

com-petent clinician approaches any cosmetic dilemma in this

manner We therefore organized this text to duplicate this

sequence of thought processes and clinical operations

A troubleshooting guide (Section I) quickly directs

the practitioner to appropriate information in this

text-book It permits diagnosis and treatment planning at a

glance and provides cross-references to more detailed

dis-cussions of material selection and clinical technique

Section II, "Principles of Esthetics," lays the

founda-tion of basic esthetic principles A detailed discussion of

the fundamentals of esthetics and the relevancy to

den-tistry is presented The principles are referred to

through-out the textbook to link clinical relevancy to basic theory

Section III, "Esthetic Materials and Techniques," aids

in selecting the correct materials for a specific clinical

sit-uation The concise discussion of basic material science

of using the various materials currently available Further,this serves as a basis of comparison, enabling an effectiveevaluation of new materials as they are introduced De-tailed step-by-step clinical techniques delineate appropri-ate armamentarium and include specific procedural nu-ances and numerous highlighted Clinical Tips Thisfacilitates a sound clinical approach Also included is acomprehensive discussion of special considerations, indi-cations, and contraindications for each technique and ma-terial presented, as well as numerous case presentations.Section IV, "Esthetics and Other Clinical Applica-tions," is a specialty-oriented section that presents anoverview of other clinical applications by eminent practitioners Included are such dental specialties as orthodon-tics, periodontics, and oral and maxillofacial surgery Also

i ncluded are emerging fields such as implantology, implantsurgery, and laser surgery as well as other clinically rele-vant topics such as dental photography and plastic surgery.The clinical relevance to the esthetic dentist is stressed byusing case studies, sample laboratory prescriptions, officeforms, and clinical techniques Advanced techniques andcriteria are presented to aid the dentist in determiningwhen to refer a patient for specialty care

Section V, "Esthetic Practice Management," details

i mportant patient psychology, marketing, and dence information Today's clinician will find this sectionhelpful in meeting the challenges facing dentistry and inmanaging a successful dental practice

jurispru-As our profession enters the twenty-first century, thetic dentistry offers a new era of doctor and patient sat-isfaction and excitement We hope we have shared ourown enthusiasm in the pages of this text

es-KENNETH W ASCHHEIM, DDS, FACD

BARRY G DALE, DMD, FACD

ix

We feel privileged to have had the opportunity to work

closely with such talented individuals We are grateful to

Dr Rella Christensen and the Clinical Research

Associ-ates Staff for generously providing the resource list We

also would like to extend special thanks to Dr Gordon

Christensen for honoring us by contributing the foreword

We were particularly impressed with each and every

one of the individuals we had the pleasure of working

with at Mosby/Harcourt They all exhibited the highest

degree of professionalism, while at the same time

main-taining a sense of humor and good will during this

ardu-ous task We are greatly indebted to Penny Rudolph and

Linda Duncan and the executives at Mosby/Harcourt for

agreeing to undertake the second edition We also want

to thank Kimberly Frare, our developmental editor, and

Rene Saller, our production editor, who kept us on track

after we were continuously faced with the realization that

in 6 years we had forgotten just how much work went

into producing a textbook We would also like to thank

Amy Buxton, our designer, and the entire production

de-partment who took a manuscript and some photographs

and created a true work of art In addition, we wish to

thank everyone else at Harcourt, from Marketing to

Pro-duction, from the Art Department to the Editorial

De-partment, without whose efforts this book could not have

been a success

We also wish to thank all the laboratory technicians

and manufacturers' representatives who supplied us with

much of the necessary technical information We must

extend a special thank you to Adrian Jurim at Jurim

Den-tal Studios; the late Jack Karp, Beth Karp, and Arthur

Saltzman at Americus Dental Labs; Zwe Padeh at Studio

46; and Steven Pigliacelli and Eva Pop of Marotta Dental

and also aided us in compiling many of the clinical casesnecessary for this text We also owe particular gratitude to

Dr Jack Hirsch, who, despite seeing his office overruntwice with "bookwork," was still able to provide much ap-preciated insight and guidance An additional thank you

to Ellen Horowitz Dale and Eric Zaidins, Esq., for theiradvice and counsel

We owe much to our colleagues at the Department ofDentistry of The Mount Sinai/NYU Medical Center fortheir continued support and guidance, especially Dr JackKlatell, Dr Daniel Buchbinder, and the attending andsupport staff for providing the resources and encourage-ment necessary to produce this text

A note of appreciation must be extended to our ical illustrator, Caroline Meinstein, whose first edition illus-trations stood the test of time Her good spirits, combinedwith her excellent technical skills, were an integral part ofconveying many of the techniques illustrated in the book.Finally, we wish to thank our families After 4 years ofwork on the first edition, they still gave us 4 more years ofsupport and encouragement to allow us to update this text-book Their unwavering love, encouragement, and moralsupport not only made our lives easier but was ultimatelythe most important force ensuring a successful result.This is not merely a book of our experiences withdental esthetics but a work of the combined experiences

med-of all med-of the above Through their efforts, we hope wehave been able to describe the state of esthetic dentistrytoday and perhaps lay a basic framework for the estheticdentist of tomorrow

Kenneth W Aschheim, DDS, FACDBarry G Dale, DMD, FACD

9 PORCELAIN LAMINATE VENEERS AND OTHER PARTIAL COVERAGE RESTORATIONS, 151

Kenneth W Aschheim Barry G Dale

10 ADHESIVE RESIN BONDED CAST RESTORATIONS, 185

Morton Wood Van Thompson

11 ACRYLIC AND OTHER RESINS: PROVISIONAL RESTORATIONS, 199

CLINICAL APPLICATIONS

14 ESTHETICS AND ORAL PHOTOGRAPHY, 269

Kenneth W Aschheim Mark P King

15 ESTHETICS AND ELECTROSURGERY, 289

Mark P King

16 ESTHETICS AND IMPLANT PROSTHETICS, 301

Richard J Lazzara Stephan S Porter

20 ESTHETICS AND ORAL AND MAXILLOFACIAL

PLACEMENT, 531

Barry G Dale

Barry G Dale Kenneth W Aschheim

INDEX, 583

Size and Shape Problems

• Anterior flared teeth-major, 7

• Anterior flared teeth-minor, 7

• Tooth color-too dark, 13

• Tooth color-too light, 13-14

• Multiple missing teeth, 15

• Single missing tooth, 15

• Acrylic veneer facing-dislodgment, 16

• Carious restoration margins, 16

• Aging, 17

• Bruising, 17

• Scars, 17

• Wrinkles, 17Facial Contours and Skeletal Problems

"If a man's teeth become yellow thou shalt bray

to-gether "salt of Akkad," ammi, lolium, pine-turpine with

these, with thy fingers shalt bur his teeth."

Writing in the ninth century BC, the author of the

Song of Solomon (4:2) offers a poetic description of dental

esthetics:

"Thy teeth are like a flock of well-selected sheep, which

are come up from the washing, all of which bear twins,

and there is not one among them that is deprived of her

young "

Both the Phoenicians (approximately 800 BC) and

Etruscans (approximately 900 BC)carefully carved animal

tusks to simulate the shape, form, and hue of natural

teeth for use as pontics (Fig 1-1) The Central and South

American Mayas (approximately 1000 AD) beautified

themselves by filing the incisal edges of their anterior

teeth into various shapes and designs (Figs 1-2 and 1-3)

They also placed plugs of iron pyrites, obsidian, and jade

into the labial surfaces of the maxillary anterior teeth

(Fig 1-4) This practice was common among both sexes,

and tooth mutilation is still practiced in some societies

(Figs 1-5 and 1-6)

During the Roman Empire dental cosmetic

treat-ment was available only to the affluent classes Oral

hy-giene was practiced primarily by women for reasons of

beauty rather than dental health Mouthwashes,

denti-frices, and toothpicks were common in Roman boudoirs,

Fig 1-1. Ancient Phoenician "bridge." Pontics are

ex-tracted central and lateral incisors that are attached to the maining canines with wires (From Ring ME: Dentistry: an

re-illustrated history, New York, 1985, Harry N Abrams.)

Fig 1-2. Ancient paintingdepictinga probable method

of preparing teeth used by the Mayas about 1000 AD. (FromRing ME: Dentistry: an illustrated history, New York,

1985, Harry N Abrams.)23

Fig 1-3 Various forms of tooth mutilation that were

considered beautification techniques (From Weinberger BW:

An introduction to the history of dentistry, vol 1, St

Louis, 1948, Mosby.)

Fig 1-4 Mayan specimen dating to approximately 1000

AD showing multiple inlays and turquoise restorations ( Courtesy Museo Nacional de Antropologia, Mexico City.)

Fig 1-5. Photograph taken in 1987 showing traditional

filing of the maxillary anterior teeth designed to beautify

Polynesian brides.

Fig 1-6 Ticuana tribal tooth mutilation (From Ring ME: Dentistry: an illustrated history, New York, 1985, Harry N Abrams )

and when teeth were lost, they were replaced with

substi-tutes of bone or ivory carved to the likeness of the

miss-ing ones

Interest in dental esthetics was virtually absent

dur-ing the Middle Ages It was not until the eighteenth

cen-tury that dentistry was recognized as a separate discipline

and its various branches were established The leader of

the movement to modernize and promote dentistry was

Pierre Fauchard (1678-1761) of France He, together

with several colleagues, advocated such esthetic practices

as proper oral hygiene and the use of gold shell crowns

with enamel "veneers." They also introduced a techniquefor the manufacture of mineral (as opposed to ivory orbone) "incorruptible" teeth for use in dentures In Eng-land The British Journal carried the following advertise-ment (1724):

"The incomparable powder for cleaning the teeth which has given great satisfaction to most of the nobility and gentry for above these twenty years it, at one using, makes the teeth as white as ivory, and never black or yellow."

Fig 1-7 Colonial United States advertisement that

ap-peared in the Pennsylvania Chronicle and Universal

Advo-cate on November 5, 1767, selling "artificial teeth, so as to

escape discernment." Fig 1-9 Eighteenth-century Thomas Rowlanson etching

depicting the transplantation of a tooth from a maid to her mistress (Courtesy National Library of Medicine, Bethesda, Md.)

Fig 1-8 Paul Revere's advertisement for his services as

a dentist (dated September 5, 1768) (From Ring ME:

Dentistry: an illustrated history, New York, 1985, Harry

N Abrams.)

Fig 1-10 George Washington's denture (Object tesy of National Museum of Dentistry, Baltimore, MD Image courtesy of National Museum of American History, Smithsonian Institution.)

cour-ESTHETICS IN THE UNITED STATES

In the colonial United States, primitive dental

condi-tions prevailed for almost a century (from roughly 1670 to

1770) until the arrival of "operators for the teeth," dental

professionals who had been trained in Europe They

brought with them not only medications for toothache

but also prescriptions for toothpowder "to make teeth

white" and "attend to your teeth and preserve your health

and beauty." They claimed their toothpowder "[prepared]

and [fixed] real enameled teeth, the best contrivance yet

to substitute the loss of natural ones" (Figs 1-7 and 1-8).

Transplantation of teeth between patients was practiced,

with donors being paid for their trouble: "Any person that

will dispense of the front teeth, five guineas for each"

(Fig 1-9)

Cosmetic dentistry did not meet with universal

ac-ceptance, however The following is an official edict

pub-lished by His Britannic Majesty at Perth Amboy, New

Jersey:

"All women of whatever age, rank, profession or degree, whether virgins, maids, or widow, who after this Act shall impose upon, seduce and betray unto matrimony any of His Majesty's subjects by virtue of cosmetics, scents, washes, paints, artificial teeth, false hair or high- heeled shoes, shall incur the penalty of the law in force against witchcraft and like misdemeanors."

Competent dental practitioners could be found in the leading cities of the United States by the early years

of the nineteenth century The introduction of mineral

teeth in 1817 was soon followed by the manufacture of porcelain teeth Dentures were fabricated with a gingival

component made of carved ivory or animal bone that was

designed for adaptation to ivory or bone bases (Fig 1-10) These denture bases were common until the 1850s, when

various alternative materials were introduced to affordmore esthetic results The technique of mounting artifi-cial teeth on gold or platinum fused with a continuouspink gingival body made of porcelain was patented in the

nineteenth century "Auroplasty;" colored gutta-percha;

"parkesine," a celluloid-like material; "cheoplasty," an

al-loy of tin, silver, and bismuth; "rose pearl;" collodion;

pink hecolite; and even tortoise shells were used for

es-thetic effect in dentistry Vulcanite was the first

univer-sally acceptable denture material Patented by Nelson

Goodear in 1851, it was made by heating caoutchouc

(In-dian rubber) with sulphur, resulting in a firm yet flexible

material Vulcanite, which was relatively inexpensive and

simple to make, propelled the use of dentures out of the

luxury category by allowing for relatively inexpensive and

simple fabrication Synthetic materials such as vinyl

acrylic resins, copolymer acrylic resins, and styrene

acrylic resins were introduced about 1934.

In the late nineteenth century various techniques

used in esthetic fixed prosthodontics were introduced.

The open-faced crown was invented around 1880, the

interchangeable porcelain facing (a ridged facing that

fit-ted into a grooved pontic) was developed in the 1880s,

and the porcelain jacket crown came into vogue in the

early 1900s The three-quarter crown was introduced in

1907.

Practitioners of operative dentistry sought more

es-thetic material than the gold, lead, tin, and platinum in

use in the late nineteenth century One option was "Hill's

Stopping," a mixture of bleached gutta-percha,

carbon-ates of lime and quartz, plastic, bone, and fused glass.

Porcelain was another option in restorative material By

1897 a relatively modern composition of silicate cement

was developed It consisted of powdered aluminum and

zinc oxide mixed with phosphoric and hydrofluoric acid.

After being briefly abandoned because it was difficult to

manage and became brittle, it resurfaced in modified form

in 1904 and revolutionized operative dentistry The

in-ventive combination of acid-soluble glasses blended with

a liquid containing phosphoric acid produced dentistry's

first truly translucent restorative material Further

modifi-cations continued until 1938, when the American

Den-tal Association (ADA) published its definitive

specifica-tion of acceptability known as "ADA Specificaspecifica-tion No.

9." This was the first cosmetic dental material to be

ac-cepted by the ADA However, newer and more exciting

innovations were about to arrive.

In the 1930s chemically activated acrylic resins were developed In the 1940s acrylic-veneer facings came into widespread use By the 1970s composite resins virtually replaced acrylic resins and silicate cements as "perma- nent" restorations Refinements of this basic formula of resin matrix and glass filler are currently in use.

Acid etching, often called bonding, radically changed

cavity treatment by emphasizing conservation of tooth structure It also allowed for the numerous veneering tech niques introduced in the 1970s Variations include direct resin veneers, commercially produced acrylic "shells," and laboratory-processed veneers of resin and porcelain Research continues Study groups, societies, journals, and continuing education courses dedicated to the disci- pline of cosmetic dentistry have proliferated Undoubt edly, the quest for the elusive ultimate restoration will continue to reveal new vistas in the art and science of es- thetic and cosmetic dentistry.

BIBLIOGRAPHY

Asbell MB: A bibliography of dentistry in America: 1790-1840, Cherry Hill, NJ, 1973, Sussex House.

Asbell MB: Dentistry: a historical perspective, Pittsburgh, 1988,

Dorrance & Co.

Bremmer MDK: The story of dentistry, New York, 1954, Dental

Items of Interest.

Foley GPH: Foley's footnotes: a treasury of dentistry, ford, PA, 1972, Washington Square East Publishing Guerini V A history of dentistry from the most ancient times until the end of the eighteenth century, Philadelphia, 1969, Lea &

& Febiger.

Ring ME: Dentistry: an illustrated history, New York, 1985,

Harry N Abrams.

Weinberger BW: An introduction to the history of dentistry, vols

1 and 2, St Louis, 1948, Mosby.

Fig 2-3 Hue is the name of the color. Fig 2-5. Value is the brightness of a shade A low value

is darker than a high value.

Value Fig 2-4 Chroma is the saturation or amount of hue.

and carried through the optic nerve into the occipital

lobe of the cerebral cortex The rod cells are responsible

for interpreting brightness differences and value The

cone cells function in hue and chroma interpretation If

the light source contains all the colors of the spectrum, a

true reading occurs If the light source is deficient in a

cer-tain color, a false reading occurs (see the section on

Metamerism later in this chapter) Precise description of

these colors and organization of their interrelationships,

however, did not occur until 249 years after Newton's

work Robert Louis Stevenson, one of the most concise

writers in the English language, demonstrated the

prob-lems of describing color: "red-it's not Turkish and it's

not Roman and it's not Indian, but it seems to partake of

the two last "2 In 1915 Albert Henry Munsell created an

orderly numeric system of color description that is still

the standard today In this system color is divided into

three parameters-hue, chroma, and value.'

Value (Fig 2-5) is the relative lightness or darkness of a color A light tooth has a high value; a dark tooth has a

low value It is not the quantity of the "color" gray, but rather the quality of brightness on a gray scale 5 That is,

the shade of color (hue plus chroma) either seems light and bright or dark and dim It is helpful to regard value in this way because the use of value in restorative dentistry does not involve adding gray but rather manipulating col- ors to increase or decrease amounts of grayness.

COLOR (HUE) RELATIONSHIP

The Color Wheel

Hues, as used in dentistry, have a relationship to one other that can be demonstrated on a color wheel The re- lationships of primary, secondary, and complementary hues are graphically depicted by the color wheel (Fig 2-6).

an-Hue

Hue (Fig 2-3) is the name of the color Roy G Biv (Red,

Orange, Yellow, Green, Blue, Indigo, Violet) is an

acronym for the hues of the spectrum In the younger

per-manent dentition, hue tends to be similar throughout the

mouth With aging, variations in hue often occur because

of intrinsic and extrinsic staining from restorative

mate-rials, foods, beverages, smoking, and other influences.

Primary Hues

The primary hues-red, yellow, and blue-form the basis

of the dental color system In dentistry the metal oxide pigments used in coloring porcelains are limited in form- ing certain reds; therefore pink is substituted The pri- mary hues and their relationships to one another form the basic structure of the color wheel.

Chroma (Fig 2-4) is the saturation or intensity of hue;

therefore it can only be present with hue For example,

to increase the chroma of a porcelain restoration more

of that hue is added Chroma is the quality of hue that

is most amenable to decrease by bleaching Almost all

hues are amenable to chroma reduction in vital and

non-vital bleaching 4 In general, the chroma of teeth increases

with age.

The mixture of any two primary hues forms a secondary hue When red and blue are mixed they create violet, blue and yellow create green, and yellow and red create orange Altering the chroma of the primary hues in a mixture changes the hue of the secondary hue produced Primary and secondary hues can be organized on the color wheel with secondary hues positioned between primary hues.

Fig 2-6 The color wheel The primary colors (red, yellow, and blue), mixed two at a time, produce the secondary colors (orange, green, and violet) Opposite colors on the color wheel cancel each other out and produce gray.

Complementary Hues

Colors directly opposite each other on the color wheel

are termedcomplementary hues. A peculiarity of this

sys-tem is that a primary hue is always opposite a secondary

hue and vice versa When a primary hue is mixed with a

complementary secondary hue, the effect is to "cancel"

out both colors and produce gray This is the most

impor-tant relationship in dental color manipulation.

line on the incisal edge intensifies the blue nature of anincisal color

When a portion of a crown is too yellow, lightly

washing with violet (the complementary hue of yellow)

produces an area that is no longer yellow The yellow

color is canceled out and the area will have an increased

grayness (a lower value) This is especially useful if the

body color of a crown has been brought too far incisally

and more of an incisal color is desired toward the cervical

area If a cervical area is too yellow and a brown color is

desired, washing the area with violet cancels the yellow

This is followed by the application of the desired color, in

this case brown

Complementary hues also exhibit the useful

phe-nomenon of intensification When complementary hues

are placed next to one another, they intensify one an

other and appear to have a higher chroma A light orange

Metamerism

Basic Theory Metamerism is a phenomenon thatcan cause two color samples to appear as the same hueunder one light source, but as unmatched hues under adifferent light source

There is more than one way to produce a color Itcan either be pure, or a mixture of two other colors (e.g.,pure green versus a mix of blue and yellow) Pure greenreflects light in the green band, but the green mixture

Fig 2-7 The spectral curves of two metameric green surfaces that appear identical but exhibit different reflection ties Surface B reflects light in the green wavelengths and, thus, appears green Surface A, on the other hand, reflects both cyan and yellow light, which also results in the perception of a green surface As long as all the required wavelengths of light are pres- ent, these two metameric pairs look identical If, however, the incident light is deficient in either the yellow or cyan, Surface A will not appear green and the colors will not match (Adapted from Preston JD, Bergen SF: Color science and dental art: a

proper-self-teaching program,St Louis, 1980, Mosby.)

reflects light in the blue and yellow bands

simultane-ously If both colors are exposed to a light with a full

color spectrum they will appear similar If, however,

they are exposed to a light source that does not contain

light in the blue band, the two colors will appear

dis-similar True green will still appear green, but the

mix-ture will appear yellow because without a source of light

in the blue band the blue component of the mix is not

visible to the eye A spectral curve is a measure of the

wavelength of light reflected from a surface It reveals

the actual component colors reflected from an object

(Fig 2-7).5

Color-corrected fluorescent lamps more closely proximate natural daylight and some practitioners preferthem as the standard in dental operatories If the entireoffice is illuminated by color-corrected fluorescent lamp,one room should have cool white fluorescent lighting forcomparative shade matching The color match that holds

ap-up the best in these three lights is the best choice

Clinical Relevance Metamerism complicates the

color matching of restorations A shade button may

match under incandescent lighting from the dental

oper-atory lamp but not under fluorescent lighting in the

pa-tient's workplace

A color selection that works well under a variety of

lights is preferred to a match that is exact under one

source of light but completely wrong under others.' Usu

ally, three sources of light are available in the dental

operatory:

1 Outside daylight through a window

2 Incandescent lighting from the dental

Clinical Relevance A porcelain-fused-to-metalrestoration must have a layer of opaque porcelain applied

to the metal substructure to prevent the color of themetal from appearing through the translucent body and

i ncisal porcelains Improper tooth reduction results intwo unacceptable results:

1 An ideally contoured restoration with minimalporcelain thickness and too much opaque porcelain,resulting in a "chalky" appearance

2 A bulky, poorly contoured restoration with idealporcelain thickness

Tooth reduction must be sufficient to allow enoughroom for an adequate bulk of body and incisal porcelains(Fig 2-8)

THE PRINCIPLES OF FORM

Perception

Fig 2.8 The arrows indicate underprepared areas in a

typical full crown or veneer preparation Underpreparation

results in opaque areas in the finished restoration The

cor-rect preparation is illustrated by the solid line.

As we look at a tooth in an environment of other teeth

we perceive unconsciously many qualities of that tooth.Perceptions about color, size, shape, age, and gender arebased on certain natural biases indigenous to an individ-ual's cultural background Perceptual biases can be di-vided into two types: cultural and artistic

Cultural Biases

Translucency

Translucent materials allow some light to pass through

them Only some of the light is absorbed Translucency

provides realism to an artificial dental restoration

Depth

Basic Theory In restorative dentistry, depth is a

spa-tial concept of color blending combining the concepts of

opacity and translucency In the natural dentition, light

passes through the translucent enamel and is reflected out

from the depths of the relatively opaque dentin

Clinical Relevance White porcelain colorants used

i n color modification are opaque Gray porcelain

col-orants are a mixture of black and white A tooth

restora-tion with a white opaque colorant on the surface appears

artificial because it lacks the quality of depth that would

be seen if the opaque layer were placedbeneatha

translu-cent layer of porcelain Similarly, a bright restoration

(high value) in need of graying (a decrease in value)

would appear falsely opaque if it were simply painted gray.

Adding a complementary hue, however, both decreases

the value and adds to the translucency If characterization

needs to be added to porcelain to represent white

hy-poplastic spots or gray amalgam stains, white or gray

col-Cultural biases are naturally occurring environmental servations about the world around us We perceive (andbelieve) that darker, heavily worn, highly stained, longerteeth belong to an older person because we know thatteeth naturally darken, wear, and stain in grooves andalong the cervical area with age, and that they lengthenbecause of gingival recession We perceive (and believe)rounded, smooth-flowing forms are feminine, whereasharsher, more angular forms are masculine

ob-Masculine and Feminine Culturally defined line qualities may enhance the appearance of a woman( many feminine fashions include a modification of a shirtand tie) However, usually these masculine nuances lookbest on a woman with stereotypically feminine features.Square, angular anterior teeth, therefore, may be desir-able for a more "feminine" woman, but on other womenthis tooth shape may not be as flattering In Western cul-ture, contrast evokes a certain allure With no contrast,the allure is gone

mascu-The Golden Proportion Western civilization hasdrawn the conclusion that for objects to be proportional

to one another the ratio of I :1.618 is esthetically

pleas-i ng Much has been hypothespleas-ized from thpleas-is ratpleas-io, from themathematical relationship of the chambers of the nau-tilus shell to facial proportions As a general rule, if the

apparent (see the section on The Law of the Face later in

this chapter) size of each tooth, as observed from thefrontal view, is 60% of the size of the tooth anterior to it,the relationship is considered to be esthetically pleasing.That is, if the apparent width of the central incisor is