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Volume 1 • Number 1 • Fall 2011

ISSN 2162-2833 (print)

ISSN 2162-2841 (online)

DENTISTRY

The American Journal of

Readers are invited to submit personal photographs for consideration for use in the journal. The number of photos may vary in each issue, but we hope the images will provide an interesting break between the outstanding papers within. This is an opportunity for you, the reader, to share with your colleagues some of the images you are proud of, that may otherwise never see the light of day. For this inaugural issue, we present images from Antelope Canyon, a slot canyon in northern Arizona, photo-graphed by Richard J. Simonsen (http://www.richardsimonsen.com). At certain times of the year and day, the sun may shine through from the slot above that communicates to the surface. Such canyons can be dangerous, as they fill with rainwater quickly in the event of a thunderstorm upstream, sometimes trapping those who choose to ignore nature’s warnings. It is the effect of the running water over millions of years that makes the unique patterns on the walls of the soft sandstone rock walls.

5 Editorial:Welcome aboard!

Richard J. Simonsen

10 Minimally Invasive Restorative Treatment of Hypoplastic Enamel in Anterior Teeth

Jussara Karina Bernardon

Renata Gondo

Luiz Narciso Baratieri

26 The Gray Zone Around Dental Implants: Keys to Esthetic Success

Iñaki Gamborena

Markus B. Blatz

48 Determining the Influence of Flowable Composite Resin Application on Cuspal Deflection Using a Computerized Modification of the Strain Gauge Method

Hamdi H. Hamama

Nadia M. Zaghloul

Ossama B. Abouelatta

Abeer E. El-Embaby

60 All-Ceramic Crowns and Extended Veneers in Anterior Dentition: A Case Report with Critical Discussion

Júnio S. Almeida e Silva

Juliana Nunes Rolla

Daniel Edelhoff

Élito Araujo

Luiz Narciso Baratieri

7

8

Guidelines for Authors

Mandatory Submission Form

ISSN 2162-2833 (print) ISSN 2162-2841 (online)

DENTISTRY


Editor-in-ChiEf

Richard J. Simonsen, DDS, MS

Professor, Faculty of Dentistry Health Sciences Center Kuwait University PO Box 24923, Safat 13110, Kuwait [email protected]

Editorial Board

Joel H. Berg, DDS, MS

Markus B. Blatz, DMD, PhD

Jeff Brucia, DDS

John R. Calamia, DMD

Alexander Carroll, DDS, MBA

David Chambers, EdM, MBA, PhD

Gordon J. Christensen, DDS, MSD, PhD

Theodore P. Croll, DDS

Alessandro Devigus, Dr Med Dent

Sillas Duarte Jr, DDS, MS, PhD

Newton Fahl Jr, DDS, MS

Jack L. Ferracane, PhD

Ronald E. Goldstein, DDS

Laura C. Kottemann, DMD

Gerard Kugel, DMD, MS, PhD

Tyler Lasseigne, DDS

Pascal Magne, Dr Med Dent, PhD

Tidu Mankoo, BDS

Assad F. Mora, DDS, MSD

Marc L. Nevins, DMD, MMSc

Vijay Parashar, DDS, MS

André V. Ritter, DDS, MS

Richard D. Roblee, DDS, MS

David D. Rolf II, DMD, MS

Leo E. Rouse, DDS

Frank Spear, DDS, MSD

Douglas A. Terry, DDS

Gwenlynn Werner, DMD

David Winkler, DDS

Publisher H. W. Haase

Executive Vice President William G. Hartman

Director, Journal Publications Lori A. Bateman

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Editorial

5VOLUME 1 • NUMBER 1 • FALL 2011

i am very pleased to welcome you to a new addition

to Quintessence Publishing Company’s stable of fine

journals and books in dentistry. this is the first issue of

The American Journal of Esthetic Dentistry, a journal

dedicated to promoting the highest clinical standards of

esthetic dentistry based on an evidence base and on a

minimally invasive approach. We wish to share with our

readers the research advances and clinical accomplish-

ments of the profession over the past several decades.

With our outstanding editorial board

and many others who will aid in the re-

view of papers and ideas for the journal,

we pledge to provide you with the high-

est standard of peer-reviewed informa-

tion in the form of papers submitted by

you, the reader, and fellow dedicated

members of our profession.

the theme of “esthetic dentistry” is a

broad one. one could argue that almost

all phases of clinical dentistry involve—

directly or indirectly—esthetics, and we

will publish papers in most areas of

clinical interest to the general dentist,

who is faced with the enormous task of

keeping up with new developments in

all fields of the profession. You can ex-

pect many papers of the quality you

see here in this issue from around the

globe, and also you can expect excit-

ing new developments in terms of be-

ing able to review your journal and read

the papers online with your iPad or

similar instrument in months to come.

Future editorials will discuss themes

and trends in our profession that i hope

will be of interest to a wide group of

readers. i may take a certain position

on an issue in order to stimulate con-

versation and responses such that a

broad perspective of opinions can be

aired. it will be my job as your editor to

try to stimulate such debates and com-

mentary, such as, for example, around

the current overtreatment problems

in the cosmetic dentistry arena. i also

welcome guest editorials from those of

you who may wish to tackle a particular

subject of interest to the profession. an

active and robust “letters to the Editor”

section is on my list of goals for devel-

opment as time goes on. i hope that

you will feel free to communicate with

me on any ideas or constructive criti-

cism you may have.

Please enjoy the first issue of The American Journal of Esthetic Dentistry !

richard J. Simonsen, ddS, MS

Editor-in-Chief

Welcome aboard!

DENTISTRY


Guidelines For Authors

MAnuscript subMission

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Journals:1. Al-Johany, SS, Alqahtani AS, Alqahtani

FY, Alzahrani AH. Evaluation of different esthetic smile criteria. Int J Prosthodont 2011;24:64–70.

Books:1. Gürel G. Porcelain laminate veneers:

Predictable tooth preparation for complex cases. In: Romano R (ed). The Art of Treatment Planning: Dental and Medical Approaches to the Face and Smile. Chicago: Quintessence, 2010:249–263.

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Managing EditorAmerican Journal of Esthetic DentistryQuintessence Publishing Co, Inc4350 Chandler DriveHanover Park, IL 60133

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10THE AMERICAN JOURNAL OF ESTHETIC DENTISTRYTHE AMERICAN JOURNAL OF ESTHETIC DENTISTRY

Minimally Invasive Restorative

Treatment of Hypoplastic

Enamel in Anterior Teeth

Jussara Karina Bernardon, DDS, MS, PhD

Clinical Professor, Department of Operative Dentistry,

Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil.

Renata Gondo, DDS, MS, PhD

Clinical Professor, Department of Operative Dentistry,


Luiz Narciso Baratieri, DDS, MS, PhD

Professor, Department of Operative Dentistry,


Hypoplastic enamel can compromise the smile by altering the mor-

phology and natural translucency of the teeth. To avoid performing

iatrogenic procedures, etiologic knowledge of the enamel deficiency

is essential to indicate the most appropriate treatment approach.

In the case of white stains involving the enamel and dentin, a no-

table treatment option is a direct restoration with composite resin,

which has excellent optical properties to reproduce the natural tooth

structure and appropriate mechanical properties to ensure treatment

longevity. In this article, a clinical case of a patient who reported

dissatisfaction with her smile esthetics, prompted by the presence

of hypoplastic enamel staining at the central and lateral incisors, is

presented. Treatment consisted of composite resin

restorations with the natural stratification technique.

The final esthetic result proved the possibility of

obtaining natural-looking restorations, while en-

suring the esthetic and functional satisfaction of

both the patient and clinician. (Am J Esthet Dent 2011;1:10–24.)

Correspondence to: Dr Jussara Bernardon

Armaro Antônio Viera 2489, apto 403, Itacorubi, Florianópolis, Santa Catarina, Brazil.

Fax: 55 048 38799226. Email: [email protected]

VOLUME 1 • NUMBER 1 • FALL 2011VOLUME 1 • NUMBER 1 • FALL 2011

Fig 1 Proximal view of the anterior teeth. Note the change in color and presence of white spots.

11

BERNARDON ET AL


Several factors may compro-

mise the esthetics of the

smile, including hypoplastic

enamel, which may affect the

morphology, texture, and color of

the tooth surface, the result of an

incomplete or defective forma-

tion of the enamel organic ma-

trix. The intensity and duration

of stimulation on ameloblasts

reflect the extent and location of

enamel defects.1 Lesions may

be triggered by hereditary or

environmental factors. With he-

reditary factors, generally only

the enamel of primary and per-

manent teeth is affected.2 Hy-

poplastic enamel resulting from

environmental factors, however,

can be caused by a variety of

influences, including nutritional

deficiencies, rashes (eg, mea-

sles, chickenpox, scarlet fe-

ver), syphilis, hypocalcemia,

systemic disorders, ingestion of

chemicals (eg, fluoride), trauma,

infections of the primary denti-

tion, or by idiopathic causes.2,3

Environmental factors usually af-

fect only one arch and can alter

both the enamel and dentin.4

Therefore, depending on the

etiology, stains resulting from

hypoplastic enamel may have

systemic features, affecting a

group of teeth, or be localized,

with asymmetric distribution and

isolated to specific teeth.5

These spots compromise

smile esthetics because they

have an opaque, rough, and ir-

regular appearance, compared

to the natural shine and trans-

lucency of enamel. This opacity

prevents light transmission in

the specific region of the lesion,

providing a distinct difference

between it and the surrounding

enamel. Several types of treat-

ments may be recommended

according to severity, and the

least invasive technique should

always take precedence. There-

fore, the etiologic diagnosis is of

paramount importance and aims

to prevent unnecessary treat-

ment of the hypoplastic teeth.

For mild (smooth, light) and su-

perficial lesions, tooth bleaching

can be performed, with or with-

out abrasion of the enamel. This

is a minimally invasive technique

and is limited to the enamel of

the affected area.6 In the case

of moderate or severe stains

with dentin involvement, the

preferred treatment is a direct or

indirect restorative procedure.

With the ongoing development

of composite resins, which pre-

sent a wide range of available

colors and excellent mechani-

cal properties, it has been pos-

sible to perform more esthetic,

predictable, and conservative

restorations.7 The use of com-

posite resin has the advantage

of minimal reduction of the tooth

structure and the completion of

the procedure in a single ap-

pointment.8

BERNARDON ET AL

CLINICAL CASE

The chief complaint of the patient was

esthetic dissatisfaction from discolora-

tion of the teeth and the presence of

white spots on the incisors (Figs 1 and

2). After taking the case history with a

clinical examination, it was determined

that the teeth were naturally dark and

that the white spots were hypoplastic

enamel areas at the incisal and middle

thirds of the maxillary and mandibular

incisors, without functional involvement

(Figs 3 and 4). The patient underwent

radiographic examination, and no peri-

odontal or periapical changes were

evident. The affected teeth yielded a

positive response to the vitality test.

An additional recommended base-

line examination is transillumination,

13VOLUME 1 • NUMBER 1 • FALL 2011VOLUME 1 • NUMBER 1 • FALL 2011

Fig 2 Initial appearance of the

patient. At conversation distance,

the spots, while clearly visible,

can be left untreated if they do not

bother the patient. However, in this

case, the patient was concerned

about the appearance of her teeth.

BERNARDON ET AL

14THE AMERICAN JOURNAL OF ESTHETIC DENTISTRY

which involves the use of a transillumi-

nator positioned along the palatal sur-

face of the tooth being assessed (Figs

5a to 5c). This technique allows analy-

sis of the transmission of light through

the hypoplastic defects, identification of

the thickness of the affected areas, and

verification of the degree of compro-

mised enamel (and dentin, if affected).

Thus, transillumination is effective in de-

termining the treatment approach: the

less the light propagation through the

affected areas, the greater the depth

of the stain. If the dentin is involved, the

most common treatment approach is a

direct restoration with composite resin

and limited preparation of the compro-

mised surface.

Initially, because of tooth discolora-

tion, the patient was asked to perform

Fig 3 Preoperative labial view demonstrating yellow coloration of the teeth

and the presence of white spots at the incisal and middle thirds of the maxillary

central incisors and incisal third of the left lateral incisor.

Fig 4 Occlusal view of the maxillary incisors. Note the change in morphology

and surface texture.

BERNARDON ET AL


a supervised home whitening or bleach-

ing regimen with 10% carbamide

peroxide gel for 4 weeks (2 hours/day)

(Fig 6). Home bleaching is a relatively

simple, conservative, and effective

treatment,9,10 with satisfactory results

obtained in a short time period.11

Bleaching, associated with restorative

treatment, is a common approach that

aims to establish a more homogenous

condition in terms of saturation and

brightness of the teeth to be restored.12

The restoration was performed 14 days

after completion of the bleaching pro-

cess to ensure that the adhesive proce-

dure and color selection were carried

out properly.13

A microhybrid composite resin sys-

tem (Opallis, FGM) with the appropri-

ate mechanical properties to ensure

Figs 5a to 5c Using a transilluminator placed on the palatal surface of the involved incisors, it was

possible to visualize the stain depth and relate this to the depth of the hypocalcified area.

Fig 6 Frontal view after home bleaching with 10% carbamide peroxide gel for 4 weeks (2 hours/

day). Note that the stains remained visible, confirming the need for restorative intervention.

a b c

BERNARDON ET AL


strength and maintenance of polishing

and surface brightness and sufficient

optical properties to mimic the features

found in natural teeth was selected for

the restorative procedure.14 A resin

system with both enamel and dentin

shades is recommended because the

natural tooth overlaps these structures

in different thicknesses, which creates

the polychromatic effect seen on natu-

ral teeth.15 The selected system pre-

sented several hues and saturations

for enamel and dentin beyond the

transparent resins, which reproduce

different degrees of translucency, opal-

escence, and fluorescence.

When selecting the color for the res-

toration, the teeth should be clean and

moist so that the natural translucency

is preserved.15 Color scales are essen-

tial, and it is of paramount importance

that they be of the same manufacturer

as the resin system selected to avoid

potential discrepancies between the

chemistry of the different brands avail-

able. This is because the enamel and

dentin shade guides vary in saturation

and translucency depending on the

system used. The color scale should

be positioned as closely as possible to

the tooth. The color selection for den-

tin should be performed at the cervical

third of the affected tooth, where the

dentin is thicker and more saturated,

and enamel color selection should

occur at the middle third. The system

used had separate scales for enamel

and dentin, which is an advantage be-

cause it allowed for an individual evalu-

ation of the structures. In addition, each

tab had a different thickness, and it was

possible to predict the shade of the final

restoration by altering the thickness of

the tab selected (Fig 7). By placing the

enamel shade tab on top of the dentin

shade tab, it was possible to predict

how the resins would interact in the

future restoration (Fig 8). The operative

Fig 7 (left) Choice of color using the color scale positioned on the facial surface of the affected

tooth. The enamel and dentin colors were selected separately.

Fig 8 (right) By placing the dentin shade guide against the enamel shade guide, the final shade can

be visualized.

BERNARDON ET AL


field was isolated to ensure a clean and

suitable environment for the bonding

procedures.

The cavity preparation should be

restricted to removing the hypoplastic

enamel using diamond points com-

patible to the size of the lesion under

constant irrigation to avoid heating of

the structure (Fig 9). The entire depth

of the hypoplastic enamel should be

removed. Otherwise, the resulting dif-

ference in opacity between natural and

affected tooth structure can negatively

affect the outcome of the restoration

(Figs 10 and 11).

There is no need to bevel the cavo-

superficial angle, preserving as much

healthy tooth structure as possible (Fig

12). The absence of preparations en-

sures a reversible treatment without

compromising esthetics or the adhe-

sive bond. After the preparation was

complete, conditioning was performed

with 37% orthophosphoric acid for 15

seconds on the dentin and 30 seconds

on enamel (Fig 13), followed by appli-

cation of the adhesive system, accord-

ing to the manufacturer’s instructions

(Fig 14).

Fig 11 After preparation,

the white spot was still evident,

which called for its removal

with a diamond bur of smaller

diameter.

Fig 12 Final aspect of the

hydrated cavity preparation,

which was restricted to removal

of the white spot.

Fig 9 After rubber dam was

used to isolate the affected

teeth, the white spot was re-

moved using diamond burs.

Fig 10 Occlusal view of the

preparation. Note the remaining

white spot that could compro-

mise the restorative outcome if

not removed.

Fig 13 Etching of the hard

tissue with 37% orthophosphoric

acid (15 seconds for dentin,

30 seconds for enamel).

Fig 14 Application of the ad-

hesive system according to the

manufacturer’s instructions.

BERNARDON ET AL


The restorative procedure was per-

formed using the stratification tech-

nique, based on the techniques of

building ceramics. This new trend is

also referred to as the anatomical tech-

nique.16,17 In this technique, layers of

selected materials are used to repro-

duce the enamel and dentin structures

while also respecting their thickness

and anatomical contour.

The artificial dentin reconstruction

was performed using the dentin resin

DA1 (Opallis). This resin was applied

covering the deepest portion of the cav-

ity to sculpt the shape of the mamelons

(Figs 15 and 16). Dentin mamelons can

have various shapes and determine

the translucent halo characteristics

of the tooth (Fig 17). Each layer was

photopolymerized for 40 seconds. To

complete the artificial dentin, a resin for

bleached teeth was applied at the tip

of the mamelons (D-Bleach, Opallis).

In a natural tooth, dentin presents as

an intense and very reflective opaque

white color on the tip of the mamelons.

However, when light penetrates the

dentin through the enamel, it results in

Fig 15 Composite resin was

placed in the preparation to

reproduce the dentin layer.

Fig 16 Mamelons must be

defined when applying the

composite resin.

Fig 17 Frontal aspect after

placing the second dentin resin

layer for bleached teeth. Note

the design of the mamelons.

an “orange” appearance. This is the

counter-opalescence feature of dentin.

To reproduce this effect, an opalescent

and highly translucent resin (T-Blue,

Opallis) was placed on the tips of the

mamelons and between the dentin and

incisal edge of the tooth (Fig 18).

Then, artificial enamel was recon-

structed using a single enamel resin

layer (E-Bleach) (Fig 19). In the stratifi-

cation technique, it is important to con-

sider that the artificial enamel thickness

should correspond to one third of that of

natural enamel18 to avoid value reduc-

tion of the restoration. This means that

a thicker layer of artificial enamel results

in a gray and more monochromatic res-

toration.14 This is because the refrac-

tory index of the natural tooth structure

is different from that of the composite

resin.14 The enamel surface was final-

ized at this time, avoiding use of dia-

mond points (Fig 20).

The same procedures were per-

formed for the maxillary right central

(Figs 21 to 24) and left lateral inci-

sors (Figs 25 to 28). After complete

polymerization and at a later session,

BERNARDON ET AL


Fig 18 A highly translucent

resin was placed on the opal-

escent areas of the incisal third

region of the tooth.

Fig 19 Positioning of the final

enamel composite resin layer.

Care was taken to cover all

preparation margins.

Fig 20 Proximal view of the

vertical development and lobes

shaped in the definitive restora-

tion.

Fig 24 Final aspect of the

restoration of the maxillary right

central incisor.

Fig 23 Incremental tech-

nique for resin application:

DA1, D-bleach H, T-Blue, and

Bleach (Opallis).

Fig 27 (left) Mamelon design

using dentin resin (DA1 and D-

Bleach, Opallis).

Fig 28 (right) Final aspect of

restoration. Note the contrast

between the restoration and the

natural tooth, which is dehy-

drated as a result of absolute

isolation.

Fig 21 Removal of the white

spots on the right central inci-

sor with a diamond bur.

Fig 25 Removal of the hypo-

plastic enamel on the left lateral

incisor.

Fig 22 After hydration, the

preparation was completed

with removal of the white spot.

Fig 26 Final aspect of the hy-

drated cavity preparation, which

was restricted to removing only

the hypoplastic white spot.

BERNARDON ET AL


the surface of the restoration was tex-

tured, and finishing and polishing were

completed (Figs 29 to 32). Surface tex-

turing is indispensable in ensuring a

natural-looking restoration because

an irregular surface provides light dis-

persion. Lobules and development

grooves (vertical texture), horizontal

grooves, and perikymata should be

reproduced using extra-fine diamond

Fig 30 Vertical development and

the edges were completed with an

oval format extra-fine diamond bur.

Fig 32 The restoration was pol-

ished to make the surface bright and

smooth.

Fig 29 A surface enhancer was used to identify the differ-

ent reflection areas of the teeth.

Fig 31 Note the similarity in morphology between the cen-

tral incisors after texturing.

BERNARDON ET AL


burs. Finishing was completed using

flexible disks and rubber tips. Polish-

ing with felt disks and polishing pastes

ensures surface brightness and de-

creases plaque retention. The final

result showed that composite resin

provides a suitable material to produce

esthetic effects similar to that of the

natural tooth structure (Figs 33 to 39).

Figs 33a to 33c A transilluminator was again used to visualize the similarity in light transmission

between tooth and restoration (compare to Figs 5a to 5c).

Fig 34 Final aspect of restorations, frontal view.

Fig 35 (right) Final aspect of restorations, palatal

view.

a b c

BERNARDON ET AL


Figs 36 to 38 Final smile after bleaching and restora-

tive treatment. Note the correct merging of the dental

substrate with the composite resin and reproduction of

the optical aspects in the incisal third region.

BERNARDON ET AL


Fig 39 The patient was satisfied with the end result. Note the naturalness and harmony of the smile

with the facial esthetics.

BERNARDON ET AL


CONCLUSIONS AND GUIDELINES FOR PRACTITIONERS

In cases of hypoplastic enamel, a correct

diagnosis is indispensable for an appro-

priate treatment prognosis. In lesions

with dentin involvement, direct compos-

ite resin restorations promote satisfacto-

ry results with conservation of a healthy

dental structure, excellent mechanical

properties, and reproduction of the nat-

ural tooth color and characteristics.19

Proper color selection is not enough;

satisfactory resin system selection and

proper realization of the stratification

technique must also be accomplished.

Following this protocol is critical to the

quality of treatment received.

This article is based on a chapter in the book Clinical Vision: Cases and Solutions by Dr Baratieri and was originally written in Portuguese.

REFERENCES

1. Elcock C, Smith RN, Simpson J, Abdellatif A, Bäckman B, Brook AH. Comparison of methods for measurement of hypoplastic lesions. Eur J Oral Sci 2006;114(suppl 1): 365–369.

2. Clarkson J. Review of terminol-ogy, classifications, and indices of developmental defects of enamel. Adv Dent Res 1989;3:104–109.

3. Ribas AO, Czlusniak GD. Anomalias do esmalte dental: Etiologia, diagnostico e tratamento. Biol Health Sci 2004;10:23–26.

4. Bendo CB, Scarpelli AC, Novaes JB Jr, Valle MPP, Paiva SM, Pordeus IA. Enamel hypoplasia in permanent incisors: A six-month follow-up. RGO 2007;55:107–112.

5. Sensi lG, Marson FC, Strassle H, Duarte SJ. Recuperação Cosmética de Deformidades Dentais. Pro-odont Estética, ed 2. Porto Alegre: Artmed, 2008: 156–178.

6. Croll TP. Enamel Microabrasion. Chicago: Quintessence, 1991.

7. Simonsen RJ. Developmental defect restorations. In: Simonsen RJ. Clinical Applica-tions of the Acid Etch Tech-nique. Chicago: Quintessence, 1978:63–70.

8. Machado FC, Ribeiro RA. Defeito de esmalte e cárie dentária em crianças prematu-ras e/ou de baixo peso ao nascimento. Pesq Bras Odontoped Clin Integr 2004; 4:243–247.

9. Haywood VB, Heymann HO. Nightguard vital bleaching. Quintessence Int 1989;20: 173–176.

10. Leonard RH Jr, Bentley C, Eagle JC, Garland GE, Knight MC, Phillips C. Nightguard vital bleaching: A long-term study on efficacy, shade retention, side effects and patients’ perceptions. J Esthet Restor Dent 2001;13:357–369.

11. Joiner A. The bleaching of teeth: A review of the literature. J Dent 2006;34:412–419.

12. Hirata R. Tips: Dicas em Odontologia Estética. São Paulo: Artes Médicas, 2011:576.

13. McGuckin RS, Thurmond BA, Osovitz S. Enamel shear bond strengths after vital bleaching. Am J Dent 1992;5:216–222

14. Baratieri LN, Belli R. Resinas compositas. In: Baratieri LN. Clinical Solutions—Fundamen-tals and Techniques. Flori-anópolis: Editora Ponto, 2008:131–142.

15. Baratieri LN, Belli R. Colo: Fundamentos básicos. In: Baratieri LN. Clinical Solu-tions—Fundamentals and Techniques. Florianópolis: Editora Ponto, 2008:21–55.

16. Ardu S, Krejci I. Biomimetic direct composite stratification technique for the restoration of anterior teeth. Quintessence Int 2006;37:167–174 [erratum 2006;37:408].

17. Vanini L. Light and color in anterior composite restora-tions. Pract Periodontics Aesthet Dent 1996;8:673–682.

18. Vanini L, Mangani F, Klimovs-kaia O. Colour in dentistry. In: Vanini L, Mangani F, Klimovs-kaia O. Conservative Restora-tion for Anterior Teeth. Viterbo, Italy: ACME, 2005:97–200.

19. Bernardon JK, Gondo R. Restorative treatment of hypoplastic stains in anterior teeth. In: Baratieri LN. Clinical Vision: Cases and Solutions. Florianópolis: Editora Ponto, 2010:62–101.


The Gray Zone

Around Dental Implants:

Keys to Esthetic Success

Iñaki Gamborena, DMD, MSD, FID

Private Practice, San Sebastian, Spain; Clinical Assistant Professor,

Department of Preventive and Restorative Sciences, University of Pennsylvania

School of Dental Medicine, Philadelphia, Pennsylvania, USA.

Markus B. Blatz, DMD, PhD

Professor and Chairman, Department of Preventive and Restorative

Sciences, University of Pennsylvania School of Dental Medicine, Philadelphia,

Pennsylvania, USA.

Correspondence to:

Dr Iñaki Gamborena

Resurecccion mª de Azkue, 6 20018

San Sebastian, Spain.

Email: [email protected]


Single-implant restorations in the anterior maxilla have become a routine treat-

ment option. While customized tooth-colored prosthetic components show great-

ly improved clinical outcomes, esthetic success relies not only on the restorative

result, but also on the condition of the soft tissues. A common esthetic shortcom-

ing is the grayish appearance of the peri-implant soft tissues, which are difficult

to manipulate around dental implants. The parameters and clinical guidelines that

should be used to influence esthetic success and avoid the gray zone around

implant restorations can be categorized into five key factors: (1) optimal three-

dimensional implant placement for functional and esthetic long-term implant

success; (2) maximized soft tissue thickness to conceal the implant-restorative

interface; (3) proper abutment selection to improve biocompatibility, tissue stabil-

ity, color, translucency, and fluorescence; (4) careful crown restoration to imitate

the natural teeth; and (5) awareness of the lip line, which may greatly influence the

final outcome. Mimicking the inherent optical properties, especially fluorescence,

of natural teeth with implant components and crown materials is fundamental for

ideal restorative and soft tissue esthetics. (Am J Esthet Dent 2011;1:26–46.)

27

GAMBORENA ANd BLAtz


The esthetic success of a dental

restoration is judged by its inte-

gration with the surrounding dentition

in respect to position, angulation, di-

mensions, proportions, shape, surface

morphology, and shade.1–3 Other cru-

cial esthetic parameters that are often

overlooked include the morphology,

texture, and ultimately the color of the

surrounding gingiva.3,4 The soft tissue

is the natural frame of the teeth and

any dental restoration and is, therefore,

a fundamental parameter for esthetic

success.1,3,5 This aspect is often ne-

glected because successful soft tissue

outcomes—including handling, manip-

ulation, and healing—are very demand-

ing, time intensive, and unpredictable.5

Magne et al6 described a prevalence

of grayish soft tissue discolorations

around tooth-supported full-coverage

porcelain-fused-to-metal and even all-

ceramic restorations. Interestingly, oth-

er perioral facial parameters such as

position of the upper lip and height of

the smile line7–9 also seem to influence

the degree of gingiva discoloration.

The authors note that “this problem is

particularly evident in the presence of

the upper lip, which can generate an

‘umbrella effect’ characterized by gray

marginal gingivae and dark interdental

papillae.”6

This umbrella effect is magnified with

dental implant restorations in the an-

terior maxilla because the supporting

hard and soft tissues are often com-

promised even before restorative treat-

ment and are influenced by the color

and design of the implant, its prosthetic

components, and the definitive resto-

ration.10–17 Therefore, ideal periodontal

and restorative esthetic success with

maxillary anterior implant-supported

restorations presents a great challenge

for the entire dental team and depends

on a variety of parameters.10–14

The parameters and clinical guide-

lines that should be used to influence

esthetic success and avoid the gray

zone around implant restorations can

be categorized into five key factors: (1) optimal three-dimensional (3D) implant

placement for functional and esthetic

long-term implant success; (2) maxi-

mized soft tissue thickness to conceal

the implant-prosthetic component inter-

face; (3) proper abutment selection to

improve biocompatibility, tissue stabil-

ity, and color to provide a perfect blend

with surrounding tissues and teeth; (4) careful crown restoration to imitate the

natural teeth; and (5) awareness of the

lip line, which may greatly influence the

final outcome.

3D IMPLANT PLACEMENT

The fundamental factor for long-term

functional and esthetic success as well

as soft tissue color and stability is opti-

mal 3D implant placement.18 A simple

but essential guideline is to position the

implant as close as possible to where

the natural tooth was or ideally would

be.10 If a line is drawn at the center of

the implant along its long axis and ex-

tending through the tooth restoration,

it should run through the center of the

incisal edge of the prospective tooth

(Fig 1). The greater the 3D mismatch

between the crown and implant body,

the poorer and less stable the final

GAMBORENA ANd BLAtz


outcome will be. The incisal edge is

also the target for the angulation of

the implant. An implant that is angu-

lated too far to the buccal aspect will

result in greater tissue recession under

functional load. Conversely, a palatally

placed implant leads to a more ex-

treme emergence profile, resulting in

increased bone resorption and thinning

of the tissues. Both situations will lead

to an intensified grayish appearance of

the soft tissues at the gingival margin.

The third dimension is determined

by the depth of the implant in respect

to the marginal bone and soft tissue.

An implant placed at the proper depth

allows for the development of an ideal

emergence profile and a soft tissue col-

lar void of a gray zone. It is impossible

to create a proper emergence profile

when the implant is placed too shal-

low, while an implant placed too deep

is difficult to manage clinically and in-

creases the possibility of peri-implant

infection, inflammation, and bone loss.

A surgical guide fabricated from the

diagnostic wax-up/setup is an indis-

pensible tool to ensure proper 3D im-

plant placement. The anticipated incisal

edge position of the final tooth restora-

tion determines the position, angulation,

and depth of the implant in all three di-

mensions, which directly influence the

position, height, and thickness of the

surrounding hard and soft tissues.10,12

SOFT TISSUE THICkNESS

Even in cases where ideal implant

placement was achieved, the esthetic

outcome may become compromised

over time due to resorption of the mar-

ginal bone and soft tissues.5,19

Fig 1 (right) Maxillary anterior implants should

be positioned and angulated so that a virtual line

through the center of the implant along its long

axis would run through the center of the incisal

edge of the prospective crown.

GAMBORENA ANd BLAtz


Case 1 (Figs 2 to 6) illustrates a situa-

tion where a single implant was placed

immediately after extraction of the

maxillary right central incisor without

any hard or soft tissue augmentation. A

modified metal abutment was fabricat-

ed, and the definitive restoration was

inserted (Figs 2 and 3). A follow-up

photograph taken several years post-

operatively reveals a grayish appear-

ance of the soft tissue surrounding the

implant restoration (Fig 4). This discol-

oration becomes increasingly evident

11 years after completion as a result of

Figs 2a and 2b A modified metal abutment was used after im-

mediate implant placement at the maxillary right central incisor site

without bone or soft tissue augmentation.

Fig 3 Postoperative situation

showing the implant-supported

crown.

Fig 4 (above left) Follow-up view after several years reveals a

grayish appearance of the soft tissues.

Fig 5 (above right) Follow-up view after 11 years showing soft tis-

sue discoloration due to the metal abutment.

Fig 6 (left) Periapical radiograph after 11 years reveals loss of

buccal bone.

Case 1

GAMBORENA ANd BLAtz


the resorption of the buccal bone and

surrounding soft tissues, revealing the

unfavorable gray color of the metal im-

plant abutment (Figs 5 and 6).

To avoid this result, it is advisable

to maximize tissue thickness in every

case and for both delayed and imme-

diate implant placement.19–22 In fact,

the mucosal characteristics of the peri-

implant tissues necessitate connective

tissue grafting for long-term esthetic

success.21 With clear surgical objec-

tives, a modern approach should al-

ways include the most conservative

procedure that satisfies the esthetic

and functional requirements. For ex-

ample, if a bone graft is unnecessary,

stage-one surgery should always be

performed with a minimal flap incision,

such as a split-thickness flap or even

no flap, to avoid unnecessary exposure

of the underlying bone. Several authors

have indicated that flapless surgical

implant placement using computer-

assisted surgical guides minimizes

bone resorption, preserves soft tissue

architecture, and improves the healing

process.23 While some of these results

still need to be verified in long-term clin-

ical trials, the positive effects of flapless

implant placement on patient comfort

due to the minimally invasive nature

of the procedure are clearly evident.23

The key components of this surgical

process are maintenance of the inter-

proximal bone, minimal bone exposure

only on the implant site, precise coro-

nal graft suturing central to the implant

axis, and tension-free flap closure and

adaptation.

The design of the healing abutment,

which can be placed during or after

connective tissue grafting, is another

critical issue. Connective tissue grafts

(CTGs) are placed around implants to

enhance gingival margin stability and

create a more fibrous and less mobile

tissue complex.19–22 In dentistry today,

the clinician’s search for soft tissue

abundance in the early stages of im-

plant treatment means creating a large

amount of soft tissue during or soon af-

ter implant placement and manipulat-

ing these tissues during the prosthetic

phase. This is a shift from traditional ap-

proaches in which multiple subsequent

soft tissue grafts are performed until

the desired thickness was achieved.

Multiple surgical interventions, how-

ever, are less predictable because

the scarring and compromised blood

supply make every subsequent graft-

ing attempt more challenging. For

ideal prosthetic soft tissue manipula-

tion, the healing abutment should be

significantly narrower than the tooth to

be replaced. At first, the tissue will not

have the same scalloped architecture

as found around natural teeth. How-

ever, when the provisional restoration

is placed, its subgingival contour and

shape will determine the position and

scallop of the soft tissue margin.10,13 It

also seems advantageous to connect

the definitive abutment as early as pos-

sible and not to remove it after that time.

Thicker peri-implant soft tissue

masks the implant-abutment-restoration

interface and provides a better color

match between the soft tissues around

the implant and those around the neigh-

boring teeth.15–17 Some basic guide-

lines for tissue thickness and abutment

selection are as follows:

GAMBORENA ANd BLAtz


• A soft tissue thickness greater than

3 mm allows for the use of titanium or

zirconia abutments without negative

esthetic implications.

• A thin soft tissue of less than 2 to

3 mm requires either a CTG or zirco-

nia abutment.

• A dentin-colored abutment is always

preferred.

In Case 2 (Figs 7 to 13), a colored in-

stead of a white zirconia abutment was

placed due to the presence of less than

1 mm of labial soft tissue. This approach,

along with the adequate soft tissue sup-

port and contour, provided a satisfying

outcome.

ABUtMENt sELEctiON

In an evaluation of the soft tissue around

single-tooth implant crowns, Fürhauser

et al24 showed that the color of the peri-

implant soft tissue matched that of the

reference tooth in no more than one-

third of cases. Another study found that

all-ceramic implant abutment and crown

Case 2

Fig 7 Thin peri-implant soft

tissue of only 1 mm was

evident on the buccal aspect.

Fig 8 A custom-colored

zirconia abutment (Procera, No-

bel Biocare) was fabricated to

optimize the esthetic outcome.

Fig 9 Colored zirconia abut-

ment and alumina crown

(Procera Crown Alumina, Nobel

Biocare).

Fig 10 Intraoral occlusal view

showing the soft tissue support.

Fig 11 Postoperative buc-

cal view. The tooth-colored

abutment and all-ceramic

crown blend favorably with the

adjacent teeth and surrounding

soft tissue despite the compro-

mised soft tissue thickness.

Fig 12 Postoperative peri-

apical radiograph.

Fig 13 (left) Occlusal view of

the definitive implant-supported

restoration.

GAMBORENA ANd BLAtz


materials provide a better soft tissue

color match with neighboring teeth than

do conventional metal-alloy compo-

nents.16 zirconia has been shown to be

the preferred implant abutment material

due to its high strength13,25,26 and ex-

cellent biocompatibility.27–29 The short-

comings of zirconia include its higher

cost and unfavorable optical properties

in regard to color and fluorescence.30

Case 3 (Figs 14 to 55) includes all

previously described factors and treat-

ment parameters. The missing maxillary

left central incisor was replaced with a

Case 3

Fig 14 Preoperative periapi-

cal radiograph of the missing

maxillary left central incisor.

Fig 15 Preoperative intraoral situation.

Fig 17 Intraoral view of the edentu-

lous ridge topography.

Fig 18 Virtual

implant placement for

guided surgery.

Fig 16 Lateral

tomogram showing

the extent of the ridge

defect.

dental implant (Figs 14 to 18). Ideal 3D

implant placement was planned on the

computer and transferred via guided

surgery. During stage-one surgery,

the implant (3.5 × 13 mm, NobelAc-

tive, Nobel Biocare) was inserted, and

a CTG harvested from the maxillary

tuberosity was placed to increase tis-

sue thickness (Figs 19 to 23). Figure

24 shows the augmented edentulous

ridge 6 months postoperatively. Next,

a zirconia abutment was connected to

the implant, and a provisional restora-

tion was fabricated, relined in the oral


GAMBORENA ANd BLAtz


cavity, and cemented (Figs 25 to 29).

The different lighting conditions (natu-

ral and ultraviolet [UV] light) shown in

Figs 30 to 33 reveal the optical short-

comings of these materials, especially

the lack of natural fluorescence. Figure

Fig 19 Implant placement (3.5 × 13 mm,

NobelActive, Nobel Biocare).

Fig 20 A subepithelial CTG was harvested

from the maxillary tuberosity to augment the

deficient ridge.

Fig 21 After placement of the CTG, the flaps

were adapted without tension and sutured with thin

suture material to limit trauma.

Fig 22 Labial view of the adapted flap after

suturing.

Fig 23 Intraoral situation 1 week postopera-

tively.

Fig 24 Postoperative situation after 6 months

reveals improved ridge morphology.

Case 3 Continued

GAMBORENA ANd BLAtz


34 shows the detailed optical charac-

teristics of natural enamel and dentin

under different light sources.

Fluorescence is a crucial property

for natural esthetics.30–32 Colorants

and fluorescent modifiers that can be

applied to zirconia abutments even af-

ter milling and finishing have recently

been developed.30 The abutment or

framework is dipped into a fluores-

cent coloring liquid before sintering

to infiltrate the zirconia (Colour Liquid

Case 3 Continued

Fig 25 Definitive zirconia abutment and provi-

sional restoration.

Fig 26 (right) Insertion of the colored zirconia

abutment.

Fig 27 (above left) Try-in of the provisional crown.

Fig 28 (above right) Precision of fit was verified extraorally.

Fig 29 (right) Periapical radiograph used to verify fit.

GAMBORENA ANd BLAtz


Fluoreszenz, zirkonzahn). the abut-

ment is blow dried after the dipping

process to remove the excess and then

placed under a drying lamp to prevent

damage to the heating elements of the

sinter furnace.

In addition to the regular zirconia, a

more translucent zirconia (Prettau

zirconia “translucent,” zirkonzahn)

along with 16 coloring liquids (zirkon-

zahn) are available. Figures 35 to 37

illustrate the infiltration process and its

Fig 32 Optical properties of the zirconia abut-

ment under natural light.

Fig 33 Optical properties of the zirconia abut-

ment under UV light reveals a lack of fluores-

cence.

Fig 34 Color charac-

teristics of natural enamel

and dentin: (a) The three

basic color zones; (b)

areas of brightness/value;

(c) enamel characteristics

under a polarizing filter;

(d) color characteristics

of dentin; (e) degrees

of dentin fluorescence

under UV light.

Fig 31 Optical properties of the provisional

crown under UV light. Note the lack of fluores-

cence.

Fig 30 Optical properties of the provisional

crown under natural light.

Case 3 Continued

GAMBORENA ANd BLAtz


effect on the optical appearance under

different light sources. Three different

abutments were fabricated: translucent

zirconia with and without fluorescence

and conventional zirconia with fluores-

cence. Figures 38 to 40 show the pa-

tient’s favorable soft tissue thickness

and the clinical try-in of the three differ-

ent abutments under regular and UV

light. Interestingly, the translucent abut-

ment provided the best match in natu-

ral light but the worst under UV light.

Fig 35 Three different abutments were fab-

ricated with conventional zirconia, a more

translucent zirconia (Prettau zirconia “translu-

cent”), and fluorescent colorants (Colour Liquid

Fluoreszenz): colored translucent zirconia with

fluorescence (transl + fluoresc) and without fluo-

rescence (translucent), and conventional zirconia

with fluorescence (zr + fluoresc). Natural light

reveals the chroma characteristics.

Fig 36 Fabrication of a fluorescent abutment:

(a) Provisional composite abutment; (b) duplicat-

ed zirconia abutment before the sinter process;

(c) dipping of the zirconia abutment into fluo-

rescent colorants before sintering; (d) definitive

abutment after sintering.

Fig 37 The three different abutments under UV

light. Conventional colored zirconia and fluoresc-

ing liquid (zr + fluoresc) reveal the most favora-

ble effect.

Case 3 Continued

GAMBORENA ANd BLAtz


The most favorable fluorescent effect

was achieved with colored convention-

al zirconia and fluorescing liquid.

In summary, the selection of zirconia

implant abutments should be based on

the following factors:

• 3D implant position: The screw-

access opening in the abutment

should not compromise mechani-

cal strength, and the circumferential

thickness should be at least 0.8 mm.

• Soft tissue thickness: A minimum of

3 mm is ideal.

• Interocclusal space: Sufficient abut-

ment height is required for ideal

strength and resistance.

• Implant abutment color: The order

of priority should be fluorescence/

value, translucency, and shade

(chroma and hue).

• Color of the intended crown restora-

tion (alumina versus zirconia).

For optimal stability and fit of the

coping, the preparation margin of the

implant abutment is generally a circum-

ferential chamfer or rounded shoulder.

On the labial aspect, the margin is typi-

cally placed deeper than on the palatal

aspect, but should not extend more than

1 mm subgingivally to avoid difficulties

during cement removal. The abutment

should support approximately 90% of

the total surrounding soft tissue con-

tour, with the crown supporting no more

than 10%.30

Fig 38 (above left) Intraoral try-in of the three

abutments under natural light.

Fig 39 (above right) Ideal soft tissue thickness

(> 3 mm).

Fig 40 (left) Intraoral try-in of the three abut-

ments under UV light.

Case 3 Continued

GAMBORENA ANd BLAtz


The provisional restoration generally

remains in place for 4 to 6 weeks until

the position of the tissue is stable. A

final impression of the abutment should

then be made to transfer this informa-

tion to the laboratory for fabrication of

the definitive restoration.

CROWN RESTORATION

The definitive crown material is se-

lected based on its core structure to

enhance the optical characteristics of

the intended restoration. The coping

is chosen by its ability either to mask

underlying structures or to complement

the underlying abutment color. zirconia

is increasingly used as a coping ma-

terial due to its versatility in respect to

strength, thickness, color, and translu-

cency, but especially due to its inherent

brightness and options for fluorescence

through infiltration.13–17,30 It seems only

logical that when a fluorescent abut-

ment is used, the material selected for

the definitive crown should also offer a

certain degree of fluorescence to match

the adjacent natural dentition.30–32 It is

important to evaluate the optical prop-

erties of the coping in relation to the

remaining natural dentition under differ-

ent light sources. UV light reveals the

dramatic effects of fluorescence, which

provides the vitality and brightness ex-

hibited by natural teeth.

Fluorescence is an inherent property

of natural teeth31,32 but is rarely found

in “esthetic” dental materials.33–40 In

natural teeth, the root and coronal den-

tin show the highest degree of fluores-

cence, especially in the gingival third,

while enamel has low fluorescent prop-

erties.30–32 Ceramic coping materials

such as alumina37 and zirconia39 do

not provide natural fluorescence and,

therefore, are treated with fluorescent

modifiers and/or veneered with fluores-

cent dentin stains, liners, and shoulder

porcelains.30,37,39 As in natural teeth,

the fluorescent effect is most prominent

in the gingival third of the restoration.

Therefore, natural fluorescence does

not only influence the optical effects of

the restoration itself, but also greatly in-

fluences the color and appearance of

the surrounding soft tissues.30

Figures 41 to 55 show the selection

of the definitive coping material and the

final outcome of Case 3. Figures 41 and

42 reveal the influence of fluorescent

stains on the value and chroma of alu-

mina and zirconia copings under natu-

ral and UV light. The impact of using a

fluorescent (Fig 43) versus a nonfluo-

rescent coping (Fig 44) is quite obvious

on the stone cast (Figs 45 and 46) and

even more so in the oral cavity (Figs 47

to 55). The definitive implant-supported

crown shows optical and fluorescent

properties that ideally match the exist-

ing natural dentition under various light

sources.

LIP LINE

A high lip line or “smile line” that reveals

all anterior teeth and large amounts of

gingival tissue7,8 is a great challenge

for the dental team since it is impossible

to hide the implant-restorative interface.

A high smile line may be due to vertical

maxillary excess or a hypermobile lip.

GAMBORENA ANd BLAtz


It is a common rule that, besides be-

ing symmetric, the most cervical aspect

of the gingival margins of the central in-

cisors should be at the same level as the

canines, while the margins of the lateral

incisors should be approximately 1 mm

below an imaginary line drawn from

the canine-centrals-canine.1 It seems

Fig 43 Definitive fluorescent abutment on the

stone cast demonstrating ideal fluorescence

under UV light.

Fig 44 Nonfluorescent coping on the cast

under UV light.

Fig 45 Fluorescent coping on the cast under

UV light.

Fig 46 Definitive crown showing fluorescent

properties under UV light.

Fig 41 The influence of fluorescent stains on

the value and chroma of alumina and zirconia

copings under natural light: (a and c) without

fluorescence; (b and d) with fluorescence.

Fig 42 Fluorescent properties of alumina and

zirconia copings under UV light: (a and c) without

fluorescence; (b and d) with fluorescence.

Case 3 Continued

GAMBORENA ANd BLAtz


advisable for central incisor implant

restorations to initially place the gingi-

val margin slightly more incisally. This

slight “overcompensation” will prove

extremely helpful to counterbalance

tissue recession typically seen over

time. The CTG now becomes an essen-

tial aspect for functional and esthetic

Case 3 Continued

Fig 48 Intraoral try-in under UV light demon-

strates ideal blending of the fluorescent properties

of the definitive crown with the adjacent teeth.

Fig 49 Definitive implant restoration.

Fig 51 (right) The definitive abutment and res-

toration provide the same degree of fluorescence

as a natural tooth.

Fig 47 Intraoral try-in of definitive crown under

natural light shows an excellent blend with the

shade of the adjacent teeth.

Fig 50 Postoperative occlusal view showing

the soft tissue support and contour.

GAMBORENA ANd BLAtz


integration of the implant-supported

restoration, especially in the presence

of a high lip line.

Occasionally, unfavorable changes

of the gingival margin levels may occur

at the teeth adjacent to the implant res-

toration. These are based on the dis-

tance between the free gingival margin

and the supporting bone and may re-

quire more extensive tissue grafting

to control gingival levels at both the

natural and implant-supported teeth.

The added connective tissue causes

the fibrotic mucosa around the implant

to migrate more coronally. In rare cas-

es, the additional soft tissue becomes

so abundant that a gingivectomy fol-

lowed by a fibrotomy becomes neces-

sary to establish ideal crown lengths

and gingival margin contours.

The unfavorable umbrella effect is

most prevalent in patients with a high

Fig 52 Postoperative view under natural light

showing the color match of the implant-supported

crown with the natural dentition.

Fig 53 Postoperative view under UV light

showing the ideal blend of fluorescent properties

between the restoration and natural dentition.

Fig 54 Postoperative intraoral situation. No gray zone is evident. Fig 55 One-year postopera-

tive peri apical radiograph of

the implant at the left central

incisor site.

Case 3 Continued

GAMBORENA ANd BLAtz


smile line.6 The gray zone may become

visible at the implant restoration site

even when all of the key factors are im-

plemented perfectly. Differences in soft

tissue thickness and volume may cause

these color dissimilarities, which are

then amplified by the shear presence of

the upper lip, causing a shadow on the

soft tissue and the light to be reflected

and transferred in a different manner.

Case 4 (Figs 56 to 61) demonstrates

a situation in which the maxillary left cen-

tral incisor was replaced with an implant-

supported crown in a patient with a high

Fig 56 Intraoral view of the definitive zirconia

abutment.

Fig 57 A CTG was placed earlier to ensure

ideal soft tissue thickness.

Case 4

Fig 58 Intraoral situation after 1 year reveals

differences in peri-implant soft tissue color and

morphology.

Fig 59 Preoperative view showing the patient’s

high lip line.

Fig 60 Postoperative situation. An unfavorable

gray zone is visible during an average smile.

Fig 61 A high smile reveals the gray zone

through the umbrella effect.

GAMBORENA ANd BLAtz


smile line. A CTG was placed to en-

hance the soft tissue contours. While all

of the key aspects were implemented

successfully, the slight differences in

soft tissue volume created an unfavora-

ble grayish effect (Figs 60 and 61).

In contrast to the previous case,

Case 5 (Figs 62 to 67) exemplifies

successful implementation of these

key factors in a patient with a high lip

line for long-term esthetic and func-

tional success.

Fig 62 Intraoral view of the crown prepara-

tion of the right central incisor and the definitive

colored zirconia implant abutment at the left

central incisor.

Fig 63 UV light reveals the natural fluores-

cence of the modified zirconia implant abutment.

Fig 64 Preoperative intraoral view of the failing

central incisor crowns.

Fig 65 Postoperative intraoral situation show-

ing the color and soft tissue match.

Fig 66 Initial situation. Note the high lip line. Fig 67 Successful implementation of the five

key factors prevented the appearance of a gray

zone despite the high smile line.

Case 5

GAMBORENA ANd BLAtz


CONCLUSIONS

Five key factors were identified to avoid

the gray zone around maxillary ante-

rior implant restorations: 3D implant

placement, soft tissue thickness, abut-

ment selection, crown restoration, and

lip line. Mimicking the inherent optical

properties, especially fluorescence, of

natural teeth with ideal prosthetic im-

plant components and crown materials

is fundamental for ultimate restorative

and soft tissue esthetics.

ACkNOWLEDGMENTS

The authors would like to thank Iñigo Casares for the beautiful porcelain work featured in this article and Fernando zozaya for the detailed fabrication on the zirconia abutments.

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17. van Brakel R, Noordmans HJ, Frenken J, de Roode R, de Wit GC, Cune MS. The effect of zirconia and titanium implant abutments on light reflection of the supporting soft tissues [epub ahead of print 20 Jan 2011]. Clin Oral Implants Res.

18. Garber DA. The esthetic dental implant: Letting restoration be the guide. J Am Dent Assoc 1995;126:319–325.

19. Grunder U. Crestal ridge width changes when placing implants at the time of tooth extraction with and without soft tissue augmentation after a healing period of 6 months: Report of 24 consecutive cases. Int J Periodontics Restorative Dent 2011;31:9–17.

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20. Linkevicius T, Apse P, Grybauskas S, Puisys A. The influence of soft tissue thickness on crestal bone changes around implants: A 1-year prospective controlled clinical trial. Int J Oral Maxillo-fac Implants 2009;24:712–719.

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23. Esposito M, Grusovin MG, Maghaireh H, Coulthard P, Worthington HV. Interventions for replacing missing teeth: Management of soft tissues for dental implants. Cochrane Database Syst Rev 2007;(3):CD006697.

24. Fürhauser R, Florescu D, Benesch t, Haas R, Mailath G, Watzek G. Evaluation of soft tissue around single-tooth implant crowns: The pink esthetic score. Clin Oral Implants Res 2005;16:639–644.

25. Att W, kurun S, Gerds T, Strub JR. Fracture resistance of single-tooth implant-supported all-ceramic restorations after exposure to the artificial mouth. J Oral Rehabil 2006; 33:380–386.

26. Nothdurft FP, Merker S, Pospiech PR. Fracture behaviour of implant-implant- and implant-tooth-supported all-ceramic fixed dental prostheses utilising zirconium dioxide implant abutments. Clin Oral Investig 2011;15: 89–97.

27. Scarano A, Piattelli M, Caputi S, Favero GA, Piattelli A. Bacterial adhesion on com-mercially pure titanium and zirconium oxide disks: An in vivo human study. J Periodon-tol 2004;75:292–296.

28. Rimondini L, Cerroni L, carrassi A, torricelli P. Bacte-rial colonization of zirconia ceramic surfaces: An in vitro and in vivo study. Int J Oral Maxillofac Implants 2002;17: 793–798.

29. Degidi M, Artese L, Scarano A, Perrotti V, Gehrke P, Piattelli A. Inflammatory infiltrate, microvessel density, nitric oxide synthase expression, vascular endothelial growth factor expression, and proliferative activity in peri-implant soft tissues around titanium and zirconium oxide healing caps. J Periodontol 2006;77:73–80.

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Determining the Influence of

Flowable Composite Resin

Application on Cuspal

Deflection Using a

Computerized Modification of

the Strain Gauge Method

Hamdi H. Hamama, BDS, MDS Assistant Lecturer, Conservative Dentistry Department, Faculty of Dentistry,

Mansoura University, Mansoura, Egypt.

Nadia M. Zaghloul, BDS, MDS, PhD Associate Professor, Conservative Dentistry Department, Faculty of Dentistry,


Ossama B. Abouelatta, BEng, MSc Engg, PhD

Associate Professor, Production Engineering and Mechanical Design

Department, Faculty of Engineering, Mansoura University, Mansoura, Egypt.

Abeer E. El-Embaby, BDS, MDS, PhD Lecturer, Conservative Dentistry Department, Faculty of Dentistry,


Correspondence to: Dr Hamdi H. Hamama

Conservative Dentistry Department, Faculty of Dentistry,

Mansoura University, PO Box 35516, Mansoura, Egypt.



49

This study evaluated the influence of the application of flowable composite resin

on cuspal deflection using a computerized modification of the strain gauge

method. Forty sound extracted mandibular molars, which received a mesio-

occlusodistal slot preparation, were divided into two groups of 20 molars each

based on the type of restorative materials used. Each group was further divided

into two subgroups of 10 molars each relative to the application of flowable

composite resin at cavity internal line angles. Cuspal deflection was measured

using a new computerized modification of the strain gauge method. The mean

cuspal deflection values (µm/m) and standard deviations were calculated and

subjected to normality and homogeneity of variances tests. If they passed the

tests, they were subjected to parametric statistical analysis (independent sample

t test). The results showed that groups containing flowable composite resin

exhibited higher cuspal deflection values than groups without flowable composite

resin. The application of flowable composite resin at the internal cavity line angles

increased cuspal deflection, possibly due to the material’s high volumetric

shrinkage levels, which exerted more stress at the tooth-restoration interface.

Further, the validity of the new computerized modification of the strain gauge

method was proven by the agreement found between the output results and those

of previous studies of cuspal deflection. (Am J Esthet Dent 2011;1:48–59.)

HAMAMA ET AL


Rapid development of resin-based

dental composites is one of the

main characteristics of modern esthetic

dentistry. Resin-based composite is now

widely used as an alternative to amal-

gam in stress-bearing areas.1 Consider-

ing the polymeric nature of composite

resin, it has an inherited volumetric po-

lymerization shrinkage property that

leads to contraction stresses at the

restoration-cavity interface.2 This poly-

merization shrinkage has been reported

to be one of the factors directly respon-

sible for marginal leakage at the com-

posite restoration–cavity wall interface.3

The interaction of the polymerization

shrinkage stresses and the adhesive

bond plays a large role in the long-term

function of a composite resin restora-

tion. At sites where these stresses are

higher than the bond strength between

the restoration and dental substrate, a

microgap will form, increasing the prob-

ability of postoperative sensitivity and

recurrent caries.4,5 On the other hand,

if the bond strength is higher than the

polymerization contraction stresses,

the stresses will transfer to the cusps,

resulting in cuspal deflection.2,6–8

A class of low-viscosity composite

resins, commonly called “flowable”

composite resins, has been commer-

cially introduced for restorative dentist-

ry. Flowability is regarded as a desirable

handling property because it allows the

material to be injected through small-

gauge dispensers, thus simplifying the

placement procedure and amplifying

the range of applications suggested

by the manufacturers.9,10 The effective-

ness of flowable composite resin as an

intermediate layer at the internal cavity

line angles is one of the most contro-

versial topics in dentistry. Some stud-

ies support its use due to its stretching

capability (ie, its low Young modulus

of elasticity), which provides sufficient

elasticity to relieve polymerization con-

traction stresses.5,10–14 In contrast,

some studies suggest that the appli-

cation of flowable composite resin in-

creases contraction stresses due to the

material’s high resin content.15–17

Cuspal deflection is a common bio-

mechanical phenomenon observed in

teeth restored with composite resin. It

results from the interactions between

the polymerization shrinkage stresses

of the composite resin and the com-

pliance of the cavity wall.18 There are

many methods to measure cuspal de-

flection, including noncontact methods

(photography,19 microscopy,20,21 laser

scanning,22 and three-dimensional

microcomputed tomography23) and

contact methods (strain gauge,6,24

interferometers,25 and linear vari-

able differential transformers26–29).

Because these methods depend pri-

marily on measuring the difference

between precuring and postcuring val-

ues, they have not provided detailed

data regarding how cuspal deflection

happens in relation to time. However,

the present authors introduce a modi-

fication of the strain gauge method,

which was developed in cooperation

between the engineering and dental

teams of this study.

This study was designed to evaluate

the effect of the application of flowable

composite resin on cuspal deflection of

mesio-occlusodistal (MOD) composite

restorations. Cuspal deflection was

HAMAMA ET AL


measured using the new modification

of the strain gauge method. The null

hypothesis was that application of flow-

able composite resin does not increase

the cuspal deflection of MOD compos-

ite resin restorations.

MATERIALS AND METHODS

The materials used in this study are

listed in Table 1.

Tooth selection and preparation

A total of 40 sound extracted mandibu-

lar molars were collected from the Oral

Surgery Department, Faculty of Den-

tistry, Mansoura University, Mansoura,

Egypt. The patients were informed that

the voluntarily donated extracted teeth

would be used for research purposes.

To be included in the study, the mo-

lars were required to have the following

crown dimensions: 9-mm buccolingual

distance and 10- to 11-mm mesiodistal

distance. The collected molars were

observed under magnification (×10) in

a binocular stereomicroscope (LOMO

SF-100 Binocular Stereo Microscope,

MBC-10). Teeth with preexisting cracks,

caries, or attrition were discarded. The

selected molars were carefully cleaned

using an ultrasonic scaler (UDS-J

Ultrasonic Scaler, Ningbo Sunglow Imp

& Exp) and then debrided with pumice

(Americos Industries) using a rotary

brush (Merssage Brush, Shofu). The

molars were disinfected with 0.2% so-

dium azide solution for 48 hours.30 To

prevent dehydration, they were stored

in physiologic saline for a period of no

more than 1 month at 37°C until the

time of the test.

The molars were randomly divid-

ed into two groups (20 molars each)

based on the restorative material used

(Tetric EvoCeram or Grandio). Next,

each group was randomly subdivided

into two subgroups (n =10) relative to

the application of flowable composite

resin at the internal cavity line angles.

Table 1 Composite resin systems used in this study

Material Scientific classification Trade name Batch no. Manufacturer

Composite resin

Restoration NanohybridTetric EvoCeram HB

Grandio

J13387 J14049

Ivoclar Vivadent VOCO

Restoration liner NanohybridTetric EvoFlow

Grandio Flow

K15010 Ivoclar Vivadent

VOCO

Bonding system

Filled, light-curing single component bonding agent for enamel and dentin in conjunction with the

acid etch technique

Etching gel containing 37% phosphoric acid

Excite

Total Etch

J25791 J25793

J25470 K20207

Ivoclar Vivadent

Ivoclar Vivadent

HAMAMA ET AL


Each specimen received a nonreten-

tive MOD slot preparation with the fol-

lowing criteria: occlusogingival depth

of 4 ± 0.3 mm without an axial wall and

a buccolingual diameter of 3 ± 0.3 mm.

The remaining buccal and lingual cav-

ity walls were measured using an elec-

tronic digital caliper (MAX-CAL) after

preparation for verification of the buc-

colingual diameter. The preparation

was carried out using a no. 59 carbide

bur (Komet Dental).

Cuspal deflection test

A 3-cm polyvinyl chloride tube was filled

with acrylic resin (Rapid Repair, Dent-

sply) in the dough stage. The molar’s

roots were positioned at the tube center

and parallel to its long axis, leaving the

crown and 2 mm of the root below the

cementoenamel junction uncovered to

accommodate the leads of the strain

gauge. A dental surveyor was used to

verify that the tooth was parallel to the

tube. After setting of the acrylic resin,

the parallelism of the cavity buccal

and lingual walls was confirmed by the

same surveyor.

All prepared cavities were etched

using Total Etch for 15 seconds accord-

ing to the manufacturer’s instructions.

Two precision strain gauges (KFG-2N-

120-C1-11L1M2R, Kyowa Electronic

Instruments) were attached to the buc-

cal and lingual surfaces of each unre-

stored specimen and bonded with

epoxy adhesive resin (Strain Gauge

Cement, Kyowa Electronic Instruments)

to the middle third of the cavity’s exter-

nal buccal and lingual walls (Fig 1). The

leads of the strain gauge indicator were

connected to the gauge so that the

gauge constituted one-half of a Wheat-

stone bridge, with the other half internal

to the strain gauge indicator. One layer

of the Excite universal bonding system

was applied and cured using a light-

curing unit (Bluephase C8, Ivoclar

Vivadent) at 800 mW/cm2 for 20 sec-

onds. The light intensity was checked

by radiometer (Bluephase Meter,

Ivoclar Vivadent) prior to performing

the test to confirm that the light inten-

sity was not less than 700 mW/cm2.

The teeth were restored with resin-

based composite materials in shade

A2 according to the following groups:

• Group A: Flowable composite resin

(Tetric EvoFlow) was applied at the

internal cavity line angles with a

small-gauge needle and cured for

20 seconds. Tetric EvoCeram was

inserted horizontally in increments.

Each increment was approximately

2-mm thick and cured for 60 sec-

onds: 20 seconds from the occlusal

aspect, 20 seconds from the mesial

aspect, and 20 seconds from the

distal aspect.

• Group B: This group was similar to

group A, except it did not receive

flowable composite resin prior to in-

sertion of Tetric EvoCeram.

• Group C: Flowable composite resin

(Grandio Flow) was applied at the

internal cavity line angles with a

small-gauge needle and cured for

20 seconds. Grandio was inserted

horizontally in increments. Each in-

crement was approximately 2-mm

thick and cured for 60 seconds: 20

seconds from the occlusal aspect,

HAMAMA ET AL


20 seconds from the mesial aspect,

and 20 seconds from the distal as-

pect.

• Group D: This group was similar to

group C, except it did not receive

flowable composite resin prior to in-

sertion of Grandio.

During polymerization, the strain

gauge recorded the changes in volt-

age signals, which were then amplified

by the recording system. The ampli-

fied signals were transferred using an

analog-to–digital converter (AD) card

to a specially designed computer pro-

gram (SIProg) for analysis. The results

appeared as a curve between the time

(seconds) and strain values. These

readings for the Wheatstone bridge

are directly proportional to the internal

cuspal deflection of the buccal and

lingual cusps of tested specimens.31

The present study is based on the data

range, ie, the difference between the

maximum and minimum strain values.

However, the data curves will be ana-

lyzed in detail in future studies.

Strain measurement system

The strain measurement system con-

sisted of a three-channel amplifier

circuit (Metrology Lab, Faculty of En-

gineering, University of Mansoura), an

AD card, and a personal computer with

the Strain Indicator Program (SIProg),

which was designed for this study by

Dr Abouelatta (Fig 2).

SIProg was fully written in house us-

ing Matlab packages. The main inter-

face is shown in Fig 3. It consists of

a title bar, menu bar, measuring infor-

mation panel, processing panel, option

panel, and display area. To calibrate

Fig 1 (above) Buccal view

of the strain gauges bonded to

the middle third of the external

cavity wall.

Fig 2a to 2c (right) The

strain measurement system.

Personal computerStrain indicator program

AD cardTooth fixation

3-channel amplifierCuring unit

a

b c

HAMAMA ET AL


the strain measuring system, specific

microstrain (με) values were applied

on a sample tooth. The strain meas-

urements were recorded using P-3500

Strain Indicators and SB-10 Switch and

Balance Units (Vishay Measurements

Group). The same values were record-

ed by the system in millivolts. A graph

representing the relation between the

strain measurement and correspond-

ing voltage was plotted using an Excel

spreadsheet (Microsoft).

Data analysis

Ten specimens were tested for each

group. SAS version 6.12 for Windows

(SAS Institute) was used for all statis-

tical analyses. The mean cuspal de-

flection values (µm/m) and standard

deviations were calculated and sub-

jected to normality and homogeneity of

variance tests. If they passed the tests,

they were subjected to parametric sta-

tistical analysis (independent sample

t test). All tests were two-sided analy-

ses, and differences were considered

statistically significant when P < .05

with a confidence level of 95%.

RESULTS AND DISCUSSION

The independent sample t test showed

a statistically significant difference (P <

.001) between flowable and nonflow-

able groups in both the buccal and lin-

gual cusps. This finding led to a rejection

of the null hypothesis. Specimens with

flowable composite resin had higher

cuspal deflection values than speci-

mens without flowable composite resin.

The results of the statistical analyses

are shown in Tables 2 and 3. Figure 4

shows an example of the output curves.

The mean cuspal deflection values

obtained from the buccal cusp for

flowable composite resin groups were

41.91 μm/m for Tetric EvoCeram and

44.59 μm/m for Grandio. The mean

cuspal deflection values of the non-

flowable groups were 32.64 μm/m and


Grandio, respectively. This showed

Fig 3 Graphical user interface of the Strain Indicator

Program (SIProg).

Title bar

Menu bar

Display area

HAMAMA ET AL


that groups without flowable composite

resin exhibited less cuspal deflection

than groups with flowable composite

resin (Table 2).

The mean cuspal deflection val-

ues obtained from the lingual cusp for

flowable composite resin groups were


21.73 μm/m for Grandio. The mean cus-

pal deflection values of the nonflowable

groups were 16.02 μm/m and 16.51 μm/m

for Tetric EvoCeram and Grandio, re-

spectively. This showed that groups

without flowable composite resin exhib-

ited less cuspal deflection than groups

with flowable composite resin (Table 3).

This study used two commercial

nanohybrid composite resin systems,

each with its own flowable composite

resin. This was done to exclude the

manufacturing factor and to avoid bias

toward one brand. The width of the buc-

colingual cavity was slightly larger than

that of an ideal clinical situation. This

was selected to decrease the remaining

buccal and lingual walls and increase

the sensitivity of the strain gauge. The

selection of a nanofilled universal two-

step etch-and-rinse adhesive system

was based on previous studies showing

that this system is the gold standard for

bonding with dentin. The advantage of

the new computerized measuring sys-

tem used in this study was that it provid-

ed accurate details about the process

of deflection in a curve format consist-

ing of peaks and valleys, which will be

further explained in future studies. The

Table 2 Comparison (t test) of cuspal deflection in specimens with and without flowable composite resin (buccal cusp)

P SE SDMean

(μm/m) NFlowable

compositeComposite

system

< .001*1.71 4.52 41.91 10 Yes

Tetric EvoCeram0.51 1.35 32.64 10 No

< .001*0.57 1.79 44.59 10 Yes

Grandio0.34 1.09 39.40 10 No

SE = standard error; SD = standard deviation. *Significantly different at P < .05.

Table 3 Comparison (t test) of cuspal deflection in specimens with and without flowable composite resin (lingual cusp)

P SE SDMean

(μm/m) NFlowable

compositeComposite

system

< .001*0.55 1.46 22.24 10 Yes

Tetric EvoCeram1.18 3.12 16.02 10 No

< .001*0.41 1.29 21.73 10 Yes

Grandio0.36 1.13 16.51 10 No

SE = standard error; SD = standard deviation. *Significantly different at P < .05.

HAMAMA ET AL


accuracy of measurements even when

based only on deflection range values

(difference between the postcuring and

precuring values) is more reliable than

with conventional measuring systems

because the data are automatically cal-

culated by SIProg. This new measuring

system also provides a large amount of

data storage and easy recall.

The results showed that the highest

levels of strain were produced during

exposure of the restoration to the light

source for polymerization. The high

stresses associated with the applica-

tion of flowable composite resin may

be explained by the material’s low fill-

er content and high resinous content,

which increases the polymerization

shrinkage.9,32–35 The strain levels did

not decrease during placement of the

restoration, and any stress relaxation

resulting from the flow of the material

was not sufficient to overcome the poly-

merization shrinkage.

The results support the findings of

previous studies. One study suggested

that flowable composite resins shrink

more than conventional composite res-

ins, creating more stress on the bond-

ing agent during curing and possibly

allowing for premature deflection of

the overlaying conventional composite

resin. The authors attributed this to the

difference in flexural modulus caused

by the changes in filler content.33 An-

other study disagreed with the concept

that shrinkage stress generated by a

subsequent layer of higher modulus

composite resin could be absorbed

by an elastic intermediary layer.17 A

review article on polymerization shrink-

age noted that flowable composite

resins produced stress levels similar

to those of nonflowable materials.36 In

addition, an in vitro study concluded

that the use of flowable materials does

not lead to marked stress reduction

and increases the risk of debonding

at the adhesive interface as a result of

polymerization shrinkage.37 Oliveira et

al38 strongly confirmed that using flow-

able composite resin as a liner or base

Fig 4 Sample of an output

curve drawn using SIProg.3630

3620

3610

3600

359010 20 30 40 50 60

Time (s)

Stra

in (µ

m/m

)

HAMAMA ET AL


material under a composite resin resto-

ration increases polymerization shrink-

age stresses at the adhesive interface,

potentially leading to adhesive failure.

Chuang et al39 concluded that the use

of flowable composite resin lining may

aggravate cusp flexure.

On the other hand, some studies did

not support the current results. One

study showed that the use of composite

resin liners with a low elastic modulus

was a satisfactory technique for partial

absorption of the stress generated by

polymerization shrinkage; however, this

study was performed using composite

resin blocks, which were not inserted

in prepared cavities.40 Another study

supported the inverse relationship be-

tween filler percentage and shrinkage

strain, which was explained by the cor-

responding decrease in the volume

fraction of monomers present to un-

dergo polymerization. The conclusion

of this study should not be generalized,

however, because it showed bias to-

ward two types of flowable composite

resins and ultimately stated that these

types still suffered from polymerization

shrinkage.41 Finally, a study introduc-

ing a new method of measuring cuspal

deflection reported that polymerization

shrinkage tended to decrease as filler

content increased. This study used a

noncontact cuspal deflection measur-

ing method based on a laser displace-

ment sensor; unfortunately, the validity

of noncontact measurements is still un-

der investigation.22

Based on the results of this study,

the null hypothesis that application of

flowable composite resin does not in-

crease cuspal deflection of MOD com-

posite resin restorations was rejected.

Further, the validity of the new comput-

erized modification of the strain gauge

method was proven by the agreement

of the results with those of other cuspal

deflection studies.

CONCLUSIONS

Under the conditions of this study, it

was concluded that the application of

flowable composite resin at the inter-

nal cavity line angles increased cus-

pal deflection, possibly due to the

material’s high volumetric shrinkage,

which exerts more stress at the tooth-

restoration interface. The limitation of

the new measuring system used was

the need to obtain two symmetric buc-

cal and lingual channels to be able to

judge whether the deflection occurs

simultaneously in both cusps or in one

cusp more than the other. This limita-

tion can now be addressed by the en-

gineering team of this study.

The use of flowable composite resin

is not preferred in MOD cavities be-

cause it increases internal polymeri-

zation stress, which leads to greater

cuspal deflection. Further investigation

is needed to carefully study the SIProg

output curves.

ACKNOWLEDGMENTS

The authors express their deepest gratitude and appre-ciation to Dr Geoff Smith, Center for Applied English Studies, The University of Hong Kong, for his work in revising the article’s language. They also thank VOCO for supplying the Grandio and Grandio Flow materials.

HAMAMA ET AL


REFERENCES

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11. Beun S, Bailly C, Dabin A, Vreven J, Devaux J, Leloup G. Rheological properties of experimental Bis-GMA/TEGDMA flowable resin composites with various macrofiller/microfiller ratio. Dent Mater 2009;25:198–205.

12. Lindberg A, van Dijken JMV, Hörstedt P. In vivo interfacial adaptation of class II resin composite restorations with and without a flowable resin composite liner. Clin Oral Investig 2005;9:77–83.

13. Roberson TM, Heymann H, Swift EJ, Sturdevant CM. Sturdevant’s Art and Science of Operative Dentistry, ed 5. St Louis: Elsevier Mosby, 2006.

14. Summitt JB. Fundamentals of Operative Dentistry: A Contem-porary Approach, ed 3. Chicago: Quintessence, 2006.

15. Stefanski S, van Dijken JW. Clinical performance of a nanofilled resin composite with and without an intermediary layer of flowable composite: A 2-year evaluation [epub ahead of print 23 Nov 2010]. Clin Oral Investig.

16. Gallo JR, Burgess JO, Ripps AH, et al. Three-year clinical evaluation of two flowable composites. Quintessence Int 2010;41:497–503.

17. Unterbrink GL, Liebenberg WH. Flowable resin composites as “filled adhesives”: Literature review and clinical recommen-dations. Quintessence Int 1999;30:249–257.

18. Lee MR, Cho BH, Son HH, Um CM, Lee IB. Influence of cavity dimension and restoration methods on the cusp deflec-tion of premolars in composite restoration. Dent Mater 2007; 23:288–295.

19. Segura A, Donly KJ. In vitro posterior composite polymeri-zation recovery following hygroscopic expansion. J Oral Rehabil 1993;20:495–499.

20. Alomari QD, Reinhardt JW, Boyer DB. Effect of liners on cusp deflection and gap formation in composite restorations. Oper Dent 2001; 26:406–411.

21. Suliman AA, Boyer DB, Lakes RS. Cusp movement in premolars resulting from composite polymerization shrinkage. Dent Mater 1993; 9:6–10.

22. Miyasaka T, Okamura H. Dimensional change measure-ments of conventional and flowable composite resins using a laser displacement sensor. Dent Mater J 2009; 28:544–551.

23. Sun J, Lin-Gibson S. X-ray microcomputed tomography for measuring polymerization shrinkage of polymeric dental composites. Dent Mater 2008; 24:228–234.

24. Meredith N, Setchell DJ. In vitro measurement of cuspal strain and displacement in composite restored teeth. J Dent 1997;25:331–337.

25. Suliman AA, Boyer DB, Lakes RS. Interferometric measure-ments of cusp deformation of teeth restored with compos-ites. J Dent Res 1993;72: 1532–1536.

26. Jantarat J, Panitvisai P, Palamara JE, Messer HH. Comparison of methods for measuring cuspal deformation in teeth. J Dent 2001;29:75–82.

27. Li JY, Fok ASL, Satterthwaite J, Watts DC. Measurement of the full-field polymerization shrinkage and depth of cure of dental composites using digital image correlation. Dent Mater 2009;25:582–588.

28. Pearson GJ, Hegarty SM. Cusp movement of molar teeth with composite filling materials in conventional and modified MOD cavities. Br Dent J 1989; 166:162–165.

29. Pearson GJ, Hegarty SM. Cusp movement in molar teeth using dentine adhesives and composite filling materials. Biomaterials 1987;8:473–476.

30. Dietschi D, Olsburgh S, Krejci I, Davidson C. In vitro evalua-tion of marginal and internal adaptation after occlusal stressing of indirect class II composite restorations with different resinous bases. Eur J Oral Sci 2003;111:73–80.

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31. Donly KJ, Wild TW, Bowen RL, Jensen ME. An in vitro investigation of the effects of glass inserts on the effective composite resin polymerization shrinkage. J Dent Res 1989;68:1234–1237.

32. Alvarez-Gayosso C, Barceló-Santana F, Guerrero-Ibarra J, Sáez-Espínola G, Canseco-Martínez MA. Calculation of contraction rates due to shrinkage in light-cured composites. Dent Mater 2004;20:228–235.

33. Bayne SC, Thompson JY, Swift EJ Jr, Stamatiades P, Wilkerson M. A characterization of first-generation flowable composites. J Am Dent Assoc 1998;129:567–577.

34. Kleverlaan CJ, Feilzer AJ. Polymerization shrinkage and contraction stress of dental resin composites. Dent Mater 2005;21:1150–1157.

35. Stansbury JW, Trujillo-Lemon M, Lu H, Ding X, Lin Y, Ge J. Conversion-dependent shrinkage stress and strain in dental resins and composites. Dent Mater 2005;21:56–67.

36. Braga RR, Ferracane JL. Alternatives in polymerization contraction stress manage-ment. Crit Rev Oral Biol Med 2004;15:176–184.

37. Cadenaro M, Marchesi G, Antoniolli F, Davidson C, Dorigo ED, Breschi L. Flowabil-ity of composites is no guarantee for contraction stress reduction. Dent Mater 2009;25:649–654.

38. Oliveira LCA, Duarte S Jr, Araujo CA, Abrahão A. Effect of low-elastic modulus liner and base as stress-absorbing layer in composite resin restorations. Dent Mater 2010;26: e159–e169.

39. Chuang SF, Chang CH, Chen TY. Spatially resolved assess-ments of composite shrinkage in MOD restorations using a digital-image-correlation technique. Dent Mater 2011; 27:134–143.

40. Cunha LG, Alonso RC, Sobrinho LC, Sinhoreti MA. Effect of resin liners and photoactivation methods on the shrinkage stress of a resin composite. J Esthet Restor Dent 2006;18:29–36.

41. Baroudi K, Saleh AM, Silikas N, Watts DC. Shrinkage behaviour of flowable resin-composites related to conversion and filler-fraction. J Dent 2007;35: 651-655.


All-Ceramic Crowns and

Extended Veneers in Anterior

Dentition: A Case Report with

Critical Discussion

Júnio S. Almeida e Silva, DDS, MSc

PhD Student, Operative Dentistry Division, Federal University of Santa Catarina,

Florianópolis, Brazil; Visiting Researcher, Department of Prosthodontics,

Ludwig-Maximilians University, Munich, Germany.

Juliana Nunes Rolla, DDS, MSc, PhD

Professor, Department of Conservative Dentistry,

Federal University of Rio Grande do Sol, Porto Alegre, Brazil.

Daniel Edelhoff, DDS, MSc, PhD

Associate Professor, Department of Prosthodontics,

Ludwig-Maximilians University, Munich, Germany.

Élito Araujo, DDS, MSc, PhD

Professor, Integrated Clinic, Federal University of Santa Catarina,

Florianópolis, Brazil.

Luiz Narciso Baratieri, DDS, MSc, PhD

Professor and Chair, Operative Dentistry Division,

Federal University of Santa Catarina, Florianópolis, Brazil.

Correspondence to: Dr Júnio S. Almeida e Silva

Goethestrasse 70 apt. 314, LMU Dental School, Munich, Germany 80336.



All-ceramic crowns and veneers have been used extensively in prosthodontics

with proven clinical success. The development of new reinforced ceramics has

led to a broader range of indications. Traditional veneer preparations are now

often replaced with extended defect-oriented preparation designs, ie, extended

veneers. However, although extended veneers can serve as an alternative to full-

crown preparations, they are not the best choice for all clinical situations. Choos-

ing correctly between all-ceramic crowns and extended veneers when restoring

the anterior dentition is crucial to achieving a conservative and long-lasting treat-

ment. This article addresses key evidence-based considerations regarding the

rehabilitation of the anterior dentition using all-ceramic crowns and veneers. Fur-

ther, a case report involving both types of restorations is presented. (Am J Esthet Dent 2011;1:60–81.)

61

Ceramic is known as the most

natural-looking synthetic re-

placement for missing teeth and is

available in a range of shades and

translucencies.1,2 In the past, due to

its relatively low tensile strength and

brittleness, ceramic was generally

fused to a metal substrate to increase

fracture resistance, and its indication

was limited to full-coverage crowns for

ALMEIDA E SILVA ET AL


both anterior and posterior dentition.3

However, the metal base compromises

esthetics by decreasing light trans-

mission through the porcelain and by

creating metal ion discolorations that

can cause significant darkening of the

surrounding gingiva. This is known as

the umbrella effect.4 To overcome such

problems, new ceramic systems and

innovative restorative techniques that

wed esthetics with function have been

introduced, along with scientific evi-

dence endorsing their clinical applica-

tion. As a result, all-ceramic systems

now represent an excellent restorative

alternative for fixed dental prostheses,

single crowns, and veneers in the an-

terior dentition.5,6

The successful clinical performance

of all-ceramic crowns and veneers has

been well established.6–12 However, the

combination of media-driven treatment

plans, rushed-to-the-market products,

and dentists eager to satisfy their pa-

tients’ esthetic demands have formed

a dangerous triad with little concern

for the risk/benefit calculus of den-

tal treatment.13 The resulting overuse

of ceramic veneers is likely a result of

these new reinforced ceramics, which

have a broader range of indications

and which have led to the replacement

of traditional veneer preparations with

extended defect-oriented preparation

designs. These extended veneers of-

fer an alternative to full crowns in the

anterior dentition.10,14–17

The remarkable clinical success of

all-ceramic veneers and crowns not-

withstanding,5,6 the restoration enters

into a restorative cycle as soon as it is

placed following tooth preparation.18,19

All-ceramic crowns have been used

extensively in prosthodontics over the

past few years because their clinical

success has been similar to that of

metal-ceramic crowns, with excellent

survival rates of 98.9% in the ante-

rior region after 11 years.5,6,13,20 The

main causes of failure include cata-

strophic fracture, chipping of the ve-

neer ceramic, and secondary caries.5

Although ceramic veneers are a mini-

mally invasive approach compared to

crowns, less tooth reduction does not

always result in increased longevity. It

has been shown that after 10 years of

clinical service, reintervention without

restoration replacement occurs in 36%

of teeth restored with ceramic veneers,

whereas 7% of teeth restored with ce-

ramic veneers might receive a more

invasive treatment approach.21,22 The

main reported causes of ceramic ve-

neer failure include fracture, microleak-

age, and debonding. That is to say,

ceramic veneers are more suscepti-

ble to future interventions; therefore,

it is crucial that the clinician be aware

of the correct indications for ceramic

veneers to provide the ideal result in

terms of longevity.19 Nevertheless, nei-

ther all-ceramic crowns nor traditional

ceramic veneers should always be the

first choice in the anterior dentition be-

cause several factors must be taken

into consideration before elaborating a

treatment plan.

This article addresses key evidence-

based considerations regarding the

rehabilitation of the anterior dentition

using all-ceramic crowns and veneers.

Further, a case report involving both

types of restorations is presented.



63VOLUME 1 • NUMBER 1 • FALL 2011VOLUME 1 • NUMBER 1 • FALL 2011

CASE REPORT

The following case report describes the

rehabilitation of the anterior dentition

with all-ceramic crowns and extended

veneers as well as two ceramic partial-

coverage restorations on the maxillary

left and right first premolars using leucite

glass-ceramic (IPS Empress, Ivoclar

Vivadent). The 29-year-old male patient

presented for esthetic rehabilitation of

the anterior teeth. Clinical and radio-

graphic examination revealed the pres-

ence of unsatisfactory Class III and IV

composite resin fillings, some of which

were associated with secondary car-

ies, discolored teeth due to root canal

treatment, and slight tooth misalignment

with length discrepancies in the ante-

rior dentition (Figs 1 and 2). Periodontal

evaluation found no pathologic probing

depths. Occlusal examination revealed

Fig 1 Preoperative labial view. Note the unesthetic appearance of the anterior dentition.

Fig 2 Preoperative palatal view showing proximal excess of the former composite resin fillings, es-

pecially on the mesial surface of the maxillary left central incisor.



normal Class 1 occlusion with function-

al canine and incisal guidance and the

presence of a slight anterior overjet. No

signs of parafunction were observed.

Both lateral incisors and the left cen-

tral incisor had been endodontically

treated, and their clinical crowns were

deeply compromised. For these nonvi-

tal teeth, fiber posts were cemented, the

pulp chambers were restored, and the

pre-existing Class III and IV compos-

ite resin fillings were replaced. The old

composite resin fillings of the remaining

vital teeth were replaced as well. Three

all-ceramic crowns were planned to re-

store the nonvital teeth. Extended ce-

ramic veneers were planned to restore

the anterior vital teeth, and each pre-

molar would receive a partial-coverage

ceramic restoration.

The decision to prepare the vital an-

terior teeth for extended veneers was

based on the extension of the pre-

existing composite resin fillings, which

further oriented the preparations pala-

tally.10 Moreover, since these ceramic

veneers would be placed adjacent to

ceramic crowns, an extended prepara-

tion allowed the crowns and veneers to

be made with the same ceramic. There

is usually an interproximal cosmetic mis-

match due to the differing thicknesses

of the adjacent restorations, which can

be corrected by the ceramist if extend-

ed veneer preparations are made.23

The maxillary premolars were included

in the rehabilitation because both had

unsatisfactory mesio-occlusodistal

composite resin restorations, which

were not only associated with second-

ary caries, but also showed enamel

cracks at the mesial and facial surfaces.

Although some of the composite resin

fillings were associated with secondary

caries, the patient did not present high

caries activity. Caries lesions were more

likely to be developed due to proximal

composite resin excess and poor bond-

ing of the former restorations; therefore,

removal of the pre-existing restorations

eliminated the source of microleakage

and secondary caries incidence.

Leucite glass-ceramic was the ma-

terial of choice because it allows for

adhesive cementation. All vital teeth

displayed plenty of enamel, and

even the nonvital teeth had prepara-

tion margins completely bounded by

enamel. Further, the longevity of this

ceramic system for both crowns and

extended veneers has been well estab-

lished.5,6,10,20 Finally, this esthetic ma-

terial was a feasible choice because

the patient did not present any para

functional habits.

Crown preparation

The first phase of the crown preparation

involved the use of a spherical diamond

bur, which was positioned 45 degrees

perpendicular to the tooth long axis on

the facial cervical area so that the reduc-

tion would end at half of the bur’s diameter

(Fig 3). A cylindric, tapered, round-end

diamond bur was used in the second

phase to create three facial reduction

grooves respecting the axial inclinations

of the tooth. The grooves were subse-

quently evened (Figs 4 to 6). The depth of

each reduction was constantly controlled

using the silicone guide. The final crown

preparations would be approximately

2.0 mm deep.



Fig 3 (right) First phase of crown preparation of the maxillary

left central incisor. The spherical diamond bur was positioned

45 degrees perpendicular to the tooth long axis.

Figs 4 to 6 (below) Second phase of crown preparation.

Facial reduction grooves were created respecting the tooth

axial inclinations.



The incisal reduction was carried out

in the third phase of the preparation.

Because the silicone guide registered

a pre-existing incisal space of approxi-

mately 1.5 mm according to the wax-

up, an additional 1.5-mm reduction was

performed with the cylindric, tapered,

round-end diamond bur to achieve a

3-mm incisal reduction (Fig 7).

The fourth phase consisted of the

interproximal and palatal wraparound.

A very thin and tapered diamond bur

was used to create a slit from the fa-

cial to palatal surfaces (Figs 8 and 9).

This maneuver created space for the

application of a larger bur for the wrap-

around (Figs 10 and 11). The palatal

surface was then reduced with the aid

of a spherical diamond bur positioned

parallel to the tooth long axis to create a

supragingival cervical groove (Fig 12).

Next, a cylindric, tapered, round-end

diamond bur and a rounded bur were

applied parallel to the tooth long axis

on the palatal surface and palatal con-

cavity, respectively, to create functional

room for the ceramic (Figs 13 and 14).

Following these reductions, the gross

preparation was completed.

Fig 7 Third phase of crown preparation. A 1.5-mm reduction

was still necessary to achieve the desired 3 mm. Incisal reduction

was performed using the same diamond bur used for the second

phase.



Special extra-fine finishing diamonds

with decreasing coarseness were used

along with rubber points to obtain a well-

refined preparation and working cast

(Figs 15 and 16). Finishing is essential

to eliminate sharp angles and undercut

and provide smooth contours.24 Well-

finished preparations reduce the risk of

postbonding cracks and facilitate the

technician’s work.25,26

Figs 8 to 14 Fourth phase of crown preparation, which consisted of the interproximal and palatal

wraparound.

Figs 15 and 16 Finishing

was carried out using extra-fine

diamond finishing burs with

decreasing coarseness.



Extended veneer preparation

The preparation sequence for the ex-

tended veneers was similar to that

described for the crown reductions.

However, veneer preparations are by

nature less invasive and do not involve

the entire palatal surface. The first

phase consisted of the use of a spheri-

cal diamond bur with a 1-mm-diameter

head. The diamond was positioned 45

degrees perpendicular to the tooth long

axis on the facial cervical area so that

the reduction would end at half of the

bur’s diameter, thus generating an ap-

proximate 0.5-mm depth reduction. A

cylindric, tapered, round-end diamond

bur was used in the second phase.

Three facial reduction grooves were

created respecting the axial inclinations

of the tooth, and the grooves were sub-

sequently evened. The interproximal

finish lines were extended to the linguo-

proximal line angle. If pre-existing resin

restorations are located at the prepara-

tion margins, the linguoproximal exten-

sion is extended deeper into the palatal

surfaces until the margins are on sound

enamel. The extended veneer prepara-

tions were then finished and polished

similarly to as described for the crown

preparations.

The completed preparations are

shown in Figs 17 to 19. The extended

Figs 17 to 19 Completed tooth preparations.



veneer preparations were kept slightly

supragingival because no discoloration

was shown for the vital teeth, whereas

the crown preparation margins were

kept in the intrasulcular space for es-

thetic reasons.

Provisionalization

Provisionalization was carried out with

acrylic resin–based restorations, which

were fabricated at the laboratory. The

provisional restorations (Fig 20) were

contoured so that a smooth emergence

profile could be achieved. The patient

was then able to floss under the connec-

tors of the provisionals. After 1 week,

the patient assessed the function and

esthetics of the restorations. Following

clinical evaluation of the function, pho-

netics, and esthetics, along with the

patient’s feedback, it was decided that

the definitive restorations should be at

least 1 mm shorter in length. A trans-

fer impression with the provisionals in

place was made and sent to the labo-

ratory along with instructions regarding

the definitive restorations.

Impression taking

Appropriate reproduction of the prepa-

rations, adjacent teeth, and surround-

ing soft tissues is mandatory. To obtain

Fig 20 Acrylic resin–based provisional restorations.



a high-quality impression, addition

silicone materials (polyvinyl siloxane)

are recommended due to their elastic-

ity and resistance to tearing. They also

allow multiple pours, which is an es-

sential requirement for fabrication of

adequate master casts.27

A double-cord technique was used

for gingival deflection. The cords were

soaked in astringent solution (25%

aluminum sulfate; Gel Cord, Pascal

International). Compression cord with

a small diameter (no. 00, Ultrapak, Ul-

tradent) was placed at the bottom of

the sulcus. Next, a more superficial and

thicker deflection cord (no. 0, Ultrapak)

was inserted in the entrance of the sul-

cus. Deflection of the gingival sulcus

was carried out for 4 minutes while the

deflection cord expanded due to wa-

ter sorption. With this technique, the

first compression cord must remain in

place during impression taking to seal

the sulcus and limit the flow of the crev-

icular fluid, whereas the deflection cord

is removed after deflection.

A one-step, double-mix impression

technique was carried out. The deflec-

tion cord was removed, and the gingi-

val sulcus remained deflected due to

its viscoelastic behavior. It is important

to emphasize that the deflection cord

must be wet during removal so that it

does not attach to the inner walls of the

gingival sulcus and cause bleeding. Af-

ter removal of the deflection cord, the

gingival sulcus was air dried, and the

light-body impression material was in-

serted throughout the gingival sulcus

to penetrate into the sulcus and slight-

ly beyond the preparation margins of

each tooth. Gentle air was blown on the

light-body material to ensure penetra-

tion into the sulcus. A full-mouth metallic

tray was loaded with the heavy-body

impression material, inserted into the

patient’s mouth for 5 minutes, and then

removed.

Definitive restorations

After 2 weeks, the patient returned for

placement of the definitive ceramic res-

torations (Figs 21 and 22). Try-in of the

definitive restorations must be carried out

before initiating the luting procedures. Af-

ter removal of the provisional restorations,

the preparations were cleaned with

pumice and dried. The transparent

try-in paste (Variolink II Try In, Ivoclar

Vivadent) was placed, and any excess

was removed with a spatula. The adap-

tation of the restorations was checked

with a probe, and the patient assessed

the esthetics of the final restorations with

the aid of a mirror.

Adequate surface treatment for both

the hard tissues and ceramic is crucial

to achieve successful bonding.5 The ce-

ramic restorations were placed on the

original stone die, and addition silicone

was manipulated and placed over them.

After setting, the addition silicone was

removed with the restorations attached

(Fig 23). This provided protection of the

glazed external ceramic surfaces and

facilitated the handling of the ceramic

during surface treatment. A hydro-

fluoric acid was applied at the inner

walls of the restorations for 60 seconds

(Fig 24). After rinsing, the ceramic resi-

dues and remineralized salts were elimi-

nated by applying phosphoric acid for

20 seconds, followed by rinsing and air



Figs 21 and 22 Leucite glass-ceramic restorations.



drying (Figs 25 to 27). Silane, a chemical

coupling agent, was applied with a mi-

crobrush to the inner surfaces of the res-

torations and left for 1 minute (Fig 28).

No rubber dam was used for adhe-

sive placement. Although total isolation

could be achieved for some teeth, other

abutments, especially those with crown

preparations and subgingival mar-

gins, did not allow proper isolation. The

cementation sequence depends on the

arrangement of proximal contact points,

which can be better controlled when all

teeth are isolated at the same time. A

relative isolation with retraction cords is

feasible and allows good isolation, es-

pecially for the maxillary anterior denti-

tion. Thus, relative isolation was used.

Compression cord was inserted at the

bottom of each tooth’s gingival sulcus

Figs 26 (above) and 27 (top right) The phosphoric acid was

rinsed off, and the restoration was air dried.

Fig 28 (bottom right) Silanization.

Fig 23 Removal of the addi-

tion silicone with the restorations

attached for surface treatment.

Fig 24 Etching of the inner

walls of the restorations with

hydrofluoric acid for 60 seconds.

Fig 25 Application of 35%

phosphoric acid to the inner

walls for 20 seconds.



(Fig 29), and surface conditioning of the

preparations was carried out following

the two-step etch-and-rinse strategy.

First, 35% phosphoric acid was applied

on the preparations and approximately

2 mm beyond the preparation margins

for 30 seconds on enamel and 15 sec-

onds on dentin, when such tissue was

present (Figs 30 and 31). After rinsing

and air drying (Fig 32), a dual-curing

adhesive (Excite DSC, Ivoclar Vivadent)

was rubbed against the preparation sur-

faces and a little beyond the surrounding

preparation margins, followed by gentle

air thinning, and was left unpolymerized

(Figs 33 and 34). A coat of the adhe-

sive was applied to the inner walls of the

restorations, which were then loaded

using the transparent paste of the light-

curing resin cement system (Variolink II,

Figs 29 to 32 Insertion of compression cord

and application of 35% phosphoric acid onto

each abutment tooth. Note that the entire ex-

tended veneer preparation is located within the

enamel shell.



Ivoclar Vivadent). Both restorations were

slowly seated by gentle finger pressure

along the insertion axis (Figs 35 to 37).

Gross excess of the resin cement was

eliminated with a spatula. The instru-

ment was guided using a cutting motion

parallel to the margin to avoid extraction

of resin cement from the marginal joint

(Fig 38). Flossing should be avoided

before light curing because it can dis-

locate or detach the ceramic from the

teeth. Light curing was performed at the

Fig 37 (left) Placement of the restoration with

gentle finger pressure.

Figs 33 and 34 Hybridization of the dental hard tissues and application of a dual-curing adhesive

system onto the maxillary right central incisor.

Figs 35 and 36 Application of a coat of adhesive onto the previously silanized ceramic restoration

and subsequent loading with the transparent paste of the light-curing resin cement.



facial, incisal, and palatal surfaces for

90 seconds at each surface (Fig 39).

Next, the gingival cord was removed

using dental pincers, and excess resin

cement was removed and chipped off

with a no. 12 surgical blade (Figs 40

and 41). Refined finishing and polish-

ing were performed at a subsequent

session. The cementation sequence is

shown in Figs 42 and 43. The final result

is shown in Figs 44 to 50.

Figs 42 and 43 Placement sequence.

Figs 40 and 41 Removal of the compression cord and scraping of the polymerized resin cement

with a surgical blade.

Figs 38 and 39 Removal of excess resin cement with a spatula, followed by light curing.



Figs 44 to 50 Final result.



DISCUSSION

To optimize the longevity of all-ceramic

crowns and veneers on anterior denti-

tion, the clinician must have a thorough

understanding of all patient-related fac-

tors, the quality of the remaining tooth

tissue, and the proper ceramic system

for the individual situation.5,16,17

Patient-related factors

Several patient-related factors can in-

fluence the survival of crowns and ve-

neers. As with any restorative approach,

patients with high caries activity do not

respond well to treatment because of

the high incidence of secondary caries,

especially if the preparation margins

are localized on dentin.28,29 For these

patients, any attempt to restore the an-

terior dentition with all-ceramic crowns

and veneers should only be made if

preventive and monitoring measures

have been carried out.30

Age matters. The longevity of all-

ceramic restorations can be compro-

mised in individuals over the age of

60.18 There may be an increased load

due to the lack of posterior dentition,

reduced salivary flow resulting from

the use of medication, and periodontal

problems that can weaken the stability of

the tooth. Because enamel thickness di-

minishes over time, ceramic restorations

in elderly patients also do not perform

as well because the cervical area of the

tooth may have little or no enamel.18,31

Root dentin exposure is common,32 and

thus the preparation margins are usually

localized on dentin, which is related to

microleakage incidence.33 Due to these

factors, extra attention and strong moni-

toring must be conducted for elderly

patients with all-ceramic restorations.

Patient compliance with the clinician’s

recommendations is also particularly

important in such cases.

Remaining tooth tissue

The amount and quality of remaining

tooth tissue is an essential factor when

choosing between all-ceramic crowns

and veneers in the anterior dentition.

During elaboration of the treatment

plan, the clinician must verify whether

the tooth is endodontically treated or

vital. If the tooth is nonvital, the need for

placement of intraradicular posts must

be evaluated, and the clinician should

bear in mind that a minimum of 1 mm

of sound dentin must be maintained

circumferentially as ferrule design af-

ter post placement.34 The presence

of darkened substrate is common for

nonvital teeth, and an extra reduction

of approximately 2 mm may be re-

quired to provide room for an esthetic

restoration.35,36 All-ceramic crowns

are superior to veneers for nonvital

teeth because they provide increased

strength, retention, esthetics, and lon-

gevity.35–37 However, stability of the

endodontically treated abutment tooth

can be diminished by the large amount

of tooth structure removed.5,6,37

Ceramic veneers should only be

chosen when bonding is a completely

feasible option, which means the more

enamel the better. The tooth prepara-

tion should be confined primarily with-

in the enamel shell or should display

a substantial (50% to 70%) enamel



area, especially at the preparation

margins.33,38 Debonding of ceramic

veneers has been reported to occur

when dentin comprises 80% or more

of the tooth substrate. In contrast,

debonding is highly unlikely when a

minimum of 0.5 mm of enamel remains

peripherally.13,33,38 Therefore, to avoid

microleakage and secondary caries, it

is crucial that the preparation margins

are bound by enamel and do not end in

composite resin fillings.18,39 Moreover,

partial adhesion to dentin or to exten-

sive composite resin restorations and

high load during static and/or dynamic

occlusion increase susceptibility to ce-

ramic fracture.18 If dentin is the main

bondable substrate or if there are ex-

tensive Class III and IV composite resin

restorations whose dimensions extend

beyond the crown, all-ceramic crowns

should be the first restorative choice.

Ceramic system

In a recent review conducted by Della

Bona and Kelly,6 it was concluded that

for veneers and crowns for single-rooted

anterior teeth, clinicians may choose

from any of the all-ceramic systems

available. However, the choice of ce-

ramic system is highly dependent on

the type of restoration (crown or ve-

neer), type of cementation (adhesive or

traditional), and esthetic and functional

demands.

Ceramic is particularly well suited for

veneer restorations and should be pri-

marily used with an additive approach

to restore missing enamel. Therefore, it

is paramount that the ceramic system

allows for surface treatment by etching

with hydrofluoric acid followed by silani-

zation prior to bonding to the tooth sub-

strate.13,36 Further, since esthetics is of

primary concern for the anterior denti-

tion, an adequate ceramic system for

veneers should have a relatively trans-

lucent core for the ceramist to build in

color intrinsically. Leucite glass-ceramic

and traditional feldspathic ceramic are

the two systems that best meet such

requirements.5,6,10,36

For all-ceramic crowns, a broader

range of systems can be used. Leu-

cite glass-ceramic and lithium-disilicate

glass-ceramic (IPS e.max, Ivoclar Vi-

vadent) are suitable for cases in which

adhesive bonding is possible. Leucite

glass-ceramics especially rely on the

bond strength between tooth and ce-

ramic and provide good esthetics with

proven longevity.5,6,12,20 Ceramics that

cannot be etched and bonded, such as

alumina- and zirconia-based ceramics,

are known as high-strength all-ceramic

materials due to their improved physi-

cal properties. These are best used in

patients with high functional or parafunc-

tional loads. On the other hand, such ce-

ramics present inferior esthetic features

compared to glass-ceramics. Alumina

and zirconia systems are recommended

for cases in which adhesive cementation

is not feasible.5,6 These systems, along

with monolithic lithium-disilicate crowns

for the posterior dentition, can be con-

ventionally luted with glass-ionomer or

zinc-phosphate cements, which are

less technique-sensitive than adhesive

cementation.32,40,41 Table 1 summarizes

the advantages and disadvantages of

all-ceramic crowns and extended ve-

neers in the anterior dentition.



Critical discussion of case report

Some specific aspects of the illustrated

case report should be discussed. Leu-

cite glass-ceramic was the material of

choice due to the possibility of adhe-

sive cementation since all vital teeth

displayed a sufficient amount of enam-

el. Even the preparation margins of the

nonvital teeth were totally bounded by

enamel. Finally, leucite glass-ceramic

has proven long-term results for both

crowns and extended veneers.5,6,10,20

Although the restorations can be con-

sidered esthetically successful overall,

a subtle value mismatch is evident be-

tween the maxillary right lateral incisor

and the remaining restorations. This

value discrepancy was not noticed dur-

ing try-in, most likely because the final

chromatic result of the cured resin ce-

ment can be different from that achieved

with the homologous glycerin-based

try-in paste.42 The value mismatch

might have been caused by a lack of

ceramic thickness due to insufficient

facial reduction during preparation.

Since extra reduction of endodontically

treated teeth is not recommended,43

the use of a lithium-disilicate glass-

ceramic system with adequate mask-

ing power (IPS e.max Press LT or MO)

could be an alternative to overcome the

insufficient masking ability of the leu-

cite glass-ceramic. Lithium-disilicate

glass-ceramic provides better strength

and responds better chromatically to

small thicknesses than does leucite

glass-ceramic in cases with discolor-

ed abutment teeth.5,44,45 If lithium-

disilicate glass-ceramic is selected to

mask the discolored abutment tooth,

the authors recommend restoring all

other teeth with the same system to

achieve a harmonic esthetic outcome.

Table 2 summarizes the indications for

all-ceramic crowns and extended ve-

neers in the anterior dentition.

Table 1 Advantages and disadvantages of all-ceramic crowns and extended veneers in anterior dentition

All-ceramic crowns Extended veneers

Tooth structure removal – +

Restoration stability + −

Abutment stability − +

Risk of discoloration due to abutment tooth + − / +*+ = recommended; – = not recommended*If translucent glass-ceramic is employed.



CONCLUSIONS

Restoring the anterior dentition with ce-

ramic is an excellent approach if the

correct treatment plan is developed.

Several patient-related and material

factors can determine the success or

failure of all-ceramic crowns and ve-

neers. Neglecting even a single step

of the restorative process can severely

compromise the treatment outcome.

ACKNOWLEDGMENTS

Special thanks to Wilmar Porfírio for manufacturing the ceramic restorations. The first author was supported by the Brazilian Federal Agency for Support and Evalu-ation of Graduate Education (CAPES) (grant no. BEX 2354101).

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