2003 - clinical procedures for predictable results

8/17/2019 2003 - Clinical Procedures for Predictable Results

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Ceramic Inlavs and Onlavs:Clinical Procedures for Predictable Results

A L F R E D 0 M E Y E R F I L H O , DD S , M S

L U I Z C L O V I S C A R D O S O V IE I R A , D D S ,MS, P H D ~

6 L I T O A R A U J O , D D S , M S , PH D *L U I Z N A R C I S O B A R AT I E R I , D D S ,M S , P H D ~

ABSTRACT

The use of ceramics as restorative materials has increased substantially in the past two decades.This trend can be att ributed to the greater interest of patients and dentists in this esthetic and

long-lasting material, and to the ability to effectively bond metal-free ceramic restorations to

tooth structure using acid-etch techniques and adhesive cements. The purpose of this article is to

review the pertinent literature o n ceramic systems, direct internal buildup materials, and adhesive

cements. Current clinical procedures for the planning, preparation, impression, and bonding of

ceramic inlays and onlays are also briefly reviewed. A representative clinical case is presented,illustrating the technique.

CLINICAL SIGNIFICANCE

When posterior teeth are weakened owing to the need for wide cavity preparations, the success of

direct resin-based composites is compromised. In these clinical situations, ceramic inlays/onlayscan be used to achieve esthetic, durable, and biologically compatible posterior restorations.

v Esthet Restor Dent 15:338-352,2003)

e restoration of posteriorT eeth with tooth-colored mate-rials is not a new trend in restora-

tive dentistry. Porcelain inlays were

used in the nineteenth century, but

the lack of an adequate adhesivecementing medium along with the

poor esthetics of those early porce-

lains yielded less than optimal

resu1ts.l In the early 1980s Simonsenand Calamia reported on the tech-

nique of resin composite adhesion

to porcelain by means of acid etch-

ing the porcelain surface with

hydrofluoric acid.2 The strong bond

afforded by this technique allowed

the first adhesive porcelain restora-

tions to be made on anterior teeth,

as reported by Ho rn in 1983.3 Theuse of dental ceramics to restore

posterior teeth was a logical conse-

quence of the success of these first

adhesive porcelain restorations. In

addition, the introduction in 1985of specific dental ceramics for use

in posterior teeth: as well as the

continuous development of ceramic

materials with improved mechani-

cal properties, allowed these mate-

rials to be used free of metal.5

New processing methods of dentalceramics include fabrication tech-

niques such as the lost wa x tech-

nique and centrifugal casting

(castable glass-ceramic), the pres-

sure injection of ceramic ingots

(pressable ceramics), and the

computer-aided design and manu-

*Gradua te student, Departm ent o f Operative Den tistry, and associate professor, Depa rtment of DentalClinics, Universidade Federal de Santa Catarina, Floriandpolis, Santa Catarina, BrazilProfessor, Department of O perative Dentistry, Universidade Federal de Santa Catarina, Floriantjpolis,

Santa Catarina, BrazilProfessor, Departm ent o f Dental Clinics, Universidade Federal de Santa Catarina, Floriandpolis, Santa

Catarina, Brazil

338 J O U R N A L O F E S T H E T I C A N D R E S T O R A T I V E D E N T I S T R Y


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M E Y E R F I L H O ET A I ,

facturing (CAD/CAM) of premanu-

factured ceramic b l o ~ k s . ~ , ~ heseinnovations have resulted in an

esthetic revolution and a height-

ened interest of dentists and

patients in the use of dental ceram-

ics for posterior restorations.

DIRECT VERSUS INDIRE CT

RESTORATIONS

Thanks to the development of

improved adhesives and resin-basedrestorative systems, resin composites

have become predictably successful

in the restoration of posterior

teeth.*-1° However, even wi th the

demonstrable improvements in

physical and mechanical properties,

the use of resin composites in a

direct technique should be restricted

to selected clinical application^.^^-^^Posterior teeth weakened owing to

wide mesio-occlusodistal prepara-

tions should ideally be restored

with materials capable of providing

structural support,14 which cannot

be achieved totally with directly

placed resin composites.15 In such

cases indirect restorations often are

indicated owing to their superior

mechanical qualities and improved

contour, anatomy, marginal adapta-

tion, interproximal contact, and

surface t e x t ~ r e . ~ ~ J ~lso, with an

indirect technique, there is less

polymerization shrinkage and, con-

sequently, reduced microleakage. 8

Another important criterion when

selecting the appropriate type of

material and restorative technique

is the number of teeth to be

r e ~ t 0 r e d . l ~ or example, in cases

where multiple large restorations

are to be done, particularly in the

same quadrant, it is easier, faster,and more economic to fabricate

them indirectly.

Indirectly made resin-based com-

posite inlays/onlays have achieved a

high level of technologic develop-

ment. This improvement in physical

and mechanical properties has

made choosing between the use of

resin composite o r ceramic moredifficult. 16,20,21 Ceramics possess

distinct advantages when compared

with resin composites. Generally

ceramics exhibit incomparable

esthetics, superior wear resistance,

and exceptional bond strength totooth structure when bonded adhe-

sively. Ceramic materials are similar

to tooth structure and best mimic

the natural tooth, allowing poste-

rior teeth with extensive structural

loss to recuperate up to 100 ofthe original rigidity of c ~ s p i d s . ~ ~ > ~ ~

This strengthening is due primarily

to the reinforcement imparted bythe st rong adhesion between etched

ceramic and the tooth structure.

Scheibenbogen an d colleagues

evaluated processed resin compos-

ite and ceramic inlays in posterior

teeth.24 The decision to restore

using either of the t wo materials

was influenced by the size of theisthmus. Preparations with a n isth-

mus width greater than two-thirds

of the intercuspal distance (large

preparations) were restored with

ceramics. Those with an isthmus

width smaller than two-thirds of

the distance between the cuspid tips

were restored with resin composite.

Notwithstanding this indication inless favorable situations, ceramic

inlays showed better clinical per-

formance than did composite^.^^

INDICATIONS AND

CONTRAINDICATIONS

Ceramic inlays and onlays are

indirect esthetic restorations that

involve par t of the clinical crown

of the tooth. Inlays involve occlusaland proximal tooth surfaces only,

whereas onlays are extended to

involve the cusps either partially or

totally. They are indicated where

esthetics and structural reinforce-

ment become primary requisites

and tooth preparation goes beyond

the recommended limits for direct

application of resin composites.

This is particularly true in cases

involving complex restorations or

mesio-occlusodistal preparations in

which the isthmus width covers half

or more of the distance between

cusp Onlays are also indi-

cated to restore optimal occlusionin caries-free teeth.26

Indications and contraindications

for ceramic inlays and onlays must

consider several factors, such as

structural integrity of the tooth,

cusp load capacity, and localization

of occlusal contact points. Posterior

adhesive ceramic restorations are

contraindicated for patients with

poor oral hygiene. Teeth exhibiting

gross wear or having insufficientdental structure for bonding also

are contraindicated, as are cases in

which adequate moisture control

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C E R A MI C I N L AY S A N D O N L AY S : C L I N I C A L P R O C E D I J RE S FO R P R E D I C TA B L E R E S U LT S

cannot be achieved. Teeth needing

significant color alterations also arenot candidates for ceramic onlays

when optimal esthetics is a requisite

since this degree of color change is

best obtained with all-ceramic

crowns.25 Teeth requiring conser-

vative classes I or I1 restorations

involving little extension also are

not indicated for ceramic inlays or

onlays and should be restored more

conservatively with direct resincomposites. The preparation for an

indirect restoration would remove

too much sound tooth structure to

provide the needed divergence.

For patients who exhibit parafunc-

tional activity (bruxism), ceramic

restorations should not be consid-

ered at unless the patient is

willing to use an occlusal bite-

guard.25 f the patient does not agree

to wear a biteguard, an indirect resin

composite restoration polymerized

in the laboratory would be a better

alternative considering the high inci-

dence of ceramic inlay fracture when

placed in patients who exhibit brux-

ism. A study published in 1994 by

Aberg and colleagues reported that

63.6 of fractured ceramic inlaysoccurred in patients with signs of

active b r ~ x i s m . ~ ~

B A SE A N D F I L L I N G M AT E R I A L S :

T H E I N T E R N A L B U I L D U P

An important factor t o be consid-

ered when planning an all-ceramic

inlay or onlay is the selection of the

material to be used as a base or

internal buildup, if needed. Bases

are employed in restorative den-

tistry for several reasons, such as

to protect the pulp and as a fillingmaterial to eliminate internal

undercuts. Mat and Cheung recom-

mend the use of a layer of glass

ionomer cement in vital teeth to

protect the exposed dentin and

minimize the possibility of postop-

erative sensitivity.28 However, other

authors consider this application

an unnecessary procedure when

an effective adhesive system isemployed in association with adhe-

sive cement^.^^.^În addition, glassionomer is not adequate for use as

a substrate for all-ceramic restora-

tions owing to its low compressive

strength. Therefore, its use should

preferably be limited to the correc-

tion of small irregularities and

undercuts in the pr e pa ra t i ~ n. ~~

Because of the brittle nature of

ceramic materials, they must be

bonded to a substrate capable of

supporting functional stress. For

this reason, base materials must

have high compressive strength.

When stress is applied to a system

composed of materials with differ-

ent elastic moduli, the larger par t

of stress is absorbed by the material

of greatest rigidity.32 If the substrate

has low compressive strength,fracture of the ceramic restoration

directly supported by that substrate

might occur when the critical ten-

sion limit of this material (0.1 offlexure) is reached. The compres-

sion load generated on the occlusal

surface is turned into tensile stresses

on the inferior surface of the restora-

tion, and if the substrate yields, the

ceramic fails. This failure mechanism

has been confirmed by Tsai andcolleagues in a study conducted to

analyze fracture modalities of glass-

ceramic disks of various thicknesses

supported by dentin-simulating

materials.33 Results confirmed the

initial hypothesis: when glass-

ceramic disks are supported by a

material having an elastic modulus

similar to tha t of dentin (lower than

that of enamel), the fracture startsat the inferior surface that is in con-

tact with the substrate. Scherrer

and de Rijk have observed that the

resistance to fracture offered by a

ceramic restoration became signifi-

cantly increased when the elastic

modulus of the support substrate to

which the restoration was attached

also was increased.34 n other words,

the more flexible the substrate,

the smaller the load necessary to

fracture the ceramic restoration

supported by this substrate.

According to Moscovich and col-

leagues, glass ionomer cements

currently available do not offer the

ideal mechanical properties to act

as a base for ceramic restoration^.^^The authors suggest that resin com-

posites should be used as bases

under ceramic restorations owing to

their greater modulus of elasticity.

S E L E C T I O N O F T H E C E R A M I C

S Y S T E M

Various ceramic systems have been

developed in the past few years in

an effort to improve the physicaland mechanical properties of these

materials. The majority of these



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M E Y E R F I L H O E T A L

materials are variations of tradi-

tional feldspathic porcelain rein-forced with the addition of metaloxides or by induced cry~tallization.~After firing, porcelain exhibits oneor more crystalline phases, usuallymade up of small alumina, leucite,or mica crystals, embedded in anoncrystalline amorphous matrix.These small crystals dispersed in theceramic structure are responsible

for the enhanced strength of thematerial; they retard the propaga-tion of cracks, which usually beginas a flaw in the material.36 Unfortu-nately, although the increased num-ber of crystals dispersed in the glassmatrix gives it greater strength, italso lessens the ceramic translu-cency. Ceramic materials with anessentially crystalline structuresuch as the In-ceram System@(Vita Zahnfabrik, Bad Sackingen,

Germany) have greater flexural

strength but are more 0paque.~~33~They also are acid resistant owingto their significant crystallinecomposition and the small amountof glass matrix available foracid etching5

The demand for esthetic restora-tions keeps growing, and consider-able research has been oriented

toward improving the propertiesof ceramics. To select the ceramicsystem best indicated for eachclinical situation, the dentistshould be familiar with the varioustypes available. Four types ofceramic systems are now used,including conventional feldspathicporcelains (fired ceramic), castableceramics, machinable ceramics(CAD/CAM), and pressableceramics (Table 1 ) .

TABLE 1 ALL-CERAMICS SYSTEM CLA SSIFICATION TO PRODUCE INL AYS AND ONLAYS.

lechniquea

Fired ceramic

Casta bleceramic

Machinableceramic

Pressa bleceramic

Procedums

Layering technique; restoration isbuilt up on refractory die usingpowder-water slurry

A glass made by lost-wa x techniqueand centrifugal casting, subsequentlyheat treated under controlledcrystallization (ceramming)

controlMilling ceramic ingot by comp uter

Pressing molten ceramic into a lostwax mold

The criteria for selection of appro-

priate ceramic systems should bebased on a combination of clinicalrequirements and material proper-ties. Three criteria are traditionallyconsidered: marginal adaptation,esthetics, and ~ t re ng t h .~

Marginal AdaptationLongevity of ceramic restorations islargely determined by resistance to

fracture, marginal adaptation, andwear resistance of the luting agent.A direct relationship exists betweeninitial poor marginal adaptationand dissolution of cement (withresultant microleakage). Thus, inselecting a ceramic system one mustconsider which will provide the bestadaptation (and smaller marginalgap) possible.3942 Interestingly,however, recent studies indicatethat the ceramic-resin interface is

Examples

Optec HSP@ Jeneriflentron,Wallingford, CT, USA)

Duceran LFC@ (Degussa,Bloomfield, CT, USA)

Dicor (Dentsply)

Cerec@Vitablocs Mark I and(Vident, Brea, CA, USA)

Dicor MGC@ Dentsply)

Optec O P P UeneridPentron)

IPS Empress

T Y W

Leucite-reinforcedfeldspathic porcelain

Hydromineral low-fusingporcelain

Mica-reinforced glassceramic

Feldspathic porcelain

Mica-reinforcedfeldspathic glass ceramic

feidspathic porcelain

feidspathic porcelain

Leucite-reinforced

Leucite-reinforced

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particularly fragile when the cement

is too thin; it has been proposedthat a 50 to 100 pm marginal gapis ideal to prevent wear of the

marginally exposed resin cement

and to preserve the a d h e ~ i o n . ~ ~ > ~ ~

Marginal adaptat ion of this magni-

tude can be considered excellent for

adhesively cemented ceramic

restorations and can be obtained

with any of the currently used

ceramic system^.^^^^T̂his factorwas confirmed in a study by Aberg

and colleague^.^^ No secondarycaries was detected on adhesively

cemented onlays in spite of 46

of the considered patients being ofhigh caries risk. The authors att rib-

uted this positive result t o shrink-

age and microleakage reduction

afforded by the indirect technique

owing to the fine cement film and

favorable marginal fit of these

ceramic restorations.

EstheticsMachinable ceramics (CAD/CAM

systems) available as colored pre-

fired blocks make it possible to pro-

duce restorations with satisfactory

esthetics in posterior teeth; how-

ever, they require special equipment

and can be quite ~o st ly .4 ~

Castable ceramics (Dicor@,

Dentsply/Caulk, Mildford, DE,

USA), supplied in the form of

shaded glass ingots, produce

ceramic restorations that are ini-

tially made as a glass by the lost-

wax technique and centrifugal

casting. They subsequently undergo

devitrification with a heat treat-

ment (ceramming) o convert theminto a stronger crystalline body

that possesses high translucency.6

Surface staining is used to obtain

the final shade and characteriza-

tion. If there is a need for occlusal

adjustment after inlay/onlay

cementation, these surface stains

can be lost, resulting in compro-

mised esthetics.

The conventional manufacturing

of ceramic restorations by fusing

porcelain in a refractory cast pro-

duces the most esthetic dental

restorations. However, this is a

technique-sensitive procedure that

requires a skilled dentist and techni-

cian to produce a high-quality result.

The IPS Empress@ ystem (IvoclarVivadent, Schaan, Liechtenstein)

produces equally esthetic restora-

tions in a simpler way through a

lost-wax technique of fabrication.This simplicity in fabrica tion is

largely responsible for the resur-

gence in popularity of all-ceramic

restorations in recent years.

Strength

Studies conducted with various

ceramic systems point t o fracture asthe main cause of ceramic restora-

tion f a i l ~ r e . ~ ~ - ~ ~racture resistance

of a dental ceramic is one of themost important factors for success

for inlays/onlays. Fracture resis-

tance depends on the ability of the

material to inhibit crack initiation

and propagation. Crack initiation is

controlled by the surface condition

of the material, whereas resistance

to propagation of the defect isdetermined by the inner structure of

the materiaLs4 Strength tests are

often employed but are highly influ-

enced by the fabrication process of

the sample and by the methodology

used, and do not always simulate

the clinical mode of f a i l ~ r e . ~ ~ . ~ ~

Thompson and colleagues obtained

stress failure resistance values in

vivo of approximately half thosereported for in vitro tests with the

same material (Dicor glass-

ceramic).57 The development of

flaws at the time the ceramic is

processed or when the restoration is

placed in the mouth might reduce

resistance to fracture, meaning

smaller forces would be required to

cause failures.

Fired ceramic restorations present

porosities with the inherent poten-

tial to initiate crack formation as

a result of the sintering process.6

These porosities can be minimized

through restoration fabrication

processes involving casting in place

of ~intering.~ ven so, cast ceramicsystems such as the Dicor glass-

ceramic that require subsequent

ceramming might still experience

porosities as a consequence of this

p r o c e ~ s . ~ AD/CAM ceramic sys-tems using premanufactured and

precerammed blocks do not have

these fabrication problems.58

In the IPS Empress system, glass-

ceramic is supplied in the form ofingots, similarly precerammed and



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M E Y E R F I L H O E T AL

preshaded. The restoration is pro-

duced with the lost-wax techniqueand pressure injection of the melted

ceramic. Subsequent heat processes

for surface pigmentation or lamina-

tion do not produce porosities and,

in addition, increase the strength of

this material.s9

Understanding the multiple factors

that interfere with the clinical per-

formance of a ceramic restoration isimport ant in ensuring its success. In

addition to material properties and

failures induced by restoration fab-

rication, other factors also must be

considered to reduce stress and frac-

ture of ceramic restorations. Among

such factors are the elastic modulus

of the base material, ceramic thick-

ness, cavity preparation design,

cement selection, adhesion proce-dures, and surface polishing.60

C L I N I C A L P R O C E D U R E S

Tooth Preparation

Correct tooth preparation for

ceramic inlays and onlays is critical

to achieving a lasting restoration.

Ceramic restorations are extremely

fragile before adhesion. Conse-

quently, the principles guiding this

procedure are different from those

for gold restorations.

Because of the inherent fragility

exhibited by this material, three pri-

mary requirements are important

when preparing a tooth for ceramic

restorations of this type: ( 1 ) avoid-ance of internal stress concentration

areas, (2) provision for adequate

thickness of ceramic, and (3 )creationof a passive insertion axis. Internalstress concentrations can be avoided

by eliminating undercuts of the pre-

pared surface and by rounding

internal line a ng l e~ .~ O- ~ ~ eramic

strength is proportional to its thick-

ness but only up to a certain point.

A study has shown that ceramic

thickness > 2 mm increases therisks of pulp damage (deeper pre-

paration) without significantlyenhancing the restoration fracture

strength.62 Therefore, a uniform

2.0 mm occlusal thickness is con-sidered ideal for ceramic inlays and

also for onlays involving functional

cusps.25>60-63 he occlusal prepara-

tion floor must present a shallow

V shape following the anatomy ofthat surface.64 Axial reduction

allowing a uniform thickness of

1.5 mm for the restora tion is suffi-cient for any of the currently used

ceramic systems.65 Passive insertion

axis is determined by the inclina-

tion of the preparation walls, which

must be more inclined than those of

gold inlay ~/onl ays.~~ t is important

to remember that the ceramic

restoration does not bend or giveduring the seating for try-in. A

divergence between opposing walls

of about 10 is sufficient to attain

this requisite without the unneces-

sary removal of sound tooth struc-

t ~ r e . ~ ~n addition, cavosurface

angles must be 90° with the cervi-cal margin ending in a deep cham-

fer or a butt joint. Occlusal bevels

should be avoided since they reduce

porcelain thickness in a region

where the restoration is subject to

strong occlusal stress.66 n cases inwhich the cusps are weakened, the

preparation must cap these cusps to

reduce the risk of postoperative

porcelain or cusp fra~ture.60361,~'

Cement Selection and

Bonding Procedures

As already noted, fracture strength is

the most important factor affecting

longevity of ceramic inlays/onlays.All ceramic restorations luted with

zinc phosphate cement are subject

to stress concentrations in localized

areas during function, creating a

fracture potential of the material.

The use of adhesive cements ca-

pable of adhering tooth structure

and ceramic results in a stronglybonded restoration that is much

more resistant to fracture.

Hydrofluoric acid is used to selec-

tively dissolve the glass matrix, cre-

ating microporosities around the

leucite crystals. Low-viscosity adhe-sive resins applied to this condi-

tioned surface fill these microscopic

areas, creating a strong microme-

chanical bond between resin and

p o r ~ e l a i n . 3 ~ > ~ ~ilane coupling

agents are adhesion promoters

capable of forming chemical bonds

with organic and inorganic sur-

faces. Bonding to the resin occurs

by an additional polymerization

reaction between methacrylate

groups of the matrix resin and the

silane molecule during curing of thecomposite. The bond with ceramics

occurs via a condensation reaction

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between the silanol group (Si-OH)

of the ceramic surface and thesilanol group of the hydrolyzed

silane molecule, creating a siloxane

bond (Si-0-Si) and producing a

water molecule (H20) b y p r ~ d u c t . ~ ~

Silanes also enhance porcelain-resin

bonds by promoting the wetting ofthe ceramic surface, thus making

the penetration of the resin into themicroscopic porosities of the acid-

conditioned porcelain more com-~le te .~O he use of the hydrofluoric

acid and a silane coupling agent

enhances this union and constitutes

the most effective ceramic surface

treatment, allowing maximum

adhesive p~ te nt ia l . ~O -~ ~ his adhe-

sion mechanism associated with the

development of new resin cements,

dental adhesive systems, and

ceramic materials has significantlyimproved the clinical success of

ceramic inlays/onlays.

Adhesive cements commonly used

for ceramic restorations include

conventional or resin-modified

glass ionomer cements, and dual-

cured or chemically cured resin-

based cements. Glass ionomer

cements offer some apparent

advantages, such as chemical bond

to enamel and dentin, relatively

low solubility in the oral environ-

ment, and release of fluoride.27

However, bond strengths between

glass ionomer cements and acid-

etched ceramics are lower than

those found between resin cements

and ceramics.53 Clinical and labora-

tory studies point to a low fracture

strength of ceramic restorations

cemented with glass ionomer

cements compared with resincements, particularly for inlays fab-

ricated with feldspathic porcelain

(fired ceramic); they are therefore

not r e ~ o m m e n d e d . ~ ~ , ~ ~ , ~ ~ , ~ ~

Resin-modified glass ionomer

cements have been used as an

alternative to conventional glassionomer cements because of their

superior mechanical properties.Recent short-term clinical studies

found the clinical performance of

resin-modified glass ionomer

cements to be similar to that of

resin-based However,

another study revealed a lower

cohesive strength compared with

that of composite resin cements.76

Regarding fluoride release, it is

important to mention that the

effective period of fluoride release

may be too short to have clinical

i m p ~ r t a n c e . ~ ~

Table 2 summarizes the requisitesof an ideal adhesive cement for

inlays/onlays. If no material can befound exhibiting the desirable prop-

erties listed in Table 2 , the adhesivecement selection must take into

consideration the most important

properties affecting the specific

clinical ~it uat ion .'~

Resin-based composite cement's

ability to adhere to multiple sub-

strates, biocompatibility, high

strength, insolubility in the oral

environment, and esthetic potential

make it the best choice for use with

ceramic inlay don lay^.^^Also, the

fact that it penetrates microscopic

irregularities such as aroundleucite crystals allows it to create a

strong micromechanical bond that

increases fracture resistance of

both tooth and

Resin cements are divided into

three groups: light, chemical, and

dual activated. Light-activated

agents can be used for cementing

indirect restorat ions if the light cur-ing time is extended.81 However,

on posterior ceramic restorations,

thickness, color, and opacity level

make polymerization difficult

and, consequently, may negatively

affect the cement microhardness

owing to the limitations in light

p e n e t r a t i ~ n . ~ ~ - ~ ~

Dual-cured resin-based cements are

the most frequently used to cement

ceramic inlayslonlays (Table 3) .80This preference is explained by the

fact that these materials have the

TABLE 2 REQUISITES OF A N IDEAL

LUTING CEMENT

Adhesion to tooth structure and tothe restorative material

dislodged by functional loadsSufficient resistance not to be

Adequate film thickness

Insolubility in oral fluids

Optica l properties similar to thoseof dental tissues

Adequate viscosity

Biocompatibdity

Anticariogenic potential

Easy o handle

Adapted from Cnrdash HS a l. '

344 J O U R N A L OF E S T H E T I C A N D R E S T O R A T I V E D E N T I S T R Y


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7.

8.

9.

damp cotton pellet leaving the

substrate slightly moist.Apply a thin layer of the adhe-

sive system to both substrates

(restoration and preparation) in

accordance with instructions

given by the manufacturers of

the resin cement.

Apply the resin-based cement to

both the restoration and the

preparation; seat the restoration

with slight pressure.Remove gross excesses of

cement from the margins with

a microbrush.

10. Cure the cement for 60 secondsin each direction (facial, lingual,

and occlusal) using a light-curing

unit with a minimum power of

450 mW/cm2. A clear glycerin-based gel may be applied to all

accessible margins t o preventthe occurrence of the oxygen-

inhibited resin layer.

11. Remove residual excess cement,using either a probe or a no. 12

blade held in a Bard Parker sur-

gical handle.

Occlusal Adjustment and PolishingCeramic restorations frequently

need occlusal adjustments following

cementation. Unfortunately, this

step introduces minor defects on

the restoration surface, increasing

the abrasion potential against

opposing tooth and introducing

flaws to the ceramic. Final polish-

ing can be achieved with intraoral

instrumentation using diamond-

impregnated finishing points and

uolishing gels.88 Addine glaze to

surfaces has been found t o make

the restoration. more resistant t ofracture; however, this step is not

possible when occlusal adjustment

must be made.89

C A SE R E P O R T

This clinical case illustrates the

potential of the described inlay/onlay

ceramic techniques in generating a

natural-looking restoration in a

compromised posterior tooth. Thepatient was a young female with a

large mesio-occlusodistal amalgam

restoration in her mandibular left

first molar. An occlusal amalgam

restoration was present in the left

second molar (Figure 1 . Afterplacement of a rubber dam, the

amalgam restorations and carious

tissues were removed (Figure 2).Structural reinforcement of the first

molar was a primary requisite; the

selection was made for a ceramic

inlay. To eliminate internal under-

cuts, a hybrid resin composite

(Z250@, M ESPE, St. Paul, MN,

USA) was selected and applied inincrements (Figure 3) . After internalbuildup was placed, the cavity was

prepared to the proper cavity form

(Figure 4 . Impressions were made

Figure 1 . Unsatisfactory large m esio-occlusodistal am algamrestoration on the mandibular left first molar; an occlusalamalgam restoration is present on the second molar.

Figure 2. A rubber dam i s installed, andthe amalgam restoration and carioustissue are remove d.

Figure 3 . The selected hybrid resinisapplied in increments.



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resin cement (Rely X ARC@, 3M

ESPE)was used (Figure 10).

The final view of the restoration

before occlusal adjustments is pre-

sented in Figure 11. Figure 12shows the restoration at a 1-month

follow-up appointment. A direct

resin-based composite restoration

Figure 6. A rubber dam is placed andthe ca vity is cleaned.

was performed in theleft second molar.

Figure 7. Enamel and dentin are etchedwith 35 phosp horic acid gel.

C O N C L U S I O N

Considering patients’ growing

demands for esthetic restorations,

the dent ist of the new millennium

should be aware of the need for a

“biomimetic” restorative materia l

such as denta l ceramics. Restorative

materials of this type are biocom-

patible, capable of resisting occlusal

forces, and exhibit favorable wear

characteristics. Bonded ceramic

restorations represent a n excellent

alternative for restoring posterior

teeth esthetically.Figure 8. Adhesive is appliedon theprepared teeth with a microbrush.

Figure 9. Th e adhesive s light cured.

Figure 10. Dual-cured resin cement is used as thecementation medi um. adjustments is seen.

Figure 11. T he final restoration prior to occlusal



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M E Y E R F I L H O E T A L

Figure 12. Illustrated is the restoration a t the 1 -monthfollow-up appointment. Note also a direct resin-based

composite restoration in the mandibular leftsecond molar.

D I S C L O S U R E A N DA C K N O W L E D G M E N T

The authors thank Edson Araiijo,

DDS, MS, for assistance in theoperatory procedures shown here,

Skrgio Araiijo, CDT, for the use of

IPS Empress, and Andrk Ritter, DDS,MS, and Harald Heymann, DDS,MEd, for their editorial assistance.

The authors do not have any finan-

cial interest in any of the materials

discussed in the manuscript.

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