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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
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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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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. '
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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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C E RA M I C I N L A Y S AN D O N L A Y S : C L I N I C A L P R O C E D U R E SF O R P R E D I C T A B L E R E S U L T S
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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