302THE INTERNATIONAL JOURNAL OF ESTHETIC DENTISTRY
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CLINICAL RESEARCH
Restoration of discolored
endo dontically treated anterior teeth:
a minimally invasive chemo-
mechanical approach
Filippo Del Curto, Dr
Assistant, University Clinics of Dental Medicine, Division of Cariology and Endodontology,
University of Geneva, Geneva, Switzerland
Private Practice, Geneva, Switzerland
Giovanni Tommaso Rocca, Dr med dent
Chef de Clinique Scientifique, University Clinics of Dental Medicine,
Division of Cariology and Endodontology, University of Geneva, Geneva, Switzerland
Private Practice, Morges, Switzerland
Ivo Krejci, Prof Dr med dent
President, University Clinics of Dental Medicine, and
Director, Division of Preventive Dental Medicine and Primary Dental Care, and
Chairman, Division of Cariology and Endodontology, University of Geneva,
Geneva, Switzerland
Correspondence to: Dr Filippo Del Curto
University Clinics of Dental Medicine, Division of Cariology and Endodontology, University of Geneva, 1, rue Michel-Servet,
1211 Genève 4, Switzerland; Tel: +41 223794100; Email: [email protected]
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Abstract
In the case of discolored devitalized
anterior teeth, several treatments are
available to enhance the esthetic out-
come, from noninvasive external/internal
bleaching to freehand resin composites
and more complex prosthetic solutions
such as veneers or full crowns. Innova-
tive computer-aided design/computer-
aided manufacturing (CAD/CAM) chair-
side technologies and the introduction of
new industrially polymerized composite
resin blocks coupled with modern adhe-
sive strategies have reduced both bio-
logical and financial costs compared to
the classic post-core-crown approach.
The aim of this article is to show how
these new materials can be used in as-
sociation with noninvasive internal and
external tooth bleaching to restore a
discolored, fractured, non-vital central
incisor.
(Int J Esthet Dent 2018;13:302–317)
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discoloration such as traumatic shocks,
which provoke pulp hemorrhaging and
root resorption, as well as iatrogenic
causes such as fluorosis and tetracy-
clines. Internal causes of discolora-
tion are changes in normal tooth shade
caused by dentinal caries and dental
restorations, especially metallic ones.
For anterior teeth, the origin of a discol-
oration is frequently associated with a
loss of tooth vitality or with an endodon-
tic treatment. The many chemical prod-
ucts used during root canal disinfection
and obturation can be identified as po-
tential causes of discoloration (irrigating
solutions, root canal cements, intracanal
medicaments).1
Traditionally, discolored devitalized
teeth were covered by porcelain fused to
metal (PFM) full-ceramic crowns, which
are usually based on a core anchored
in the root by an endodontic post. The
presence of a metallic or high-strength
opaque ceramic coping over the dis-
colored core of the tooth and beneath
the esthetic ceramic masks the core
discoloration and ensures the esthetic
outcome. During the past 40 years, sev-
eral in vivo studies have confirmed the
effectiveness of this technique.2,3 How-
ever, this approach is invasive, both for
the crown and the root, exposing the
tooth to a higher risk of fracture. More-
over, the fabrication of a crown involves
many steps such as postcementation,
core buildup, a temporary crown, and
potential crown lengthening, which in-
creases treatment time and costs. With
the advent of adhesive techniques, the
indications for crowns have been recon-
sidered, and today, therapeutic options
for devitalized teeth based on adhesive
strategies are available. The main reason
Introduction
Esthetic needs of dental patients have
continuously increased over the years.
In industrialized countries, people of
both genders and all ages are constant-
ly confronted with information from the
media that tells them that the way to suc-
cess is through a healthy, beautiful, and
‘white’ smile. The result of this propagan-
da is that esthetics is considered a must
in dentistry today.
A beautiful smile can be jeopard-
ized by tooth and gum disease (caries,
trauma, gingivitis), by tooth and bone ar-
chitecture (orthodontic problems), and
by tooth discoloration. Tooth discolora-
tion (dyschromia) has been widely de-
scribed in the scientific literature and
can be due to extrinsic, intrinsic, and
internalized discolorations.1
Extrinsic causes of tooth discolora-
tion are always associated with extrinsic
direct stimuli such as tea, coffee, ciga-
rettes, plaque, and poor oral hygiene.
Teeth can also be indirectly stained, eg,
by chlorhexidine. All of these agents
concern only erupted teeth. However,
both erupted and non-erupted teeth
can be affected by intrinsic causes of
Fig 1 Patient’s initial condition. Tooth 11 appears
discolored and darker than tooth 21.
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DEL CURTO ET AL
for this paradigm shift is the availability of
efficient adhesive systems that allow for
a more conservative approach as they
do not require any mechanical retention.4
However, the partial or total preserva-
tion of the visible parts of the discolored
tooth is not always an esthetic benefit. In
the case of intrinsic and visible discol-
oration, achieving good esthetics with
minimally invasive restorations can be
a challenge. Thus, the combination of
partial adhesive restorations with chem-
ical bleaching techniques may become
mandatory to obtain satisfactory esthetic
results. This article describes a clini cal
case where bleaching was combined
with a partial indirect adhesive compos-
ite restoration.
Clinical step-by-step
procedure
The presented case was a 25-year-old
male who required emergency treatment
due to the loss of a fragment of tooth 11,
which was previously reattached after
trauma in childhood. The tooth was non-
vital and displayed a non-esthetic dys-
chromia in its coronal third. Tooth 21 also
presented a fragment reattachment, but
was still vital.
The patient’s needs were, firstly, to re-
attach the fragment. Secondly, he want-
ed to improve the esthetics of his smile,
change the old restorations, and remove
the grayish aspect of tooth 11 (Fig 1).
The fragment was first tried in the mouth
to verify if it was repositionable. Then,
it was cleaned, sandblasted, selectively
etched with 35% orthophosphoric acid
(Ultra-Etch, Ultradent), and gently dried.
After the adhesive procedures with a
Fig 2 Fragment reattachment bonding proced-
ures: adhesive treatment of the tooth fragment.
(a) Sandblasting of the old luting composite with
aluminum oxide powder. (b) The residual enamel
and dentin are acid etched selectively with 35% or-
thophosphoric acid for 30 s and 10 s, respectively.
(c) Primer and bonding resin are then applied over
the conditioned surface. The fragment is kept under
light protection.
FL, Kerr), the fragment was protected
from ambient light (Fig 2). Rubber dam
was applied, and the same cleaning
a
b
c
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procedures were performed on the
tooth. The same adhesive system was
applied on the tooth, which was gen-
tly dried and not polymerized (Fig 3). A
preheated restorative hybrid composite
resin (Tetric, shade A2, Ivoclar Vivadent)
was used for the adhesive luting of the
tooth fragment, which was polymerized
Fig 3 Fragment reattachment procedures: adhesive treatment of the tooth. The same adhesive proced-
ures as described for Fig 2 are performed on the residual tooth. (a) The anterior sextant is isolated with
rubber dam. (b) Sandblasting of the old luting composite with aluminum oxide powder. (c) The enamel
and dentin are acid etched with 35% orthophosphoric acid for 30 s and 10 s, respectively. (d) Primer and
bonding resin are then applied over the conditioned surfaces.
Fig 4 Fragment reattachment bonding procedures: luting of the fragment. (a) A pre-warmed restorative
composite resin is inserted into the cavity before repositioning the fragment. (b) The excesses are removed
and the luting cement polymerized.
ba
dc
ba
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from the buccal and palatal aspects for
40 s each (Fig 4).
During the same appointment, to bet-
ter integrate the fragment of tooth 11,
it was slightly cut back on the buccal
side to allow for stratification of a free-
hand composite resin layer (Fig 5). A
correct micro and macro anatomy were
reshaped on both maxillary central in-
cisors to enhance the esthetics of the
smile (Fig 6).
It was decided to restore the devitalized
incisor with a chairside computer-aided
design/computer-aided manufacturing
(CAD/CAM) composite resin restoration
following the old fracture line of the de-
tached fragment and without any inva-
sive ‘crown-like’ tooth preparation. An
internal bleaching session was planned
before the restorative procedure.
Internal bleaching appointment
for tooth 11
The aim of this appointment was to elimi-
nate or at least reduce the grayish aspect
of the visible part of tooth 11 (Fig 7). The
appointment started with the preparation
Fig 5 Once the polymerization is completed, a
small cavity is prepared on the vestibular surface
of tooth 11, and a new freehand composite resin is
stratified to hide the margin between the tooth and
the fragment.
Fig 6 Micro and macro details of the anatomy are
reshaped on the buccal surface of both central inci-
sors.
of the palatal cavity to fill in the bleach-
ing product. The cavity was 1 to 2 mm
deeper than the free gingival margin due
to the specific sinusoidal anatomy of the
dentinal tubules in the cervical region.
Thus, before placing rubber dam to iso-
late the tooth (which would displace the
gum), the position of the free gingival
margin (minus 2 mm) in relationship to
the incisal tooth edge was recorded. This
measurement would be used later dur-
ing transferral to the tooth cavity (Fig 8).
Following rubber dam isolation of the
tooth, the palatal cavity was excavated
until the previously recorded measure-
ment and the integrity of the endodon-
tic treatment were checked with a probe
and with apical radiography (Fig 9). The
peripheral enamel was etched with 35%
orthophosphoric acid (Ultra-Etch) for
30 s, rinsed with cop ious water spray,
and dried. A mixture of distilled water
and sodium perborate was placed in-
to the cavity (Fig 10). The enamel was
cleaned of bleaching mixture excesses
with a wet applicator, and the entire sur-
-
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this etched enamel ‘ring’ and polymer-
ized for 20 s with a LED light-curing lamp
(L.E. Demetron II, 1200 mW/cm2, Kerr).
A flowable composite resin (Tetric Evo-
Flow, Ivoclar Vivadent) was then applied
over the mixture into the small remaining
cavity and polymerized immediately for
20 s. After rubber dam removal, the oc-
clusion was checked and adjusted. The
mixture was left in place for 1 week, and
the procedure was repeated for another
week. A good whitening effect was ob-
tained after these two internal bleaching
sessions (Fig 11).
After removal of the bleaching mix-
ture at the end of the bleaching proced-
ure, the cavity was abundantly rinsed
Fig 7 The result after 1 week. After rehydration
of the teeth, the discoloration of the cervical part is
clearly visible.
Fig 8 the future internal cavity (the distance between the
incisal edge to 2 mm below the free gingival margin)
is recorded with a red marker on a periodontal probe.
This measurement will later guide cavity excavation.
Fig 9 (a) The cavity is ex-
cavated and the endodontic
treatment checked. (b) Apical
radiograph of tooth 11 shows
no signs of periapical suffering.
with water and a temporary restoration
(Cavit, 3M ESPE) was inserted and left
in place for 1 week. An interval of at least
1 week must be respected before the
permanent palatal adhesive composite
restoration to avoid potential negative in-
terference of the bleaching radicals with
the adhesive procedures.5
External home-bleaching session
The esthetic aspect of both incisors was
reevaluated 2 weeks later. Tooth 21 ap-
peared darker and more yellow than
tooth 11. A potential cause for this ef-
fect might have been a progressive de-
velopment of sclerotic dentin, which is
ba
DEL CURTO ET AL
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common in traumatized teeth.6 For this
reason, a home bleaching agent (PURE
10% carbamide peroxide, Axis Dental)
was programmed to reduce the differ-
ence in the shade between the central
incisors before the restoration. A global
home bleaching on all teeth for 4 days
was first realized, followed by a local-
ized home bleaching of tooth 21 for an-
other 2 weeks.
Cavity preparation for the
definitive CAD/CAM restoration
digital impression of tooth 11 was taken
(Cerec Omnicam software, version 4.4,
Sirona) to copy the shape of the central
incisor. The temporary restoration was
removed with diamond burs under cop-
ious water spray. The cavity was then
isolated and all dentinal surfaces sealed
with an adhesive system (Optibond FL),
following the immediate dentin sealing
or dual bonding procedure.7
Afterwards, the cavity was coated
with a thin layer of composite resin
(Tetric EvoCeram, shade A2, Ivoclar
Vivadent) to fill undercuts and the pulpal
chamber. A small cavity (3-mm deep)
was cut in the middle of the composite
resin in the region of the pulpal cham-
ber. The purpose of this cavity was to
increase the adhesive surface and re-
tain the position of the restoration dur-
ing adhesive luting.8 -
pressions were taken, the peripheral
enamel was finished with fine diamond
burs (granulometry 40 μm) (Fig 12). An
optical impression of the cavity was
taken (Cerec Omnicam), and the com-
posite resin endocrown restoration was
Fig 10 A mixture of sodium perborate and dis-
tilled water is inserted into the cavity without any
gutta percha protection.
Fig 11 Esthetic result after two internal bleaching
sessions. A small overbleached result is not unwel-
come because of the potential of a relapse of the
bleaching effect.
Fig 12 Cavity preparation. Peripheral enamel is
refreshed with a fine diamond bur.
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fabricated chairside (Cerasmart, shade
A1 HT, GC) (Fig 13).
Adhesive luting of the endocrown
The CAD/CAM restoration was finished
and polished and then tried in the mouth
with a glycerin gel (Fig 14). The global
anatomy, the interproximal surface con-
tacts, and the fit of the margins were
checked. Then, the internal surfaces
of the indirect resin composite restor-
ation were adhesively treated and pro-
tected from ambient light (Fig 15). The
next step was the adhesive treatment of
the cavity (Fig 16). The presence of only
enamel and composite resin, without the
exposure of dentin, facilitates the adhe-
sive procedure. A conventional photo-
polymerizable hybrid composite resin
was used as luting cement (Tetric A140,
shade A2).
-
ity, the restorative composite resin was
heated to a temperature of about 50°C
to decrease its viscosity.9 Immediately
thereafter, the restoration was inserted
into the cavity and coerced in place
manually. Excesses of luting compos-
ite at margins were removed with the
Fig 13 After optical impression of the cavity, the
restoration is digitally designed (CAD).
Fig 14 CAM restoration is tried in the mouth to check the
marginal adaptation, the interproximal contact
points, and the esthetic integration.
Fig 15 Adhesive procedures for the CAD/CAM restoration. (a) The internal surface is sandblasted with
27 μm aluminum oxide powder. (b) The conditioned surface is then treated for 60 s with a silane solution.
(c) A thin layer of bonding resin is spread over the intaglio surface, then dried gently. The workpiece is
placed under light protection.
ba c
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Fig 16 Adhesive procedures for the tooth cavity. (a) After isolation with rubber dam, the cavity is sand-
blasted with 27 μm aluminum oxide powder. (b) Acid etching on enamel (30 s). (c) Alcoholic primer is
applied on the composite resin to clean the sandblasted surface, then dried gently. (d) The bonding resin
is applied and dried gently without polymerizing it.
Fig 17 A restorative hybrid composite resin (Tet-
ric A140, shade A2) is used as luting cement. (a) After preheating, the composite resin is spread onto
the entire cavity. The restoration is first put in place
with a finger. (b) Ultrasonic energy is used to de-
finitively set the CAD/CAM restoration. (c) After the
removal of the excesses, the luting cement is pho-
dam removal, the restoration is fine polished.
a b
c d
a b
c
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Fig 18 Rubber dam is removed and static/dy-
namic occlusions are checked. The patient is able
to leave the practice with a permanent restoration.
Fig 19 A thin layer of about 1.5 mm of the CAD/
CAM monolithic restoration was cut back on the
buccal side with a diamond bur. At the same time,
the old composite on tooth 21 was removed.
Fig 20 Esthetic modifications of the CAD/CAM restoration. (a) After isolation with rubber dam, the buc-
cal side of the CAD/CAM restoration is sandblasted with 27 μm aluminum oxide powder. (b) Orthophos-
phoric acid etching gel is applied first on the enamel, previously beveled (for 30 s), and then on the dentin
(10 s). (c)later dried gently. The application of alcoholic primer on the CAD/CAM composite restoration cleans the
sandblasted surface. This is a fundamental step in case of accidental dentin exposure during the cutback
procedure. (d)
help of a probe and interproximal floss.
A final push with a plastic ultrasonic tip
helped to seat the restoration in its final
position. A first light polymerization with
a high-power LED unit (L.E. Demetron
II, 1200 mW/cm2) to harden the surface
a b
c d
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(e)in the reconstitution of the palatal wall of tooth 21. (f) Thanks to the palatal silicone index, the palatal wall
of tooth 21 is built up (Filtek Supreme XTE, shade A1 enamel). (g) A dentinal core is built up on both teeth,
-
fect, shade Azur, Edelweiss DR) is applied between the three lobes, and the bevel is covered with a medium
translucency composite resin (Filtek Supreme XTE, shade A1 body). (h) A final layer of high translucency
composite resin is applied, and both restorations are polished before rubber dam removal.
of the luting composite was performed
for 5 s per surface, from the buccopala-
tal direction. Then, full polymerization in
contact with the irradiated surface was
achieved by light curing for 90 s per sur-
face, under simultaneous air and inter-
mittent water spray cooling (Fig 17).10
Any remaining composite excess
was subsequently removed with fine
diamond burs, and the margins were
polished with flexible discs and silicone
points with slight pressure. Finally, rub-
ber dam was removed and the occlu-
sion was checked (Fig 18).
Final esthetic modifications
of the CAD/CAM restoration
After 1 week and full rehydration of the
tooth, the shade integration was eval-
uated. As it did not correspond to the
patient’s expectations, a thin layer of
the CAD/CAM monolithic restoration
(1.5 mm) was cut back on the buccal
side and the old composite on tooth 21
was removed (Fig 19). A new esthetic
freehand composite resin was layered
on both teeth (Filtek Supreme XTE,
shade A2 dentin, A1 body, A1 enamel,
3M ESPE) (Fig 20). The final integration
of the restorations was evaluated after
1 month (Fig 21).
e f
g h
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Discussion
In the case of a discolored devitalized
anterior tooth, the margins of the restor-
ation should be put into the cervical third,
close to the free gingival line, to hide the
discoloration and achieve an optimal es-
thetic outcome. Unfortunately, this prep
configuration, which is typical for a PFM
or full-ceramic crown preparation, would
mean a radical loss of sound hard den-
tal tissue. At the same time, it is difficult
to reach a perfect esthetic integration
when restoration margins are localized
in the middle of the buccal wall, espe-
cially when the cervical part of the tooth
shows a major staining. Therefore, in the
presented case, the decision to associ-
ate a chemical treatment (internal tooth
bleaching) with a conservative restora-
tive technique (‘endocrown’ or partial-
crown restoration) was taken in order to
be conservative as well as achieve good
esthetics.
For this case report, a chairside CAD/
CAM composite resin endocrown with a
minimal extension into the pulp cham-
ber was used. Considering the exten-
sion of the incisor fracture (more than
half of the tooth), an industrially poly-
merized resin was preferred to a free-
hand direct composite resin, because
of the improved mechanical proper-
ties. In fact, a resin CAD/CAM block
is fabricated under standardized and
controlled high-pressure/high-temper-
ature polymerization conditions. The
resin composite produced is highly
homogeneous, and its mechanical
properties are superior to those pro-
duced by chairside photopolymerized
resin. On the other hand, concerns
may arise due to the limited esthetics
of a monochromatic CAD/CAM restor-
ation. An esthetic modification of the
raw workpiece after milling was nec-
essary to enhance the esthetics of the
buccal surface. For this purpose, the
superficial part of the raw restoration
was removed (approximately 1.5 mm),
and a new esthetic composite resin
was layered over the buccal surface.
Rocca et al11 have recently shown in vitro that for premolar endocrowns, this
buccal veneering does not jeopardize
the mechanical integrity of the milled
restoration. A more expensive alterna-
tive to this buccal re sin veneering could
have been a laboratory-made ceramic
veneer. Compared to a classical post-
core-crown solution, both strategies al-
low for an easy reintervention into the
root canal in case of endodontic prob-
lems or bleaching relapse.
Fig 21 (a) One-month recall.
This final intraoral photograph
shows an optimal esthetic inte-
gration of both restorations. (b) Postoperative radiograph.
a b
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must be prepared properly to contain the
bleaching mixture. The internal side of
the buccal wall must be cleaned of any
generic restorative materials or medical
paste that could invalidate the diffusion
of the mixture through dentinal tubules.
The cavity should be extended up to
2 mm below the free gingival margin, as
in this zone tubules have a distinctive
sinusoidal anatomy. In the present case,
a mixture of sodium perborate and dis-
tilled water was used,12,13 and two ap-
plications of the bleaching agent were
necessary to obtain the desired result.
Depending on local jurisdiction, it may
be more advisable to use a CE-marked
product for this purpose.
A mild bleaching agent was chosen to
reduce the risk of external resorption14
as well as to prevent the reduction of
both enamel and dentin surface micro-
hardness.15 The association between
sodium perborate with distilled water or
H2O2 at different percentages has been
thoroughly debated. Some authors re-
port no significant differences in the ef-
fectiveness of these two mixtures.16,17
Another study underlined the fact that
with a mixture of sodium perborate and
distilled water, results were more stable
in time.18
Once the cavity is prepared, the
bleaching mixture is applied directly into
the root canal in contact with the gutta
percha obturation. The scientific litera-
ture has previously suggested the need
to protect the gutta percha material with a
composite resin or a glass-ionomer layer
to prevent the diffusion of the bleaching
agent into the root canal and into the tu-
bules of the cervical dentin.19,20 Steiner
and West21 suggested that the sealing
material should reach the level of the
cementoenamel junction (CEJ), which
corresponds to the epithelial attachment
level in healthy conditions, to avoid the
leakage of bleaching agents into the
periodontium. According to the normal
anatomy of the CEJ, at the interproximal
sites its level is more in a coronal pos-
ition rather than in the palatal and buc-
cal regions. Thus, as the gutta percha
capping is normally flat, many dentinal
tubules in the interproximal area are still
open toward the perio dontium. This is
why the same authors suggested that
the barrier should be placed 1 mm more
coronal to the buccal CEJ level. Con-
cerns regarding this technique derive
from the fact that the use of this protective
material can hinder the effectiveness of
the mixture in the cervical region, where
the bleaching effect is mainly expected.
Thus, in case of a mild bleaching mixture
(eg, sodium perborate mixed with dis-
tilled water), the gutta percha capping
can be avoided.22 In addition, the risk of
root cervical resorption could be associ-
ated with other preconditions such as an
orthodontic treatment, a trauma, and/or
an internal bleaching with heat activa-
tion.23 Sodium perborate mixtures seem
less involved in resorption problems; a
potential reason for this could be that
sodium perborate prevents the action of
macrophages during bone resorption.24
The negative interaction of bleaching
agents with adhesive systems has also
been discussed. In particular, oxygen
radicals that derive from the degradation
of H2O2 are supposed to inhibit the poly-
merization of adhesive systems and thus
reduce adhesion to bleached tissues.25
A time interval of at least 1 week needs
to be respected before the application
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CLINICAL RESEARCH
of the adhesive systems to allow for the
dispersion effects of the radicals.26,27 A
more recent article showed that there is
no statistically significant difference in
bond strength values between 7, 14,
and 21 days after bleaching.5 In any
case, the neutralization of the residual
pero xide degradation radicals is time
dependent.28 The use of water to rinse
the cavity has been demonstrated to ac-
celerate the neutralization of the expect-
ed radicals because hydrogen peroxide
is extremely unstable in the presence of
water.29,30
A flowable composite resin was used
as a temporary filling after each bleach-
ing appointment instead of the clas-
sic glass-ionomer cement. Flowable
composite resin is easy to apply, and
once polymerized is more resistant than
class ical glass-ionomer materials. In-
ternal bleaching requires a stable and
tough temporary restoration to avoid the
diffusion of the bleaching agent into the
mouth as well as prevent the recontami-
nation of the pulp chamber by bacteria
or staining agents.31 The choice of a re-
storative composite resin for a temporary
restoration is discouraged, as this resin
as an interim restoration, being highly
viscous, can push the whitening product
outside the cavity during application. A
flowable composite resin, on the other
hand, can be directly applied on the soft
bleaching mixture without any pressure.
Due to the combination with an adhesive
system, it allows for a perfect seal.
Conclusion
The clinical case presented in this re-
port shows how the association between
modern adhesive procedures with an
internal bleaching technique allows for
the esthetic restoration of a discolored
endodontically treated incisor without
the use of classic invasive prosthetic
solutions. This combination can recon-
cile the restoration of devitalized teeth
to faster and cheaper minimally invasive
esthetic treatments.
Acknowledgment
The authors would like to thank Dr Eric
Romelli for the revision of the English
language.
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