the ideal restoration of endodontically treated teeth structural and esthetic considerations a...
TRANSCRIPT
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SCIENTIFIC SESSION
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The ideal restoration of endodonti-
cally treated teeth structural and
esthetic considerations: a review of
the literature and clinical guidelines
for the restorative clinician
Konrad Meyenberg, DMD Private Office for Reconstructive Dentistry
Zrich, Switzerland
Correspondence to: Konrad Meyenberg
Private Office for Reconstructive Dentistry, Rennweg 58 / Eingang Oetenbachgasse 26, 8001 Zrich, Switzerland;
E-mail: [email protected]; Web: www.zahnaerzte-rennweg.ch
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One of the most challenging dilemmas
faced by todays clinician is the manage-
ment of the structurally and esthetically
compromised endodontically treated
tooth. Certainly, in recent years there has
been a tendency to take the simplified
approach of extraction and implant
but this does not always prove to be as
simple as we would like to think. Has
the popularity of dental implantology
made the restorative dentist complacent
in regards to the possibilities that good
endodontic, periodontal and restorative
treatments can achieve? Without doubt
the dental implant option has its place,
and rightly so, but in many cases, I sus-
pect, the endodontic/restorative option
does not always receive its due merits.
Whenever we are faced with such a
compromised tooth, we have to con-
sider the following question: is the tooth
maintainable? If so, then this is surely
our primary goal. However, the question
is complicated by the context ie, is this
a young patient? Is this a bridge abut-
ment? Is there an esthetic challenge, ie,
a dark tooth? In the younger patient, it
may be desirable to maintain a poten-
tially hopeless tooth for as long as pos-
sible in order to buy time and delay the
day of implant placement and its subse-
quent eventual failure. Retreatment of a
tooth is, more often than not, simpler with
a broader range of options than retreat-
ment of a failed implant, particularly in
the esthetic zone. If this can be done
239THE EUROPEAN JOURNAL OF ESTHETIC DENTISTRY
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for the younger patient, then why cant
it be done for the older patient? On the
other hand, perhaps it is more predict-
able in a given case to remove the tooth
and restore it with a dental implant res-
toration. These and other issues are real
concerns we have as practitioners and it
is important to have objective as well as
the subjective criteria on which to base
our decision for the choice of restorative
protocol.
Are all endodontically treated teeth
really less predictable than a dental
implant-supported restoration? Are they
really more likely to fail? Do they really
have a poor prognosis? Do implants re-
ally have fewer complications? Is retreat-
ment as easy? Do anterior and posterior
teeth behave the same? When is the
prognosis of the tooth unfavorable and
at what point is extraction and an im-
plant the best option? These and many
other relevant questions are eloquently
addressed below by our essayist and
EAED Active Member, Dr Konrad Mey-
enberg. My hope is that this paper will
serve to help us to question our treat-
ment choices more critically in this area,
suggest useful answers to many of the
questions in this dilemma, provide us
with objective criteria on which to base
our judgements and finally offer solu-
tions so that we can make better choices
for the treatment of our patients.
Dr Tidu Mankoo, BDS
Moderator/Editors Introduction
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Abstract
In restorative dentistry, the non-vital tooth
and its restoration have been extensively
studied from both its structural and es-
thetic aspects.
The restoration of endodontically
treated teeth has much in common with
modern implantology: both must include
multifaceted biological, biomechanical
and esthetic considerations with a pro-
found understanding of materials and
techniques; both are technique sensitive
and both require a multidisciplinary ap-
proach. And for both, two fundamental
principles from team sports apply well:
firstly, the weakest link determines the
limits, and secondly, it is a very long way
to the top, but a very short way to failure.
Nevertheless, there is one major dif-
ference: if the tooth fails, there is the op-
tion of the implant, but if the implant fails,
there is only another implant or nothing.
The aim of this essay is to try to an-
swer some clinically relevant concep-
tual questions and to give some clinical
guidelines regarding the reconstructive
aspects, based on scientific evidence
and clinical expertise.
Rebuilding the ideal tooth from an endodontically treated tooth what does this mean?Essentially, the goal is to restore the ap-
pearance and biomechanical properties
comparable to those of a vital, complete-
ly intact tooth. In addition, the coronal
restoration should prevent bacterial re-
colonisation of the endodontically treat-
ed root canal system.1
Clinically, most of non-vital teeth must
be considered as structurally and es-
thetically compromised.2 The fracture
rate and as a consequence the risk for
tooth loss is considerably higher com-
pared to vital teeth.
Part 1: Structural considerations
What are the causes of fractures?
There are several causes for the in-
creased risk of cracks in endodontically
treated teeth to be considered. Cracks
predispose the tooth immediately or af-
ter some time to fracture. The following
four factors contribute to this predisposi-
UJPO'JHTo Structural loss of tooth substance due
to pre-endodontic restorative proce-
dures or the endodontically induces
access cavity preparation and root
canal enlargements.5,6
Increased brittleness by age induces
changes in the dentin and the loss of
free unbound water from the root ca-
nal lumen and the dentinal tubules in
pulpless teeth.7-11
Weakening effects by endodontic ir-
SJHBOUT /B0$M &%5" BOENFEJDB-tions (CaOH2 PO EFOUJO FGGFDUT PGbacterial interactions with the dentin
substrates, corrosive effects of restor-
ative materials, and negative mechan-
ical effects through crack inducing or
crack propagating endodontic and
restorative methods and instruments,
including endodontic files.12-16
The reduced level of proprioception
of non-vital teeth causes a reduced
level of control of forces by the normal
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protective neuromuscular inhibition
mechanism.17
Some of these factors may be influ-
enced or modified to improve the prog-
nosis, however the most important factor
for success is to avoid any unnecessary
loss of tooth substance in general and
to preserve as much as possible after
removal of all decayed material.
Recent research shows that dentin
has some very effective inherent proper-
ties to inhibit crack progression (fracture
UPVHIFOJOHNFDIBOJTNT
UP PQUJNBMMZdistribute local stresses and to partially
repair defects, as long as a tooth is vi-
tal.8,9 However, a non-vital tooth will lose
some of these properties over time. A
key consideration is that the amount of
collagen fibers in endodontically treated
Fig 2 Fracture of first upper premolar due to deep cavity with endodontic treatment.
Fig 1 Cracks in lower first molar due to deep cavity.
Fig 4 Fracture originating from the apex of a canine due to the use of inadequate endodontic techniques.
Fig 3 Fracture of palatal root of upper first molar due
to endodontic treatment.
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teeth decreases, which means that this
dentin is much less fatigue resistant.17
In addition, even vital dentin loses some
of its initial strength over its lifetime: it
shows a different fracture behavior as
the mineral content increases over time
and causes a less favorable fracture be-
havior because of the increased brittle-
ness.18,19
Restorative options: what is the ideal concept?
As a consequence, any attempts to
restore a non-vital tooth must include
not only the use of restorative materi-
als with properties similar to the dental
components, but also the use of clinical
concepts that allow to compensate the
inherent reduction of the mechanical re-
sistance of endodontically treated teeth.
A true so-called biomimetic con-
cept20 therefore does not only implicate
the use of particular materials similar in
their properties to dentin and enamel,
but also sometimes the use of particular
materials with different properties to re-
store the incomplete tooth as a whole in
all its mechanical, biological and esthet-
ical aspects,21 above all if the remaining
tooth structure is compromised.
Post or no post are posts destructive?
In the past, fractures of teeth often have
simply been attributed to inadequate re-
storative procedures, be it by the use of
inadequate core materials or the use of
posts and screws. The introduction of ad-
hesive techniques and their successful
integration in almost all current restora-
tive procedures has allowed the clinician
to dispense with posts in many indica-
tions, as they are no longer required for
the retention of a core build-up.
However, mindful clinicians can still
observe a relatively high rate of vertical
root fractures despite the absence of
posts and even with the use of adhe-
sive techniques above all in curved
and small roots; indeed some authors
report up to 20% of vertical fractures of
endodontically treated teeth. Man-
dibular molars and maxillary premolars
are most often affected.25,26 Provided
there is enough coronal dentin structure
NPSFUIBOUXPUIJSETBWBJMBCMFJUTFFNTthat there is no difference between teeth
restored with or without posts in this re-
spect.27 Interestingly in this article, 86%
of molars with vertical root fractures had
the fracture in a root without a post.
Therefore, as long as no active posts
or screws are used, which may produce
detrimental lateral forces on the den-
tin walls,28 and as long as inadequate
placement techniques with risk of per-
forations are not used, posts per se
may not be considered as destructive.
When is a post indicated?
The main reason to use a post today
is no longer to increase the retention
and resistance of a core build-up, since
there are very effective adhesive tech-
niques available. As discussed, provid-
ed there is sufficient tooth structure avail-
able, there is no longer a need to place
a post. In premolars with limited
amount of tooth destruction and molars
where, in general, more dentin walls with
greater surface area can be engaged
to be bonded as compared to anterior
teeth, a direct bonded core build-up is
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not be compensated simply by adhe-
sive techniques using fiber posts and
composite cores. In a recent long-term
study over 7 to 11 years, the mechani-
cal failures reached 7 to 11% and were
always related to a lack of coronal tooth
structure.
If anterior teeth and premolars pre-
sent with large defects that require
crowning, however, adequate transfer
of forces from the crown into the core
build-up and from there into the root is
not possible without a post. Importantly,
the function of the post is not only the
increase of the retention of the core, but
also the optimization of the resistance
form. In addition, the mechanical prop-
erties of a composite core alone may
also not be sufficient in the case of a
narrow abutment diameter and cannot
reduce high stresses in the critical cervi-
cal area, which in such a case, is prone
to horizontal fractures. A clinical study
PWFS UPZFBSTXJUIDSPXOTCPOEFEdirectly to a reduced macroretention ge-
ometry without posts clearly showed
that the concept can work for molars
(8795% success, depending from the
BNPVOUPGSFTJEVBMDBWJUZXBMMT
CVUEJEnot work for premolars, if there were no
cavity walls at all and the crown was just
bonded directly into the residual pulp
DIBNCFSTVDDFTTSBUFTherefore, the purpose of a post and
core as a unit is primarily to transfer the
loads into the root and secondly, the
post is used as a reinforcing element of
the core build-up.
The downside of this concept is the
weakening effect on the root itself;
to compensate for this, the ferrule effect
must be incorporated into the restoration
design.
clinically the concept of choice; it can be
regarded clinically as well established,
reliable and perhaps preferable to con-
ventional post-core concepts. In addi-
tion, by avoiding posts, the risk of cracks
due to thin residual root walls or perfora-
tions can be eliminated.
For anterior teeth and heavily compro-
mised premolars, however, this state-
ment is limited to teeth that present with
small to moderate defects and that will
later not be crowned.
For posterior teeth, the best prognosis
is achieved if in addition to a bonded
core foundation a ferrule effectis cre-
ated by the final restoration. This means
that full cuspal coverage is used, be it
a partial or full crown. Adhesive tech-
niques alone without cuspal coverage
may still lead to catastrophic failures
over time (ie, untreatable long axis frac-
UVSFTBOEDBOOPUCFSFHBSEFEBTDMJOJ-cally safe.
It must be stated at this point that the
ferrule effect is the most effective way of
mechanical stabilization, ie, of optimiz-
ing the resistance form, of any endodon-
tically treated teeth.Given the weaker
structure, as previously discussed, the
effect of the better load distribution into
the cervical zone and the avoidance of
any wedging effect by the post or core
build-up into the coronal part of the root
cannot be overemphasized. Therefore,
in order to provide a ferrule in situa-
tions without sufficient tooth structure
above the zone of the biological width,
orthodontic extrusion or surgical crown
lengthening should be considered. A
ferrule length of 1.5 to 2 mm is recom-
mended.
It must also be stated that, obviously,
the lack of coronal tooth structure can-
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The ferrule effect may also compen-
sate unexpected breakdown of adhe-
sion after bonding and luting proce-
dures in unqualified dentin conditions.
A safe clinical concept always implies
the incorporation of a belt and braces
approach to offset routes of potential
failure.
A special indication for a post is the
immature root, presenting with a large
root canal.
Obviously neither gutta-percha nor
MTA nor composite have a significant
reinforcing effect. In this instance, the
only significant reinforcing effect is
achieved with a post. This is in line with
the clinical observation of increased risk
of fracture in immature teeth left without
post and core-build up after endodontic
treatment.
If a post is indicated: what post concept should be used: stiff or flexible?
If something can break, it will break, and
it will always break at the weakest point
this basic finding and classic rule for
construction is also true for this applica-
tion and may explain the significant con-
troversies regarding what would be the
best of all the available concepts. The
question may be not whether something
will break, but rather where it will break.
Almost all dental materials have been
used clinically for posts. Still clinically
relevant today are gold-alloys, chrome-
cobalt, titanium, zirconia and glass fib-
er posts. Carbon fiber posts have no
clinical significance due to poor clinical
performance and disastrous potential;
therefore they will not be discussed in
this article.
#BTJDBMMZUIFSFBSFUXPDPOGMJDUJOHJT-sues causing some disagreements on
the ideal material of a post.2 From a me-
chanical standpoint, it is evident that a
post stiffer than dentin can take up more
load but induces more stress in some api-
cal parts of the root, which can increase
the risk of a vertical root fracture. Con-
versely, a post that has an elastic modu-
lus closer to dentin will, in fact, induce
less stress concentration apically in the
root, but more in the cervical region.
In addition, the interface between
post and core and between core and
dentin is also subjected to stress, so one
can expect to see more root fractures
JSSFQBSBCMF GSBDUVSFTXJUITUJGGFSQPTUTmade from metallic or ceramic materi-
als, whereas more flexible posts would
show more post fractures, debonding of
core materials and loss of retention (pos-
TJCMZSFQBJSBCMFXJUITVCTFRVFOUQSPC-lems of leakage and caries. The latter
may lead to endodontic reinfection and
catastrophic coronal destruction of tooth
substance, thus leveling out the poten-
tial advantage of this latter concept over
the first one.
The dilemma for the clinician is the
meaningful interpretation of the litera-
ture, as countless studies have been
published in this field, most of them being
in vitro studies with questionable clinical potential relevance. Numerous theoreti-
cal studies using finite element analysis
have also been performed, which would
all need to be verified according to clas-
sic engineering principles in a real mod-
el, but only a minority of the in vitro stud-ies have been performed with dynamic
or fatigue loading under a simulated
oral environment. Another difficulty is
that study results are also influenced by
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the structural condition, various types of
natural teeth utilized and the respective
loading pattern.
One of the more clinically relevant in vitro studies compared cast posts and DPSFTUJUBOJVN5JQPTUTXJUIDPNQPT-ite cores, zirconia posts with composite
cores and zirconia posts with ceramic
cores, using, in all groups, adhesive
techniques and a ferrule of 1 to 2 mm
on central incisors where all teeth were
crowned. The most favorable results
JOUFSNTPGGSBDUVSFTUSFOHUI/BOETVSWJWBMSBUFDPVMECFBDIJFWFEwith the stiffest concept (zirconia posts
XJUIBDFSBNJDDPSF
BOEUIF MFBTU GB-vorable with the cast post and core sys-
UFN/In contrast to this study with ideal tooth
substrate, another study compared dif-
ferent degrees of tooth destruction, us-
ing fiber posts and composite cores or
composite cores alone on premolars.
It was shown that posts had a significant
positive effect on fracture strength if only
1 or 2 cavity walls were left, whereas no
EJGGFSFODFDPVMECFGPVOEJGPSDBWJUZwalls were left. However, if a completely
flat profile without any substance above
the preparation line is used, most likely
the post will debond as predominant
mode of failure.
Two facts are of special importance in
the judgment of studies comparing dif-
ferent concepts:
The results of these in vitro studies largely depend on the presence or
BCTFODFPGBGJOBMSFTUPSBUJPODSPXOPrincipally, differences in materials of
posts and cores level out from the mo-
ment where a crown is placed.
If metal-free post and core concepts
are to be successfully used, the es-
tablishment of proper bonding be-
tween all substrates is of paramount
importance.51 If bonding fails, much
less favorable stress patterns occur
both in the root, above all in the critical
cervical area, and in the post and core
itself.52 As a clinical consequence,
loss of retention of the core and post
is still unfortunately the major compli-
cation.
Most of the clinical studies are difficult
to interpret in their outcome, since the
amount of tooth loss and the condition
of the remaining dentin (pre-existing
cracks, aging, endodontic treatment
NPEBMJUJFTBSFOPULOPXOBOENBZIBWFinfluenced the choice of the concept.
The scientific dilemma is very nicely
expressed in a systematic review about
the simple final question, whether a
crown or a filling is more effective in the
clinical performance for an endodonti-
cally treated tooth. The authors con-
clude There is insufficient evidence
to support or refute the effectiveness
of conventional fillings over crowns for
the restoration of root filled teeth. Until
more evidence becomes available cli-
nicians should continue to base deci-
sions on how to restore root filled teeth
on their own clinical experience, whilst
taking into consideration the individual
circumstances and preferences of their
patients.
This statement shows not only the
complexity of the topic, but also that
clinical multifactorial reality does not al-
low clear definition of one simple gener-
ally valid concept.
Nevertheless, there is still a need
for clear clinical guidelines, based on
scientific evidence paired with clinical
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expertise. Only this combination finally
leads to clinical evidence.
As a conclusion from numerous clini-
cal studies, it must be stated that there is
OPTVQFSJPSDPODFQUJOBMMSFTQFDUT#PUIdirect and indirect concepts and gold,
Ti, fiber and zirconia posts work well if
the respective concepts are properly ex-
ecuted. The single most important point
is to preserve as much remaining tooth
structure as possible.
Two additional arguments may require
consideration for the reconstructive cli-
nician: a) fiber posts offer the highest potential for reintervention due to their
relative ease of removal, however their
successful use clinically is much more
technique sensitive,58 and b) post and cores with a high modulus of elasticity
NFUBM PS [JSDPOJB PGGFS B IJHIFS GSBD-ture resistance as a foundation of the
crown,50 which may be of significance
for the long-term success of all-ceramic
crowns.59,60
What about bonding a post into the root canal space? Does bond-ing help in cases with extended amount of tooth destruction? What is the ideal surface condi-tioning of fiber posts?Looking at the results of a recent clini-
cal 10-year fiber post study, a surpris-
JOHMZIJHIBOOVBMGBJMVSFSBUFPGJTreported and an overall failure rate of
XJUIGJCFSQPTUGSBDUVSFTBOE11% post debondings.61 The highest
probability of a failure was reported for
anterior teeth with no cavity walls.
This is confirmed by another clini-
cal study62 where premolars of varying
degrees of destruction were restored
with different concepts of build-ups. All
teeth were finally crowned with porcelain
GVTFEUPNFUBM1'.DSPXOT"OPWFSBMMfailure rate in this 6-year survival study of
XBTSFQPSUFE8IFOPOMZBDJSDVMBSferrule of 2 mm or less was left, the fail-
ure rate increased to nearly 90 to 100%
GPSUIFOPQPTUDPODFQUUPUPGPSprefabricated posts, and to around 70%
for the customized post concept.
The results clearly suggest that pre-
fabricated fiber posts are superior
to customized fiber posts (glassfiber
CBOESFTJOJNQSFHOBUFEPSDPNQPTJUFcores without any posts, if there are only
2 walls or less remaining. However, even
if in addition to the bonded core a pre-
fabricated fiber post is used, the con-
cept obviously fails to be convincingly
successful in cases with extended tooth
destruction.
*ODPOUSBTUUPUIJTPWFSBMMGBJMVSFrate over 6 years of non-metallic posts
and build-ups, a 10-year report of pre-
fabricated metal posts and cast metal
QPTUTBOEDPSFTSFTVMUFEJOBBOEPWFSBMMGBJMVSFSBUF
RetentionThe almost doubled overall failure rate
of fiber posts and the surprisingly high
debonding rate must raise the question
about the effectiveness and efficiency
of this concept in general practice. Per-
haps it is unsurprising given the inher-
ently more technique-sensitive concept
of the required adhesive techniques and
the lack of a simple clear user protocol.
A recent study compared the reten-
tion of different fiber posts with different
surface conditionings (performed ac-
cording to the manufacturers recom-
NFOEBUJPOTBOE MVUJOHBHFOUT JOEFO-
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tin Ti-posts luted with conventional zinc
phosphate-cement served as the con-
trol group. The control Ti-post showed,
together with some combinations of the
test group, the highest pull-out strength,
whereas some combinations of the test
group showed surprisingly low values.
This is in line with another study, where
adhesively luted fiber posts were not
superior to gold posts either adhesively
luted or conventionally cemented with
glass ionomer cement.65
Adhesion to radicular dentinAdhesively luting a post into root den-
tin is a controversial issue. Conflicting
results have been published about the
efficacy of bonding to radicular dentin.
Probably due to the structural differenc-
es in radicular dentin, bond strengths
improve from the apical to the coronal
section. Comparing the use of compli-
cated separated dentin bonding and lut-
ing procedures with simpler self-etching
cements, it seems clinically more relia-
ble to use self-etching and self priming
cements taking into account the poten-
tially somewhat lower bond strength to
dentin.66-71 Inadequate ability to cure
the luting agents precludes the use
of light-curing materials. Dual-cure or
chemically curing materials should be
used instead, since different fiber posts
indeed differ in their light transmitting
properties, however posts with optimal
mechanical properties do not allow
enough light penetrating all over the
whole length of the post to sufficiently
polymerize light-cured materials.72
Adhesion to post surfaceTo improve bond strength to the pre-
fabricated fiber posts, chemical (silane,
etching with hydrogen peroxide for
NJO PS NFUIZMFOF DIMPSJEF GPS Tor micromechanical treatments (sand-
CMBTUJOHPSBDPNCJOBUJPOPGCPUIIBWFbeen proposed. Surprisingly, sand-
blasting seems to not affect the mechan-
ical properties of the fiber posts.75 Sand-
blasting with silanization is, therefore, an
efficient, simple and predictable way of
surface conditioning a fiber post before
bonding.77,78 However, fiber posts are
susceptible to water degradation, and
damaging the surface will increase this
phenomenon. Thus, a predictable bond-
ing procedure that completely seals the
post surface and avoids any voids is of
paramount importance to preserve frac-
ture resistance.79 Some manufacturers
now use a coating on their posts to fur-
ther simplify and improve the bonding.80
Nevertheless, care should be taken to
consider both the manufacturers rec-
ommendations and their scientific basis.
Mechanical propertiesMajor differences in the mechanical
properties of different brands of posts
is another critical point. Since there
are now countless brands of posts on
the market with a sometimes-unknown
origin, a proper selection based on in-
dependent scientific investigations is
imperative to avoid basic mechanical
failures.81,82 Using a fatigue resistance
test, a difference of roughly 7,000 cy-
cles until fracture for the worst and up
to 2,000,000 cycles for the best post in
UIJTSFTQFDUFRVJWBMFOUUPOPCSFBLBHFcould be shown. The quality of the man-
ufacturing processes including type of
fiber and matrix, pre-tensioning of fibers,
bond between fibers and matrix, among
other factors, play an important role.
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Fig 5 Case 1: initial radiograph of non-vital cen-tral incisors with different degree of remaining tooth
substance, final radiograph of build-ups with short
GJCFSQPTUTQMBDFEPVUMJOFEGPSCFUUFSWJTJCJMJUZ
Fig 6 Case 1: initial clinical situation, large com-posite build-ups, discolorations.
Fig 7 Case 1: abutment teeth after removal of ex-isting composite cores.
Therefore, both a sensitive indication
and technique is mandatory for the suc-
cessful use of the concept of fiber posts
combined with composite cores (Figs 5
UP
Fig 8 Case 1: abutment teeth after internal bleach-ing.
Fig 9 Case 1: build-ups of abutment teeth com-pleted with fiber posts and composite core, buccal
view.
Fig 10 Case 1: build-ups of abutment teeth com-pleted with fiber posts and composite core, occlusal
view.
Fig 11 Case 1: final clinical result.
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Concluding remarks regarding the structural aspects
The following statements regarding the
structural aspects may be made:
Where a crown is fabricated and a
proper ferrule effect is created, neither
the material (Ti, gold alloys, zirconia,
HMBTTGJCFSOPSUIFTIBQFBOEMFOHUIof the post are a significant influence,
as long as clinically reasonable con-
cepts are used.
Conversely, insufficient coronal tooth
structure will always lead to an in-
creased failure rate independent of
the concept of restoration.
Increasing the coronal diameter of the
post helps to reduce the fracture risk
of all posts, however the residual den-
tin wall thickness needs to be consid-
ered.
Huge differences in the quality of fib-
er posts require a careful selection to
avoid post fractures.
Materials with potential of corrosion
TUBJOMFTT TUFFM CSBTT NBZ JOEVDFfractures of materials and dentin and
therefore should not be used.
Adhesive cementation of fiber posts
is mandatory.
Adhesive cementation of metallic
posts is not mandatory.
Core build-ups should always be
bonded, even if a metal post is not
bonded.
Regarding the clinical reality, the fol-
lowing additional statements must be
made:
$FSBNJD QPTUT [JSDPOJB DBOOPU CFremoved after luting, offer no potential
for reintervention and should therefore
be used in selected cases only.
For abutment teeth presenting large
defects and requiring crowning, or
longer span bridges, or in general
heavy loads, metallic posts are pref-
FSBCMFPWFSGJCFSQPTUT'JHTUP
Fig 12 Case 2: initial radiograph of second lower premolar with fiber post and PFM crown.
Fig 13 $BTFSBEJPHSBQIZFBSTBGUFSUIFSBQZshowing post fracture, composite core debonding
and crown dislodgement.Fig 14 Case 2: clinical view showing fractured fiber post and extensive caries destruction under-
neath debonded composite core.
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SCIENTIFIC SESSION
250THE EUROPEAN JOURNAL OF ESTHETIC DENTISTRY
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References, Part 1 .BOOPDDJ'#IVWB#
Stern S. Restoring teeth following root canal re-treat-ment. Endodontic Topics 2011;19:125152.
2. Kishen A. Mechanisms and risk factors for fracture pre-dilection in endodontically treated teeth. Endodontic 5PQJDTo
(IFS.&+S%VOMBQ3.Anderson MH, Kuhl LV. Clinical survey of fractured teeth. J Am Dent Assoc o
$IBO$1-JO$15TFOH4$Jeng JH. Vertical root frac-ture in endodontically versus nonendodontically treated UFFUIBTVSWFZPGcases in Chinese patients. Oral Surg Oral Med Oral Pathol Oral Radiol Endod o
5. Reeh ES, Messer HH, Douglas WH. Reduction in tooth stiffness as a result of endodontic and restora-tive procedures. J Endod 1989;15:512516.
6. Asundi A, Kishen A. Digital photoelastic investigations on the tooth-bone interface. +#JPNFE0QUo
7. Jantarat J, Palamara JE, Lindner C, Messer HH. Time dependent properties of human root dentin. Dent .BUFSo
8. Kishen A, Asundi A. Experi-mental investigation on the role of water in the mechani-cal behavior of structural EFOUJO+#JPNFE.BUFS3FT"o
9. Kruzic JJ, Nalla RK, Kin-ney JH, Ritchie RO. Crack blunting, crack bridging and resistance-curve fracture mechanics in dentin: effect PGIZESBUJPO#JPNBUFSJBMTo
(BMF.4%BSWFMM#8%FOUJOpermeability and tracer tests. J Dent 1999;27:111.
11. Jameson MW, Hood JA, 5JENBSTI#(5IFFGGFDUTPG
dehydration and rehydra-tion on some mechanical properties of human dentin. +#JPNFDIo1065.
12. Grigoratos D, Knowles J, Ng YL, Gulabivala K. Effect of exposing dentin to sodium hypochlorite and calcium hydroxide on its flexural strength and elastic modulus. Int Endod J o
(PMETNJUI.(VMBCJWBMBK, Knowles JC. The effect of sodium hypochlorite irri-gant concentration on tooth surface strain. J Endod 2002;28:575579.
4BMFI""&UUNBO8.Effect of endodontic irriga-tion solutions on microhard-ness of root canal dentin. J %FOUo
4PV[B#JFS$"4IFNFTIH, Tanomaru-Filho H, Wesselink PR, Wu M. The ability of different nickel-titanium rotary instruments to induce dentinal damage during canal preparation. J &OEPEo
16. Ferrari M, Mason PN, Goracci C, Pashley DH, Tay FR. Collagen degradation in endodontically treated teeth after clinical function. +%FOU3FTo
17. Randow K, Glanz PO. On cantilever loading of vital and non-vital teeth. An experimental clinical study. Acta Odontol Scand o
#BKBK%4VOEBSBN//B[-ari A, Arola D. Age, dehy-dration and fatigue crack HSPXUIJOEFOUJO#JPNBUFSJ-als 2006;27:25072517.
19. Viguet-Carrin S,Garnero P,Delmas PD. The role of collagen in bone strength. Osteoporos Int o
20. Magne P, Douglas WH. Rationalization of esthetic restorative dentistry based on biomimetics. J Esthet Dent 1999;11:515.
21. Ni CW, Chang CH, Chen TY, Chuang SF. A multipara-metric evaluation of post-restored teeth with simulat-FECPOFMPTT.FDI#FIBW#JPNFE.BUFSo
22. Tsesis I, Rosen E, Tamse A, Taschieri S, Kfir A. Diagno-sis of vertical root fractures in endodontically treated teeth based on clinical and radiographic indices: a systematic review. J Endod o
'VTT;-VTUJH+5BNTF"Prevalence of vertical root fractures in extracted endo-dontically treated teeth. Int &OEPE+o
$PQQFOT$3.%F.PPSRJG. Prevalence of vertical root fractures in extracted endodontically treated teeth. *OU&OEPE+
25. Tamse A, Fuss Z, Lustig J, Kaplavi J. An evaluation of endodontically treated vertically fractured teeth. J Endod 1999;25:506508.
26. Vire DE. Failure of endodon-tically treated teeth: clas-sification and evaluation. J &OEPEo
27. Salvi GE, Siegrist Guldener #&"NTUBE5+PTT"-BOHNP. Clinical evaluation of root filled teeth restored with or without post-and-core systems in a specialist practice setting. Int Endod J o
28. Kishen A, Kumar GV, Chen NN. Stressstrain response in human dentin: rethinking fracture predilection in post-core restored teeth. Dent 5SBVNBUPMo
29. Zarow M, Devoto W, Sara-cinelli M. Reconstruction of endodontically treated posterior teeth with or without post? Guidelines for the dental practitioner. Eur J &TUIFU%FOUo
4PV[B&.EP/BTDJNFOUPLM, Maia Filho EM, Alves CM. The impact of post preparation on the residual dentin thickness of maxil-
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'FSSBSJ.$BHJEJBDP.$Goracci C, Vichi A, Mason PN, Radovic I, Tay F. Long-term retrospective study of the clinical performance of fiber posts. Am J Dent 2007;20:287291.
1JFSSJTOBSE-#PIJO'3FOBVMU1#BSRVJOT.$PS-ono-radicular reconstruction of pulpless teeth: a mechani-cal study using finite ele-ment analysis. J Prosthet %FOUo
#JOEM"3JDIUFS#.SNBOOWH. Survival of ceramic computer-aided design/manufacturing crowns bonded to preparations with reduced macroretention geometry. Int J Prosthodont o
4BUIPSO$1BMBNBSB+&Palamara D, Messer HH. Effect of root canal size and external root surface mor-phology on fracture suscep-tibility and pattern: a finite element analysis. J Endod o
#PMIVJT)1#%F(FF"+Feilzer AJ, Davidson CL. Fracture strength of different core build-up designs. Am J %FOUo
)FZEFDLF(#VU[')VT-sein A, Strub JR. Fracture strength after dynamic load-ing of endodontically treated teeth restored with different post-and-core systems. J 1SPTUIFU%FOUo
4DINPMEU4+,JSLQBUSJDL5$Rutledge RE, Yaccino JM. Reinforcement of simulated immature roots restored with composite resin, mineral trioxide aggregate, gutta-percha, or a fiber post after thermocycling. J Endod o
.BOHPME+5,FSO.*OGMV-ence of glass-fiber posts on the fracture resistance and failure pattern of endodonti-cally treated premolars with varying substance loss: An in vitro study. J Prosthet %FOUo
lary molars. J Prosthet Dent o
,SFKJ*%VD0%JFUTDIJ%EFCampos. Marginal adapta-tion, retention and fracture resistance of adhesive com-posite restorations on devital teeth with and without posts. 0QFS%FOUo
'PLLJOHB8"-F#FMM".Kreulen CM, Lassila LV, Vallittu PK, Creugers NH. Ex vivo resistance of direct composite complete crowns with and without posts on maxillary premolars. Int &OEPE+o
(V[Z(&/JDIPMT+**Ovitro comparison of intact endodontically treated teeth with and without endo-post reinforcement. J Prosthet %FOUo
4PV[B&.EP/BTDJNFOUPLM, Maia Filho EM, Alves CM. The impact of post preparation on the residual dentin thickness of maxil-lary molars. J Prosthet Dent o
)FZEFDLF(#VU['4USVCJR. Fracture strength and survival rate of endodon-tically treated maxillary incisors with approximal cavities after restoration with different post and core systems: an in vitro study. J %FOUo
'FSSBSJ.$BHJEJBDP.$Grandini S, De Sanctis M, Goracci C. Post placement affects survival of endodon-tically treated premolars. J %FOU3FTo
4UBOLJFXJD[/38JMTPOPR. The ferrule effect: a literature review. Int Endod J o
+VMPTLJ+3BEPWJD*Goracci C, Vulicevic ZR, Ferrari M. Ferrule effect: a literature review. J Endod o
4PSFOTFO+".BSUJOPGG+5Intracoronal reinforcement and coronal coverage: a study of endodontically treated teeth. J Prosthet %FOUo
/H$$%VNCSJHVF)#"M#BZBU.*(SJHHT+"Wakefield CW. Influence of remaining coronal tooth structure location on the fracture resistance of restored endodontically treated anterior teeth. J Pros-thet Dent 2006;95:290296.
)FZEFDLF(1FUFST.$The restoration of endodon-tically treated, single-rooted teeth with cast or direct posts and cores: a system-atic review. J Prosthet Dent o
50. Dietschi D, Duc O, Krejci *4BEBO"#JPNFDIBOJ-cal considerations for the restoration of endodontically treated teeth: a systematic review of the literature, Part II (Evaluation of fatigue behavior, interfaces, and in WJWPTUVEJFT2VJOUFTTFODF*OUo
51. Krejci I, Duc O, Dietschi D, de Campos E. Marginal adaptation, retention and fracture resistance of adhe-sive composite restorations on devital teeth with and without posts. Oper Dent. o
4BOUPT"'.FJSB+#5BOBLB$#9BWJFS5"#BMMFTUFSRY, Lima RG, Pfeifer CS, Versluis A. Can fiber posts increase root stresses and reduce fracture? J Dent Res 2010;89:587591.
3BTJNJDL#+8BO+.VTJ-LBOU#-%FVUTDI"4"review of failure modes in teeth restored with adhe-sively luted endodontic dowels. J Prosthodont o
'FEPSPXJD[;$BSUFS#de Souza RF, de Andrade Lima Chaves C, Nasser M, 4FRVFJSB#ZSPO14JOHMFcrowns versus conventional fillings for the restoration of root filled teeth. Cochrane Database Syst Rev 2012:16:CD009109.
55. Fokkinga WA, Kreulen CM, #SPOLIPSTU&.$SFVHFSTNH. Up to 17-year controlled
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clinical study on post-and-cores and covering crowns. +%FOUo
4JHOPSF"#FOFEJDFOUJ4,BJUTBT7#BSPOF."OHJ-ero F, Ravera G. Long-term survival of endodontically treated, maxillary anterior teeth restored with either tapered or parallel-sided glass-fiber posts and full-ceramic crown coverage. +%FOUo
57. Jung RE, Kalkstein O, Sailer I, Roos M, Hmmerle CH. A comparison of composite post buildups and cast gold post-and-core buildups for the restoration of nonvital teeth after 5 to 10 years. Int J 1SPTUIPEPOUo
'FSSBSJ.#SFTDIJ-(SBO-dini S. Fiber posts and endodontically treated teeth: a compendium of scientific and clinical perspectives, ed 1. Wendywood, South Africe: Modern Dentist Media. Wendywood, 2006.
59. Malament KA, Socransky SS. Survival of Dicor glass-ceramic dental restorations over 20 years: Part IV. The effects of combinations of variables. Int J Prosthodont o
60. Malament KA, Socransky SS, Thompson V, Rekow D. Survival of glass-ceramic materials and involved clinical risk: variables affecting long-term survival. Pract Proced Aesthet Dent 4VQQMo
61. Naumann M, Koelpin M, #FVFS'.FZFS-VFDLFM)10-year survival evaluation for glass-fiber-supported postendodontic restoration: a prospective observa-tional clinical study. J Endod o
62. Ferrari M, Vichi A, Fadda GM, Cagidiaco MC, Tay '3#SFTDIJ-1PMJNFOJ"Goracci C. A randomized controlled trial of endodonti-cally treated and restored premolars. J Dent Res 2012;91:72S78S.
(NF[1PMP.-MJE#Rivero A, Del Ro J, Celemn A. A 10-year retrospective study of the survival rate of teeth restored with metal prefabricated posts versus cast metal posts and cores. +%FOUo
8SCBT,5,BNQF.5Schirrmeister JF, Altenburg-er MJ, Hellwig E. Retention of fiber posts dependent on different resin cements. Schweiz Monatsschr Zahn-NFEo
65. Kremeier K, Fasen L, Klaib-FS#)PGNBOO/*OGMVFODFof endodontic post type (glass fiber, quartz fiber or HPMEBOEMVUJOHNBUFSJBMPOpush-out bond strength to dentin in vitro. Dent Mater o
66. Ferrari M, Mannocci F, Vichi "$BHJEJBDP.$.KS*"#POEJOHUPSPPUDBOBMstructural characteristics of the substrate. Am J Dent o
$BMJYUP-3#BOEDB.$Clavijo V, Andrade MF, Vaz LG, Campos EA. Effect of resin cement system and root region on the push-out bond strength of a translu-cent fiber post. Oper Dent o
68. Huber L, Cattani-Lorente M, 4IBX-,SFKDJ*#PVJMMBHVFUS. Push-out bond strengths of endodontic posts bonded with different resin-based luting cements. Am J Dent 2007;20:167172.
69. Monticelli F, Ferrari M, Toledano M. Cement system and surface treatment selection for fiber post lut-ing. Med Oral Patol Oral Cir #VDBM&o
#BSBCBOUJ/.BEJOJ-Krokidis A, Acquaviva PA, Cerutti F, Cerutti A. Polymerization degree and cementation methods of two different self-adhesive lut-ing cements used for glass fiber post cementation. Minerva Stomatol 2012;61: o
71. Sterzenbach G, Karajouli G, /BVNBOO.1FSP[*#JUUFSK. Fiber post placement with core build-up materials or resin cements An evalu-ation of different adhesive approaches. Acta Odontol 4DBOEo
72. Radovic I, Corciolani G, Magni E, Krstanovic G, Pavlovic V, Vulicevic ZR, Ferrari M. Light transmission through fiber post: the effect on adhesion, elastic modu-lus and hardness of dual-cure resin cements. Dent .BUFSo
.POUJDFMMJ'0TPSJP34BEFLFT, Radovic I, Toledano M, Ferrari M. Surface treatments for improving bond strength to prefabri-cated fiber posts: a lit-erature review. Oper Dent o
:FOJTFZ.,VMVOL4Effects of chemical sur-face treatments of quartz and glass fiber posts on the retention of a compos-ite resin. J Prosthet Dent o
75. Radovic I, Monticelli F, Goracci C, Cury AH, Coniglio I, Vulicevic ZR, Garcia-Godoy F, Ferrari M. The effect of sandblasting on adhesion of a dual-cured resin composite to methacrylic fiber posts: microtensile bond strength and SEM evaluation. J Dent o
76. Soares CJ, Santana FR, Pereira JC, Araujo TS, Menezes MS. Influence of airborne-particle abrasion on mechanical proper-ties and bond strength of carbon/epoxy and glass/bis-GMA fiber-reinforced resin posts. J Prosthet Dent o
77. Valandro LF, Yoshiga S, de Melo RM, Galhano GA, Mallmann A, Marinho CP, #PUUJOP.".JDSPUFOTJMFbond strength between a quartz fiber post and a resin cement: effect of post sur-
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face conditioning. J Adhes Dent 2006;8:105111.
78. Zicari F, De Munck J, Scotti R, Naert I, Van Meerbeek #'BDUPSTBGGFDUJOHUIFcement-post interface. Dent Mater 2012;28:287297.
79. Vano M, Carvalho C, Sedda M, Gabriele M, Garca-Godoy F, Ferrari M. The influ-ence of storage condition and duration on the resist-ance to fracture of different fiber post systems. Am J %FOUo
80. Schmage P, Nergiz I, Marko-poulou S, Pfeiffer P. Resist-ance against pull-out force of prefabricated coated FRC posts. J Adhes Dent o
81. Cheleux N, Sharrock PJ. Mechanical properties of glass fiber-reinforced endo-EPOUJDQPTUT"DUB#JPNBUFSo
82. Grandini S, Goracci C, Monticelli F, Tay FR, Ferrari M. Fatigue resistance and structural characteristics
of fiber posts: three-point bending test and SEM evaluation. Dent Mater 2005;21:7582.
(SBOEJOJ4$IJFGGJ/Cagidiaco MC, Goracci C, Ferrari M. Fatigue resistance and structural integrity of different types of fiber posts. Dent Mater J 2008;27:687
Part 2: Esthetic considerations
Introduction
In addition to the numerous issues dis-
cussed in part 1 of this paper, non-vital
teeth are frequently esthetically com-
promised. This frequently presents sig-
nificant and special challenges when it
comes to meeting the demand for nat-
ural-looking, esthetically pleasing teeth
sought by our patients today.
The aim of the second part of this pa-
per is to try to answer several clinically
relevant conceptual questions and to
provide some clinical guidelines regard-
ing the management of the esthetic as-
pects, based on scientific evidence and
clinical expertise.
Why are most endodontically treated teeth dark?
The discoloration of endodontically
treated teeth is a common observation.
In the posterior region, this phenom-
enon is seldom esthetically disturbing
or is largely addressed with full crowns,
since endodontically treated posterior
teeth present mostly with large recon-
structions that require optimal stabiliza-
tion by full or partial crowns.
In the anterior zone, however, esthet-
JDTDBOCFTUSPOHMZEJTUVSCFECZOFHB-tive effects:
Discolouration of the clinical crown.
Discolouration of the cervical region.
Discolouration of the gingiva and mu-
cosa.
There are various causes of these en-
dodontically induced intrinsic discolora-
tions:
Intrapulpal haemorrhage.
Pulpal necrosis.
Incomplete removal of pulp tissue
during the endodontic treatment.
Endodontic irrigants, medications
and root canal filling material (root
BOEDFSWJDBM[POF Restorative materials (cervical zone
BOEDSPXO Coronal leakage.
Dentin sclerosis.
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Unfortunately almost all root canal seal-
ers including Zinc Oxide-Eugenol and
")UPBMFTTFSFYUFOUMFBEUPEJTDPM-PSBUJPOBCPWFBMMJOUIFDFSWJDBM[POFAlso the use of MTA, be it grey or white,
will ultimately lead to a greyish appear-
ance or darkening of the root.5,6
Furthermore, the calcification pro-
cess in the dentin through obliteration
of the dentinal tubules and changes in
the free water content before and after
endodontic treatment and through ag-
ing processes, contributes to an altered
optical appearance in addition to the in-
creased brittleness.7-10
How can we improve the color of UIFUPPUITVCTUBODF #MFBDIJOHor replacing discoloured coronal dentin?
Although some of the above mentioned
negative factors can be clinically modi-
fied, it is evident that a non-vital tooth
inevitably loses some esthetic qualities
in terms of the color. As a matter of prin-
ciple, replacing discolored dentin to cor-
rect the color is not the preferable op-
tion from a structural viewpoint. In part 1,
the mechanical aspects to support this
axiom have already been extensively
discussed.
Therefore, bleaching the existing
substance is always the better option,
if we agree on the principle that hav-
ing a discolored tooth is preferable to
having no tooth. Most discolorations
are bleachable except those caused by
metal ions (amalgam, or silver and other
IFBWZNFUBMDPOUBJOJOHNBUFSJBMT2 So the only indication to remove discolored
dentin may be if small spots that do not
contribute to the structural resistance of
the tooth are heavily discolored and do
not respond to the bleaching procedure.
Do bleaching procedures lead to external resorption?
Cervical root resorption is a serious
complication that is difficult to treat11,12
and ultimately can lead to tooth loss.
There are various reasons for this phe-
nomenon. Orthodontic treatment and
tooth trauma are the most common pre-
disposing factor. Internal bleaching may
increase the combinatory risk, however
it seems to be limited to cases where
extensive concentrations of H2O2 com-
bined with heat (the thermo-catalytic
NFUIPE XBT VTFE The presence of defects at the cemento-enamel junc-
tion seem to play a major role, allowing
the bleaching agent to penetrate into the
periodontal space.15
The recommendations today are
therefore not to heat the bleaching agent
in the access cavity, to seal the residual
root filling well before application of the
bleaching agent and to generally use
less aggressive bleaching chemicals
instead of high concentrations of H2O2.
The best clinical compromise of ef-
fect, side-effects, risks and long-term
experience is in the use of the so called
walking bleach technique16 where,
classically, sodium perborate is mixed
with water.
In the authors long-term experience,
this is clinically as efficient as other more
aggressive chemicals, provided a cor-
rect cervical and coronal seal of the
bleaching cavity have been realized.
The cervical seal is preferably achieved
with a modified glass ionomer cement,
classically applied at the level of the con-
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nective tissue attachment, whereas the
coronal seal is achieved with adhesively
luted composite to ensure an optimal
penetration of the bleaching agent into
the dentin. Hence, leaving the access
cavity open and using at-home tech-
niques with open trays is not advisable.17
Success largely depends from the ap-
plication duration of the bleaching agent
oEBZToUJNFTBOECZGBSPVUQFS-forms alternative quick in-office tech-
niques in the long run.18 In a recent study
it could also be shown that this concept
compares very favorably to more ag-
gressive mixtures of chemicals in terms
of H2O2 leakage at different root locations
with and without external defects.19,20
Since cervical defects are difficult to
detect with conventional radiographs
and require cone beam computed to-
NPHSBQIZ$#$5UFDIOJRVFT21 the use of this less-aggressive concept makes
additional sense in avoiding added un-
known risks while producing good es-
thetic results.
Do bleaching procedures weaken the tooth or may dark roots also be bleached?
Recent research clearly shows that
bleaching chemicals weaken tooth sub-
stance.
Since the endodontic treatment itself
already weakens the dentin consider-
ably through chemical and mechanical
effectsCZUPJOTUSFOHUI25 additional care must be taken if a bleach-
ing procedure is being considered.
First of all, internal removal of dis-
colored dentin should be avoided. It
does not lead to better results with the
described bleaching technique and will
further compromise the strength of the
residual tooth structure. This is an im-
portant consideration particularly if ad-
ditional reconstructive measures are to
be executed26 and if the potential for re-
intervention is taken into account.
Second, as mentioned, bleaching
agents themselves lead to a weakening
of the tooth structure through the chemi-
cal modification of the dentin.27,28 A re-
cent publication supported the use of
sodium perborate mixed with water in
this respect, since this combination led
to a significantly smaller additional open-
ing of the dentinal tubules compared to
all other bleaching agents. Interestingly
DBSCBNJEF QFSPYJEF DBVTFE UIFworst effect.29
Another important consideration is
the influence of bleaching on dentin
bonding. As emphasized in part 1, the
quality of the internal reconstruction af-
ter endodontic therapy is of key impor-
tance in reconstituting the resistance to
fracture. Using an adhesive approach is
advisable but technique sensitive and,
in general, all bleaching agents lead to
reduced bond strengths and increased
microleakage. Consequently, the use
of antioxidants has been advocated to
counteract this effect (eg, sodium ascor-
CBUFBOEPSEFMBZJOHUIFCPOEJOHQSP-cedure for at least 10 days after washing
out the bleaching agent The antioxi-
dant is especially necessary and should
be mandatory if bonding with simplified
single bond dentin adhesives, or if de-
layed bonding is not warranted or pos-
sible.
However, good dentin adhesion can be
achieved if: a) sodium perborate mixed with water is used to bleach, b) the tooth is left with saline solution for 7 days after
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removal of the bleaching agent, and c) a scientifically and clinically well estab-
lished self-etching 2-step dentin bonding
TZTUFNFH$MFBSGJM4&CPOEJTVUJMJ[FE For enamel, the same principle of waiting
after washing off the bleaching agent is a
simple and successful strategy. Recent
proposals for new resin formulations that
are supposed to allow immediate bond-
ing after bleaching have not proved as
effective.
Since adhesion within the root remains
a challenge even in ideal experimental
Fig 15 $BTFEJTDPMPSFEOPOWJUBMSJHIUDFOUSBMincisor with PFM crown, initial clinical situation.
Fig 16 $BTF JOJ-tial radiographic situ-
ation. A carbon com-
posite post had been
placed.
Fig 17 $BTFBCVUNFOUUPPUIBGUFSDSPXOBOEpost removal.
Fig 18 $BTFIPMMPXDPNQPTJUFCVJMEVQGPSJOUFS-nal bleaching of coronal part of the abutment tooth.
conditions owing to unfavorable ovoid
root canal configurations and dentin mi-
crostructure in the deeper parts of the
root canal the root should not be
further compromised by using bleach-
ing techniques inside the root canal.
As long as the intracoronal bleaching
is performed within the access cavity
reaching to the level where the connec-
tive tissue attachment ends coronally,
the results constitute a sufficient com-
promise esthetically,26 even in the criti-
DBMDFSWJDBM[POF'JHTo
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Fig 19 $BTFDPNQMFUFECVJMEVQPGBCVUNFOUtooth with bonded fiber post and core, after internal
bleaching with sodium perborate and water.
Fig 20 $BTF HMBTT DFSBNJD DSPXO MBZFSJOHtechnique.
Fig 21 $BTFGJOBMDMJOJDBMSFTVMU Fig 22 $BTF GJOBM SBEJPHSBQIshowing good adaptation of the short
fiber post and bonded core to the den-
UJOBMXBMMTMJHIUDVSFENBUFSJBMTVTFE
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What about the predictability and stability of bleaching procedures?
There has been some debate about the
predictability and long-term effective-
ness of internal bleaching, with de-
scribed esthetic success rates of around
90% after 2 years, 75% after 5 years and
60% after 16 years. The potential causes
for the recurrence of discoloration have
been suggested as: a) the same sub-stances as those having caused the ini-
tial discoloration, or b) penetration of pig-ments from the oral cavity, or c) bacterial reinfection of the root canal system with
subsequent infiltration into the cervical
and coronal dentin.1
From long-term studies and clinical
observations, the following can be con-
cluded:
Internal bleaching is a technique-
sensitive approach. Potential rea-
sons for failures are numerous, with
coronal or apical leakage being the
most frequent, and short-cut treat-
ment protocols are more likely to have
QSPCMFNT#PUI UIF DPSPOBM BOE UIFapical-cervical seal, along with the
optical quality of the access restora-
tion, account for success or failure.
The prognosis of the bleaching pro-
cedure is more prone to recurrence
of discoloration if the tooth became
rapidly discolored after the endodon-
tic treatment.
Subjective and objective satisfaction
of the dentist or the patient may differ
substantially.
The potential for intervention and the
concept of a progressive (conserva-
UJWFBQQSPBDIEVSJOH UIF MJGFUJNFPGa discolored tooth are essential. Ag-
gressive reconstructive concepts
based just on esthetic considerations
and early crowning can lead to prema-
ture tooth loss. Therefore, bleaching
instead of removing tooth substance
is the preferable treatment, both for
non-reconstructive and reconstruc-
tive cases.26
May crowns or veneers compensate darkened coronal tooth structure?
First of all it is important to understand
the concept of illumination of the oral tis-
sues. The tooth with its clinical crown
and root, the gingiva, the bone and the
periodontium form an optical unit. Light
is transmitted by diffuse reflection into
the tissues. It is therefore critical not to
disturb this delicate system with discol-
Fig 23 Limited light conducting properties of fib-er posts with good mechanical properties preclude
the use of long posts, if light-cured materials are to
be used.
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orations or by the introduction of inad-
equate opaque or dark restorative ma-
terials. Of particular importance in this
respect is a soft color transition from the
cervical third of the clinical crown into
the adjacent gingival tissues.
Since the mid 1960s, dental techni-
cians and prosthodontists tried to imple-
ment this concept in order to improve
the esthetics of full crown margins. In the
1980s, PFM crowns without metal collars
were introduced, using shoulder and ve-
neering porcelains with better light con-
ducting properties to illuminate the adja-
cent tissues. Despite these efforts,
the results were never completely sat-
isfying when the underlying tooth struc-
ture was dark, or if there were vital and
rather translucent teeth to be matched.
Hence the search and development of
true light conducting materials as frame-
works with lower opacity than metal or
the pre-existing all-ceramic cores.
Today, in the case of vital teeth with
adequate tooth substance, more con-
servative bonded porcelain restorations,
such as veneers and anterior partial all-
ceramic crowns, are increasingly the
treatment of choice as compared to full
crowns, due to esthetic, technical and
biological advantages. It is impor-
tant to understand that the success of
these restorations is largely based on
the esthetic and mechanical advantag-
es of the natural uncompromised tooth
substrate as the foundation of the resto-
ration rather than an artificial substrate.
As a consequence of this success, the
concept has been extended to endo-
dontically treated teeth, with the idea be-
hind to convert darkened tooth structure
into vital looking tissues. Naturally
this is not only relevant to bonded lami-
nates and all-ceramic partial crowns,
as a wide variety of all-ceramic crown
systems exist today with excellent opti-
cal properties and long-term survival, in
particular, the new generation of glass-
ceramic materials. In addition, these
materials allow the provision of bonded
full coverage veneer type crowns with
SFEVDFEQSFQBSBUJPOTJNJMBSUPEF-HSFFWFOFFSQSFQBSBUJPO'JHTo
Consequently, the management of
discolored tooth substrate becomes
increasingly important. It should be re-
membered that all attempts to mask out
discolored tooth substance will invari-
ably end up with increased opacity and
therefore unnatural reflection of the light
instead of a diffuse reflection inside the
materials. This is of particular importance
when veneering a tooth with a discolored
cervical zone, as the fine veneer margins
cannot create the appropriate color tran-
sition from the tooth crown into the gin-
giva. If a full crown is provided in such a
case, a pleasing result can be achieved
by using opaque all-ceramic framework
materials, provided that adjacent struc-
tures are also more opaque and the gin-
gival tissue is thick, but this is rather the
exception than the rule.57,58 The same is
true if opaque cements are used to cover
dark underlying substance.
Above all, trying to mask out dis-
colored teeth should not result in over-
preparation:59 the mission statement of
Hippocrates primum nihil nocere (first EPOPIBSNTIPVMEBMTPCFUIFHVJEJOHQSJODJQMFIFSF'JHTBOE
Thus the clinical concept for man-
agement of discolored tooth substance
should always consider internal bleach-
ing as first option, even if the result will
not be absolutely perfect.
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If the tooth needs an additional indi-
rect restoration, a veneer or full cover-
age veneer-crown is an attractive and
less invasive solution. In the authors
own experience over the last 15 years
from when the concept first was used,
long-term results for esthetics and sur-
vival rates in both types of restorations
are comparable to all-ceramic crowns.
However, in the literature there are only
studies with vital teeth available at the
moment, which show a survival rate of
PWFS ZFBST GPS WFOFFST BOE100% for extended veneers over 5
years.60,61 The observation of small su-
perficial cracks not influencing survival
is similar to what can be observed within
the enamel of natural teeth.
One drawback certainly is if the dis-
colored tooth has already been restored
with a post. If removal of the post without
risk of damage to the root is viable, then
the internal bleaching can be performed
before a new post and core is fabricat-
ed. If this is considered too risky, metallic
posts and cores can at least be masked
with a tooth-colored opaquer and com-
posite to avoid to improve the substrate
color for an all-ceramic framework.
This leads to the next question: Can
tooth-colored posts enhance the color
of dark roots?
Tooth-colored posts have long been
advocated in esthetic dentistry. Since
early trials around 1965 by John McLean
with Alumina posts, the concept has
been further developed to mechanically
more reliable posts, with the introduc-
tion of the first Zirconia posts in 1995
and the first fiber posts in 1990.
The proposed reasons for tooth-color-
ed posts for esthetics in root treated
teeth are:
To illuminate the root and cervical re-
gion and thus brighten up darkened
tooth substance.
Fig 24 $BTFEJTDPMPSFEBCVUNFOU UFFUIXJUIcast post and cores, leading to a disturbance in the
illumination of the adjacent tissues.
Fig 25 $BTFGJOBMQJDUVSFXJUI1'.DSPXOT%VFto the symmetry of the case, the suboptimal color
transition from the abutment margins into the gin-
gival tissues fortunately does not disturb too much
in this case.
Fig 26 Case 5: left central incisor with polished cast post and core, right lateral incisor with tooth-
colored post and core.
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To prevent any darkening effect of a post
on non-discolored tooth substance.
To create a tooth-colored basis for the
core and the crown.
While the first reason has already been
disputed early on by experienced cli-
nicians not being able to see any dif-
ference in the color between a metallic
post and a tooth-colored post put into
the same dark root under natural light
conditions, the second two points are
good arguments for tooth-colored posts.
In fact a recent study showed that there
is no difference in the cervical color of
abutment teeth between white and me-
tallic posts, however tooth-colored posts
and cores were beneficial for the overall
color of the all-ceramic crowns.65 This
is in line with observations of clinicians
aware of these subtle differences.66
Some care must be taken when trying
to translate in vitro studies about color influences into clinical practice. Some
subtle components of the color, such as
the quality of the internal diffuse reflec-
tion depending on the intensity of light
and the softness of the transition into the
marginal gingiva cannot be measured
Fig 27 Case 5: final picture showing the good reflection properties of the polished metal part of the
left central abutment tooth.
Fig 28 Case 6: abutment teeth with various de-grees of discolorations.
by photospectroscopic studies67 and
may lead to incorrect clinical recom-
mendations in specific cases.
However, given the clinical and sci-
entific evidence, there is actually little
reason to take out existing well adapted
and luted cast post and cores if the re-
maining dentin itself is not discolored
and does not require bleaching. It is
clinically sufficient to mask the buccal
part of the metal with a tooth-colored
opaquer. If space and residual thick-
ness of a gold alloy post and core do
not allow to do this, another smart ap-
proach is to polish the buccal part of
the exposed metal to a high gloss, thus
creating total reflection of the light at the
core surface.68 This concept has been
widely used by the author for years with
no adverse effects regarding the reten-
UJPOPGUIFMVUFEDSPXOT'JHToIn conclusion, it can be stated that
the color of the remaining tooth sub-
strate is of much greater importance
than the color of the post and cannot
be influenced positively by the post in
the cervical and apical region, however
having a tooth-colored post is beneficial
for the core.
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Can soft tissue thickening compensate darkened cervical root structure?
A soft color transition from the crown
into the soft tissue is essential for an
esthetically pleasing result. In the pre-
ceding pages, the focus was placed
on the root and crown of the tooth and
how negative effects can be managed.
However, if discolorations are still pre-
sent in the critical cervical supra- and
subgingival zone, it makes sense to
consider influencing the soft tissue
characteristics.
The margin of the soft tissue cover-
ing the cervical part of the root plays
an important role as a curtain to hide
unpleasing structures. In addition, the
buccal bone plate has also some mask-
ing effect over a discolored root. A thick
bone plate can virtually completely mask
out the root discoloration. In periodontol-
ogy, there is little information available
about the masking effect of the soft tis-
sue. In oral implantology, however, some
studies have been performed looking at
the influence of various abutment ma-
terials on the color of the existing soft
tissues, and how variations in the soft
tissue thickness can modify the overall
color resulting from abutment and cov-
ering soft tissue. Since these abutments
all have a subgingival component and a
titanium implant base, this would appear
to offer a situation well in line with a dis-
colored root. Comparing zirconia, pol-
ished gold alloys and machined titanium
in a pig model, a visible difference was
always present if the tissue thickness
XBT CFMPX NN #FUXFFO UP NNin thickness, only zirconia (regardless of
BOZWFOFFSJOHEJEOPUJOEVDFBDIBOHF*GUIFUIJDLOFTTXBTNNPSNPSFUIFmaterial itself had no influence.69 In a
human study, comparing metal abut-
ments and PFM crowns with all-ceramic
abutments and crowns, the latter be-
haved better, but there was still a visible
difference for both groups compared
to the adjacent teeth.70 Another study
presented similar results,71 although no
correlation between the thickness of the
mucosa and the respective amount of
discoloration could be found.
In essence, the fiber content and the
degree of keratinization may play a more
important role for the masking ability
than the soft tissue thickness alone. In
this respect, the use of a connective tis-
sue graft taken from the palate with its
higher content of collagen fibers is the
most promising approach using an en-
velope technique to improve the esthetic
integration of the augmented tissue.
Some modifications in the technique, in-
cluding a microsurgical approach, have
been introduced to further decrease
Fig 29 Case 6: layered glass ceramic crowns with internal opaquer and varying opacities of
frameworks.
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healing complications and unesthetic
tissue scars.
An additional benefit of this approach
is the easier tissue handling during the
reconstructive phase and the preven-
tion of post-reconstructive recessions
over time, which may expose further dis-
colored root parts. Indeed, since many
of the discolored teeth exhibit some cer-
vical tissue loss over time anyway, this
procedure can also be considered as a
preventive treatment of a cervical reces-
sion,76 dealing not primarily with health,
but with stable, esthetic tissue levels. It
may also serve to counteract the loss in
cervical tissue height that occurs by tis-
sue modeling during the aging process,
which is more noticed around discolor-
ed roots and is independent of the pres-
ence or absence of dental restorations.
As a conclusion, soft tissue thicken-
ing may not completely solve the prob-
lem of the discolored cervical hard and
soft tissue zone, but it can improve the
overall result by at least stabilizing soft
tissue contours and preventing further
exposure of discolored root surfaces.
Final consideration: at what point should we give up and extract?
It is fair to state that a tooth should be
saved as long as there is a predictable
way to functionally and biologically do
so with a reasonable prognosis. This
2-part article has shown various possi-
bilities to overcome classic biomechani-
cal and esthetic problems with respect
to minimizing reconstructive risks. The
basis for reconstructive survival in the
context of this article, however, is the
quality of the endodontic treatment as
the starting point.
It can also be stated that today too
many teeth are extracted in favor of im-
plants, with insufficient regard for the
extensive reconstructive options avail-
able to maintain them. Furthermore, the
Fig 30 Case 6: final picture of the four anterior teeth, showing an acceptable color transition be-
UXFFOUIFQPOUJDSJHIUMBUFSBMJODJTPSBOEUIFPUIFSabutment teeth.
Fig 31 Case 6: final picture of the right side, showing an acceptable color transition between the
QPOUJDMBUFSBMJODJTPSUIFWJUBMDBOJOFBOEUIFOPOvital discolored central incisor.
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short- and long-term biologic, esthetic
and technical complications of implants
are not fully appreciated.77 Unfortu-
nately, poor endodontic treatment is still
a major factor in premature tooth loss.
However, if performed correctly, results
are at least as good as replacement with
implants for single units.77 It is striking
that despite this fact, today a tendency
towards a more extraction-oriented re-
constructive concept can be observed
in practice. There are two main reasons
for this.
The first reason is that in clinical de-
cision-making, the predictability of the
whole procedure is of primary impor-
tance in respect of complications and
cost. Obviously there is some pessimism
among clinicians regarding the progno-
sis of endodontic treatments in general
and this is not completely unfounded.
The combined failure rate of endodonti-
cally treated teeth in general practice is
higher than described in earlier reports:
PWFSZFBSTBDVNVMBUJWFGBJMVSFSBUFPGup to 20% is documented.78 In general,
the outcome of endodontic treatments
may have been overestimated in previ-
ously published reviews because of the
general lack of correct apical diagnosis.
*GIJHISFTPMVUJPO$#$5JTOPUVTFEPGUFOthe endodontic status cannot correctly
be analyzed. The authors of a current
review state: In conclusion, the serious
limitations of longitudinal clinical studies
restrict the correct interpretation of root
canal treatment outcomes. Systematic
reviews reporting the success rates of
root canal treatment without referring
to these limitations may mislead read-
ers.79 Therefore, the trend towards sim-
plified endodontic protocols may also
be based on incorrect interpretations of
previous studies and may produce less
successful results than expected or than
achieved with the classic concepts of
experienced endodontic specialists. A
MPOHUFSNTUVEZPWFSZFBSTDPOEVDU-ed in a private practice by a specialist,
documented an overall success rate of
91.5%.80 Initial endodontic treatments
IBEBIJHIFSTVDDFTTSBUFDPN-pared to the non-surgical retreatment
HSPVQ 5IJT TIPXT WFSZ DMFBSMZhow important the quality of the first en-
dodontic treatment is for the long-term
success. In addition, the coronal resto-
ration has a significant influence in the
success of the endodontic treatment.
Thus, to strive in every respect for an
optimal restoration is as essential as an
optimal endodontic treatment alone.81
The second reason is that measures
to potentially save a compromised tooth
can later preclude the placement of
an implant or make it very demanding.
Therefore, if an endodontic retreatment
due to recurrent apical pathology is
considered, above all, careful diagnos-
tic steps including soft and hard tissue
probing and radiographs are required.
Conventional radiographs do not allow
proper analysis and interpretation of the
root and remaining bone housing around
the root. The possible causes for the
endodontic failure (eg, crack, fracture,
perforation, insufficient root filling or ac-
DFTTPSZSPPUDBOBMTDBOOPUCFQSPQFSMZestablished without a high-resolution
$#$5BOEDPOTFRVFOUMZUIFQSPHOPTJTand appropriate treatment approach
can only be determined based on an
accurate diagnosis.
Periapical microsurgery should be
performed exclusively if non-surgical
endodontic retreatment is not viable,
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and if the remaining bone housing is suf-
ficient. The surgical approach seems to
be more successful in the short term, but
MFTTTPJOUIFMPOHUFSNPWFSUP6 years for the non-surgical approach,
WFSTVTPWFSNPSFUIBOZFBSTGPSthe surgical approach.82 In addition, the
added bone loss caused by the surgical
access osteotomy and incomplete heal-
ing can make the placement of an im-
plant after a potential failure and eventful
extraction very difficult.
Ultimately, when we examine the treat-
ment outcome of implant versus non-vi-
tal tooth-supported restorations, there is
no clear winner in terms of sustainabil-
JUZFTUIFUJDTCJPMPHZBOEGVODUJPO#PUIsolutions require a perfect synergy of all
the fields of specialties involved and the
treatment steps to achieve the optimal
result for the individual patient.
AcknowledgementsThe author would like to thank Dr Tidu Mankoo for
the systematic and thorough editing of the whole es-
TBZ%S'SBOL1BRVGPSIJTTVQQPSUJOUIFEJTDVTTJPOof the endodontic aspects, and Walter Gebhard and
Nic Pietrobon for their contribution in creating the
dental ceramics.
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