SCIENTIFIC SESSION
The ideal rest restoration oration of endodontically treated teeth – structural and esthetic considerations: a review of the literature literature and clinical guidelines for the restorative clinician clinician Konrad Meyenberg, DMD Private Office for Reconstructive Dentistry Zürich, Switzerland
Correspondence to: Konrad Meyenberg Private Office for Reconstructive Dentistry, Rennweg 58 / Eingang Oetenbachgasse 26, 8001 Zürich, Switzerland; E-mail: k.meyenberg@blu
[email protected]; ewin.ch; Web: www.zahna www.zahnaerzte-rennweg.ch erzte-rennweg.ch
238 THE EUROPEAN JOURNAL OF ESTHETIC DENTISTRY
MEYENBERG
Moderator/Editor’s Moderator/Editor’ s Introduction One of the most challenging dilemmas
for the younger patient, then why can’t
faced by today’s today’s clinician is the manage-
it be done for the older patient? On the
ment of the structurally and esthetically compromised endodontically treated
other hand, perhaps it is more predictable in a given case to remove the tooth
tooth. Certainly, in recent years there has
and restore it with a dental implant res-
been a tendency to take the simplified
toration. These and other issues i ssues are real
approach of “extraction and implant”
concerns we have as practitioners and it
but this does not always prove to be as
is important to have objective as well as
simple as we would like to think. Has
the subjective criteria on which to base
the popularity of dental implantology
our decision for the choice of restorative
made the restorative dentist complacent
protocol.
in regards to the possibilities that good
Are all endodontically treated teeth
endodontic, periodontal and restorative
really less predictable than a dental
treatments can achieve? Without doubt
implant-supported restoration? Are they
the dental implant option has its place,
really more likely to fail? Do they really
and rightly so, but in many cases, I sus-
have a poor prognosis? Do implants re-
pect, the endodontic/restorative option
ally have fewer complications? Is retreat-
does not always receive its due merits.
ment as easy? Do anterior and posterior
Whenever we are faced with such a
teeth behave the same? When is the
compromised tooth, we have to con-
prognosis of the tooth unfavorable and
sider the following question: is the tooth
at what point is extraction and an im-
maintainable? If so, then this is surely
plant the best option? These and many
our primary goal. However, However, the question
other relevant questions are eloquently
is complicated by the context – ie, is this th is
addressed below by our essayist and
a young patient? Is this a bridge abut-
EAED Active Member, Dr Konrad Mey-
ment? Is there an esthetic challenge, ie,
enberg. My hope is that this paper will
a dark tooth? In the younger patient, it
serve to help us to question our treat-
may be desirable to maintain a potentially hopeless tooth for as long as pos-
ment choices more critically in this area, suggest useful answers to many of the
sible in order to “buy time” and delay the
questions in this dilemma, provide us
day of implant placement and its subse-
with objective criteria on which to base
quent eventual failure. Retreatment of a
our judgements and finally offer solu-
tooth is, more often than not, simpler with
tions so that we can make better choices
a broader range of options than retreat-
for the treatment of our patients.
ment of a failed implant, particularly in the esthetic zone. If this can be done
Dr Tidu Mankoo, BDS
239 THE EUROPEAN JOURNAL OF ESTHETIC DENTISTRY
SCIENTIFIC SESSION
Abstract
Clinically,, most of non-vital Clinically non- vital teeth must be considered as structurally and es-
In restorative dentistry, dentistry, the non-vital tooth
thetically compromised.2 The fracture
and its restoration have been extensively
rate and as a consequence the risk for
studied from both its structural and es-
tooth loss is considerably higher com-
thetic aspects. The restoration
pared to vital teeth.
of
endodontically
treated teeth has much in common with modern implantology: both must include multifaceted biological, biomechanical and esthetic considerations with a profound understanding of materials and
Part 1: Structural considerations What are the causes of fractures?
techniques; both are technique sensitive and both require a multidisciplinary ap-
There are several causes for the in-
proach. And for both, two fundamental
creased risk of cracks in endodontically
principles from team sports apply well:
treated teeth to be considered. Cracks
firstly, the weakest link determines the
predispose the tooth immediately or af-
limits, and secondly, secondly, it is a very ver y long way
ter some time to fracture. The following
to the top, but a very short way to failure. fai lure.
four factors contribute to this predisposi-
Nevertheless, there is one major difference: if the tooth fails, there is the op-
Structural loss of tooth substance due
tion of the implant, but if the implant i mplant fails,
to pre-endodontic restorative proce-
there is only another implant or nothing.
dures or the endodontically induces
The aim of this essay is to try to an-
access cavity preparation and root
swer some clinically relevant conceptual questions and to give some clinical
canal enlargements.5,6 Increased brittleness by age induces
guidelines regarding the reconstructive
changes in the dentin and the loss of
aspects, based on scientific evidence
free unbound water from the root ca-
and clinical expertise.
nal lumen and the dentinal tubules in pulpless teeth.7-11
Rebuilding the ideal tooth from an endodontically treated tooth – what does this mean?
Weakening effects by endodontic ir tions (CaOH2 bacterial interactions with the dentin substrates, corrosive effects of restorative materials, and negative mechan-
Essentially, the goal is to restore the ap-
ical effects through crack inducing or
pearance and biomechanical properties
crack propagating endodontic and
comparable to those of a vital, complete-
restorative methods and instruments,
ly intact tooth. In addition, the coronal
including endodontic files.12-16
restoration should prevent bacterial re-
The reduced level of proprioception
colonisation of the endodontically treat-
of non-vital teeth causes a reduced
ed root canal system.1
level of control of forces by the normal
240 THE EUROPEAN JOURNAL OF ESTHETIC DENTISTRY
MEYENBERG
Fig 1
Cracks in lower first molar due to deep cavity.
Fig 2
Fracture of first upper premolar due to deep
cavity with endodontic treatment.
Fig
3
Fracture of palatal
root of upper first molar due
Fig 4
Fracture originating from the apex of a canine due to the use of
inadequate endodontic techniques.
to endodontic treatment.
protective neuromuscular inhibition mechanism.17
Recent research shows that dentin has some very ver y effective inherent properties to inhibit crack progression (fracture
Some of these factors may be influ-
enced or modified to improve the prog-
distribute local stresses and to partially
nosis, however the most important factor
repair defects, as long as a tooth is vi-
for success is to avoid any unnecessary
tal.8,9 However However,, a non-vital tooth to oth will lose
loss of tooth substance in general and
some of these properties over time. A
to preserve as much as possible after
key consideration is that the amount of
removal of all decayed material.
collagen fibers in endodontically treated
241 THE EUROPEAN JOURNAL OF ESTHETIC DENTISTRY
SCIENTIFIC SESSION
teeth decreases, which means that this
to dispense with posts in many indica-
resistant.17
tions, as they are no longer required for
dentin is much less fatigue
In addition, even vital dentin loses some
the retention of a core build-up.
of its initial strength over its lifetime: it
However, mindful clinicians can still
shows a different fracture behavior as
observe a relatively high rate of vertical
the mineral content increases over time and causes a less favorable fracture fractu re be-
root fractures despite the absence of posts and even with the use of adhe-
havior because of the increased brittle-
sive techniques – above all in curved
ness.18,19
and small roots; indeed some authors report up to 20% of vertical fractures of
Restorative options:
endodontically treated teeth. Man-
what is the ideal concept?
dibular molars and maxillary premolars are most often affected.25,26 Provided
As a consequence, any attempts to
there is enough coronal dentin structure
restore a non-vital tooth must include
not only the use of restorative materi-
that there is no difference between teeth
als with properties similar to the dental
restored with or without posts in this re-
components, but also the use of clinical
spect.27 Interestingly in this article, 86%
concepts that allow to compensate the
of molars with vertical root fractures had
inherent reduction of the mechanical re-
the fracture in a root without a post.
sistance of endodontically treated teeth. A
true
so-called
con-
or screws are used, which may produce
does not only implicate
detrimental lateral forces on the den-
the use of particular materials similar in
tin walls,28 and as long as inadequate
their properties to dentin and enamel,
placement techniques with risk of per-
but also sometimes the use of particular
forations are not used, posts per se
materials with different properties to re-
may not be considered as destructive.
cept20 therefore
biomimetic
Therefore, as long as no active posts
store the incomplete tooth as a whole in all its mechanical, biological and esthetical
aspects,21 above
When is a post indicated?
all if the remaining
tooth structure is compromised.
The main reason to use a post today is no longer to increase the retention
Post or no post –
and resistance of a core build-up, since
are posts destructive?
there are very effective adhesive techniques available. As discussed, provid-
In the past, fractures of teeth often have
ed there is sufficient tooth structure avail-
simply been attributed to inadequate re-
able, there is no longer a need to place
storative procedures, be it by the use of
a post. In premolars with limited
inadequate core materials or the use of
amount of tooth destruction and molars
posts and screws. The introduction of ad-
where, in general, more dentin walls with
hesive techniques and their successful
greater surface area can be engaged
integration in almost all current restora-
to be bonded as compared to anterior
tive procedures has allowed the clinician
teeth, a direct bonded core build-up is
242 THE EUROPEAN JOURNAL OF ESTHETIC DENTISTRY
MEYENBERG
clinically the concept of choice; it can be
not be compensated simply by adhe-
regarded clinically as well established,
sive techniques using fiber posts and
reliable and perhaps preferable to con-
composite cores. In a recent long-term
ventional post-core concepts. In addi-
study over 7 to 11 years, the mechani-
tion, by avoiding posts, the risk of cracks
cal failures reached 7 to 11% and were
due to thin residual root walls or perforations can be eliminated.
always related to a lack of coronal tooth structure.
For anterior teeth and heavily compro-
If anterior teeth and premolars pre-
mised premolars, however, this state-
sent with large defects that require
ment is limited to teeth that present with
crowning, however, adequate transfer
small to moderate defects and that will
of forces from the crown into the core
later not be crowned.
build-up and from there into the root is
For posterior teeth, the best prognosis
not possible without witho ut a post. Importantly Impor tantly,,
is achieved if – in addition to a bonded
the function of the post is not only the
core foundation – a ferrule effect is cre-
increase of the retention of the core, but
ated by the final restoration. This means
also the optimization of the resistance
that full cuspal coverage is used, be it
form. In addition, the mechanical prop-
a partial or full crown. Adhesive tech-
erties of a composite core alone may
niques alone without cuspal coverage
also not be sufficient in the case of a
may still lead to catastrophic failures
narrow abutment diameter and cannot
over time (ie, untreatable long axis frac-
reduce high stresses in the critical cervi-
-
cal area, which in such a case, is prone
cally safe.
to horizontal fractures. A clinical study
It must be stated at this point that the
ferrule effect is the most effective way of
directly to a reduced macroretention ge-
mechanical stabilization, ie, of optimiz-
ometry without posts clearly showed
ing the resistance form, of any endodon-
that the concept can work for molars
tically treated
teeth.
Given the weaker
(87–95% success, depending from the
structure, as previously discussed, the
effect of the better load distribution into
not work for premolars, if there were no
the cervical zone and the avoidance of any wedging effect by the post or core
cavity walls at all and the crown was just bonded directly into the residual pulp
build-up into the coronal part of the root
cannot be overemphasized. Therefore,
Therefore, the purpose of a post and
in order to provide a ferrule in situa-
core as a unit is primarily to transfer the
tions without sufficient tooth structure
loads into the root and secondly, the
above the zone of the biological width,
post is used as a reinforcing element of
orthodontic extrusion or surgical crown
the core build-up.
lengthening should be considered. A
The downside of this concept is the
ferrule length of 1.5 to 2 mm is recom-
weakening effect on the root itself;
mended.
to compensate for this, the ferrule effect
It must also be stated that, obviously, the lack of coronal tooth structure can-
must be incorporated into the restoration design.
243 THE EUROPEAN JOURNAL OF ESTHETIC DENTISTRY
SCIENTIFIC SESSION
The ferrule effect may also compen-
-
sate unexpected breakdown of adhe-
sues causing some disagreements on
sion after bonding and luting proce-
the ideal material of a post.2 From a me-
dures in unqualified dentin conditions.
chanical standpoint, it is evident that a
A safe clinical concept always implies
post stiffer than dentin can take up more
the incorporation of a ‘belt and braces’ approach to offset routes of potential
load but induces more stress in some apical parts of the root, which can increase
failure.
the risk of a vertical root fracture. Con-
A special indication for a post is the
versely, a post that has an elastic modu-
immature root, presenting with a large
lus closer to dentin will, in fact, induce
root canal.
less stress concentration apically in the
Obviously neither gutta-percha nor
root, but more in the cervical region.
MTA nor composite have a significant
In addition, the interface between
reinforcing effect. In this instance, the
post and core and between core and
only
is
dentin is also subjected to stress, so one
is in line with
can expect to see more root fractures
the clinical observation of increased risk
of fracture in immature teeth left without
made from metallic or ceramic materi-
post and core-build up after endodontic
als, whereas more flexible posts would
treatment.
show more post fractures, debonding of
significant
achieved with a
reinforcing
post. This
effect
core materials and loss of retention (pos-
If a post is indicated:
-
what post concept should be
lems of leakage and caries. The latter
used: stiff or flexible?
may lead to endodontic reinfection and catastrophic coronal destruction of tooth
“If something can break, it will break, and
substance, thus leveling out the poten-
it will always break at the weakest point”
tial advantage of this latter concept over
– this basic finding and classic rule for
the first one.
construction is also true for this applica-
The dilemma for the clinician is the
tion and may explain the significant con-
meaningful interpretation of the litera-
troversies regarding what would be the best of all the available concepts. The
ture, as countless studies have been published in this field, most of them being
question may be not whether something
studies with questionable clinical in vitro studies
will break, but rather where it will break.
potential relevance. Numerous theoreti-
Almost all dental materials have been
cal studies using finite element analysis
used clinically for posts. Still clinically
have also been performed, which would
relevant today are gold-alloys, chrome-
all need to be verified according to clas-
cobalt, titanium, zirconia and glass fib-
sic engineering principles in a real mod-
er posts. Carbon fiber posts have no
el, but only a minority of the in vitro stud stud-
clinical significance due to poor clinical
ies have been performed with dynamic
performance and disastrous potential;
or fatigue loading under a simulated
therefore they will not be discussed in
oral environment. Another difficulty is
this article.
that study results are also influenced by
244 THE EUROPEAN JOURNAL OF ESTHETIC DENTISTRY
MEYENBERG
the structural condition, various types of
tablishment of proper bonding be-
natural teeth utilized and the respective
tween all substrates is of paramount
loading pattern.
importance. 51 If bonding fails, much
One of the more clinically relevant in
less favorable stress patterns occur
vitro studies compared cast posts and
both in the root, above all in the critical
ite cores, zirconia posts with composite
cervical area, and in the post and core itself.52 As a clinical consequence,
cores and zirconia posts with ceramic
loss of retention of the core and post
cores, using, in all groups, adhesive
is still unfortunately the major compli-
techniques and a ferrule of 1 to 2 mm
cation.
on central incisors where all teeth were crowned. The most favorable results
Most of the clinical studies are difficult
to interpret in their outcome, since the
amount of tooth loss and the condition
with the stiffest concept (zirconia posts
of the remaining dentin (pre-existing
-
cracks, aging, endodontic treatment
vorable with the cast post and core co re sys-
influenced the choice of the concept.
In contrast to this study with ideal tooth
The scientific dilemma is very nicely
substrate, another study compared dif-
expressed in a systematic review about
ferent degrees of tooth destruction, us-
the simple final question, whether a
ing fiber posts and composite cores or
crown or a filling is more effective in the
composite cores alone on premolars.
clinical performance for an endodonti-
It was shown that posts had a significant
cally treated tooth. The authors con-
positive effect on fracture strength if only
clude “There is insufficient evidence
1 or 2 cavity walls were left, whereas no
to support or refute the effectiveness
of conventional fillings over crowns for
walls were left. However, if a completely
the restoration of root filled teeth. Until
flat profile without any substance above
more evidence becomes available cli-
the preparation line is used, most likely
nicians should continue to base deci-
the post will debond as predominant mode of failure.
sions on how to restore root filled teeth on their own clinical experience, whilst
Two facts are of special importance impor tance in
taking into consideration the individual
the judgment of studies comparing dif-
circumstances and preferences of their
ferent concepts:
patients”.
The results of these in vitro studies
This statement shows not only the
largely depend on the presence or
complexity of the topic, but also that
clinical multifactorial reality does not al-
Principally,, differences in materials Principally mater ials of
low clear definition of one simple gener-
posts and cores level out from the mo-
ally valid concept.
ment where a crown is placed.
Nevertheless, there is still a need
If metal-free post and core concepts
for clear clinical guidelines, based on
are to be successfully used, the es-
scientific evidence paired with clinical
245 THE EUROPEAN JOURNAL OF ESTHETIC DENTISTRY
SCIENTIFIC SESSION
expertise. Only this combination finally
with different concepts of build-ups. All
leads to clinical evidence.
teeth were finally crowned with porcelain
As a conclusion from numerous clini-
cal studies, it must be stated that there is
failure rate in this 6-year survival survi val study of
direct and indirect concepts and gold, Ti, fiber and zirconia posts work well if
ferrule of 2 mm or less was left, the failure rate increased to nearly 90 to 100%
the respective concepts are properly ex-
ecuted. The single most important point
prefabricated posts, and to around 70%
is to preserve as much remaining tooth
for the customized post concept.
structure as possible. Two additional arguments argu ments may require
The results clearly suggest that prefabricated
fiber
posts
are
superior
consideration for the reconstructive cli-
to customized fiber posts (glassfiber
nician: a) fiber posts offer the highest
potential for reintervention due to their
cores without any posts, if there are only
relative ease of removal, however their
2 walls or less remaining. However, However, even
successful use clinically is much more
if in addition to the bonded core a pre-
technique sensitive,58 and b) post and
fabricated fiber post is used, the con-
cores with a high modulus of elasticity
cept obviously fails to be convincingly
-
successful in cases with extended tooth
ture resistance as a foundation of the
destruction.
crown,50 which may be of significance
for the long-term success of all-ceramic
rate over 6 years of non-metallic posts
crowns.59,60
and build-ups, a 10-year report of prefabricated metal posts and cast metal
What about bonding a post into
the root canal space? Does bond-
ing help in cases with extended amount of tooth destruction?
Retention The almost doubled overall failure rate
What is the ideal surface conditioning of fiber posts?
of fiber posts and the surprisingly high debonding rate must raise the question
Looking at the results of a recent clini-
about the effectiveness and efficiency
cal 10-year fiber post study, a surpris-
of this concept in general practice. Per-
haps it is unsurprising given the inher-
reported and an overall failure rate of
ently more technique-sensitive concept
of the required adhesive techniques and
11% post debondings.61 The highest
the lack of a simple clear user protocol.
probability of a failure was reported for
A recent study compared the reten-
anterior teeth with no cavity walls.
tion of different fiber posts with different
This is confirmed by another clini-
surface conditionings (performed ac-
cal study62 where premolars of varying
cording to the manufacturer‘s recom-
degrees of destruction were restored
-
246 THE EUROPEAN JOURNAL OF ESTHETIC DENTISTRY
MEYENBERG
tin Ti-posts luted with conventional zinc
etching
phosphate-cement served as the con-
trol group. The control Ti-post showed,
or micromechanical treatments (sand-
together with some combinations of the
test group, the highest pull-out strength,
been proposed. Surprisingly, sand-
whereas some combinations of the test group showed surprisingly low values.
blasting seems to not affect the mechanical properties of the fiber posts.75 Sand-
This is in line with another study, where
blasting with silanization is, therefore, an
adhesively luted fiber posts were not
efficient, simple and predictable way of
superior to gold posts either adhesively
surface conditioning a fiber post before
luted or conventionally cemented with
bonding.77,78 However, fiber posts are
glass ionomer cement.65
susceptible to water degradation, and
with
hydrogen
peroxide
for
damaging the surface will increase this Adhesion to radicular dentin
phenomenon. Thus, a predictable bond-
Adhesively luting a post into root den-
ing procedure that completely seals the
tin is a controversial issue. Conflicting
post surface and avoids any voids is of
results have been published about the
paramount importance to preserve frac-
efficacy of bonding to radicular dentin.
ture resistance.79 Some manufacturers
Probably due to the structural differenc-
now use a coating on their posts to fur-
es in radicular dentin, bond strengths
ther simplify and improve the bonding.80
improve from the apical to the coronal
Nevertheless, care should be taken to
section. Comparing the use of compli-
consider both the manufacturers’ rec-
cated separated dentin bonding and lut-
ommendations and their scientific basis.
ing procedures with simpler self-etching cements, it seems clinically more relia-
Mechanical properties
ble to use self-etching and self priming
Major differences in the mechanical
cements taking into account the poten-
properties of different brands of posts
tially somewhat lower bond strength to
is another critical point. Since there
dentin.66-71 Inadequate ability to cure
are now countless brands of posts on
the luting agents precludes the use
the market with a sometimes-unknown
of light-curing materials. Dual-cure or chemically curing materials should be
origin, a proper selection based on independent scientific investigations is
used instead, since different fiber posts
imperative to avoid basic mechanical
indeed differ in their light transmitting
failures.81,82 Using a fatigue resistance
properties, however posts with optimal
test, a difference of roughly 7,000 cy-
mechanical
allow
cles until fracture for the worst and up
enough light penetrating all over the
to 2,000,000 cycles for the best post in
whole length of the post to sufficiently
polymerize light-cured materials.72
could be shown. The quality of the man-
properties
do
not
ufacturing processes including type of Adhesion to post surface
fiber and matrix, pre-tensioning of fibers,
To improve bond strength to the pre-
bond between fibers and matrix, among
fabricated fiber posts, chemical (silane,
other factors, play an important role.
247 THE EUROPEAN JOURNAL OF ESTHETIC DENTISTRY
SCIENTIFIC SESSION
Fig 5
Case 1: initial radiograph of non-vital cen-
tral incisors with different degree of remaining tooth
Fig 6
Case 1: initial initial clinical situation, large com-
posite build-ups, discoloratio discolorations. ns.
substance, final radiograph radiograph of build-ups with short
Fig 7
Case 1: abutment teeth after removal of ex-
Fig 8
Case 1: abutment teeth after internal bleach-
isting composite cores.
ing.
Fig 9
Fig 10
Case 1: build-ups of abutment teeth com-
Case 1: build-ups of abutment teeth com-
pleted with fiber posts and composite core, buccal
pleted with fiber posts and composite core, occlusal
view.
view.
Therefore, both a sensitive indication and technique is mandatory for the successful use of the concept of fiber posts combined with composite cores (Figs 5 Fig 11
Case 1: final clinical result.
248 THE EUROPEAN JOURNAL OF ESTHETIC DENTISTRY
MEYENBERG
Fig 12
Case 2: initial radiograph of second lower
premolar with fiber post and PFM crown. Fig 13
showing post fracture, composite core debonding and crown dislodgement.
Fig 14
Case 2: clinical view showing fractured
fiber post and extensive caries destruction underneath debonded composite core.
Concluding remarks regarding the structural aspects
Materials with potential of corrosion
fractures of materials and dentin and
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,
therefore should not be used. Adhesive cementation of fiber posts
is mandatory. Adhesive
cementation
of
metallic
posts is not mandatory mandatory.. Core build-ups should always be
of the post are a significant influence,
bonded, even if a metal post is not
as long as clinically reasonable con-
bonded.
cepts are used. Conversely, insufficient coronal tooth
Regarding the clinical reality, the fol-
structure will always lead to an in-
lowing additional statements must be
creased failure rate independent of
made:
the concept of restoration.
Increasing the coronal diameter of the
removed after luting, offer no potential
post helps to reduce the fracture risk
for reintervention and should therefore
of all posts, however the residual den-
be used in selected cases only.
tin wall thickness needs to be consid-
For abutment teeth presenting large
ered.
defects and requiring crowning, or
Huge differences in the quality of fib-
longer span bridges, or in general
er posts require a careful selection to
heavy loads, metallic posts are pref-
avoid post fractures.
249 THE EUROPEAN JOURNAL OF ESTHETIC DENTISTRY
SCIENTIFIC SESSION
References, Part 1
Stern S. Restoring teeth following root canal re-treatment. Endodontic Topics 2011;19:125–152.
dehydration and rehydration on some mechanical properties of human dentin. 1065. 12. Grigoratos D, Knowles J, Ng YL, Gulabivala K.
2.
Kishen A. Mechanisms and risk factors for fracture predilection in endodontically treated teeth. Endodontic Anderson MH, Kuhl LV. Clinical survey of fractured teeth. J Am Dent Assoc Jeng JH. Vertical root fracture in endodontically versus nonendodontically treated cases in Chinese patients. Oral Surg Oral Med Oral Pathol Oral Radiol Endod
Effect of exposing dentin to sodium hypochlorite and calcium hydroxide on its flexural strength and elastic modulus. Int Endod J K, Knowles JC. The effect of sodium hypochlorite irrigant concentration on tooth surface strain. J Endod 2002;28:575–579. Effect of endodontic irrigation solutions on microhardness of root canal dentin. J
22. Tsesis I, Rosen E, Tamse A, Taschieri S, Kfir A. Diagnosis of vertical root fractures in endodontically treated teeth based on clinical and radiographic indices: a systematic review. J Endod Prevalence of vertical root fractures in extracted endodontically treated teeth. Int RJG. Prevalence of vertical root fractures in extracted endodontically treated teeth.
Reeh ES, Messer HH, Douglas WH. Reduction in tooth stiffness as a result of endodontic and restorative procedures. J Endod 1989;15:512–516. 6. Asundi A, Kishen A. Digital photoelastic investigations on the tooth-bone interface. 7. Jantarat J, Palamara JE, Lindner C, Messer HH. Time dependent properties of human root dentin. Dent 8. Kishen A, Asundi A. Experimental investigation on the role of water in the mechanical behavior of structural 9. Kruzic JJ, Nalla RK, Kinney JH, Ritchie RO. Crack blunting, crack bridging and resistance-curve fracture mechanics in dentin: effect permeability and tracer tests. J Dent 1999;27:1–11. 11. Jameson MW, MW, Hood JA,
H, Tanomaru-Filho H, Wesselink PR, Wu M. The ability of different nickeltitanium rotary instruments to induce dentinal damage during canal preparation. J Ferrari M, Mason PN, Goracci C, Pashley DH, Tay FR. Collagen degradation in endodontically treated teeth after clinical function. Randow K, Glanz PO. On cantilever loading of vital and non-vital teeth. An experimental clinical study. Acta Odontol Scand ari A, Arola D. Age, dehydration and fatigue crack als 2006;27:2507–2517. Viguet-Carrin S,Garnero P,Delmas PD. The role of collagen in bone strength. Osteoporos Int Magne P, Douglas WH. Rationalization Rationalizatio n of esthetic restorative dentistry based on biomimetics. J Esthet Dent 1999;11:5–15.
25. Tamse A, Fuss Z, Lustig J, Kaplavi J. An evaluation of endodontically treated vertically fractured teeth. J Endod 1999;25:506–508. 26. Vire DE. Failure of endodontically treated teeth: classification and evaluation. J 27. Salvi GE, Siegrist Guldener NP. Clinical evaluation of root filled teeth restored with or without post-andcore systems in a specialist practice setting. Int Endod J 28. Kishen A, Kumar GV, Chen NN. Stress–strain response in human dentin: rethinking fracture predilection in postcore restored teeth. Dent 29. Zarow M, M, Devoto W, Saracinelli M. Reconstruction of endodontically treated posterior teeth – with or without post? Guidelines for the dental practitioner. Eur J LM, Maia Filho EM, Alves CM. The impact of post preparation on the residual dentin thickness of maxil-
5.
16.
17.
19.
20.
250 THE EUROPEAN JOURNAL OF ESTHETIC DENTISTRY
21. Ni CW, CW, Chang CH, Chen TY TY,, Chuang SF. A multiparametric evaluation of postrestored teeth with simulat
MEYENBERG
lary molars. J Prosthet Dent Campos. Marginal adaptation, retention and fracture resistance of adhesive composite restorations on devital
Goracci C, Vichi A, Mason PN, Radovic I, Tay F. Longterm retrospective study of the clinical performance of fiber posts. Am J Dent 2007;20:287–291.
Wakefield CW. Influence of remaining coronal tooth structure location on the fracture resistance of restored endodontically
teeth with and without posts. Kreulen CM, Lassila LV, Vallittu PK, Creugers NH. Ex vivo resistance of direct composite complete crowns with and without posts on maxillary premolars. Int vitro comparison of intact endodontically treated teeth with and without endo-post reinforcement. J Prosthet LM, Maia Filho EM, Alves
ono-radicular reconstruction of pulpless teeth: a mechanical study using finite element analysis. J Prosthet WH. Survival of ceramic computer-aided design/ manufacturing crowns bonded to preparations with reduced macroretention geometry. Int J Prosthodont Palamara D, Messer HH. Effect of root canal size and
treated anterior teeth. J Prosthet Dent 2006;95:290–296. The restoration of endodontically treated, single-rooted teeth with cast or direct posts and cores: a systematic review. J Prosthet Dent 50. Dietschi D, Duc O, Krejci Krejci cal considerations for the restoration of endodontically treated teeth: a systematic review of the literature, Part II (Evaluation of fatigue behavior, interfaces, and in
CM. The impact of post preparation on the residual dentin thickness of maxillary molars. J Prosthet Dent JR. Fracture strength and survival rate of endodontically treated maxillary incisors with approximal cavities after restoration with different post and core systems: an in vitro study. J Grandini S, De Sanctis M, Goracci C. Post placement affects survival of endodontically treated premolars. J PR. The ferrule effect: a literature review. Int Endod J Goracci C, Vulicevic ZR, Ferrari M. Ferrule effect: a literature review. J Endod Intracoronal reinforcement and coronal coverage: a study of endodontically treated teeth. J Prosthet
external root surface morphology on fracture susceptibility and pattern: a finite element analysis. J Endod Feilzer AJ, Davidson CL. Fracture strength of different core build-up designs. Am J sein A, Strub JR. Fracture strength after dynamic loading of endodontically treated teeth restored with different post-and-core systems. J Rutledge RE, Yaccino JM. Reinforcement of simulated immature roots restored with composite resin, mineral trioxide aggregate, guttapercha, or a fiber post after thermocycling. J Endod ence of glass-fiber posts on the fracture resistance and failure pattern of endodontically treated premolars with varying substance loss: An in vitro study. J Prosthet
51. Krejci I, Duc O, Dietschi D, de Campos E. Marginal adaptation, retention and fracture resistance of adhesive composite restorations on devital teeth with and without posts. Oper Dent. RY, Lima RG, Pfeifer CS, Versluis A. Can fiber posts increase root stresses and reduce fracture? J Dent Res 2010;89:587–591. review of failure modes in teeth restored with adhesively luted endodontic dowels. J Prosthodont de Souza RF, de Andrade Lima Chaves C, Nasser M, crowns versus conventional fillings for the restoration of root filled teeth. Cochrane Database Syst Rev 2012:16:CD009109. 55. Fokkinga WA, WA, Kreulen CM, NH. Up to 17-year controlled
251 THE EUROPEAN JOURNAL OF ESTHETIC DENTISTRY
SCIENTIFIC SESSION
clinical study on post-andcores and covering crowns. ero F, Ravera G. Long-term survival of endodontically
Rivero A, Del Río J, Celemín A. A 10-year retrospective retrospective study of the survival rate of teeth restored with metal prefabricated prefabrica ted posts versus cast metal posts and cores.
71. Sterzenbach G, Karajouli G, K. Fiber post placement with core build-up materials or resin cements – An evaluation of different adhesive approaches. Acta Odontol
treated, maxillary anterior teeth restored with either tapered or parallel-sided glass-fiber posts and fullceramic crown coverage. 57. Jung RE, Kalkstein O, Sailer I, Roos M, Hämmerle 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 dini S. Fiber posts and endodontically treated teeth: a compendium of scientific
Schirrmeister JF, Altenburger MJ, Hellwig E. Retention of fiber posts dependent on different resin cements. Schweiz Monatsschr Zahn 65. Kremeier K, Fasen L, Klaib of endodontic post type (glass fiber, fiber, quartz fiber or push-out bond strength to dentin in vitro. Dent Mater 66. Ferrari M, Mannocci F, Vichi
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 modulus and hardness of dualcure resin cements. Dent FT, Radovic I, Toledano M, Ferrari M. Surface treatments for improving bond strength to prefabricated fiber posts: a literature review. Oper Dent
59.
60.
61.
62.
and clinical perspectives, ed 1. Wendywood, South Africe: Modern Dentist Media. Wendywood, 2006. Malament KA, Socransky SS. Survival of Dicor glassceramic dental restorations over 20 years: Part IV. The effects of combinations of variables. Int J Prosthodont 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 Naumann M, Koelpin M, 10-year survival evaluation for glass-fiber-supported postendodontic restoration: a prospective observational clinical study. J Endod Ferrari M, Vichi A, Fadda GM, Cagidiaco MC, Tay Goracci C. A randomized controlled trial of endodontically treated and restored premolars. J Dent Res 2012;91:72S–78S.
68.
69.
structural characteristics of the substrate. Am J Dent Clavijo V, Andr ade MF, MF, Vaz LG, Campos EA. Effect of resin cement system and root region on the push-out bond strength of a translucent fiber post. Oper Dent Huber L, L, Cattani-Lorente Cattani-Lorente M, S. Push-out bond strengths of endodontic posts bonded with different resin-based luting cements. Am J Dent 2007;20:167–172. Monticellii F, Ferrari M, Monticell Toledano M. Cement system and surface treatment selection for fiber post luting. Med Oral Patol Oral Cir Krokidis A, Acquaviva PA, Cerutti F, Cerutti A. Polymerization degree and cementation methods of two different self-adhesive luting cements used for glass fiber post cementation. Minerva Stomatol 2012;61:
252 THE EUROPEAN JOURNAL OF ESTHETIC DENTISTRY
Effects of chemical surface treatments of quartz and glass fiber posts on the retention of a composite resin. J Prosthet Dent 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 dualcured resin composite to methacrylic fiber posts: microtensile bond strength and SEM evaluation. J Dent 76. Soares CJ, Santana FR, Pereira JC, Araujo TS, Menezes MS. Influence of airborne-particle abrasion on mechanical properties and bond strength of carbon/epoxy and glass/ bis-GMA fiber-reinforced resin posts. J Prosthet Dent 77. Valandro LF, Yoshi oshiga ga S, de Melo RM, Galhano GA, Mallmann A, Marinho CP, bond strength between a quartz fiber post and a resin cement: effect of post sur-
MEYENBERG
face conditioning. J Adhes Dent 2006;8:105–111. 78. Zicari F, De Munck J, Scotti R, Naert I, Van Meerbeek cement-post interface. Dent Mater 2012;28:287–297.
80. Schmage P, Nergiz I, Markopoulou S, Pfeiffer P. Resistance against pull-out force of prefabricated coated FRC posts. J Adhes Dent 81. Cheleux N, Sharrock PJ.
79. Vano M, Carvalho C, Sedda M, Gabriele M, GarcíaGodoy F, F, Ferrari M. The influence of storage condition and duration on the resistance to fracture of different fiber post systems. Am J
Mechanical properties of glass fiber-reinforced endo 82. Grandini S, Goracci C, Monticelli F, Tay FR, Ferrari M. Fatigue resistance and structural characteristics
Part 2: Esthetic considerations
of fiber posts: three-point bending test and SEM evaluation. Dent Mater 2005;21:75–82. Cagidiaco MC, Goracci C, Ferrari M. Fatigue resistance and structural integrity of different types of fiber posts. Dent Mater J 2008;27:687–
or is largely addressed with full crowns, since endodontically treated posterior teeth present mostly with large reconstructions that require optimal stabiliza-
Introduction
tion by full or partial crowns.
In addition to the numerous issues dis-
In the anterior zone, however, esthet-
cussed in part 1 of this paper, non-vital
-
teeth are frequently esthetically com-
tive effects:
promised. This frequently presents sig-
nificant and special challenges when it
comes to meeting the demand for nat-
ural-looking, esthetically pleasing teeth
Discolouration of the clinical crown. Discolouration of the cervical region. Discolouration of the gingiva and mucosa.
sought by our patients today. today. The aim of the second part of this pa-
There are various causes of these en-
per is to try to answer several clinically
dodontically induced intrinsic discolora-
relevant conceptual questions and to provide some clinical guidelines regard-
tions: Intrapulpal haemorrhage.
ing the management of the esthetic as-
pects, based on scientific evidence and
clinical expertise.
Pulpal necrosis. Incomplete removal of pulp tissue during the endodontic treatment. Endodontic
irrigants,
medications
Why are most endodontically
and root canal filling material (root
treated teeth dark?
Restorative materials (cervical zone
The
discoloration
of
endodontically
treated teeth is a common observation.
Coronal leakage.
In the posterior region, this phenom-
Dentin sclerosis.
enon is seldom esthetically disturbing
253 THE EUROPEAN JOURNAL OF ESTHETIC DENTISTRY
SCIENTIFIC SESSION
Unfortunately almost all root canal seal-
the tooth are heavily discolored and do
ers including Zinc Oxide-Eugenol and
not respond to the bleaching procedure.
-
Do bleaching procedures lead to
Also the use of MTA, MTA, be it grey or white,
external resorption?
will ultimately lead to a greyish appearance or darkening of the root.5,6
Cervical root resorption is a serious
Furthermore, the calcification pro-
complication that is difficult to treat11,12
cess in the dentin through obliteration
and ultimately can lead to tooth loss.
of the dentinal tubules and changes in
There are various reasons for this phe-
the free water content before and after
nomenon. Orthodontic treatment and
endodontic treatment and through ag-
tooth trauma are the most common pre-
ing processes, contributes to an altered
disposing factor. factor. Internal bleaching blea ching may
optical appearance in addition to the in-
increase the combinatory risk, however
creased brittleness.7-10
it seems to be limited to cases where extensive concentrations of H2O2 com-
How can we improve the color of
bined with heat (the thermo-catalytic
The presence
or replacing discoloured coronal dentin?
of defects at the cemento-enamel junction seem to play a major role, allowing the bleaching agent to penetrate into the
Although some of the above mentioned negative factors can be clinically modi-
periodontal space.15 The
recommendations
today
are
fied, it is evident that a non-vital tooth
therefore not to heat the bleaching agent
inevitably loses some esthetic qualities
in the access cavity, to seal the residual
in terms of the color co lor.. As a matter of prin-
root filling well before application of the
ciple, replacing discolored dentin to cor cor--
bleaching agent and to generally use
rect the color is not the preferable op-
less aggressive bleaching chemicals
tion from a structural viewpoint. In part 1,
instead of high concentrations of H 2O2.
the mechanical aspects to support this
The best clinical compromise of ef-
axiom have already been extensively discussed.
fect, side-effects, risks and long-term experience is in the use of the so called
existing
“walking bleach technique”16 where,
substance is always the better option,
classically, sodium perborate is mixed
if we agree on the principle that “hav-
with water.
Therefore,
bleaching
the
ing a discolored tooth is preferable to
In the author‘s long-term experience,
having no tooth”. Most discolorations
this is clinically as efficient as other more
are bleachable except those caused by
aggressive chemicals, provided a cor-
metal ions (amalgam, or silver and other
rect cervical and coronal seal of the
2 So
bleaching cavity have been realized.
the only indication to remove discolored
The cervical seal is preferably achieved
dentin may be if small spots that do not
with a modified glass ionomer cement,
contribute to the structural resistance of
classically applied at the level of the con-
254 THE EUROPEAN JOURNAL OF ESTHETIC DENTISTRY
MEYENBERG
nective tissue attachment, whereas the
further compromise the strength of the
coronal seal is achieved with adhesively
residual tooth structure. This is an im-
luted composite to ensure an optimal
portant consideration particularly if ad-
penetration of the bleaching agent into
ditional reconstructive measures are to
the dentin. Hence, leaving the access
be executed26 and if the potential for re-
cavity open and using at-home techniques with open trays is not advisable.17
intervention is taken into account. Second, as mentioned, bleaching
Success largely depends depen ds from the ap-
agents themselves lead to a weakening
plication duration of the bleaching agent
of the tooth structure through the chemi-
-
cal modification of the dentin. 27,28 A re-
forms alternative quick in-office tech-
cent publication supported the use of
niques in the long run.18 In a recent study
sodium perborate mixed with water in
it could also be shown that this concept
this respect, since this combination led
compares very favorably to more ag-
to a significantly smaller additional open-
gressive mixtures of chemicals in terms
ing of the dentinal tubules compared to
of H2O2 leakage at different root locations
all other bleaching agents. Interestingly
with and without external defects.19,20
Since cervical defects are difficult to
worst effect.29
detect with conventional radiographs
Another important consideration is
and require cone beam computed to-
the influence of bleaching on dentin
21 the
use
bonding. As emphasized in part 1, the
of this less-aggressive concept makes
quality of the internal reconstruction af-
additional sense in avoiding added un-
ter endodontic therapy is of key impor-
known risks while producing good es-
tance in reconstituting the resistance to
thetic results.
fracture. Using an adhesive approach is advisable but technique sensitive and,
Do bleaching procedures weaken
in general, all bleaching agents lead to
the tooth – or may dark roots also
reduced bond strengths and increased
be bleached?
microleakage. Consequently, the use of antioxidants has been advocated to
Recent research clearly shows that bleaching chemicals weaken tooth sub-
counteract this effect (eg, sodium ascor -
stance.
cedure for at least 10 days after washing
Since the endodontic treatment itself
out the bleaching agent The antioxi-
already weakens the dentin consider-
dant is especially necessary and should
ably through chemical and mechanical
be mandatory if bonding with simplified
effects 25
single bond dentin adhesives, or if de-
additional care must be taken if a bleach-
layed bonding is not warranted or pos-
ing procedure is being considered.
sible.
First of all, internal removal of dis-
However,, good dentin adhesion However adhe sion can be
colored dentin should be avoided. It
achieved if: a) sodium sodium perborate mixed
does not lead to better results with the
with water is used to bleach, b) the the tooth
described bleaching technique and will
is left with saline solution for 7 days after
255 THE EUROPEAN JOURNAL OF ESTHETIC DENTISTRY
SCIENTIFIC SESSION
Fig 16
--
tial radiographic situation. A carbon composite post had been placed. Fig 15
incisor with PFM crown, initial clinical situation.
removal of the bleaching agent, and c)
conditions – owing to unfavorable ovoid
a scientifically and clinically well estab-
root canal configurations and dentin mi-
lished self-etching 2-step dentin bonding
crostructure in the deeper parts of the
root canal – the root should not be
For enamel, the same principle of waiting
further compromised by using bleach-
after washing off the bleaching agent is a
ing techniques inside the root canal.
simple and successful strategy. Recent
As long as the intracoronal bleaching
proposals for new resin formulations that
is performed within the access cavity
are supposed to allow immediate bond-
reaching to the level where the connec-
ing after bleaching have not proved as
tive tissue attachment ends coronally,
effective.
the results constitute a sufficient com-
Since adhesion within the root remains
promise esthetically, esthetically,26 even in the criti-
a challenge even in ideal experimental
Fig 17
Fig 18
post removal.
256 THE EUROPEAN JOURNAL OF ESTHETIC DENTISTRY
--
nal bleaching of coronal part of the abutment tooth.
MEYENBERG
Fig 19
tooth with bonded fiber post and core, after internal
Fig 20
technique.
bleaching with sodium perborate and water.
Fig 21
Fig
22
showing good adaptation of the short fiber post and bonded core to the den
257 THE EUROPEAN JOURNAL OF ESTHETIC DENTISTRY
SCIENTIFIC SESSION
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” treatment protocols are more likely to have apical-cervical seal, along with the optical quality of the access restoration, 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 endodontic treatment. Subjective and objective satisfaction
of the dentist or the patient pati ent may differ substantially. Fig 23 Limited light conducting properties of fiber posts with good mechanical properties preclude
The potential for intervention and the
the use of long posts, if light-cured materials are to
concept of a progressive (conserva-
be used.
a discolored tooth are essential. Aggressive
What about the predictability and stability of bleaching procedures?
reconstructive
concepts
based just on esthetic considerations and early crowning can lead to premature tooth loss. Therefore, bleaching
There has been some debate about the
instead of removing tooth substance
predictability and long-term effective-
is the preferable treatment, both for
ness of internal bleaching, with de-
non-reconstructive and reconstruc-
scribed esthetic success rates of around
tive cases.26
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 substances as those having caused the ini-
May crowns or veneers compensate darkened coronal tooth structure?
tial discoloration, or b) penetration penetration of pig-
First of all it is important to understand
ments from the oral cavity ca vity,, or c) bacterial bacterial
the concept of illumination of the oral tis-
reinfection of the root canal system with
sues. The tooth with its clinical crown
subsequent infiltration into the cervical
and root, the gingiva, the bone and the
and coronal
dentin.1
periodontium form an optical unit. Light
From long-term studies and clinical
is transmitted by diffuse reflection into
observations, the following can be con-
the tissues. It is therefore critical not to
cluded:
disturb this delicate system with discol-
258 THE EUROPEAN JOURNAL OF ESTHETIC DENTISTRY
MEYENBERG
orations or by the introduction of inad-
nates and all-ceramic partial crowns,
equate opaque or dark restorative ma-
as a wide variety of all-ceramic crown
terials. Of particular importance in this
systems exist today with excellent opti-
respect is a soft color transition from the
cal properties and long-term survival, in
cervical third of the clinical crown into
particular, the new generation of glass-
the adjacent gingival tissues. Since the mid 1960s, dental techni-
ceramic materials. In addition, these materials allow the provision of bonded
cians and prosthodontists tried to imple-
full coverage “veneer type” crowns with
ment this concept in order to improve
-
the esthetics of full crown margins. In the
1980s, PFM crowns without metal collars
Consequently, the management of
were introduced, using shoulder and ve-
discolored
tooth
substrate
becomes
neering porcelains with better light con-
increasingly important. It should be re-
ducting properties to illuminate the adja-
membered that all attempts to ‘mask out’
cent tissues. Despite these efforts,
discolored tooth substance will invari-
the results were never completely sat-
ably end up with increased opacity and
isfying when the underlying tooth struc-
therefore therefor e unnatural reflection of the light
ture was dark, or if there were vital and
instead of a diffuse reflection inside the
rather translucent teeth to be matched.
materials. This is of particular importance impor tance
Hence the search and development of
when veneering a tooth with a discolored
true light conducting materials as frame-
cervical zone, as the fine veneer margins
works with lower opacity than metal or
cannot create the appropriate color tran-
the pre-existing all-ceramic cores.
sition from the tooth crown into the gin-
Today, in the case of vital teeth with
giva. If a full crown is provided in such a
adequate tooth substance, more con-
case, a pleasing result can be achieved
servative bonded porcelain restorations,
by using opaque all-ceramic framework
such as veneers and anterior partial all-
materials, provided that adjacent struc-
ceramic crowns, are increasingly the
tures are also more opaque and the gin-
treatment of choice as compared to full
gival tissue is thick, but this is rather the
crowns, due to esthetic, technical and
exception than the rule.57,58 The same is
biological advantages. It is important to understand that the success of
true if opaque cements are used to cover dark underlying substance.
these restorations is largely based on
Above all, trying to mask out dis-
the esthetic and mechanical advantag-
colored teeth should not result in over-
es of the natural uncompromised tooth
preparation:59 the mission statement of
substrate as the foundation of the resto-
Hippocrates primum nihil nocere (first
ration rather than an artificial substrate.
As a consequence of this success, the
concept has been extended to endo-
Thus the clinical concept for man-
dontically treated teeth, with the idea be-
agement of discolored tooth substance
hind to convert darkened tooth structure
should always consider internal bleach-
into vital looking tissues. Naturally
ing as first option, even if the result will
this is not only relevant to bonded lami-
not be absolutely perfect.
259 THE EUROPEAN JOURNAL OF ESTHETIC DENTISTRY
SCIENTIFIC SESSION
Fig 24
Fig 25
cast post and cores, leading to a disturbance in the
to the symmetry of the case, the suboptimal color
illumination of the adjacent tissues.
transition from the abutment margins into the gingival tissues fortunately does not disturb too much in this case.
If the tooth needs an additional indirect restoration, a veneer or full cover-
is similar to what can be observed within with in the enamel of natural teeth.
age veneer-crown is an attractive and
One drawback certainly is if the dis-
less invasive solution. In the author’s
colored tooth has already been restored
own experience over the last 15 years
with a post. If removal of the post without
from when the concept first was used,
risk of damage to the root is viable, then
long-term results for esthetics and sur-
the internal bleaching can be performed
vival rates in both types of restorations
before a new post and core is fabricat-
are comparable to all-ceramic crowns.
ed. If this is considered too risky, risky, metallic
However, in the literature there are only
posts and cores can at least be masked
studies with vital teeth available at the
with a tooth-colored opaquer and com-
moment, which show a survival rate of
posite to avoid to improve the substrate
color for an all-ceramic framework.
100% for extended veneers over 5 years.60,61 The
observation of small su-
perficial cracks not influencing survival
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 introduction of the first Zirconia posts in 1995 and the first fiber posts in 1990. The proposed reasons for tooth-colortooth-colo red posts for esthetics in root treated teeth are:
Fig 26
Case 5: left left central central incisor with polished polished
To illuminate the root and cervical re-
cast post and core, right lateral incisor with tooth-
gion and thus brighten up darkened
colored post and core.
tooth substance.
260 THE EUROPEAN JOURNAL OF ESTHETIC DENTISTRY
MEYENBERG
To prevent any darkening darkeni ng effect of a post
by photospectroscopic studies67 and
on non-discolored tooth substance.
may lead to incorrect clinical recom-
To create a tooth-colored basis for the
mendations in specific cases.
core and the crown.
However, given the clinical and scientific evidence, there is actually little
While the first reason has already been disputed early on by experienced cli-
reason to take out existing well adapted and luted cast post and cores if the re-
nicians not being able to see any dif-
maining dentin itself is not discolored
ference in the color between a metallic
and does not require bleaching. It is
post and a tooth-colored post put into
clinically sufficient to mask the buccal
the same dark root under natural light
part of the metal with a tooth-colored
conditions, the second two points are
opaquer. If space and residual thick-
good arguments for tooth-colored posts.
ness of a gold alloy post and core do
In fact a recent study showed that there
not allow to do this, another smart ap-
is no difference in the cervical color of
proach is to polish the buccal part of
abutment teeth between white and me-
the exposed metal to a high gloss, thus
tallic posts, however tooth-colored posts
creating total reflection of the light at the
and cores were beneficial for the overall
core surface.68 This concept has been
color of the all-ceramic crowns.65 This
widely used by the author for years with
is in line with observations of clinicians
no adverse effects regarding the reten-
aware of these subtle
differences.66
Some care must be taken when trying
In conclusion, it can be stated that
to translate in vitro studies about color
the color of the remaining tooth sub-
influences into clinical practice. Some
strate is of much greater importance
subtle components of the th e color, color, such as
than the color of the post and cannot
the quality of the internal diffuse reflec-
be influenced positively by the post in
tion depending on the intensity of light
the cervical and apical region, however
and the softness of the transition into the
having a tooth-colored post is beneficial
marginal gingiva cannot be measured
for the core.
Fig 27
Fig 28
Case 5: final picture showing the good
reflection properties of the polished metal part of the
Case 6: abutment abutment teeth with various various de-
grees of discolorations.
left central abutment tooth.
261 THE EUROPEAN JOURNAL OF ESTHETIC DENTISTRY
SCIENTIFIC SESSION
sue. In oral implantology, however, however, some studies have been performed looking at the influence of various abutment materials 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 covering 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 discolored root. Comparing zirconia, polished gold alloys and machined titanium in a pig model, a visible difference was Case 6: layered glass ceramic ceramic crowns
always present if the tissue thickness
with internal opaquer and varying opacities of
Fig 29
frameworks.
in thickness, only zirconia (regardless of
Can soft tissue thickening
compensate darkened cervical
material itself had no influence.69 In a
root structure?
human study, comparing metal abut-
A soft color transition from the crown
abutments and crowns, the latter be-
into the soft tissue is essential for an
haved better, better, but there was still a visible
esthetically pleasing result. In the pre-
difference for both groups compared
ceding pages, the focus was placed
to the adjacent teeth.70 Another study
on the root and crown of the tooth and
presented similar results,71 although no
how negative effects can be managed.
correlation between the thickness of the
However, if discolorations are still pre-
mucosa and the respective amount of
sent in the critical cervical supra- and
discoloration could be found.
subgingival zone, it makes sense to consider influencing the soft tissue
In essence, the fiber content and the degree of keratinization may play a more
characteristics.
important role for the masking ability
ments and PFM crowns with all-ceramic
The margin of the soft tissue cover-
than the soft tissue thickness alone. In
ing the cervical part of the root plays
this respect, the use of a connective tis-
an important role as a “curtain” to hide
sue graft taken from the palate with its
unpleasing structures. In addition, the
higher content of collagen fibers is the
buccal bone plate has also some mask-
most promising approach using an en-
ing effect over a discolored root. A thick
velope technique to improve the esthetic
bone plate can virtually completely mask
integration of the augmented tissue.
out the root discoloration. In periodontol-
Some modifications in the technique, in-
ogy, there is little information available
cluding a microsurgical approach, have
about the masking effect of the soft tis-
been introduced to further decrease
262 THE EUROPEAN JOURNAL OF ESTHETIC DENTISTRY
MEYENBERG
Fig 30
Case 6: final picture of the four anterior
Fig 31
Case 6: final picture picture of the right right side,
teeth, showing an acceptable color transition be-
showing an acceptable color transition between the
abutment teeth.
vital discolored central incisor.
healing complications and unesthetic
tissue contours and preventing further
tissue scars.
exposure of discolored root surfaces.
An additional benefit of this approach is the easier tissue handling during the reconstructive phase and the prevention of post-reconstructive recessions over time, which may expose further discolored root parts. Indeed, since many
Final consideration: at what point should we give up and extract?
of the discolored teeth exhibit some cer-
It is fair to state that a tooth should be
vical tissue loss over time anyway, this
saved as long as there is a predictable
procedure can also be considered as a
way to functionally and biologically do
preventive treatment of a cervical reces-
so with a reasonable prognosis. This
76
sion, dealing not primarily with health, but with stable, esthetic tissue levels. It
2-part article has shown various possibilities to overcome classic biomechani-
may also serve to counteract the loss in
cal and esthetic problems with respect
cervical tissue height that occurs by tis-
to minimizing reconstructive risks. The
sue modeling during the aging process,
basis for reconstructive survival in the
which is more noticed around discolor-
context of this article, however, is the
ed roots and is independent of the pres-
quality of the endodontic treatment as
ence or absence of dental restorations.
the starting point.
As a conclusion, soft tissue thicken-
It can also be stated that today too
ing may not completely solve the prob-
many teeth are extracted in favor of im-
lem of the discolored cervical hard and
plants, with insufficient regard for the
soft tissue zone, but it can improve the
extensive reconstructive options avail-
overall result by at least stabilizing soft
able to maintain them. Furthermore, the
263 THE EUROPEAN JOURNAL OF ESTHETIC DENTISTRY
SCIENTIFIC SESSION
short- and long-term biologic, esthetic
previous studies and may produce less
and technical complications of implants
successful results than expected or than
are not fully appreciated.77 Unfortu-
achieved with the classic concepts of
nately,, poor endodontic treatment is still nately
experienced endodontic specialists. A
a major factor in premature tooth loss.
-
However, if performed correctly, results are at least as good as replacement with
ed in a private practice by a specialist, documented an overall success rate of
implants for single units.77 It is striking
91.5%. 80 Initial endodontic treatments
that despite this fact, today a tendency
-
towards a more extraction-oriented re-
pared to the non-surgical retreatment
constructive concept can be observed
in practice. There are two main reasons
how important the quality of the first en-
for this.
dodontic treatment is for the long-term
The first reason is that in clinical de-
success. In addition, the coronal resto-
cision-making, the predictability of the
ration has a significant influence in the
whole procedure is of primary impor-
success of the endodontic treatment.
tance in respect of complications and
Thus, to strive in every respect for an
cost. Obviously there is some pessimism
optimal restoration is as essential as an
among clinicians regarding the progno-
optimal endodontic treatment alone.81
sis of endodontic treatments in general
The second reason is that measures
and this is not completely unfounded.
to potentially save a compromised tooth
The combined failure rate of endodonti-
can later preclude the placement of
cally treated teeth in general practice is
an implant or make it very demanding.
higher than described in earlier reports:
Therefore, if an endodontic retreatment
due to recurrent apical pathology is
up to 20% is documented.78 In general,
considered, above all, careful diagnos-
the outcome of endodontic treatments
tic steps including soft and hard tissue
may have been overestimated in previ-
probing and radiographs are required.
ously published reviews because of the
Conventional radiographs do not allow
general lack of correct apical diagnosis.
proper analysis and interpretation of the
the endodontic status cannot correctly
root and remaining bone housing around the root. The possible causes for the
be analyzed. The authors of a current
endodontic failure (eg, crack, fracture,
review state: “In conclusion, the serious
perforation, insufficient root filling or ac-
limitations of longitudinal clinical studies
restrict the correct interpretation of root
established without a high-resolution
canal treatment outcomes. Systematic
reviews reporting the success rates of
and appropriate treatment approach
root canal treatment without referring
can only be determined based on an
to these limitations may mislead read-
accurate diagnosis.
ers”.79 Therefore, the trend towards sim-
Periapical microsurgery should be
plified endodontic protocols may also
performed exclusively if non-surgical
be based on incorrect interpretations of
endodontic retreatment is not viable,
264 THE EUROPEAN JOURNAL OF ESTHETIC DENTISTRY
MEYENBERG
and if the remaining bone housing is suf-
tal tooth-supported restorations, there is
ficient. The surgical approach seems to
no clear winner in terms of sustainabil-
be more successful in the short term, but
solutions require a perfect synergy of all
6 years for the non-surgical approach,
the fields of specialties involved and the
the surgical approach.82 In addition, the
treatment steps to achieve the optimal result for the individual patient.
added bone loss caused by the surgical access osteotomy and incomplete heal-
Acknowledgements
ing can make the placement of an im-
The author would like to thank Dr Tidu Mankoo for
plant after a potential failure and eventful
the systematic and thorough editing of the whole es-
extraction very difficult.
Ultimately Ultimate ly,, when we examine the treatment outcome of implant versus non-vi-
References, Part 2 1.
Arens D. The role of bleaching in esthetics. Dent Clin North Am NM, Pameijer CH, Somma F. Nonvital tooth bleaching: a review of the literature and clinical procedures. J Endod teeth. A clinically relevant literature review. Schweiz Monatsschr Zahnmed puter analysis of crown discolouration from commonly used endodontic sealers. 119. Lambrianidis T. Ex vivo study of the efficiency of two techniques for the removal of mineral trioxide aggregate used as a root canal filling material. J Endod
6.
of the endodontic aspects, and Walter Gebhard and Nic Pietrobon for their contribution in creating the dental ceramics.
Jacobovitz M, de Lima RK. Treatment of inflammatory internal root resorption with mineral trioxide aggregate: a case report. Int Endod J 7. Porter AE, Nalla RK, Minor A, Jinschek JR, Kisielowski C, Radmilovic V, Kinney JH, Tomsia AP, Ritchie RO. R O. A transmission electron microscopy study of mineralization in age-induced rials 2005;26:7650–7660. mination of age in humans from root dentin transparency. Acta Odontol Scand 9. Kinney JH, Nalla RK, Pople Age-related transparent root dentin: mineral concentration, centratio n, crystallite size, and mechanical properties. A, Arola D. Age, dehydration and fatigue crack growth 2006;27:2507–2517.
Will mineral trioxide aggregate replace calcium hydroxide in treating pulpal and periodontal healing complications subsequent to dental trauma? A review. Dent 12. Schwartz RS, Robbins JW, JW, Rindler E. Management of invasive cervical resorption: observations from three private practices and a report of three cases. J Endod SW, Marin PD. Incidence of invasive cervical resorption in bleached root-filled teeth. stein I. Effect of bleaching time and temperature on the radicular penetration of hydrogen peroxide. Endod Dent Traumatol 1991;7:196– 198. 15. Rotstein I, Torek Torek Y, Misgav R. Effect of cementum defects on radicular pen 2O2 during intracoronal bleaching. J
265 THE EUROPEAN JOURNAL OF ESTHETIC DENTISTRY
SCIENTIFIC SESSION
16. Spasser HA . A simple bleaching technique using sodium perborate. New York 17. Liebenberg WH. Intracoronal lightening of dis-
electron microscopic study. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 25. White JD, Lacefield WR, Chavers LS, Eleazer PD. The effect of three com-
LO, Milani C, Alfredo E, Messias DC, Silva-Sousa YT. Effect of bleaching protocols and post-bleaching times on
colored pulpless teeth: a modified walking bleach 1997;28:771–777. 18. Dietschi D. Nonvital bleaching: general considerations and report of two failure cases. Eur J Esthet Dent 2006;1:52–61. 19. Sharma DS, Sharma S, Natu SM, Chandra S. An in vitro evaluation of radicular penetration of hydrogen peroxide from bleaching agents during intra-coronal tooth bleaching with an insight of biologic response. J Clin
monly used endodontic materials on the strength and hardness of root dentin. 26. Meyenberg KH. Nonvital teeth and porcelain laminate veneers – a contradiction? Eur J Esthet Dent 2006;1:192–206. 27. Vieira C, Silva-Sousa YT, Pessarello NM, Rached-Junior FA, Souza-Gabriel AE. Effect of high-concentrated bleaching agents on the bond strength at dentin/ resin interface and flexural
C, Kijsamanmith K, Messer HH. Effect of bleaching agents on bonding to pulp chamber dentin. Int Endod J - vated bleaching on various adhesive restorative systems. J Esthet Restor Dent cal considerations for the restoration of endodontically treated teeth: a systematic
20. Palo RM, Valera MC, Camargo SE, Camargo CH, Cardoso PE, Mancini MN, Pameijer CH. Peroxide penetration from the pulp chamber to the external root surface after internal bleaching. Am J Dent lu 21. Kamburog lu K , Kurs un S, Yüksel S, Oztas ability to detect ex vivo simulated internal or external cervical root resorption. 22. Tamse A. Vertical root fractures in endodontically treated teeth: diagnostic signs and clinical management. Endodontic Topics 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 N. Effect of a lowconcentration EDTA solution on root canal walls: a scanning
28. de Oliveira DP, Teixeira EC, Ferraz CC, Teixeira bleaching agents on dentin microhardness. J Endod 29. Maleknejad F, Ameri H, Kianfar I. Effect of intracoronal bleaching agents on ultrastructure and mineral content of dentin. J Conserv A, Attin R. Effect of bleaching on restorative materials and restorations – a systematic review. Dent Mater Khodamoradi R. Fracture resistance of endodontically-treated teeth: effect of combination bleaching and an antioxidant. Oper Dent Comparison of the effect of hydrogel and a solution of sodium ascorbate on dentincomposite bond strength after bleaching. J Contemp Dent Pract 2008;1;9:105– 112.
review of the literature, Part II (Evaluation of fatigue behavior, interfaces, and in bleaching of teeth: an analysis of 255 teeth. Aust Dent J. Farella M, Riccitiello F. endodontically: long-term evaluation of a case series. prognosis of intentional endodontics and internal bleaching of tetracyclinestained teeth. Compend Contin Educ Dent ing: long-term outcomes and complications. J Am Dent Assoc 1997;128 Suppl:51S–55S. -eseder K, Städtler P. Fiveyear follow-up of internal 1999;10:105–110.
266 THE EUROPEAN JOURNAL OF ESTHETIC DENTISTRY
MEYENBERG
Lambjerg-Hansen H. root canal treated teeth. results. Tandlaegebladet
restoration of endodontically treated teeth. Pract Periodontics Aesthet Dent 1999;11:761–768.
compatible Materials Sys Schärer P. Zirconia posts: a new all-ceramic concept for nonvital abutment teeth. J
and Art of Dental Ceram Publishing, 1979. esthetics – a European perspective. J Esthet Dent owed zones: an important aspect of the creative shad von Licht und Schatten. In: tionelle Frontzahn-Aesthetik. München: Neuer Merkur
An 11-year clinical evaluation of leucite-reinforced glass-ceramic crowns: a 55. Gehrt M, Wolfart S, Rafai N, Reich S, Edelhoff D. Clinical results of lithium-disilicate crowns after up to 9 years of service. Clin Oral Investig ceramic restorations in different indications: a case series. J Am Dent Assoc. 57. Fabbri G, Mancini R,
F. New concept of coronoradicular reconstruction: the Composipost [in French]. 65. Sailer I, Thoma A, Khraisat A, Jung RE, Hämmerle CH. Influence of white and gray endodontic posts on color changes of tooth roots, composite cores, and all-ceram 66. Paul SJ, Schärer P. Post and core reconstruction for fixed prosthodontic restora-
ceramic crown. J Prosthet The Willi‘s glas crown: a new solution in the dark and shadowed zones of esthetic porcelain restorations. Additive contour of porcelain veneers: a key element in enamel preservation, adhesion, and esthetics for aging dentition. J Adhes Dent 1999;1:81–92. Porcelain Restorations in the 51. Magne P, Magne M. Treatment of extended anterior crown fractures using Type IIIA bonded porcelain restorations. J Calif Dent Assoc 52. Setien VJ, Roshan S, Nelson PW. Clinical management of discolored teeth. Gen Dent
discolored teeth restored with procera all-ceramic restorations: a clinical evaluation of the esthetic outcome based on the thickness of the core selected. Eur J Esthet Dent 2011;6:76–86. Volpato CA, Monteiro S Jr Jr,, de Andrada MC, Fredel MC, Petter CO. Optical influence of the type of illuminant, substrates and thickness of ceramic materials. Dent excessive reduction. Pract Proced Aesthet Dent Clinical performance of porcelain laminate veneers for up to 20 years. Int J Prosthodont 2012;25:79–85. Guess PC, Stappert CF. Midterm results of a 5-year prospective clinical investigation of extended ceramic veneers. Dent Mater. Lüthy H, Schärer Schärer P, Gauckler L. New materials in dentistry: zirconia posts. Abstract IV-2 of The Monte -
tion. Pract Periodontics Aes Vichi A, Ferrari M, Davidson CL. Influence of ceramic and cement thickness on the masking of various types of opaque posts. J Prosthet Carossa S, Lombardo S, Pera P, Corsalini M, Rastello ML, Preti Preti PG. Influence of posts and cores on light transmission through different all-ceramic crowns: spectrophotometric and clinical evaluation. Int J Jung RE, Sailer I, Hämmerle CH, Attin T, Schmidlin P. In vitro color changes of soft tissues caused by restorative materials. Int J Periodontics Restorative Dent 2007; 27:251–257. Jung RE, Holderegge Holdereggerr C, Sailer I, Khraisat A, Suter A, Hämmerle CH. The effect of all-ceramic and porcelain-fused-to-metal restorations on marginal peri-implant soft tissue color: a randomized controlled clinical trial. Int J Periodontics Restorative
58.
61.
62.
67.
68.
69.
70.
267 THE EUROPEAN JOURNAL OF ESTHETIC DENTISTRY
SCIENTIFIC SESSION
71. Bressan E, Paniz G, Lops D, Corazza B, Romeo E, Favero G. Influence of abutment material on the gingival color of implant-supported all-ceramic restorations: a prospective multicenter
76. Allen EP, Winter RR. Interdisciplinary treatment of cervical lesions. Compend Contin Educ Dent 2011;32 Spec No 5:16–20. 77. Ricci G, Ricci A, Ricci C. Save the natural tooth or
80. Imura N, Pinheiro ET ET,, Gomes BP, Zaia AA, Ferraz CC, Souza-Filho FJ. The outcome of endodontic treatment: a retrospective study of 2000 cases performed by a specialist. J Endod
study. Clin Oral Implants Res 2011;22:631–637. 72. Langer B, Langer L. Subepithelial connective tissue graft technique for root coverage. J Periodontol 1985;56:715–720. 73. Raetzke PB. Covering localized areas of root exposure employing the “envelope” technique. J Periodontol 1985;56:397–402. 74. Burkhardt R, Lang NP NP.. Coverage of localized gingival recessions: comparison of micro- and macrosurgical techniques. J Clin Periodontol 2005;32:287–293.
place an implant? Three periodontal decisional criteria to perform a correct therapy. Int J Periodontics Restorative Dent 2011;31:29–37. 78. Bernstein SD, Horowitz AJ, Man M, Wu H, Foran D, Vena DA, Collie D, Matthews AG, Curro FA, Thompson VP, Craig RG. Outcomes of endodontic therapy in general practice: A study by the Practitioners Engaged in Applied Research and Learning Network. J Am Dent Assoc 2012;143:478– 487.
2007;33:1278–1282. 81. Balto K. Root-filled teeth with adequate restorations and root canal treatment have better treatment outcomes. Evid Based Dent 2011;12:72–73. 82. Naito T. T. Surgical or nonsurgical treatment for teeth with existing root filings? Evid Based Dent 2010;11:54–55. 83. Torabinejad M, Anderson P, Bader J, Brown LJ, Chen LH, Goodacre CJ, Kattadiyil MT, Kutsenko D, Lozada J, Patel R, Petersen F, Puterman I, White SN. Outcomes of root canal treatment and
75. Burkhardt R, Hürzeler MB. Utilization of the surgical microscope for advanced plastic periodontal surgery. Pract Periodontics Aesthet Dent 2000;12:171–180.
79. Wu MK, Shemesh H, Wesselink PR. Limitations of previously published systematic reviews evaluating the outcome of endodontic treatment. Int Endod J 2009;42:656–666.
268 THE EUROPEAN JOURNAL OF ESTHETIC DENTISTRY
restoration, implant-supported single crowns, fixed partial dentures, and extraction without replacement: a systematic review. J Prosthet Dent 2007;98:285–311.
