Managment of endodontically treated tooth /certified fixed orthodontic courses by Indian dental academy

MANAGEMENT OF
ENDODONTICALLY
TREATED TOOTH

www.indiandentalacademy.com

INDIAN DENTAL ACADEMY
Leader in continuing dental education



CONTENTS
1. Introduction.
2. Definitions
3. History
4. Review of literature
5. Changes in endodontically treated
teeth.
6. Pretreatment evaluation.

7. Treatment planning for restoration of
endodontically treated teeth.
8. Principles of tooth preparation.
9. Basic components used in restoration
of endodontically treated tooth.
a) Dowel
i) Ideal properties
ii) Classification
iii) Retentive, protective and esthetic
qualities
iv) Materials used for fabrication

v) Recent advances in post
b) Core
i) Desirable physical characteristics
ii) Various materials used in core
fabrication
c) Coronal coverage
10) Procedure for tooth preparation of
endodontically treated teeth
a) Guttapercha removal
b) Post space prepration

c) Preparation of coronal tooth
structure
11) Custom cast and core
12) Provisional restoration
13) Failures
14) Summary
15) Conclusion
16) References

INTRODUCTION


A tooth that has been pulpally involved
is often given a second chance with
endodontic treatment. However, in
most instances endodontically treated
teeth have been exposed to a variety
of insults ranging from caries, the
operative procedures that follow,

the chemical insults due to the
restorative materials, loss of
structural integrity (removal of
critical dentin during endodontic
procedures) and finally
dehydration of the tooth structure.

Restoring such a tooth involves a
range of treatment options of
varying complexity. The loss of
tooth structure makes retention of
the subsequent restoration more
problematic and increases the
likelihood of fracture during
function.

If the requirements of the tooth are
assessed carefully and the
treatment is planned appropriately,
it can resume full function and
serve satisfactorily as an abutment
for a fixed or removable partial
denture.

Restoration of the pulpless teeth
has been dated back to the 1740’s
where posts were fabricated of
gold or silver .Ever since then a
variety of techniques and materials
have been introduced to reinforce
the endodontically treated tooth.

DEFINITIONS


Dowel : a post, usually made of metal
that is fitted into a prepared root
canal of a natural tooth. When
combined with an artificial crown or
core, it provides retention and
resistance for the restoration (GPT-7)


Core : the center or base of a
structure

Post-core crown: a restoration in
which the crown and cast post is
one unit

Ferrule (GPT-7):
l: a metal band or ring used to fit the
root or crown of a tooth
2: any short tube for making a tight
joint


• Apex (GPT-7): in dentistry, the
anatomic end of a tooth root.
• Biologic width: the combined
width of connective tissue and
epithelial attachment superior to
the crestal bone

HISTORY


In 1747, Pierre Fauchard described
the process by which roots of
maxillary anterior teeth were used
for the restoration of single teeth
and the replacement of multiple
teeth.

A 6 unit bridge,
pivoted in lateral
incisor, with
canines cantilevered

Posts were fabricated of gold or
silver and held in the root canal
space with a heat-softened
adhesive called “mastic” (prepared
by gum, turpentine and white coral
powder).

In Fauchard’s days, replacement
crowns were made from bone,
ivory, animal teeth, and sound
natural tooth crowns. Gradually,
the use of these natural substances
declined, and were replaced by
porcelain.

• A pivot (what is today termed a
post) was used to retain the
artificial porcelain crown into a
root canal, and the crown-post
combination was termed a “pivot
crown.”
• In the early 1800s Dubois de
Chemant described Porcelain pivot
crowns.

• Early pivot crowns used seasoned
wood (white hickory) pivots. The
pivot was adapted to the inside of
an all-ceramic crown and also into
the root canal space. Moisture
would swell the wood and retain
the pivot in place.


• Subsequently, pivot crowns were
fabricated using wood/metal
combinations, and then more
durable all-metal pivots were used.


Metal pivot retention was achieved by
various means such as threads, pins,
surface roughening, and split designs
that provided mechanical spring
retention.


REVIEW OF LITERATURE


Hamilton et al ( JPD 1959:9;639)
In their article, Porcelain dowel
crowns, discussed about the
method of fabrication and various
advantages and disadvantages of
porcelain as restorative material

Silverstein et al ( JPD 1964: 14;372)
in their article, Reinforcement of
weakened pulpless tooth, stated
that, for the success of the
restoration, the post selected
should be longer than the crown

Colley et al ( BDJ 1968;124;63-69)
did a study on the effect of post
length on the retention of post and
concluded that increasing the
length of post in teeth increases the
retention of post.

Goldrich M et al (JPD 1970;23:173)
in his article on ‘construction of
posts for teeth with existing
restorations’, mentioned that the
post length should equal the
incisocervical or occlusocervical
dimension of the crown.

H.G.Kurer et al (JPD 1977;38:515)
Did a study to assess the axial
retention of dowels. They
concluded that threaded dowels
appear to have better resistance to
axial displacement than other
types.

Guzy et al (JPD 1979:42;39) did invitro
study on the effects of post placement on
endodontically treated teeth and concluded
that when the tooth is loaded, stresses are
greatest at the facial and lingual surfaces
of the root ( lingual surface is in tension,
while facial surface is in compression),
while the centrally located post lies in the
neutral axis (ie only minimally stressed)
and thus, does not help prevent fracture

• Richard W.Chan et al (JPD 1982;48:401)
Cast-gold post-core combination and
amalgam or composite resin cores used in
combination with cemented steel post have
been examined. Cast gold specimens
required less force before failure occurred.
All of the cast post core foundations showed
displacement from original cemented
position and most teeth showed evidence of
root fracture. Amalgam and composite resin
specimens commonly exhibited fracture of
the core but showed less evidence of post
core dislodgement and root fracture.

Gordon D. Mattison et al (JPD 1984;51:785)
Did a study to analyze the apical leakage and
effect of gutta-percha removal technique (hot
instrument, mechanical rotary instrument and
chemical solvent) on apical seal.
They concluded that mechanical method is
most desirable for gutta-percha removal in
post preparation. As the level of gutta-percha
increased to 7 mm the degree of leakage
decreased. At least 5 mm of gutta-percha is
necessary for an adequate apical seal.

John A. Sorensen et al ( JPD 1984;52:28) in
the article ‘ Clinically significant factors in
dowel design’ concluded that:
• The cast parallel-sided serrated dowel and
core and the parallel-sided serrated dowel
with an amalgam or composite resin core
recorded the highest success rate.
• The tapered cast dowel and core display a
higher failure rate than teeth treated without
intracoronal reinforcement.

• Teeth that had a dowel length
equal to or greater than the crown
length had a success rate of 97%.


R.A. Oliva et al (JPD 1987;57: 554)
Did a study to investigate the dimensional
stability of silver amalgam and a
conventional composite used as core
material. Result of this study indicates
that silver amalgam used as a core
material is dimensionally stable when
exposed to moisture. Seating of crowns
fabricated for silver amalgam cores was
not affected by exposing the cores to
moisture.

Conventional composite used a core
material in this study was found to
be dimensionally unstable when
directly exposed to moisture.
Seating of crowns fabricated to fit
the composite cores was
significantly affected by the
dimensional instability of the resin
core material

Ryle A. Radke et al (JPD 1988;59:318)
Did a study to compare the retentive
values of 4 luting agents (Zinc phosphate,
glass ionomer , polycarboxylate cement
and a composite resin ) for ability to
retain posts in prepared root canals of
extracted teeth. Zinc phosphate and glass
ionomer cements were found to be more
retentive than polycarboxylate cements
and composite resins.

Rahmat A et al
( JPD 1989:61:676-678)
did a study to examine the effect of
metal collar (with approx. 3 degree
taper) on the resistance of
endodontically treated roots to
fracture. They concluded that
reinforcement with metal collar is
necessary to enhance resistance to
root fracture.

James E Haddex et al
( JPD 1990;64: 515-519)
did a study to investigate the effect of
the method of Guttapercha removal on
apical seal. They concluded that heated
pluggers should be used to remove
guttapercha. Although rotary
instruments remove guttapercha faster,
they seem to disturbe apical seal to a
greater extent.

Felton D.A et al (JPD 1991;65:179) did a
study on the effect of post design on
incidence of root fracture and concluded
that:
• There were no statistically significant
differences in the incidence of root fracture
among any of the dowel systems evaluated
regardless of shape, taper or presence or
absence of threads.

• Most of the root fractures resulting
from dowel insertion occurred on
the mesial or distal root surfaces as
a result of reduced thickness of
dentin and the presence of external
depressions (flutes) on these
surfaces.

Hemmings et al
(JPD 1991;66:325-329)
did a study and investigated the
resistance of various post and core
designs to torsional forces and
concluded that cervical collar form
design was the most favorable
design, embracing resistance and
decreasing tooth fractures.

Anthony H.L. Tjan et al (Q Int.
1992;23:839)
• Did a study to evaluate the effect of
eugenol- containing endodontic sealer
on retention of prefabricated pots luted
with adhesive composite resin cement.
They concluded that:
• Eugenol significantly reduced the
retention of parapost dowels luted with
panavia composite resin cement.

Irrigating the post space with alcohol
or etching with phosphoric acid gel
effectively restored the retention.
• The use of alcohol (ehtyl
alcohol/ethanol) as a canal irrigant
or etching with 37% phosphoric
acid gel was found to be effective
in restoring the resistance to
dislodgement of post. Irrigation
with alcohol produced a more
consistant and reliable result.

Daniel B et al (JPD 1994: 72;591-594)
Did a study to evaluate the retention of pre
formed posts with four different cements
• Panavia (Kuraray),
• All- Bond 2 ( Bisco),
• C&B Meta bond (parkel) and
• Ketac-Cem (ESPE-Premier).
They concluded that C&B Meta bond was
most retentive, while no difference in
retention was found between Ketac-Cem
and Panavia cements. All- Bond 2 was the
least retentive cement.

Arturo M et al
(JPD 1998;80:527)
• Did a study to compare the fracture
resistance of two types of restorations:
teeth restored with pre fabricated carbon
fiber posts and composite cores to cast
dowel-core restored teeth. They
concluded that

• Significantly higher fracture threshold
values were obtained in the cast post core
group. Teeth restored with carbon fiber
post and composite cores typically
showed failure of the post core interface
before the fracture of the tooth occurred.
This failure occurred in response to
acceptably high loads. By contrast, teeth
restored with cast post and core typically
showed fracture of the tooth.

• Steele et al ( J endod 1999:25;6)
did an invitro study on the fracture
strength of endodontically treated
premolars and concluded that
premolars with access openings or
conservative MOD preparations
can be restored to nearly normal
cusp fracture values with dentine
bonding and composite resin
systems, but this strengthening
may only be temporary.

Flemming et al
( IJP 1999: 12;78-82)
did a study on the influence of post
length and crown ferrule length on
the fracture resistance of post and
concluded that an increase in
ferrule length is more important
than post length.

Mary Rafter et al
(J Prosthet Dent 2003;89:360-7.)
Did study to compare the effect of fiberreinforced composite post systems on the
fracture resistance and mode of failure of
endodontically treated teeth. Results show
that the load to failure of the stainless steel
posts were significantly stronger than all
the composite posts studied. However, the
mode of failure or deflection of the fiberreinforced composite posts is protective to
the remaining tooth structure.

M. ROSENTRITT et al (Journal of Oral
Rehabilitation 2004 31; 675–681)
• Did a study to compare the fracture
resistance and marginal adaptation of allceramic incisor crowns with all-ceramic
posts, glass–fibre-reinforced posts and
titanium posts as well as a control without
any post.
• The results showed that the restored teeth
without posts showed no significantly
different fracture strength compared with
teeth with the titanium system.

• The all-ceramic posts and the glass–fibrereinforced posts both provided a significant
higher fracture resistance than the teeth
without posts.
• The greatest marginal gap was found with
the titanium system at the interface cementcrown and with the all-ceramic posts at the
transition between cement-tooth.
• Regarding fracture resistance and the
marginal adaptation, the all-ceramic and
FRC posts may be considered as an
alternative to the commonly used titanium
post restorations.

Emine Y. et al ,(J Prosthodont 2005;14:8490.)
Did a study to compare fracture strengths of
teeth restored with cast metal and ceramic
dowel and cores supporting all-ceramic
crowns.
The comparison between metal and ceramic
dowel and cores did not reveal significant
differences in spite of the fact that In-Ceram
Spinells had lower mean fracture values. The
fracture strength of all groups was remarkably
higher than forces applied to anterior Teeth.

They concluded that In-Ceram Spinell
and IPS Empress 2 ceramic dowel and
cores may be candidates for the
restoration of endodontically treated
anterior teeth, as the fracture strengths
of these restorations are above the
maximum occlusal forces of natural
dentition.

CHANGES IN
ENDODONTICALLY
TREATED TEETH


1. Loss of tooth structure.
2. Altered physical characteristics.
3. Altered esthetic characteristics of the
residual tooth.


1. Loss of tooth structure.


Reeh et al (J Endod 1989:15;512-516)
Evaluated the effects of endodontic
procedures as compared to restorative
reduction of tooth. They concluded that
endodontic procedures reduce tooth
stiffness by only 5% (attributed
primarily to the access opening), while
restorative procedures causes
appreciable loss of tooth stiffness

Endodontic procedures reduce
tooth stiffness by only 5%


MOD cavity decreases stiffness > 60%

The endodontic
access into the pulp
chamber destroys the
structural integrity
provided by the
coronal dentin of the
pulpal roof and
allows greater flexing
of the tooth under
function.

When tooth structure is significantly reduced,
Fracture of
undermined cusp
Or
Fracture of tooth
in the area of
Smallest
circumference
(Frequently CEJ)

The decreased volume
+
The effect of prior dental procedures

Significant potential for fracture of
the endodontically treated teeth.

2. Altered physical characteristics


Changes that takes place in
endodontically treated teeth:
a) Changes in collagen cross linking
b) Dehydration of the dentine
c) Changes due to use of sealer cements.


a) Changes in collagen cross linking
Collagen


Structure of dentine

Rivera et al ( J Endod 1988: 14;195) did
a study on dentine collagen cross links
of root filled and normal teeth. They
concluded that the root canal treated
teeth have more immature and fewer
mature crosslinked collagen fibers.
Thus leading to decrease in tensile
strength. These changes in cross links
may contribute to brittleness of nonvital
teeth.

B) Dehydration of the dentine ( loss
of moisture)
Helfer et al ( OOO 1972: 34;661-670)
did a study to determine the moisture
content of vital and pulpless teeth and
concluded that there was 9% less
moisture in calcified tissues of pulpless
teeth than in vital teeth.
This moisture loss may increase
brittleness.

Messer et al (J. Endod. 1994:10;91-93)
did a study to measure the moisture
content of vital and endodontically
treated teeth and concluded that there
was no statistically significant
difference in moisture content of both.


Stephen Cohen : Path ways of pulp: 8th
edt.)
Changes in collagen cross-linking and
dehydration of the dentin result in a
14% reduction in strength and
toughness of endodontically treated
molars.


C) Changes due to use of sealer
cements
May effect the properties of
endodontically treated teeth


Jonck et al (J Endod 1979; 5: 20-24)
did an analysis of the root dentine in
teeth treated endodontically with ZOE
sealers and concluded that in sealers
containing ZOE, free Zinc competes
with calcium binding sites on the
surface of hydroxyapatite crystals.
But it is not clear whether Zinc causes
changes in physical properties of
dentine.

• Biven et al ( BDJ 2005) in their
study showed that the eugenol
present in the eugenol containing
root canal sealers increases the
microhardness of dentine.

3. Altered esthetic characteristics
.


• A) Biomechanically altered dentin
modifies light refraction through the
tooth and modifies its appearance.
• B) Inadequate endodontic cleaning and
shaping of the coronal area  staining
the dentine from degradation of vital
tissue left in the pulp horns.

C) Caries, restorations and secondary
calcifications modify the appearance.


PRE TREATMENT
EVALUATION


Before restoring, the endodontically
treated tooth should be assessed for :
• Endodontic evaluation
• Periodontal evaluation:
• Esthetic evaluation
• Restorative evaluation

Endodontic evaluation


CHECK FOR
• Apical seal
• No tenderness on
percussion
• No draining sinus.
• No mobility
• No active inflammation


Inadequate root fillings retreatment


Signs of failure Retreatment


Obturation performed with silver
cones Retreatment


If doubt  observe until there is
definitive evidence of success or
failure.


Periodontal evaluation:


In addition to performing a routine
periodontal evaluation (pocket
depth, bleeding on probing etc), the
effect of the planned restoration on
the attachment apparatus must be
considered.

Attempts to place the restorative
margins on solid tooth structure
Invade the biological attachment zone.
In such cases,
Crown
lengthening

orthodontic extrusion

Restorative evaluation

Comprises of estimating the
strategic importance of the tooth


Need extensive treatment

Most Distal tooth

Long span bridge

Avoid DEB RPD

Intermediate abutment


• Reliability of tooth after restoration
should be considered.
• Tooth must be able to withstand
functional forces placed on it.
• Large amount of missing tooth structure
must be replaced by post n core and
crown.

Esthetic evaluation


• Thin gingiva may transmit a
shadow of dark root color through
the tissue.
• Metal or dark, carbon fiber dowels
or amalgam placed in the canal can
result in unacceptable gingival
discoloration from the underlying
root.

• The translu-cency of all-ceramic crowns
must be considered in the selection of
dowel and buildup materials.
• Tooth-colored carbon fiber post, glass
fiber, or zirconia posts can be used in
esthetic areas.
• Tooth-colored, rather than opaque,
composite core material should be
selected for the esthetic case.

TREATMENT PLANNING FOR
RESTORATION OF
ENDODONTICALLY TREATED
TEETH


Important considerations are:
• The amount of remaining tooth
structure
• The anatomic position of the tooth
• The functional load on the tooth
• The esthetic requirements for the
tooth

1. The amount of remaining tooth
structure


The amount of tooth structure
damage is one of the most
important aspects in restoration of
the endodontically treated tooth.


Christensen et al (JADA1998:129:96)
Teeth with more
than half of the
tooth structure
intact can be
restored
Conservatively with
coronal restorations
and without dowels inside the roots.

• Teeth with extensive tooth structure loss
 weak making dowels, cores, and
crowns necessary.


Teeth with minimal remaining
tooth structure present several
problems :


The amount of remaining dentin is
far more significant to the longterm prognosis of the restored
tooth than is the selection of
artificial dowel, core, or crown
materials.

• Additional dentine at
the marginal area, when
encased by the crown
margin or ferrule
provides greater
protection than dowel
and core
considerations.

Treatment planning requires use of
dental specialties
• to obtain the necessary sound tooth
structure
• to design the dowel-core-crown
complex for atraumatic retention and
• also recognize when the prognosis is
poor .

2. The anatomic position of the
tooth


Anterior teeth
• Intact, nonvital,
anterior teeth
minimal risk
for fracture.
• Restorative treatment sealing of the
access cavity.

significant loss of
tooth structure

crown supported
and retained by
the dowel and
core.


• Hunter et al ( JPD 1992:68;421) and Guzy et
al (JPD 1979:42;39) did invitro study on the
effects of post placement on endodontically
treated teeth and concluded that when the
tooth is loaded, stresses are greatest at the
facial and lingual surfaces of the root
(lingual surface is in tension, while facial
surface is in compression), while the
centrally located post lies in the neutral axis
(ie only minimally stressed) and thus, does
not help prevent fracture

Disadvantage of routine use of
cemented post in intact anterior teeth:
• Requires additional operative procedure
• Removes additional tooth structure for
post space preparation.


• May be difficult to restore the teeth
later when crown is needed, because
this post may fail to provide adequate
retention for the core material.
• Post can complicate or prevent further
endodontic re treatment if it becomes
necessary.

Warren et al (J Endod 1990:16;570)
Discoloration in the absence of
significant tooth loss may be more
effectively treated by bleaching
than by placing complete crown.


When extensive tooth loss or tooth
will be serving as abutment for
FPD or RPD  complete coverage
is must.


Posterior teeth
•Subjected to greater loading than anterior
•More susceptible to fracture

Should receive cuspal coverage to
prevent fracture


Significant loss of tooth structure
post and core


• Steele et al ( J endod 1999:25;6) did an
invitro study on the fracture strength of
endodontically treated premolars and
concluded that premolars with access
openings or conservative MOD
preparations can be restored to nearly
normal cusp fracture values with
dentine bonding and composite resin
systems, but this strengthening may
only be temporary.

3. Functional load of the tooth


teeth as abutments for fixed or removable
partial dentures

bear more horizontal and torquing forces

need more extensive protective and retentive
features in the restoration.

Abutment teeth for long-span fixed
bridges and DEB RPD absorb
greater transverse loads and require
more pro-tection than do
abutments of smaller bridges or
tooth supported removable partial
dentures.


Teeth that exhibit extensive wear
from bruxism, heavy occlusion
require the full complement of
dowel-core-crown


4. Esthetic requirements of the tooth


Anterior teeth, premolars, and often
the maxillary first molar come in
the esthetic zone of the mouth.
Alterations to the color or
translucency  negative impact on
the esthetics of this zone.

• Careful selection of restorative
materials .
• Restorative materials include:
Tooth colored dowels,
Tooth colored composite resin or
ceramic cores,
Tooth colored cements and
Ceramic crowns.

Thank you
Leader in continuing dental education


Managment of endodontically treated tooth /certified fixed orthodontic courses by Indian dental academy

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