Restoration of endodontically treated teeth 1 /certified fixed orthodontic courses by Indian dental academy

RESTORATION OF
ENDODONTICALLY
TREATED TOOTH

www.indiandentalacademy.com

INDIAN DENTAL ACADEMY
Leader in continuing dental education


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


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) Recent advances
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) Bleaching as an treatment option
14) Summary
15) Conclusion
16) References

Core
The core consists of restorative material
placed in the coronal area of a tooth. It

replaces lost coronal tooth structure
and provides retention for crown


Desirable physical characteristics:
 High

compressive strength
 Dimensional stability
 Ease of manipulation
 Ability to bond to both tooth and dowel.


Cast core
Cast metal dowel and core
traditional way of restoring .
Core is integral extension
of dowel.
Does not depend upon
mechanical means for
retention to dowel.


Advantage
Avoids dislodgement of core and crown
from dowel and root when minimal tooth
structure remains
Indirect

procedure can be used making
restoration of posterior teeth easier.


Disadvantage
1. Higher rate of root fracture than
preformed dowels (JPD 1999;81;262)
2.

Needs extra appointments

3.

Casting defect- porosity at the
dowel –core interface susceptible
to fracture

Casting a core to preformed dowel made of
S.S.

Restoration not sufficiently strong to
withstand clinical forces.

Amalgam core
Advantage
1. high compressive strength,
high tensile strength and
high modulus of elasticity.
2. stable to thermal and functional stress
transmits minimal stress to residual tooth
structure and cement and crown margins.

 Amalgam

cores  highly retentive when used
as coronal and radicular restorations or with a
preformed SS dowel in posterior teeth.

require more force to dislodge than cast dowel
cores.
 Relatively

stable in the presence of water

offers resistance to leakage once it has been in
place for a period of time due to the sealing
effects of its corrosion products.

 Amalgam

is easily manipulated

 Bonded

amalgam procedures can improve
the seal at the tooth and alloy junction.

 Placement

of a fast-setting, high-copper
alloy core permits final crown preparation
at the initial operative appoint-ment,
although the early strength is low.

Disadvantage
 Potential

for corrosion and subsequent
discoloration of the gingiva or remaining
dentin.

 Require

second appointment for tooth
preparation.

Composite resin core.
Advantages
 easy

to manipulate
 High compressive strength.
 Preparation for the final restoration 
accomplished during the core placement
appoint-ment.

Disadvantages


Ultimate strength  lower than that of amalgam



Absorption of water  generation of internal stresses



Early composites  polymerization shrinkage and
contraction away from the tooth structure

marginal core and tooth opening, micro cracks and micro
leakage


Micro leakage is not entirely eliminated even by new bonding
agents.


Indications
 As

with all buildup materials more than
2 mm of sound tooth structure should
remain at the margin for optimum
composite resin core function.
 On anterior teeth where a crown is not
required and enamel margins provide
long-term resistance to leakage
 On posterior teeth where composite is
used as a build-up material, maintaining at
least 2 mm between crown margins and
the build-up should reduce leakage.

 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

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

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

Glass Ionomer Cement
Advantages
 The

major benefit  anticariogenic quality
resulting from the presence of fluoride in
the chemical composition,

 Offer

a low level of leakage

Disadvantages
 Low strength

and frac-ture toughness results in
brittleness contraindicated as buildup material in
thin anterior teeth or to replace unsupported cusps.
Use limited to small restorations in which core
strength is not required.

 Glass

ionomer cores exhibit low retention to
preformed metal dowels.

 Soluble

and sensitive to moisture

 Glass

ionomer is not strong enough for a core for an
abutment tooth.

It is indicated in posterior teeth in which
(1) a bulk of core material is possible,
(2)Sig-nificant sound dentin remains,
(3) moisture con-trol is assured,
(4) caries control is indicated.


Kovarik

et al (JADA 2000) fatiguetested crowns with amalgam,
composite and glass ionomer cores,
and found that amalgam was
significantly stronger than composite
and that glass ionomer had
inadequate strength as a core buildup.

Resin-modified glass ionomer
Are a combination of glass ionomer and
composite resin technologies exhibit
properties of both materials.
Exhibits moderate strength greater
than glass ionomer and less than
composite resin.
As a core material it is adequate for
moderate-size buildups.
Hygroscopic expan-sion can cause
fracture of ceramic crowns.

 Solubility

is between that of glass ionomer
and composite resin.

 Fluoride

release is equal to glass ionomer

 The

bond to dentin is close to that of
dentin-bonded composite resin, and it is
significantly higher than traditional glass
ionomer.

 minimal

microleakage.

Advantages of direct core (Plastic Filling) Materials.
 Maximum tooth structure can be conserved because
undercuts do not need to be removed.
 Treatment
 There

•
•
•

requires less patient visit.

are fewer laboratory procedures.

Disadvantages
Long-term success may be affected by 
corrosion of amalgam cores,
the low strength of glass ionomer,
continued polymerization and high coefficient of
thermal expansion and Microleakage of composites

CORONAL COVERAGE
 Reestablish

function

 Isolate

dentine and endodontic filling
materials from microleakage

 Protect

tooth against fracture


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.


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

Should receive cuspal coverage to
prevent fracture


Procedure for tooth
preparation


a) Removal of endodontic filling
material
b) Post space preparation
structure

a) Removal of endodontic
filling material


Obturation performed with silver
cones Retreatment


 The

amount of gutta percha to be
removed is dictated by:
 The desired dowel length
 The bone height.
 The root morphology


 First

completely obturate the root canal and then
remove GPlateral canals will be sealed.

 The

removal of gutta percha can been done using
Chemical:
involves dissolving the gutta percha by chemical
solvents such as xylene, chloroform.
Mechanical:
use of a heated plugger,
rotary instruments like paezo reamers and gates
glidden drills.

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 disturb
apical seal to a greater extent.


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.


Before removing GP
calculate appropriate length of post
( make it equal to crown
Or
2/3rd of root, leave 5mm GP)

GP be removed immediately after
obturation
warm plugger (not with rotary
instruments may disturb seal),

instrument be hot enough to cut
and remove the gutta percha.
An instrument that is too cool
melts the filling in a sticky mass
that can dislodge the entire
canal fill when the instrument is
withdrawn.


Advantage allows operator to work
in an area where root canal anatomy
is still familiar.

 If

old GP and has lost its
thermoplasticity

use rotary instruments
Use safe tip instruments(pesoreamer).
Friction generated between the RC material
and insturment softens GPallows rotary
instrument to track the canal with
reasonable predictability.
Donot use end cutting instruments(para
post drill etc) to gain lengthmay cause
root perforation.

use of chemical for gutta percha removal
should be discouraged.
The result of chemical removal may be
leakage into root canal complex or into
apical areas


b) Post space preparation
Depend on type of post used.
a) pre fabricated post
 Enlarge canal using
endodontic files, reamer or
twist drills of same dimension
as that of post
(each system comes with its
own standardized twist drills)


 Twist

drills  to parallel the walls
of post space

 Careful

not to remove excess
dentine at apical extent of post
pace

 Threaded

post appropriate drill
followed by a tap that prethreads
the internal walls of the post
space.

 b)

custom made post

Not much of preparation required


enlarge enough so that post has adequate
strength . Do not over enlarge weak walls
(1/3rd)

 Remove

any undercuts present within the

canal.

structure
 Ignore

any missing tooth
structure and prepare
remaining tooth structure as
though it were undamaged.

 Remove

external and
internal undercuts.that will
prevent withdrawal of pattern

 Remaining

wall thin (since
tooth str. Removed from out
and inside), ideally residual
coronal wall be 1mm wide.


1 mm

Wall height reduce proportionately acc to
wall thickness. (thin tall wall tend to fracture
during removal of provisional restoration)
(2mm)
Prepare part of remaining tooth str.
Perpendicular to post
provide positive stop to prevent
overseating and splitting of tooth.
Provide ferrule effect to prevent fracture
of tooth

Prevent rotation by making flat parallel plane

.

Sufficient tooth structure
Present

vertical coronal wall
prevents rotation

Coronal dentine lost
small groove
( anti rotational element)


fabrication of Custom made post


 Direct

technique
 Indirect technique
 Direct

technique recommended for
single canals
 Indirect technique more appropriate for
multiple canals

Direct technique
Materials
 Inlay wax
 Thermoplastic resin
 Autopolymerising resin
 light polymerised resin


Using auto polymerising resin
Lubricate canal
Select a loose fitting plastic dowel.
Should extend to full depth of
prepared canal
Notch it
1. add resin only to canal orifice first
Add resin on post using bead-brush
Technique Or Mix some rein  roll in
cylinder shape introuced in canal  Push with monomer
moistened dowel.

Donot allow resin to harden fully
Loosen and reset it several times
Once polymerised remove it
2. Form apical part of post by adding additional resin
 reseat and removing
Care not to lock it in canal


add additional resin for core
formation
Slightly overbuild the core
and let it polymerize

Shape the core with
carbide finishing burs.


2.Rosenstiel et al (JPD
1997;77;209) Using thermoplastic
resin material
Palstic rod selected
(Merritt EZ post system)

Should extend to full depth
of prepared canal
Be loose
Should be 1.5-2mm above
the occlusal surface


 Lubricate

canal

 Heat

thermoplastic
material

 Apply

on apical
aspect of rod

Insert the rod

Wait for 5-10 secs reseat

Inspect for completeness


Core build up from
autopolymerising resin
Trimmed to ideal tooth
preparation form
Final preparation.


3. William H. Silverstein
(JPD1964;14;374)
 First

prepare tooth for
crown

 prepare

temporary
acrylic resin crown

 Prepare

tooth for post
and core casting

Fabricate direct wax pattern with aid of
temporary resin crown.


Same procedure for
posterior teeth
1 post in major canal and
bead of wax in smaller canal


4. Light cure resin (JPD 1992)
(GC unifast LC )

Serrated plastic dowel
(dura lay plastic pins)

Resin injected

Plastic dowel placed


Curing coronal portion

Curing apical portion


Core build up with resin

Final resin pattern


Indirect procedure
Orthodontic wire bend in
J shape
Verify fit loosely fit, extend
to full depth

If too tight impression will
tear away

 Coat

wire with adhesive

 Lubricate

canal (die lubricant)

 Fill

canal with elastomeric
impression material
(using lentulo spiral)

 Seat

wire to full length

 Syringe

some impression
around teeth, insert impression tray

Remove impression

Pour cast


 In

lab, select a plastic
post (toothpick)
 Using impression as
guide make sure it
extend to full depth


Lubricate stone cast

Add inlay wax in
increments on post

Pattern fabricated

Add wax core
and shape it


(J Prosthet Dent 2002;88:555-7.)


Vinyl polysiloxane
material seated over
prepared teeth on stone
cast.

teeth prepared for
custom-cast posts

Plastic posts fitted and coated
with autopolymerizing
acrylic resin.

Posts and cores immediately
after removal of index material


Refined posts and cores


Direct technique for posterior
Shillingburg et al (JPD 1970)
Plastic tooth pick-loose

First mix of acrylic resin
ills the canal and
completely covers
the occlusal surface


Second mix of resin for completion
of core preparation

Finished pattern


2. Single piece core with auxiliary
post

Indirect approach better as
access is better
Fit prefabricated post into
prepared canal
Roughen one post, others
smooth and lubricate

All posts should extend beyond
eventual preparation.

Build core with autopolymerising resin
Shape it
Grip smooth posts with forceps and remove
Remove pattern
invest


Indirect pattern for multirooted teeth
(split core)
Wax the custom made post
Build up part of core
around first post


Remove any undercuts
adjacent to other post holes
Cast it
Wax additional sections
Cast them


Interlocking sections can be made using dove tails
Complicated
Limited benefit as final
build up is held together
by fixed cast restoration.


Provisional restoration
 To

prevent drifting of opposing teeth or
adjacent teeth provisional restoration.

 If

cast post-core is made additional
provisional restoration needed.

Retained by fitting a wire into prepared
canal.

By lining a polycarbonate crown.
Not necessary that
reline material may
extend down till full
length of post
By engaging
apical portion wire will
enhance resistance of
restoration.

Removal of existing post


 If

sufficient length
exposed coronally

thin beaked forceps
 Vibrating

with ultra
sonic scaler
weaken cement
facilitates removal

 Ultrasonic

cracks

in dentine

 Post

puller
Vise to grip post

Legs that bear on root surface
Screw activates the vise and extracts the
post.


 Using

high speed bur

 Fractured

post can not
be pulled by post puller
or tweezer

 Risk

of cutting dentine




Masserann technique for
removal of fractured posts.



Diameter of post is gauged
with sizing tool



Selected trephine is rotated
counterclockwise to create
a narrow channel around
the post



Once sufficient material
removed



Post recovered.

 Thomas

post removing

system

High speed bur used
to free the post from
the coronal tooth
structure and parallel
its sides.


A trephine bur
machines the post to
correct
diameter and places
threads for the
mandrel


Mandrel threaded on to
the post which distribute
forces evenly over the root


Beaks of plier fitted on to mandrel
Screw rotated
Beaks separated
Post removed


 Removal

kits
for fiber post


Post placement and core build up
Steps for luscent anchor system


Gutta-percha removed

The length of the post
determined in the canal


The trimmed post replaced

canal etched with
37% phosphoric acid.


etchant gently rinsed
with water and dried with
paper points

An adhesive primer
and bonding agent
applied


A flowable composite resin
The flowable composite
(Tetric Flow Ivoclar Vivadent, resin light cured
) dispensed
for 60 seconds
into the canal.

completed
core build-up

The core build up

Postoperative radiograph


Final restoration

Bleaching

as an treatment option


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.


Thermocatalytic
Walking

bleaching

bleach


Thermocatalytic bleaching/ heat and
light bleaching

 A)

cotton mat saturated with Superoxol
(30%hydrogen peroxide) on labial surface and
in pulp chamber
Repeated several times
On completion, cotton pellet moistened with
superoxol or sodium perborate is sealed in
pulp chamber till next appointment.

 B)

alternative procedure
 Activate supeoxol by using Stainless stel
instrument heated over flame.


Walking bleach
 Apply

petroleum jelly on gingival tissues

 Re-establish

the access cavity

 Remove

GP till crest of alveolar ridge (1-3
mm below the free gingival margin

 Seal

root canal orifice with cement

 Remove

smear layer by applying 25%citric
acid or 30% phosphoric acid

 Mix

superoxol and sodiumperborate

 Place

in pulp chamber

 Cover

with cotton moistened with
superoxol

 Seal
 Pt

cavity with temp. cement

recalled after 3-7 days.

Summary
An endodontically treated tooth should have good
prognosis. It can resume full function and serve
satisfactorily as an abutment for fixed or
removable partial denture
Different clinical procedures have been
advocated, many of which are successful if
properly used. Where the crown is preserved, an
anterior tooth can be safety restored with a
plastic filling. To prevent fracture of posterior
teeth, cast restorations providing cuspal
coverage are recommended.

Preserving as much tooth structure as
possible is important, particularly within
the root canal, where the amount of
remaining dentin may be difficult to
assess.
A post-and-core is used to provide
retention and support for a cast
restoration. It should be of adequate
length for good stress distribution but
not so long as to jeopardize the apical
seal. The safest method to create post
space is to use a warmed endodontic
plugger to remove the gutta-percha.

Anterior tooth, particularly those with
flared or elliptical canals, should be built

up with a custom cast post-and-core,
although prefabricated posts can be used
successfully too. Esthetic post materials
should be considered if a dark post would
ruin an esthetic restoration. Amalgam can
be used satisfactorily on posterior teeth,
although a casting may be preferred if
much coronal tooth structure is missing.

Conclusion
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.

References


1

A simplified method of making post and
cores (JPD 1970;24:287)
 2 Restoration of endodontically treated
posterior teeth (JPD 1970;24:401)
 3 Evaluation and restoration of
endodontically treated posterior teeth
(JADA 1976;93:597)
 4 Construction of a post and core to fit a
completed restoration (JPD 1977;38:229)

5

Preparation of endodontically treated teeth to
receive a post core restoration (JPD
1977;38:413)
 6 Factors influencing the retention of dowels
(JPD 1977;38:515)
 7 An amalgam coronal-radicular dowel and
core technique for endodontically treated
posterior teeth (JPD 1980;43:511)
 8 The retentive and stress distributing
properties of a threaded endodontic dowel (JPD
1980;44:398)

9

Post core foundations for endodontically
treated posterior teeth (JPD 1982;48:401)
 10 Clinically significant factors in dowel design
(JPD 1984;52:28)
 11 Intracoronal reinforcement and coronal
coverage: a study of endodontically treated teeth
(JPD 1984;51:780)
 12 Effect of post preparation on the apical seal
(JPD 1984;51:785)
 13 Endodontically treated teeth as abutments
(JPD 1985;53:631)
 14 Dimensional stability of silver amalgam and
composite used as core materials (JPD
1987;57:554)

 15

Retention of cast endodontic
posts:comparison of cementing agents (JPD
1988;59:318)
 16 Ferrule design and fracture resistance of
endodontically treated teeth (JPD 1990;63:529)
 17 Threaded endodontic dowels :effect of post
design on incidence of root
fracture (JPD
1991;65:179)
 18 An accelerated technique for casting post
and core restorations (JPD 1991;66:155)

 19

In vitro bond strength of silica coated metal
posts in roots of teeth (IJP 1992;5:373)
 20 Evaluation of fracture resistance of a
wrought post compared with a completely cast
post and core (JPD 1992;68:443)
 21 Effect of eugenol containing endodontic
sealer on retention of prefabricated post luted
with an adhesive composite resin cement (QI
1992;23:839)
 22 The dentin root complex:anatomic and
biologic considerations in restoring
endodontically treated teeth (JPD 1992;67:458)

 23

Light cured resin for post patterns (JPD
1992;68:412)
 24 Root fracture in endodontically treated teeth
related to post selection and crown design
(JPD1992;68:428)
 25 Retention of posts cemented with various
dentinal bonding cements (JPD 1994;72:591)
 26 Custom cast post fabrication with a
thermoplastic material (JPD 1997;77:209)
 27 Comparison of the fracture resistance of
pulpless teeth restored with a cast post and core
or carbon fibre post with a composite core (JPD
1998;80:527)









28 An in vitro study of the fracture resistance and
incidence of vertical root fracture of pulpless teeth
restored with six post and core systems (JPD
1999;81:262)
29 Essential endodontology – D. Orstavik and
T.R.Pittford
30 Contemporary fixed prosthodontics 3rd edn –
Rosenstiel, Land, Fujimoto
31 Pathways of the Pulp 8th edn. – Stephen Cohen,
Richard C. Burns
32 Color atlas and text book of endodontics 2nd edn –
Christopher J.
33 Preservation and restoration of tooth structure –
Graham J.Mount

The Ruddle post removal system including the
extractor. (B) A domer bur, trepan and tap used to modify and engage
the post. Ruddle post removal system (Fig. 8.4)
which consists of a series of trepans to mill the post,
tubular taps to engage the post and extraction pliers to
provide the elevation force. www.indiandentalacademy.com

(A) Masserann kit. (B) Close-up of a Masserann trepan.


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The Masserann
system is preferred to the Ruddle for removal of fractured
posts, as the metal trepans are thinner and therefore
more conservative of tooth tissue. A suitably sized
trepan is directed along the side of the post in the space
created by the ultrasonic tips. A smaller trepan may
then be used to grip and remove the fractured portion
(additional ultrasonic vibration applied to the trepan
may be useful at this point). If the post is of the screwin
type, then it may be unscrewed after the use of ultrasound
to weaken the cement seal, either by placing a
groove in its end or grasping it with a tight-fitting
trepan. If this is unsuccessful, then a trepan should be
selected which will cut along the threads of the post,
as this will minimize the amount of dentine removed
while easing the cutting of the metal. In exceptional
cases, fractured posts may be drilled out using an endcutting
bur. This procedure, however, is rarely necessary
in view of the recent developments in ultrasonic
tip design and improved magnification and lighting.

 Vented

post


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Restoration of endodontically treated teeth 1 /certified fixed orthodontic courses by Indian dental academy

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