Post endodontic restoration /certified fixed orthodontic courses by Indian dental academy

Post Endodontic
Restorations

INDIAN DENTAL ACADEMY
Leader in Continuing Dental Education
www.indiandentalacademy.com

INTRODUCTION
The goal of the endodontic restoration is to
provide optimal oral health, esthetics and
function.

Therapeutic efforts made to result in easily
maintainable and reliable treatment over long
term.

Endodontic therapy, restorative dentistry and
periodontal health are intimately related.

The purpose of this topic is to discuss this
complex relationship, treatment planning and
procedures for restoring these RC treated teeth.

HISTORY
• 1747 PIERRE FAUCHARD described
how to restore roots of pulp less teeth
--- PIVOT today termed as a post
(Made of gold or silver)
---Mastic-heat softened adhesive (mastic)
(prepared by Gum, Lac, Turpentine
and White coral powder)
• 1849 Sir John Tomes Post length and
diameter confirmed closely to today’s principles in
fabricating posts.
• 1869 G.V Black advised filling the gold foil.
• 1878 Richmond Crown – porcelain faced
dowel crowns
• 1880 U.S Seasoned wood as a pivot
• 1960 Carbon fiber post
• 1989 Modifications of Carbon fiber posts
• 1996 Meyeberg – Zirconium posts
• 2000 Everstick & Millinium white post

Definitions
Post (dowel):- Refers to a cylindrical or
tapered object that fits into the prepared
root canal of a tooth

Core :- Refers to a build up restoration ,
usually amalgam/composite placed in a
badly broken down tooth to restore the
bulk of the coronal portion of the tooth to
facilitate subsequent restoration by means
of an indirect extracoronal restoration

Changes in teeth after RCT

• Loss of tooth structure
• Absence of pulp
• Decrease in moisture content
• Physical properties (strength)
• Esthetics
• Nature of dentine toughness
• Collagen fibers alignment


When the Post Is Indicated
 Depends on how much tooth structure remains after
RCT to retain core material
 As an abutment
• Tooth which is susceptible to #

 Incisors – JC or post is not indicated (only depends
on amount of tooth structure remains and Esthetics)
 Premolars require post more often than Molars
-- Small pulp chamber
-- Less tooth structure
-- Inclined lingually
So restoring the RCT teeth with Amalgam/
composite/miraclemix will strengthen
the tooth but may #

Placement of crown on an endodontically treated tooth
reduced its Fracture only by 2% -- for anterior teeth

And 38% to 48% # for posterior teeth when left uncovered
(sorensen and Martinoff)

MOD preparation reduces stiffness by 63%

Molar teeth # at 122 Kg (left uncovered after
RCT and MOD) and teeth # at 341 Kg (when
the crown given)

 Occlusal cavity reduced cuspal stiffness by 20%

WHY THE POST IS NEEDED?
• To give support for the core material
• To replace the lost crown structure

PRE TREATMENT EVALUATION
• Endodontic evaluation
• Periodontal evaluation
• Restorative evaluation
• Esthetic evaluation

Factors which are not favorable
For post endo Rx:

 Severe curvature of root - eg:- dilaceration
of root
• Perforations caused by resorption
• Poor crown to root ratio , vertical #
• Sensitivity, inflammation, sinus opening,
exudate , apical seal, and peridontitis


Fundamental rules for “post”

• The post must be at least as long as the
crown

• The post must have parallel sides or have
a max convergence of 3-5 °

• The post must achieve a precision fit in
the canal.

Basic components used in restoration
of Non vital teeth

 Dowel

 Core material

 Coronal restoration


How much GP should be removed to
preserve apical seal
• Portell :- Tested leakage around 3,5,7 mm GP –
-leakage around only 3mm of GP left

• Nixon et al:-compared leakage around
3,4,5,6,7mm GP left by DIE INK PENETRATION
TEST and found greatest leakage around 3 mm
and least around 6mm

• Kvist et al found more periapical radiolucencies
found around 3mm GP left

• So 4-5mm www.indiandentalacademy.comgood apical seal
GP should be left for

When to remove GP?
• No difference between immediate and after 1
week -- ( Bourgeois and lemon )

NO difference between 5 mins and 48 hours
(BY DIE INK PENETARTION METHOD)—
ZMENER

• Significant difference between immediate and
after 24 hours --DICKEY et al

• So adequately condensed GP can be safely
removed immediately after obturation

What instruments remove GP without
disturbing apical seal?

• No difference in leakage between
removing GP with hot instruments (i.e.
pluggers) and rotary instruments (i.e.
gates glidden and peeso reamers)

• Less leakage when hot instruments are
used --HADDIX et al


How to Remove GP
• By chemical solvents (xylol, chloroform
and eucalyptol)
• Mechanically (by gates glidden and peeso
reamer)
• Thermally (by hot pluggers)
• Combination with one another
• Its shown that after GP removal vertical
condensation improves the apical seal


Dowel (Post)
• It is the metal post or rigid restorative
material placed in the radicular portion of
non vital teeth

Functions:
 To retain a core material
• For the distribution of masticatory forces to
the root
• To decrease the risk of root fracture

Classification of posts
Broadly categorized into
 Custom cast posts and
• Preformed post systems

Tapered Smooth
Serrated
parallel threaded


Based on material

Metallic posts Non metallic posts
Dentatus post Carbon post
Para post Aestheti plus post

Root post FRC post
Zirconium oxide post
Ceramic
post


Resistance triad
• Anti rotation
• Vertical remaining coronal tooth structure
• Crown bevel
RETENTION TRIAD
 Post length
 Post shape
 Luting cement used

Factors effecting retention & resistance
form
• Post length
• Post design
• Post diameter and remaining
dentin
• Surface preparation
• Canal preparation
• Cement used
• Anti rotational groove

Post length
• Equal to Inciso cervical
or occlusocervical dimension
• Should be longer than crown
• Half the root length
• Two thirds of root length
• Halfway between crestal
bone and root apex
• Should be as long as possible without disturbing the
apical seal
• At least 3 Quarters of post length (leary et al 1987 JOP)
• For molars should not be extended more than 7 mm
(palatal for Maxillary and distal for Mandibular)


Post diameter
• As the post diameter increases-increase in retention
(shillingburg, turner)
• No significant retention changes with diameter variation
(standlee JP, kurer)
• As the diameter increased there is increase in stresses
in the tooth
• Increased diameter decreases the tooth resistance to #
• 1 MM the tooth diameter decreases—six times the #
potential increases
• Large diameter posts showed higher root #

• POST DIAMETER SHOULD NOT INCREASE ONE
THIRD OF ROOT DIAMETER (Goodacre 1995 JOP)


Post diameter


Relation between post diameter and
the potential for root #

• Post diameter should not exceed 1/3 rd of
root diameter
• Mand. incisors 0.6-0.7 mm
• Max. central incisors 1.7 mm
• other teeth 0.8-0.9 mm
Mesial roots of Max. molars and Buccal roots
of Mand. molars should not be used for
custom posts

Post shape
Tapered form
 Less tooth structure is removed
• Act like wedge - exert lateral forces
- vertical root fracture
• Used in tapered root canals

Parallel sided
• More tooth structure is removed
• More retention & decreases force distribution.
• 2-4 times more retentive than tapered posts.


Surface of the post
SMOOTH SURFACE
• Least retentive

SERRATED SURFACE
• More retentive than smooth surfaced
• Provide mechanical undercuts for cement .
• Serrations can be Horizontal with single vertical
vent channel
Threaded
• Most retentive
• Significant stress

• Tapered posts produced the greatest stress at the
coronal shoulder, and parallel posts generate their
greatest stress at apex of the canal preparation
(Oral Sci Rev 1977)

• Parallel posts resisted tensile, shear and torquing
forces better than tapered and distribute stress
more uniformly along their length during
function
(JOE 1991)


FEA & PHOTOELASTIC studies:


Does the surface and shape of the
post influence the root #
• Tapered Threaded posts produce greatest stress and
highest potential for root # (7%)

• Tapered threaded posts increases root # by 20 times that
of parallel threaded posts (parallel sided posts distribute
stress more evenly to the root )

• Tapered cemented posts (3% root #),and parallel
cemented posts (1% root #)

• Split threaded posts produced less stresses than than
threaded posts

Cementation
• Glass ionomer cement
• Zinc phosphate cement
• Polycarboxylate cement
• Resin cement
• Cast gold luted with ZnP bond failed at 11897 cycles
ParaPost (Ti alloy) luted with Znp and Comp. core bond
failed at 24384 cycles
FiberPost luted with resin cement and Comp core bond
failed at 50,696 Cycles
( JOP 2005)
Film thickness :- Thicker layer of cement will transform
stresses to the tooth in a Different manner than a
Uniform Thin layer of cement
(JOE 1990)


• Occlusal force

micromovemants

Disintegration of brittle cement

Conc. of stresses at Apex

# of Root

ANTI ROTATIONAL GROOVE


Technique of cementation:-
Application of cement in the canal (with lentulospiral)
is essential because it produces Uniform,
Bubble-free layer of cement and voids that
Distributes stresses Evenly (OOO 1972)

(1). Post space should be free of residue
[ Residue in the canal can generate
enough force to cause root #] ( JOP 1993 )

(2). Hydrostatic pressure in the cement , excessive
seating pressure and the torque exerted by the clinician
may cause # of Root (J D RESEARCH 1985)

(3). Post space should be cleaned by a 17% EDTA
(30 sec),5.2% Naocl(30 sec) ,Rinse with H2O
and Dried withwww.indiandentalacademy.com
paper points. (J D RESEARCH 1984)

Core
• Replaces carious, missing or # tooth
structure
• It is anchored to the tooth by the direct
connection into canal or to the post
• Tooth structure can also be altered to
enhance retention, resistance and to
prevent rotation (pins, grooves and
channels)


Ideal requirements of core material:-
Morgano and brackett described as
 Adequate compressive strength
 Sufficient flexural strength
 Biocompatible
 Resistance to leakage
 Ease of manipulation
 Bonding to tooth structure
 C.E.O. thermal Exp
 Dimensional stability
 Min potential to H2O ABSORPTION
 Inhibitionwww.indiandentalacademy.com
of dental caries

CAST CORE
• It is the one piece dowel and core in
a traditional and proven method for
restoring endodontically treated teeth
• This has superior physical and
mechanical properties at the
• Dowel & core junction
• Main disadvantage is NO of
appointments and Lab. procedure


Post material
• Alloys of gold ,SS, titanium ,Ni-Cr,
Ceramic posts, FRC, and dental amalgam
• Wrought gold alloy posts are 2-4 times
stronger than cast gold alloys
Material should be:-
• Adequately stiff and high yield strength
(resistance to permanent deformation)
• Resistance to corrosive effect of oral fluids


• Success rate of 90.6% using cast post and
core as a foundation material
• Cast gold alloy type 3 and 4 as an inert
material with
6
M.O.E (stiffness of 14.5 x 10 )
6
C.E.T.E is =15 x 10 similar to those
of Enamel
Main disadvantage is Esthetics
 Metal ceramic crown is given to mask the
shade of the metal


How post metal corrode

(1). Initiation of corrosion is by access of electrolytes
via cementum dentine covering root surface

(2). Microleakage around post and core

(3). # of root during post space preparation

 Corrosion of posts is mainly because of presence
of Zn and Cu in posts (Derand et al)

 Base metal is most corrosive

 Ti posts arewww.indiandentalacademy.com
most corrosive resistant- passivation

• Nayyar amalgam core

• SECTIONED Nayyar amalgam core


COMPOSITE RESIN CORE
Advantages
• Less time consuming and ease of manipulation
• Additional retention and anti rotation features easily
achieved

Disadvantages
• Polymerization shrinkage & contraction- marginal
discrepancy
• At least 2mm coronal tooth structure - for build up
• Retention of core with zirconium posts ?
• Microleakage
• Sensitivity


GIC core

• Is indicated when there is significant
amount of dentin is remaining and an
additional retention is needed
• Main advantage is the anticariogenic
potential
• Main disadvantage is high solubility
moisture sensitivity
• Low retention to preformed dowels
• Low strength and fracture toughness
• Technique sensitivity

Resin modified GIC core
• Improved properties than conventional
GIC core
• Bond strength close to that of bonded
composite restoration
Microleakage less than GIC
 88% of tooth stiffness is recovered after
restoring the ET tooth with composite
(JADA 2005)

Disadvantage:
• Dimensional instability in the presence of
moisturewww.indiandentalacademy.com
and leads to expansion

Diaphragm
• Diaphragm or apron, usually
placed on palatal aspect
• May help to brace the tooth and
distribute forces more favorably
• It prevents conc. of stresses
around the apical portion
and leads to decrease in
horizontal or oblique #


Ferrule
Ferrule = ferrum (iron) + vairiola (bracelets)
It is a metal band that encircles the external
surface of residual tooth

• Resistance form primarily ,
and retention also
• It resists the lateral forces and leverage action
• Reduces the incidence of #
• To be effective - it must encircle the tooth(360) °


• Ferrule width is more imp than post length in
increasing the tooth resistance to #

• Bevelld or sloping ferrule is effective

• Ferrule created by crown encompassing the tooth
structure is more effective

• Circumferential contra bevel reinforces the coronal
aspect

• Positive occlusal seat - acts as a anti rotational device

• Without ferrule tooth # at 49.6 kg force applied at 135°
and with ferrule of 2mm # at 65.29kg (JOP 1989)

Types of ferrule
• Core ferrule
• Crown ferrule
• Crown ferrule is more effective
than core ferrule

what should be the width of ferrule?

• 1.5-2.0 mm ferrule of crown more effectively
enhances # resistance of custom cast post and
core
• Ferrule which covers -larger amounts of tooth
structure > than small amount of tooth structure
• Presence of 0.5-1mm of ferrule is ineffective

• Tooth restored with PFM # at 958 N (without post)
No ferrule / cast post and core / PFM # at 992 N
2mm ferrule / pre fabricated post and
resin core / PFM # at 994 N
2 mm ferrule/cast post and core # at 1793 N

(JOP 2003)
 Crowns alter the distribution of forces i.e
restoration should have subgingival collar,
which acts by its “hugging” action and prevents
vertical # of the tooth


Principles of tooth preparation
(a) CONSERVATIONISTS –
Restrict the diameter of
the post
(Mattison)
(b) PROPORTIONISTS –
Diameter should not exceed
one third of root diameter
(Stern and Hirshfled, Tilk et al)

(c) PRESERVATIONISTS –
1mm of sound dentin
surrounding the entire canal
(Halle et al)

The crown and crown prepn. Should be
• Parallel axial wall
• Min of 1-2 mm dentine axial wall
• Margins should be on sound tooth structure
• It must not invade the attachment apparatus

Resistance form:-

• Post design should distribute stresses as evenly as
possible to prevent #

• Residual tooth b/w core and gingival sulcus must be
structurally sound and min. of 2mm high for the crown
ferrule and margin


• If there is insufficient tooth structure to construct
ferrule – periodontal crown lengthening surgery
or orthodontic extrusion is indicated
• Gingivectomy


Retention form
• It is the Dislodgement of post
retained anterior crown
• It is due to inadequate retention
form of the prepared post

Retention of the post is mainly affected by
• Post length
• Post diameter
• Surface texture


CUSTOM CAST POST AND CORE
• In direct technique using inlay wax, auto polymerizing or
light polymerizing resin usually for single tooth
restoration
• Indirect technique – multiple teeth or tooth with multiple
canals
• The post/pin should extend the full length of prepared
canal
• soft wax is added or a brush bead technique is used to
add resin


Indirect tech. for the
construction of multipost
• Impression post canal rubber base

of the tooth preforrmed posts
impression

Impression of the die


• Wax pattern withdrawable post pattern
posts in 2 canals try in

• Removable post & core post-op
Posts inserted cemented


Restoration of teeth with resected root

• Tooth pre post resection
resection

Wax pattern cast post luted post op


Restoration of a hemisected tooth

• Difficulties of contouring rest. in furcation


PROVISIONAL RESTRORATIONS
It plays an important role in the successful restoration of
a tooth

FUNCTIONS
• Esthetics
• Protection of the tooth from further damage
• Prevents migration of adjacent teeth
• provides occlusal function
• Poly carbonate crowns
• Plastic posts relined with acrylic resin
• Silicone post reinforced with a paper clip or
orthodontic wire
• Braided SS wire with acrylic resin crown
• SS crowns with reinforcement

Pre fabricated posts

• Wide range of prefabricated posts are
available in various shapes and sizes

• Parallel sided prefabricated posts
are recommended for conservatively
prepared root canals with Circular
cross section.

• Excessively prepared canals managed with
custom post.

Recent advances in post system
Fiber-reinforced resin post systems:-
1) Carbon fiber post system
2) Luscent anchor post system
3) Twin luscent anchor post systems
4) Double taper post system
5) Luminex post technology
6) Parapost fiber white system
7) Anatomic post & core
8) ceramic post & core system
9) Ni-ti posts
10) Flexi post
11) Everstick post
12) Millinium post


Fiber reinforced composite post system

• The addition of fibers to a polymer matrix results
in a significant improvement in the mechanical
properties of :-
• Strength
• Fracture toughness
• Stiffness
• Fatigue resistance
• The fibers composed of WOVEN
POLYETHYLENE GLASS OR CARBON


ADVANTAGES:- Disadvantage
• One appointment tech • Tech sensitive
• No lab procedure • Need for an adhesive
• No corrosion protocol
• Root # is less
• Conserved tooth
structure
• Improved Esthetics


• Fibers are 7 – 10 micro meters in diameter
and are available in braided, woven and
longitudinal configurations
 M.O.E is 1 and 4 x 10 6 psi which is closer
to that of dentin =2 x 10 6 and this can
psi
decrease the incidence of root Fracture
 95% of FRC posts showed the success rate
 And these can be easily removed in failure
cases


Carbon fiber post system
• Introduced in 1990 by DURET,REYNAUD & DURET

• Fabricated from continuous unidirectional carbon fibers,8
micro meter in diameter and embedded in an epoxy
matrix

• The fibers constitute 64% of post weight

• Modulus of elasticity is similar to dentine

• Available in 3 diameters:1.4mm,1.8mm,2.1mm


Mechanical properties
• Compressive strength 449 mpa
• Shear strength 170 mpa
• Tensile strength 1.6 mpa
• Modulus of elasticity 8-110 Gpa
• At 90 degrees angle to the post the MOE
is 8 Gpa (that is equal to radicular dentine)
Disadvantage:-
• Not esthetic-causes black/grey shadow
• The post is radiolucent


Luscent anchor post system
• This is the one step effective procedure for
curing composites within the confines of canals
providing anchorage and esthetics
• Transmits polymerizing light within confines of
canals
• Reflects natural hues for flawless aesthetics
• Visible radiolucency in canal and through the
core material
• Available in 3 diameters to fit into very slim and
large canals


Twin luscent anchors:-
• This design gives visible assurance
against accidental debonding of adhesive
and resin core material
• Slim mid section creates Physical choke
• Vent grooves eliminates air resin
entrapment and prevents rotational
dislocation
• Twice the retention


DOUBLE TAPER POST SYSTEM (DT post
system)
• This system provides close canal
adaptation with mainimal tooth structure
removal
• Bigger taper at the coronal level so better
adaptation and less polymerizing
shrinkage

DT quartz post

Tran illuminating luminex post system
• Used in thin walled roots

• The clear light transmitting
posts polymerize light-cured
composites within the entire
root canal

• After curing LUMINEX post is removed leaving a
ready canal for a post


Advantages
• These will reinforce root strength
• Improved control
• Centered canal position
• Superior esthetics
• Technique versatility


DENTATUS CLASSIC POST SYATEM
(FRC posts)

• Made of polyethylene woven fibers that
are treated with cold gas plasma

hydrophobic to hydrophillic
(this allows complete wetting and infusion of fibers by
resin, creating lower contact angle and greater bonded surface area
to enhance adhesion to rest. material)


ADVANTAGES DISADVANTAGES
• Max. post retention • Need for careful
and core stability adhesive protocol
• Conservation of tooth • Need to demonstrate
structure long term
• Internal adaptation effectiveness
• Esthetics • tech. sensitive
• No corrosion
• M.O.E ,flexural and
T.S similar to root
dentine


Ceramic posts

Advantage Disadvantage
• Biocompatibility • Low # resistance
• High flexural • Low # toughness
strength(1400 Mpa) • Brittle
• High strength and
resilience
• Esthetics
• No corrosion


FILPOST
• Made of titanium(99.8%)
• Biologically inert, compatible with all
dental materials
• Fast and easy to place
• Can be bent and shortened to customize
• Minimizes potential of crown root #allows
placement of 2 posts in molars


• Post can be adjusted i.e bent to the size and
shape of the individual canal and cemented

World post
 supplied with primary reamer and secondary drill

 secondary drill- tier-stabilizes & bottoming out

 Length & head position

Peeso Gates Primary reamer
1 2 0
3 4 1
4 5 2
5 6 3

Advantages :-
 Passive fit post
 Parallel sided and serrated for Max. retention
 It has counter sink to prevent wedging effect of
post
 It has vent for escape of cement
 Easy to retrieve
 It can be bent
 Tensile strength is same as dentine
 Made Ti Al Vandium
 Does not corrode


ParaPost XP
 Is a parallel sided passive post..
 19mm length makes it ideal for elongated canals.
 Available in stainless steel or ti alloy
ParaPost XH
 Passive post with a rounded undercut, slotted head.
 Designed to lock on composite and glass ionomer
 Available in titanium alloy in seven sizes.
ParaPost XT
 Requiring mechanical retention.
Threads located in the coronal section of the
post to provide extra retention
Available in titanium alloy.

FLEXI POST
Parallel sided , threaded , splint shank
Advantage :-
 Absorbs the stresses of insertion
(closes during placement)
 Retention
 Twice retentive than para post
 Can be reduced 4 mm coronally
 Available in Flexi flange also


MAILLEFER RADIX ANKER LONG
( titanium alloy)


Gold coated anchorage posts

Dentatus


Sand blasted posts


C-post Millennium White
Composition:
• Glass fibres
• Epoxy polymer

• Disadvantages :

• Less penetration of bonding resins when
compared to Everstick Post


Everstick Post
Composition :
• Glass fibre
• Polymethylmethacrylate
• Bis-GMA

• Advantages :

• The degree of penetration of bonding resins is greater

• This helps in establishing a good bonding between FRC
posts , luting cements and composite cores.


Techs .of Post removal
• Masserann tech
• Post puller
• Ultrasound
• Ganon post removing system
• S.S white post extraction kit
• Fiber post removal kit
• Diamond and Largo bur( is effective than
post removal kit JOE 2003)

• Cutting the FRC post with carborundum disk showed regular
surface than with scissors and with rotary instruments (which
showed # lines along their length) SEM study JOE 2003

• Application of adhesive solution in the canal is more effective
with micro brushes than with small plastic brush (JOE 2002)

• The highest resistance to post dislodgement is shown with
taper of 0.04(i.e 79.10 lb) and lowest with taper of 0.02
(18.70 lb) JOE 2002

• Metallic posts showed greater microleakage than non metallic
posts (JOE 2002)

• Decreasing proximal dentin thickness increased the tendency
for buccolingual fracture (VRF)
IEJ 2002

Basic principles to be followed for the
restoration of endodontically treated teeth:

- Provide cuspal coverage for posterior teeth

-use post with adequate strength in thin diameters

-provide adequate post length for retention.

-Maximize resistance form including an adequate
ferrule

Common failures
Turner 1982 (Dental updates) ; a survey for 5 years showed :-
Out of 100 post – retained failures
59 caused by post loosening
apical lesions and caries next common
10 # roots
6 # posts

Sorenson & Mortinoff (JOP 1984)
Out of 420 teeth –
36 post & core failures (8.8%)
13 post dislodgement
12 non restorable tooth #
8 restorable tooth #
3 perforations

CONCLUSION:-

• The success of treatment depends on
quality endodontic treatment,
periodontal support available, shape
of the canals, and the status of
remaining tooth structure.


Post endodontic restoration /certified fixed orthodontic courses by Indian dental academy

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