Posts fabricated of gold or silver.
Heat softened adhesive called “mastic
Longevity 15-20 years
1747 Pierre Fauchard
Bone, ivory, animal teeth, natural
1800’s – Porcelain pivot crown
Dubois de chemant
Early pivot crowns – seasoned wood
Wood posts -“Morbid humors”.
1747 Pierre Fauchard
1878 Richmond crown
1 piece dowel and crown
Post and Core
• Dowel (Post):
The dowel is a metal post or other rigid
restorative material placed in the
radicular portion of a non vital tooth.
A dowel usually made of metal is fitted in to a
prepared canal of a natural tooth. When combined
with an artificial crown or core, it provides retention
and resistance for the restoration.
(Glossary of Prosthodontics)
Refers to properly shaped and well
missing coronal structure and
retains the final restoration.
A centre or a base of a structure. The core is
designed to resemble or become the crown
preparation or crown itself.
(Glossary of Prosthodontics)
• Ferrule (Rosenstile):
Is defined as a metal band that
encircles the external dimension of
the residual tooth.
• Ferrule (Weine) :
A ferrule is a metal ring or cap placed
around the end of a cane or tool, giving it
added strength. The ferrule around the
circumference of the tooth strengthens it by
increasing resistance to wedging forces.
Why to Restore ?
As prosthodontist – abutment for FPD , RPD, Over denture
As a Restorative dentist -Increase the clinical longevity of
Schwartz et al 1983 found that the failure rate of endodontically treated
teeth was almost double in cases with inadequate restoration.
Weine 1996 more endodontically treated teeth are lost due to poor
restoration than to subsequent endodontic failure.
The amount of remaining tooth structure.
The anatomical position of the tooth.
The functional load on the tooth.
The aesthetic requirements of the tooth.
The amount of remaining tooth structure
Do not need posts and full coverage crowns
Sound tooth with access
Lack of Coronal tooth
Anterior teeth are inclined at an angle to the occlusal plane
Carry greater occlusal loads
Minimal occlusal access preparations
Teeth with existing restorations involving the marginal ridge or
those with extensive loss of tooth structure
Where ever possible posts should be avoided in posterior teeth
as the roots are often narrow and or curved
Post & Core Systems
Ideal properties of a post
Maximum protection to root
Adequate retention within root
Maximum retention of the core and the crown.
Maximum protection of the crown
margin cement seal
Pleasing esthetics when indicated
High radiographic visibility
• Classification of posts ( D C N A 2002 )
Custom cast posts
Carbon fiber posts
Woven fiber composite post
• Metallic Posts
- PGP [platinum-gold- palladium]
- Nickel –chromium
- Cobalt - chromium
- Stainless steel
- Non oxidizing noble alloys
Custom cast posts :
Multiple cores- in the same arch
Angle of cores – to be changed
All – ceramic crown
Pre- fabricated posts :
Tapered posts :
Mimics natural canal shape
Least amount of retention
Parallel posts :
provides greater retention
in short canal space
• Non-Metallic Posts
Carbon fibre posts
Bundles of stretched aligned carbon fibers embedded in
an epoxy matrix
Modulus of elasticity similar to dentine
Can bond to dentine
Bond strength of composite core material to
Purton et al 1996
Millstein et al 1999 CFP < Composite core to metal post.
Carbon fibre posts
Trido et al 1999
Bond strength can be increased by air abrasion of CFP.
Drummond et al 1999 :
Found decrease in bond strength after air abrasion.
Stockson et al 1999 :
Retention of CFP = Metal posts.
Tooth coloured posts :
Zirconium coated CFP
Aesthetic post plus ( Bisco )
All zirconium posts (Cosmoposts & ceraposts )
Fibre reinforced posts
Light post ( Bisco )
Luscent anchor ( Dentatus )
Zirconium posts modulus of elasticity > Stainless steel
lower fracture resistance than metal posts & inability to bond.
Difficult to retrive
Resintritt et al in 2000 compared # strength
Titanium post & composite core
Zirconium post & composite core
↨ Vectris resin post & composite Core
↨ Custom cast gold post & core
↓ IPS Empress & All Zirconium
Steven M. Morgano & Susan E. Brackett 1999
Desirable features of a core material :
Adequate compressive strength
Sufficient flexural strength
Resistance to leakage of oral fluids at the core/tooth interface.
Ease of manipulation.
Ability to bond to remaining tooth structure
Thermal co-efficient of expansion and contraction
Minimal potential for water absorption &
Inhibition of dental caries.
Classification of core materials :
Plastic core materials
Ceramic to Zirconia
Glass ionomer cement
Resin modified GIC
Dual cure fibre reinforced cores
Kantor and pines 1977 teeth little coronal structure the cast gold
post and core was superior to a stock post and composite resin core.
Ceramic to Zirconia dowels
Pissis 1995 proposed a “Monobloc” technique for fabrication of a
post and core and a crown as a single component made out of glass
ceramic material IPS empress.
Nayyar, Walton, Leonard 1980 reported a technique of
amalgam core build up
Hoag ED, Dwyer TG 1982 Amalgam can be used for core build
ups Due to its self – sealing proprieties, durability and good
Barban 1970 was one of the first to suggest the use of
composite resin to fabricate cores.
Linde LA 1983 found that composite cores showed significantly
greater marginal leakage compared with amalgam cores.
MC lean 1985 GIC can be tooth substance remains and where
limited loading is anticipated.
Resin modified GIC not recommended in high stress situations.
Principles of tooth preparation
• Conservation of tooth structure
Preparation of the canal
Preparation of coronal tissue
• Retention form
• Resistance form
Conservation of tooth
Preparation of the canal :
• Remove minimal tooth structure form the canal.
• Excessive enlargement can perforate or weaken the root
~ Thickness of remaining dentin – Fracture resistance from
Helfer AR et al 1972. teeth cemented with thicker posts (1.8 mm)
fractured more easily than those with a thinner (1.3 mm) one.
Photo elastic studies also have show that internal stresses are
reduced with thinnerwww.indiandentalacademy.com
Most roots have proximal concavities
Felton DA 1991 said that most root fractures originate from these
concavities because the remaining dentin thickness is minimal.
Root canal should be enlarged only enough to enable the post
to fit accurately yet passively while insuring strength and
Preparation of coronal tissue :
Milton P and Stein R S 1992 if more than 2 mm of coronal
tooth structure remains, the post design probably has a limited
role in the fracture resistance of restored tooth.
A key element of tooth preparation when using a dowel and core is
the incorporation of a www.indiandentalacademy.com
A ferrule is a metal band or ring used to fit the root or crown of a tooth.
• Increased fracture resistance
The effectiveness of the ferrule has been evaluated by a variety
of methods, including
Fatigue testing and
Photo elastic analysis.
1.5 mm of ferrule height
Philip et al 2005 have investigated the resistance to static loading of
endodontically treated teeth with uniform and non uniform ferrule
2 mm uniform
> 0.5 – 2mm ferrule height non uniform
2 mm uniform &
0.5 – 2mm ferrule height non uniform
what if tooth has inadequate coronal tooth structure to
create a ferrule ?
•Consider crown lengthening and or extrusion
Surgical :Crown lengthening
Less favourable crown root ratio
increased leverage on the root during function
Gegauff 1999: showed that creating ferrule through crown
lengthening resulted in a weaker rather than a stronger restored tooth.
Post retention is affected by the
Post length & diameter
Surface texture and
Preparation geometry :
Elliptical cross section
Must be prepared with restricted amount of taper 6-8
Taper increases – retention decreases similar to extra coronal
Circular cross section
Prepared with a twist drill or reamer to provide a cavity with
parallel walls or minimal taper.
Threaded posts :
Increase the retention
Not recommended because of residual stress in dentin.
Standlee JP et al 1978 confirmed that parallel sided posts more
retentive than tapered posts and that threaded posts are most
Post length :
Studies have shown that an post length increases, so does
retention. However the relationship is not linear.
A post that is too short will fail
Post that is too long
Ideally, as long as possible
5 mm apical seal
not les than 3 mm
Post diameter :
Increasing the post diameter in an attempt to increase retention
No wider 1/3 root
2 mm of tooth structure.
Tilk M A et al 1979 :1500 teeth (125 of each tooth)
0.6 mm – Mandibular incisors
1.0mm – Maxillary CI, Max and Man canines,
Palatal root of max I molar
0.8 mm Other teeth.
Shillingburg et al 1982 in a study of 100 teeth
0.7 mm – Mandibular CI
1.7 mm – Maxillary CI.
4) Post surface texture :
A serrated or roughened post is more retentive than a smooth one.
Controlled grooving of the post and root canal increases the
retention of a tapered post.
5) Luting agent :
Traditional cements – little effect
Adhesive resin luting cements – increased retention
Note: irrigation with ethanol or etching with 37% phosphoric acid
Posterior teeth :
Long posts avoided – curved roots and elliptical or ribbon shaped
Retention is better provided by two or more relatively short posts
in the divergent canals.
Cast core can be used (made in sections that have different paths
of with drawl).
The influence of post design on stress distribution has been
Photo elastic materials.
Strain gauges and
Finite elements analysis
The greatest stress concentrations are found at the shoulder,
particularly interproximally, and at the apex.
Stresses are reduced as post length increases.
Parallel sided posts
High stress can be generated during insertion, parallel sided posts
Sharp angles should be avoided because they produces high
stresses during loading
Backed off a half turn
Rotational resistance :
Rotation can be prevented by vertical coronal wall.
a small groove placed in the canal
root is bulkiest – lingual aspect
Post & core treatment
1.REMOVAL OF THE ENDODONTIC FILLING
1. Chemical Removal
2. Thermal Removal
3. Mechanical Removal
Schnell FJ 1978 and Bourgeois R S and Lemon RR (1981)
gutta-percha can be removed with a warm condenser immediately
Dickey DJ et al 1982 Rotary instrument can disturb
apical seal if used immediately after obturation.
Steps in removal of gutta-percha & Enlargement of the canal
Calculate the appropriate length of the post
IF gutta-percha is old and has lost its thermoplasticity, use a
rotary instrument (Peeso-Reames or Gates Glidden drills)
Before enlargement of the canal, the type of post system to
be used for fabrication of the post and core must be chosen.
2.PREPARATION OF THE CORONAL
TOOTH STRUCTURE :
Remove all internal and external undercuts
prepared perpendicular to the post, to create a positive stop & to
prevent over seating and splitting of the tooth.
If insufficient tooth structure remains for this feature, an
antirotation groove should be placed in the canal
Complete the preparation by eliminating sharp angles
and establishing smooth finish lines.
Direct pattern for multi-rooted teeth :
Indirect procedure :
Pieces of orthodontic wire
Lubricate the canals
a lentulo spiral
syringe in impression material
Apply a thin coat sticky wax to the plastic post
after lubricating the stone cast,
add soft inlay wax in increments
Investing and casting
INVESTING AND CASTING
Cast post-and-core should fit somewhat loosely in the canal
Casting should be slightly undersized
Omitting the usual ring liner or
Casting at lower mold temperature
Extra-hard partial denture gold (ADA type IV) or
nickel chromium alloys
Casting defects should not interfere with
seating of the post; otherwise, root fracture
Post-and-cores should be inserted with gentle pressure
A rotary (lentulo) paste filler or cement tube
a parallel-sided post is being used, a groove should
be placed along the side of the post
Over denture abutment
Removal of existing posts :
Special hollow end-cutting tubes (or trephines)
If the fractured post is of the threaded type a groove cut in the end
of it may enable it to be unscrewed
Masseran trepan and
7. Harold Gerstein, "Technique In Clinical Endodontics" 34787.
8. Pitt Ford, "Problem-solving in Clinical Practice" 149-164.
9. Gutmann, "Problem-solving in Endodontics" 3rd Edn, 32546.
10.Stephen Cohen, "Pathways of the Pulp", 8th Edn, 765-795.
11. Franklin S. Weine, "Endodontic Therapy" 4th Edn, 653698.
12. Tylman's "Theory and Practice's of Fixed Prosthodontics",
8th Edn, 407-417.
13. Herbert T. Shillingburg, "Restoration of the Endodontically
Treated Tooth" 1982Edn. .
14. Herbert Shillingburg, "Fundamental of Fixed
Prosthodontics" 3rd Edn, 194-209.
15. Herbert Shillingburg, "Fundamental of Tooth Preparation"
2nd Edn, 321-358.
16. Rosensteil, "Contemporary Fixed Prosthodontics" 3rd
17. Endod Dent Traumatel1998; 14: 59-63.