POST AND CORE

RESTORATION OF ENDODONTICALLY TREATED TOOTH

1. POST

2. PIN

3. CORE

4. FINAL PROTECTING RESTORATION

WHY SHOULD A POST BE USED?

1. To retain restoration

2. To protect remaining tooth structure

- force distribution

rigidity for core

Weakened RC treated tooth, why?

a. caries

b. prior restoration

c. access preparation

d. canal instrumentation

e. dehydration

WHEN SHOULD A POST NOT BE USED?

1. When retention of core is not necessary.

2. When protection of the remaining structure is not necessary

Anterior teeth with sound structure ; need only resin or amalgam filling

WHEN SHOULD A POST CAN NOT BE USED?

1. Traumatically injured tooth

2. Malformed tooth

3. Severe curvatured root

4. Need for further retreatment

WHICH ROOT BE CHOSEN FOR POST INSTALLATION

IN MULTIROOT TEETH?

1. Longest, straighted, greatest circumferential diameter

2. Which root reduce the possibility of lateral or apical perforation?

Which root better distributes the stress due to occlusal loading?

---- Distal root of mandibular molar, Palatal root of maxillary molar

3. In situation of mesial (Mn.), Buccal (Mx.) --- use short post

4. Area of the root where the greastest amount of coronal tooth structure has been lost

---- adding a pin is better

WHAT TYPES OF POST EXISTS ?

A. 1. custom post

2. prefabricated post

B. 1. screw post

2. cemented post

PREFABRICATED POST SYSTEM

A. Threaded metal posts

II

1. Obturation screws (F.KG.)

2. Dentatus screw posts

3. Radix-Anchors

4. Kurer posts

B. Unthreaded metal posts

1. Endo-posts

2. Charton crown post kits

C. Pastic patterns

1. Endowels

2. Norm Plastic-Pins

3. Standard Plastic-Pins

D. Combination kits

1. C-I kits

2. PD posts

3. Colorama

4. Para-post (Whaledent)

WHAT SHOULD POST SPACE BE PREPARED?

At RC filling appointment

; use hot instrument - no deterious effect to apical seal

do not use rotary instrument -- loss of apical seal

HOW IS POST SPACE PREPARED?

A. Hot instrument

B. Gate Glidden Drills and Peeso Reamer

III

WHAT SHOULD DETERMINE THE DEMENSION OF THE POST CHANNEL?

A. Post Depth

2/3 of root length

equal or exceed the length of clinical crown

leave 3-4 mm of GP in the apical

B. Post width

depends on root width and morphology

no greater than 1/3 of the root width in its narrowest dimension

WHAT ARE IMPORTANT CONSIDERATION DURING POST CEMENTATION

1. tapered post is selfs-venting

2. parallel post should be vented

if not, hydraulic pressure root fracture or incomplete seating

3. remove the excess cement of post-tooth junction

PREPARATION FOR POST CHANNEL

Instruments

a. Gates Glidden Drill

for guid along the GP filling - non-cutting tip

shorter cutting flutes (1.5-4.0mm)

easy to bend - use only into 2-3 mm

size 1 to 6 ( diameter 0.5 - 1.5mm, 0.2mm greater)

length -- 18mm

b. Peeso Reamer

cut dentin latelly well, but do not cut dentin apically

IV

( long cutting flutes - 7.5-8.5mm )

should be used in sequential order

should always be rotating before it comes in contact

remove from the canal while it is rotating

size 1 to 6 ( diameter 0.7 - 1.7mm, 0.2mm greater )

c. Drill from the Selected Post Kits

after using Gates Glidden and Peeso Reamer

*** CAST POST ***

DESIGN OF CAST POST PREPARATION

1. Proper Length of Post Channel

- parallel side wall

- round end surface

2. Flat Vertical Planes for Occlusal Stop

3. External Bevel

- to provide finishing line

- to avoid wedging force ( ferrule effect )

4. Key Hole or Clover Form for Anti-rotation ; 1-2 holes

5. Internal Bevel for Counter-sink

MARGIN OF POST PORTION

1) final margin on post

- deep margin

- advantage; impression for final restoration is easier

2) final margin on tooth structure

V

- cover the post with metel framework of final restoration

ONE PIECE VS TWO PIECE CROWN

1) ONE PIECE

advantage; simple, cheaper

retention, strength - good

indications ; short crown

close lingual clearance - very small space between U/L teeth

2) TWO PIECE

advantage; path of insertion problem in multiple abutments

casting accuracy in post portion

- easy check of fitness of margin

- can eliminate interference easily , more complete cementation

- make triangular venting groove with inverted cone bur to prepare rework

PREPARATION

1. proper instrumentation

- retraction motion

2. orientation to the long axis of the root

- step back endodontic canal preparation

3. adequate length of the preparation

4. proper internal shaping of the canal

- slightly enlarging and modifying the existing anatomy

- preparation of the orifice for antirotation, retention

5. proper outer surface shaping

VI

IMPERSSION

A. INDIRECT TECHNIQUE

lubricate the post canal

prepare internal core for impression material

- wire, wood, plastic, file etc.

- cut to proper length

- make retentive form for impression material

injection into channel with regular type Rubber Base impression material

insert the prepared core material

over impression with regular type Rubber Base impression material

careful removal of impression

B. DIRECT TECHNIQUE

lubricate the channel

use thick file as core and handle

material - Durallay Resin

Sticky Wax

Inlay wax, Sprue wax

direct impression for post portion with up and down motion

carving core portion intra-orally

file handle cut off when make casting

indication - undercuts in post preparation

for fast, accurate casting

for DDS designed retentive core

*** AMALGAM POST ***

VII

: When remaining sound tooth material is good, well supported

: main canal preparation -- 4mm

small canal preparation -- 2mm depth

and then only amalgam packing into post channel & core portion

POSTERIOR TWO PIECE CAST POST SYSTEM

: MAKE POST INTO TWO PIECE DUE TO NON-PARALLEL ROOTS

Make one piece of main post and post and core with hole for second small post

CORES

Material 1. metal -- casted, amalgam 2. resin -- Core Max

3. Glass Ionomer + amalgam powder -- Miracle Mix

4. Glass Ionomer Silver -- KETAC SILVER

1. - good 2.- favorable in proper case 3.4.- no good

MARGIN AND CORE MATERIALS

METAL -- METAL MARGIN OR RETORATION MARGIN

any case is OK

RESIN AND GI --cover at least 2mm with final restoration

MATRIX FOR CORE

Compound Supported Tofflemire Band

Automatrix (retainerless)

Copper Band Matrix

Prefabricated Acrylic Resin Crown

VIII

PULPLESS TOOTH AS A ABUTMENT

Failure Rate of 1273 RC treated teeth ( in University of Califonia )

general ; crown (5.2%) < no crown (24.2%)

in crown ; no post (3.3%) < post (8.2%)

in no crown ; post (12.5%) < no post (24.6%)

as prosthetic type

Crown(5.2%) < FPD (10.2%) < RPD (22.6%)

as post type

Tapered cast dowel & core ( 12-16%)

Cast Para-Post, Para-post & amalgam or composite resin (0%)

GUIDELINES FOR POST IN ABUTMENT TOOTH

1. Single Crown ( less force )

- no dowel post

just amalgam coronal-radicular core is good

2. Bridge

-- stress increase as span increase

-- for anterior short bridge

; post or no-post , any case is OK

-- long span, posterior bridge ; need dowel post

3. RPD

-- high stress, high torque, especially in distal abutment

-- should prepare the dowel post

IX

Ready made (prefabricated)Custom made

4. Pulpless posterior tooth

-- protection by crown necessaryily

5. Post type

tapered -- no good

screw type -- no good due to high internal stress, high risk of root Fx.

parallel, rounded end, small diameter -- good

anti-rotation -- lock form, pin

use of prefabricated screw type post

-- select proper length and size and adjust, cementation

Casted Post & Core Restoration

Retention types of casted restoration:

1. Intra coronal retention 2. Extra coronal retention 3. Intraradicular retention

N.B:

The mean of retention in post & core is (Intraradicular retention)..Sometimes 2 types of retention present in the same restoration..As a general role, post & core is performed in endodontically treated tooth..

Posts Classification:

According to the materials:

X

Metal Stainless steelTitanium

Non-Metal Fibrous coreCeramicCarbon fiber

Cast MetalNoble

Base metal alloyAmalgam

Non MetalCompositePorcelain

Glass ionomer

According to the outer surface: Serrated Smooth Screw

According to the shape: Parallel sideded Tapered (root formed)

Core

Case selection:

Weighing the indications Vs contraindications..Weighing the benefits Vs risks..

Indication:

1. Endodontically treated tooth..2. Obturated with G.P3. Successfully clinically & radiographically..

Clinically Radiographically1. Not sensitive to percussion (pressure)..2. No mobility..3. No apical sensitivity..4. Amount of remaining tooth structure..5. No sinuses with or without drainage..

1. No root fracture..2. (Apical seal) Obturated well, no under or over

filling..3. No widening in PDL..4. Intact Lamina dura..5. No fracture, cracks, thinning of root dentin..6. Root with adequate length to satisfy crown

XI

/root ratio, which is minimally 1:1 & ideally 1:2

7. Straight root, not dilacerated..8. No oblique or vertical fracture..9. No Periapical Lesion

Contraindication:

Opposite..

N.B: Vertical & oblique fracture while horizontal fracture can be corrected.

Requirements:

1. G.P Filled root canal treated teeth..2. Leaving 3 mm of G.P from the apical seal , the average is 4 mm , the range is from 3-

5mm.N.B: If we leave less than 3mm of G.P break seal entrance of bacteria

N.B:

Retention of the post from fitness of the post in the inside wall of the root canal.. In casted post & core One metal used.. Post/core ratio:

Minimally 1/1Ideally 2/1

< 50% of remaining sound tooth structure Use Casted post and core > 50% of remaining sound tooth structure Use prefabricated post & core e.x use

parapost.. The usage of post is providing retention to the core portion, not resistance.. The weakest point is between the post & core esp. if they are of different materials.. Radiographically, the alveolar crest separate between the crown & the root, soothe

crown from the tip of the cusp to crest of bone & the root is from the root apex to the alveolar crest..

If we treat upper central incisor tooth endodontically & we need post & core , we use (casted post & core) WHY???? (due to the Direction of force on the coronal portion)

If the root canal is ∆ in cross section use casted post & core why?? (more conservative).

To prevent rotation of the post in the circular root canal prepare (Keyway) anti rotation & resistance..

The ready made post is circular in cross section while the custom made can be triangular, ribbon or oval..

Advantages of casted post & core over prefabricated posts:

1. More adaptable

XII

2. Confided to different shapes & sizes

3. More conservative

4. Stronger @ the point between post & core

Disadvantages:

1. Needs more visits

Preparation of the post & core:

2 ways of dura lay pattern fabrication but both have the same preparation:

Direct ( in the patient mouth) Indirect (in the lab)

- Prepare the remaining tooth structure as a normal preparation.- Remove all the weak areas by diamond minimally leave 1mm thickness of dentin to

perform (Root Stump).. if less fracture - Initially remove G.P by hot plugger , put rubber stopper @ least than 5mm of G.P from

the apex, insert the plugger & remove it while it’s hot- The rest of G.P removed by:

1. Parapost drill the shank is color coded according to diameter, the post should be less than drill by 1mm for placement & cementation.. (N.B: be careful from perforation)

2. G.G has a safe cutting edge so we can apply pressure..3. Pesso reamer longer working area than the G.G

- It should be done by:A) Clock wiseB) Pumping action in entrance & exist to prevent dragging (locking) inside

the root..C) Without water coalent

- To solve dragging remove it by hard instrument in anticlockwise direction..Factors affecting cast post retention (IMPORTANT):

Length of the postDiameter of the post Shape of the post hole Type of cements

- Long post & core:1. retention2. Stress distribution 3. less liability to root fracture 4. adaptability

- Then prepare (Contrabevel) bevel the outer surface of the crown WHY????

XIII

To provide (Ferrule design or ferrule effect): The complete embracing or encircling of the metal collar around the tooth surface to increase its resistance to fracture by tighten tooth together..

N.B: The ferrule effect comes from :

In the final restoration Contrabevel around the root stump

- Then prepare the antirotational groove inside the root canal , in the bulkest area or areas to perform keyway

By fissure bur # 170 Diameter 1mm Length 4 mm More common in the palatal region , we can do more than one groove if we need

Direct technique:

No isolation (partial isolation with cotton rolls & saliva ejector). Saliva act as a separating & lubricating agent prevent adhesion , so don’t dry the

tooth well. Plastic sprue trim them till they fit. Orientation notch indicator of the facial surface Seration of the plastic spre to provide retention to the dura lay 2 dapping dishes Brush the duralay on the plastic sprue & return it back inside the root (N.B: Brush the

monomer on the sprue 1st then the polymer runny or watery consistency.. Pumping in & out to avoid interloacking & setting of the dura lay in the undercut of

the root. Prepare the core with dura lay Spruing Investement Burnout Casting Finishing but no polishing Try-in (passively) with no pressure Cementation with low viscosity cement

Step by step Direct Post & Core Technique:

The tooth is prepared prior to the pattern fabrication.  A heated endodontic condensor is used to safely remove the gutta percha (this is best accomplished at the same time the endodontic therapy is rendered).   Gates & Parapost drills are used to shape the canals to an appropriate size and depth.  The most common sizes used are Brown Yellow and Red..

XIV

The minimum length of the post is equal to the length of the clinical crown.  The recommended length is two-thirds the length of the root in bone while maintaining 5 mm of gutta-percha at the apex.   Remember chances of a perforation increase as the length of the post approaches the apex of the tooth.

The prefabricated posts are inserted into the canals.  In this case a precious metal post is being used in the lingual canal because the canal diameter is only equivalent to a brown sized Parapost (Gates #3 - see table).  The precious metal posts are issued from the Dispensing Window, and require an additional fee. 

Gates Drills Parapost Drills

#3 Brown

#4 Yellow

#5 Red

#6 Black

XV

(Pesso Reamers are not recommended in the preparation of teeth for post & cores).

An assistant holds the Duralay powder, liquid, and suction - while the core portion is made in resin.  First lubricate the remaining tooth structure with a water soluble lubricant (Surgilube) then apply the resin.   The assistant may move the suction near the resin, evaporating monomer from its surface, thus preventing the resin from slumping or running.

The completed resin core is allowed to polymerize - then it is prepared to the shape of an ideal crown preparation

Using conventional diamond instruments, water and suction, the resin core is prepared in the same manner as a conventional preparation

The preparation is completed to ideal form and in this case its path of insertion is aligned with the preparation of tooth #11.

XVI

The completed post & core pattern is submitted to the Service Laboratory for investing & casting in gold alloy.

The casting is cleaned and sandblasted with alumina oxide in preparation for try-in, shaping, and cementation.  The canals are dried and the casting inserted using light pressure.  Small shiny marks on the casting surface help indicate where adjustment should be made.

Once seated, the surface is "machined" or prepared with diamond instruments to finalize preparation margins and blend the post & core with the tooth surface.  It is advisable an assistant hold the post with an instrument to prevent it dislodging during preparation - high speed suction may also be held near the area to evacuate debris.

The completed post is cemented using a Jiffy tube to inject cement into the canals which have been dried with Endodontic paper points

XVII

Indirect technique:

Use the rubber base (polyether) very stiff material with precaution: Close all the tooth undercuts Close the undersurface of the pontic

Wire L-shape Try adhesive on the wire to hold the rubber base to the wire.. Impression for the post put the impression 1st in the coronal by lentulo spiral then

insert the wire. Vasline layer as separating media because there is not slaiva.. Prepare Escape way groove for cement material using rose head bur carbide..

N.B: when use long post, well filled, low viscosity cement with no escape way

1. Fracture of the root by hydraulic pressure

2. Unfitting (incomplete seating)

We can use pin for extra mean of retention In multirooted tooth : one root for main retention & the other as an antirotation

2 cast post lock technique if the canals are diverged from each other

Temporary restoration;

Cotton fibers to ensure no cement in the apex Post Acrylic Polyarbonate crown form

1. Cue the wire clip in the form of L-shape2. Make scratches3. Put very little cotton fibers in the bottom part of the post hole.4. Start relining the wire with white acryle (temporary) 5. Select a sutable size & shape of poly carbonate crown (trim cervically)6. Fill it completely with white self cure acryle 7. Insert it onto the ire clip post.

XVIII

8. Wait until harden remove finish polish occlusal adjustment temporary cementation

Para post precaution:

Level of the head away from occlusal by 4mm so when we put the core material 4mm than occlusal reduction 2 mm reduction & 2 mm rest

If we wanna remove from parapost, so from the apical region The head should be flat & round for retention , so if we remove from the head

sharp stress conc. & no retention.. If the level of the head above the cusp

Rocking dislocation Cracks on the surface fracture

Strawberry

1440 JADA, Vol. 137 http://jada.ada.org October 2006

P E R S P E C T I V E S OBSERVATIONS

N

ot many years ago,

when a tooth had

questionable strength

characteristics and

was not vital, the

standard of care was endodontic

therapy, usually followed by

placement of a post and core and

a crown. Extraction of the questionable tooth was considered the

XIX

last resort, unless the patient did

not have the financial resources

to pay for the endodontic and

restorative therapy. When

extraction was necessary, a fixed

prosthesis replacing the missing

tooth and connecting to the adjacent teeth was considered the

treatment of choice.

Times certainly have

changed. Now, when a tooth has

questionable strength and is not

vital, the dentist and patient

must make a choice among three

options: extraction and no

replacement; endodontic therapy

and the necessary restorative

dentistry; or extraction of the

tooth, placement of an implant

and the required restorative

therapy.

I write this column from my

perspective as an experienced

prosthodontist who has accomplished many surgical implant

placements and conventional

endodontic therapeutic procedures. This column expresses

my own opinions and observations on the question of whether

a questionable tooth should be

XX

extracted and replaced with an

implant and implant-supported

crown, or whether conventional

endodontic and restorative

therapy should be accomplished.

I will consider many factors relative to this question, then present my own observations and

conclusions.

CHOOSING BETWEEN

IMPLANT AND ENDODONTIC

THERAPY: WHAT TO

CONSIDER

Informed consent. With

patients considering endodontic

therapy or implant placement,

the dentist should perform a

complete informed-consent protocol,

1-5

which includes a discussion of alternatives for care, the

advantages and disadvantages

of each, the risks involved in

each, the costs of each and what

will happen if nothing is done.

The factors discussed in the

remainder of this column should

be included in the informed consent discussion. The patient’s

input regarding the decision is

important, since the cost of the

XXI

therapy and the potential eventual outcome of the treatment

can vary significantly.

Cost. The cost of each of

Implant therapy versus endodontic

therapy

Gordon J. Christensen, DDS, MSD, PhD

Copyright ©2006 American Dental Association. All rights reserved.JADA, Vol. 137 http://jada.ada.org October 2006 1441

P E R S P E C T I V E S O B S E R V A T I O N S

the therapies varies

widely. The table shows

mean fees (as recently

reported in the American

Dental Association 2005

Survey of Dental Fees

6

(

charged by U.S. general

dentists for the replacement of a single tooth

using each of the treatment choices, using codes

from CDT-2005.

7

Using mean U.S. fees

as a guide, the implantsupported alternative can

be nearly twice as expensive as the endodontic

alternative. Although

affluent patients may not

consider the differences in

XXII

fees shown in the table to

be significant, most

patients with typical incomes

likely would consider the fee for

the endodontic alternative to be

more favorable than that for the

implant choice. People with

inadequate financial resources

likely would choose to have the

tooth extracted. Therefore, the

cost of the therapy may influence their treatment choice

inordinately.

Coronal breakdown of the

involved tooth. Evaluation of

the condition of the tooth in

question and of the potential for

success requires clinical judgment. If the chance of success of

endodontic therapy is questionable, extraction of the tooth

may be a better alternative

than leaving the tooth in the

mouth. If at least one-half of the

coronal tooth structure is

remaining and the root canal

anatomy does not present an

atypical appearance, endodontic

therapy probably is the best

choice.

XXIII

8.

A candid discussion of

the possibility for endodontic

therapy success should be held

with the patient before making

a decision.

Type of bone supporting

the questionable tooth. Usually, the best chance for implant

success is in the mandible or the

premolar and anterior portions

of the maxilla. The posterior

maxilla usually has poor bone

density and, therefore, a

reduced chance of implant success. A tooth in the posterior

maxilla with a reasonable

chance of endodontic success

should be retained, since successful placement and long-term

service of implants are less

likely in the posterior maxilla

than in other parts of the

mouth. Any area with questionable or abnormal bone density

or the presence of potentially

problematic anatomical structures should persuade practitioners to retain teeth and

choose the endodontic

alternative.

Is the tooth to support a

single crown or a fixed prosthesis? If the tooth in question

XXIV

is planned to retain a singletooth restoration, strength

requirements are lower than

those for a tooth planned to support a fixed prosthesis. For

optimum longevity expectations,

highly questionable nonvital

teeth that are planned to provide support to fixed prostheses

probably should be replaced

with implants.

Occlusion. Practitioners

know well that a significant percentage of the population experiences bruxism or clenching.

9

Teeth in these patients are

required to resist enormous

chewing forces. In such situations, teeth that have a questionable prognosis for success of

endodontic and restorative

therapy probably should be

removed. However, in bruxers

and clenchers, tooth replacement with implants and crowns

also has questionable clinical

success potential, because of the

extreme forces placed on the

teeth in such patients.

If it is elected to remove a

tooth and place an implant in a

bruxer or clencher, the dentist

should consider occlusal equiliTABLE

Mean fees charged by U.S. general practitioners* for

XXV

replacement of one tooth using each of the treatment

alternatives.

†

TREATMENT ALTERNATIVE PROCEDURE

CODE‡

* Random sample.

† Source: American Dental Association.

6

‡ Source: American Dental Association.

7

Implant Therapy

Extraction

Implant placement

Implant abutment

Porcelain-fused-to-metal (PFM) crown

TOTAL

Endodontic Therapy

Endodontic therapy, depending on

number of canals

Post and core

Crown PFM

TOTAL

D7111, D7140,

D7210, D7250

D6010

D6056, D6057

D2752

XXVI

D3310, D3320,

D3330

D2950, D2954

D2752

85-196

1,443

493-644

777

507-736

184-228

777

COST

($)

TOTAL

COST ($)

2,798-3,060

1,468-1,741

Copyright ©2006 American Dental Association. All rights reserved.1442 JADA, Vol. 137 http://jada.ada.org October 2006

P E R S P E C T I V E S O B S E R V A T I O N S

bration, followed by placement

of a postoperative occlusal

splint for nighttime wear to

reduce the expected occlusal

trauma to the implant and

restoration.

Periodontal condition. One

of my pet peeves is being asked

XXVII

to treat patients who have

received implants and who also

have periodontally treated teeth

with mobility classifications of

1+ to 2 (on the 0-to-3 scale). In

such cases, the teeth move significantly under occlusal stress,

while the implants move only

slightly during chewing. Longterm acceptability of the restorative/prosthodontic therapy is

extremely questionable.

The negative restorative considerations related to the differences between the stability of

implants and mobile periodontally treated teeth should indicate retention of questionable

nonvital teeth, if at all possible.

Teeth in such patients often do

not have to support extreme

forces. Teeth that may not be

strong enough to survive in the

mouths of clenchers or bruxers

may have adequate strength to

serve in periodontally treated

patients.

Patients’ perception of

treatment. Many patients

fear both endodontic therapy

and even the mere thought of

surgery. The dentist should

describe candidly the potential

discomfort to be expected with

XXVIII

each type of therapy to ensure

that the patient understands

what to expect during treatment.

Patients’ perception of the

psychological and physiological

trauma related to each therapy

may be one of the key factors in

their decision.

Overall health. Many factors—such as smoking, poor

systemic health and major systemic diseases—may contraindicate the placement of implants.

Similarly, some of these factors

may influence the potential success of endodontic therapy.

Patients should be advised of

these negative factors in relation to their planned therapy.

Overall health must be considered in any decision between

implants or endodontic therapy.

It has been my observation that

on the basis of overall health

characteristics, endodontic

therapy may be indicated over

implant surgery in some cases.

Time needed for treatment. Although some implant

placement situations allow

immediate loading with the restoration, many implant situations require several months for

adequate osseointegration to

occur before the restoration can

be placed.

XXIX

If the dentist anticipates a

major difference between the

two types of therapies in terms

of the time required to complete

them, patients should be

encouraged to express their

opinions related to selection of

one or the other treatment on

that basis.

The practitioner’s proficiency. Practitioners have differing degrees of expertise in

the various areas of dentistry.

Unfortunately, many patients

do not want to be referred to

other practitioners for a portion

of their treatment. In such

cases, general dentists should

advise the patient about the

expected potential for success

for each of the therapies if they

were to accomplish the treatment themselves without

referral to specialists.

If the patient feels that

because of the clinical expertise

of the practitioner, one or the

other therapy has the greatest

chance for success, that therapy

is the one to choose in that

XXX

situation.

Potential esthetic result.

Sometimes implant/restorative

therapy can be accomplished

with the expectation of

adequate or even excellent

esthetic acceptability, while

other clinical situations appear

to be difficult with regard to

esthetic acceptability using

implants and implant-supported

crowns. When the potential for

esthetic acceptability appears to

be questionable if implants and

restorative therapy are used,

retention of the affected tooth

may be a better choice.

Overall postoperative

expectations. When all of the

preceding characteristics are

considered and weighed

together, experienced practitioners can estimate the overall

potential for success of either

implant/restorative or

endodontic/restorative therapy,

and they can arrive at an educated prognosis. Consideration

of any one factor alone may lead

XXXI

to an illogical conclusion about

the best therapy.

All of the factors discussed

above must be considered to

make a valid conclusion about

whether to extract a tooth, place

an implant and restore it, or

accomplish endodontic therapy

and the required restorative

therapy.

Patients’ perception of

the psychological and

physiological trauma

related to each therapy

may be one of the key

factors in their decision.

Copyright ©2006 American Dental Association. All rights reserved.JADA, Vol. 137 http://jada.ada.org October 2006 1443

P E R S P E C T I V E S O B S E R V A T I O N S

SUMMARY

The decision to accomplish

endodontic therapy and restore

a tooth or to extract it was a relatively easy decision in the past.

However, in 2006, a complicating factor is present: the

observable success of dental

implant therapy. Many factors

discussed in this article relate to

whether a tooth should be

XXXII

retained, treated endodontically

and restored, or replaced with

an implant and an implantsupported restoration.

Dr. Christensen is the director, Practical

Clinical Courses, and co-founder and senior

consultant, CRA Foundation, 3707 N. Canyon

Road, Suite 3D, Provo, Utah 84604. Address

reprint requests to Dr. Christensen.

The views expressed are those of the author

and do not necessarily reflect the opinions or

official policies of the American Dental

Association.

1. Christensen GJ. Informing patients about

treatment alternatives. JADA

1999;130(5):730-2.

2. Pollack BR. Risk management in the

dental office. Dent Clin North Am

1985;29(3):557-80.

3. Sippy RE. Informed consent: why you

need more than a signature. Dent Assist

2006;75(2):28, 30-1.

4. Dower JS Jr, Indresano AT, Peltier B.

More about informed consent (letter). JADA

2006;137(4):438-9.

5. Graskemper JP. Informed consent: a stepping stone in risk management. Compend

Contin Educ Dent 2005;26(4):286, 288-90.

6. American Dental Association. 2005 survey

XXXIII

of dental fees. Chicago: American Dental Association; 2006:13-30.

7. American Dental Association. CDT-2005:

Current dental terminology. 5th ed. Chicago:

American Dental Association; 2004.

8. Christensen GJ. Post concepts are

changing. JADA 2004;135(9):1308-10.

9. Christensen GJ. Treating bruxism and

clenching. JADA 2000;131(2):83-5.

Copyright ©2006 American Dental Association. All rights reserved.

1308 JADA, Vol. 135, September 2004

OBSERVATIONS GORDON J. CHRISTENSEN, D.D.S., M.S.D., Ph.D.

F

ixed prosthodontic

procedures continue to

be accomplished in

significant quantities,

and it does not appear

that this trend will decline.

Many of the teeth being crowned

require endodontic therapy as a

part of the tooth preparation,

and some require endodontic

therapy after crowns or fixed

prostheses have been placed.

Post-and-core build-ups are necessary in some of these teeth.

During the last few years, there

has been a major shift away

XXXIV

from metal custom-cast posts

and cores toward prefabricated

metal posts and resin-based

composite cores, and recently

there is a clearly observable

movement toward use of fiberreinforced resin-based composite

posts used with bonded resinbased composite build-ups.

1,2

In this column, I will critique

the significant change in types

of posts available and their

evolving use in practice as

judged by current use patterns

and research.

DETERMINING WHEN AND

WHAT TYPE OF POSTS ARE

NEEDED

A few decades ago, it was considered to be necessary to place

posts and cores in every tooth

that had endodontic therapy. At

that time, posts were thought to

“reinforce” the overall strength

of endodontically treated teeth.

Subsequently, it was concluded

in many research projects that

posts are used primarily to connect the root portion of endodontically treated teeth to the buildup material placed on the

coronal portion of the teeth.

XXXV

The following suggestions are

based on numerous clinical

research projects and my own

clinical experience during many

years of practice.

Post not needed. A post

may not be needed if an endodontically treated tooth to be

crowned as an abutment, or

restored with an intracoronal

restoration, is missing no tooth

structure other than the

endodontic access hole. In such a

situation, the access hole and

the instrumented canal size

should be very small to indicate

lack of need for a post.

A few other prerequisites

should be considered before the

decision is made not to use a

post. Horizontal cracks should

not be observable in the coronal

portion of the tooth, and the

planned tooth restoration should

not be expected to be subjected

to excess occlusal stress, such as

a canine rise, heavy incisal guidance or the lateral stresses of

bruxism. If such situations are

XXXVI

present, a crown or onlay restoration and a post are recommended to increase the overall

strength of the tooth/restoration

complex and increase the potential for long-term service. If an

intracoronal restoration, such as

a resin-based composite or an

amalgam, is being used, I suggest bonding the restoration into

place to add strength to the

overall tooth/restoration complex

by connecting the facial and lingual portions of the tooth. In the

event of an extracoronal restoration, such as an onlay or crown,

the coverage of the facial and lingual cusps of the tooth provides

mechanical reinforcement of the

tooth and near-optimum

strength. Bonding agents are

used by most dentists, and this

concept still should be a

standard technique for extracoronal restorations.

Post recommended and

good prognosis expected. If a

significant portion of the coronal

tooth structure of the endodontically treated tooth is missing,

but no more than one-half of the

coronal portion is missing, I recommend a post to connect the

Post concepts are changing

Copyright ©2004 American Dental Association. All rights reserved.JADA, Vol. 135, September 2004 1309

O B S E R V A T I O N S

coronal portion of the tooth

XXXVII

build-up to the root portion.

What type of post? As I have

observed in my many continuing

education courses, very few dentists use custom-cast posts.

There are several reasons for

this lack of use. Custom-cast

posts require more removal of

tooth structure than do prefabricated posts and cores, a second

appointment to seat the post, a

difficult provisional restoration,

a significant laboratory cost and

higher clinical costs—and they

offer questionable, if any, clinical advantages over prefabricated posts and cores.

Most dentists are using prefabricated posts. A recent

research project changed my

opinions about the relative usefulness of the various types of

prefabricated posts.

3

The

common belief among dentists,

including myself, has been that

metal prefabricated posts were

stronger than the popular fiberreinforced resin-based composite

posts. The referenced study

evaluated the relative strength

characteristics of extracted,

endodontically treated teeth

XXXVIII

that received metal posts (titanium alloy or stainless steel), or

fiber-reinforced resin-based

composite posts. Strength was

measured with the resincemented posts alone in the

teeth or with the resin-cemented

posts followed by resin-based

composite build-ups. As one

might have expected, the fiber

posts alone were much weaker

than the metal posts. However,

to my great surprise, the resincemented fiber posts followed by

resin-based composite build-ups

were as strong as the metal

posts used with resin-based

composite build-ups.

The results reported in this

study are significant, because in

terms of most of the necessary

post characteristics, the fiberreinforced resin-based composite

posts are superior to metal prefabricated posts. They are toothcolored and do not impart a gray

color to the remaining tooth.

Additionally, they are easy to

place, are relatively inexpensive,

can be bonded to resin cement

and are easy to remove if the

tooth needs to be retreated

endodontically. Often, clinical

XXXIX

factors are present that make

clinicians wonder whether or not

to place a post in a tooth that is

missing as much as one-half of

its coronal structure. Some of

the factors are heavy occlusion,

such as is present in those

patients who brux or clench

their teeth; canine rise supported by the endodontically

treated tooth; incisal guidance

supported by the tooth; need for

the tooth to serve as an abutment for a fixed or removable

prosthesis; or presence of visible

horizontal cracks in the

remaining coronal tooth structure. If there is any question in

the mind of the clinician about

whether or not to place a post,

I recommend that the post be

placed.

Post recommended but

questionable prognosis

expected. When an endodontically treated tooth is missing all

of the coronal tooth structure to

the level of the gingival tissue,

in my opinion, long-term service

of the restored tooth is questionable, regardless of the type of

post or the restoration. An even

XL

worse prognosis is expected for

the tooth that has no coronal

tooth structure above the bone

level. I have treated many such

compromised teeth with custom

posts and cores, or prefabricated

posts and cores of various types,

and these restorations have

been some of the least successful

restorations I have accomplished. In my experience, restorations of severely broken-down

endodontically treated teeth fail

early. Sometimes, with a longrooted tooth broken off to the

levels described, orthodontic

extrusion is indicated to obtain

more clinical crown length.

However, in consideration of the

time involved to accomplish and

stabilize the orthodontic procedure, the relatively compromised crown-root ratio, and the

expense, a properly placed

dental implant is a better choice.

In cases in which the coronal

build-up has questionable

ability to resist rotation during

service, at least two pins placed

mesial and distal to the post are

recommended. (I prefer the pure

titanium Filpin Retention Pin

XLI

[Filhol Dental USA, Baltimore].)

When endodontically treated

teeth appear to have questionable restorative longevity potential, patients should be advised

of this.

POSTS AND THEIR USES IN

2004

The following suggestions on

prefabricated posts are my

personal recommendations

based on dentist use, worldwide

research and my own

observations:

Stainless steel. This longused type of post is strong, but

its potentially allergenic nickel

content, rigidity and potential

Bonding agents are used

by most dentists, and this

concept still should be a

standard technique for

extracoronal restorations.

Copyright ©2004 American Dental Association. All rights reserved.1310 JADA, Vol. 135, September 2004

O B S E R V A T I O N S

for gray color transfer to the surrounding structures and subsequent restoration should limit or

eliminate its use. Many companies produce stainless steel posts.

Titanium alloy or pure

titanium. When a metal post is

XLII

desired, titanium alloy (available from many manufacturers)

is my choice. These posts are

moderately radiopaque, are

relatively easy to use and do

not contain any objectionable

elements.

Zirconia. Strong, toothcolored zirconia posts are highly

radiopaque and rigid. However,

they are difficult to use, are

expensive and, unless they are

rough on the surface, do not

offer optimal retention. When a

tooth-colored post of maximum

strength is desired, these posts

should be considered, but their

extreme rigidity may contribute

to vertical tooth fracture when

stressed.

Carbon. Carbon posts have

limited use because of minimal

radiopacity and black color.

However, their ease of use and

removal and their flexibility are

favorable.

Fiber-reinforced resinbased composite. Toothcolored fiber-reinforced resinbased composite posts are easy

to use, strong when supported

with build-up material, relatively radiopaque (some brands)

XLIII

and easily removed, and they do

not impart any objectionable

color to the tooth. As I have

observed in my interactions with

practicing dentists, among the

most used brands are the

FibreKor Post (Pentron,

Wallingford, Conn.), the ParaPost (Coltène Whaledent, Cuyahoga Falls, Ohio) and Snowpost

(Danville Materials, San

Ramon, Calif.). The future for

this type of post is promising.

A SUGGESTED TECHNIQUE

FOR POST AND CORE: 2004

State-of-the-art technique can

be identified easily when one

observes practicing dentists. The

following technique is representative of the practicing profession at this time, as I have

observed it in many continuing

education courses.

dEndodontic therapy: Post

channel should be made to the

depth of about one-half the bony

supported length of the tooth

and no longer than 3 millimeters from the apex of the tooth.

dFit the selected post. Fiberreinforced resin-based composite

or titanium alloy posts are

recommended.

XLIV

dRoughen the internal surface

of the post channel with a slowly

rotating rough diamond to

create mechanical retention in

the post channel.

dPlace a bonding agent in the

canal. Among the most used

products are ED Primer II

(Kuraray America, New York)

and Linkmax Primer (GC

America, Alsip, Ill.).

dSeat the post in the canal

using a resin cement such as

Panavia F2.0 (Kuraray America)

or Linkmax (GC America),

allowing a thin layer of the

cement to cover the coronal portion of the tooth. Light cure the

portion of the dual-cure cement

accessible to the light.

dImmediately place a resinbased composite build-up.

dWait a few

minutes for the

dual-cure

cement and/or

build-up

material to set.

dPrepare the

XLV

post and core

for the subsequent

restoration.

SUMMARY

Use of post-andcore restorations has

changed

markedly in the past several

decades. Current use and

research supports techniques

using tooth-colored, fiber-reinforced resin-based composite

posts or titanium alloy posts

cemented with resin cement, followed by resin-based composite

build-ups. Although fiberreinforced resin-based composite

posts appear to be very

promising, long-term clinical

observation is needed. I have

made suggestions about when to

use posts, what type of post to

use and how to use them.

The views expressed are those of the author

and do not necessarily reflect the opinions or

official policies of the American Dental

Association.

Educational information on topics discussed

by Dr. Christensen in this article is available

through Practical Clinical Courses and can be

obtained by calling 1-800-223-6569.

XLVI

1. Christensen GJ. Building up tooth preparations for full crowns—2000. JADA 2000;131:

505-6.

2. Christensen GJ. When to use fillers, buildups, or posts and cores. JADA 1996;127:

1522-6.

3. Clinical Research Associates. Posts: a shift

away from metal? CRA Newsletter 2004;

28(5):1-3.

Dr. Christensen is

co-founder and senior

consultant of Clinical

Research Associates,

3707 N. Canyon Road,

Suite No. 3D, Provo,

Utah 84604. He has a

master’s degree in

restorative dentistry

and a doctorate in education and psychology.

He is board-certified

in prosthodontics.

Address reprint

requests to

Dr. Christensen.

Copyright ©2004 American Dental Association. All rights reserved.

XLVII