Indication to the type of restoration

O.R.GaneshMurthiM.Sc.D Endo

student

The tooth as a house

Introduction

Teeth that require endodontic treatment are

often severely broken down and can be vulnerable to fracture; they often require extensive (and expensive) restoration following root canal treatment.

A high fracture rate has been found in root-filled teeth that have mesial Occlusal distal (MOD) amalgam restorations, and it is often good practice to place some form of cusp coverage restoration to prevent destructive flexure during mastication.

Fluids No Fluids

Endodontically treated teeth are usually weak

loss of tooth structure

loss of moisture in the dentin

There is good evidence from scientific studies that the quality of coronal seal affects the prognosis of root canal treatment. It takes arelatively short time for the root-filled toothto become reinfected if it is left exposed to theoral cavity.

Sealing the Access Cavity

treatment planning

Existing endodontically treated teeth need to be assessed care fully for the following:

Good apical seal No sensitivity to pressure No exudate No fistula No apical sensitivity No active inflammation

objectives of restoration endodontically treated tooth

Stated as ‘3R’s

Reinforcement

Replacement

Retention

Reinforcement

Reinforcement of the remaining tooth structure is achieved with dowel and coping

DOWEL – post extending approximately 2/3rd the length of the root canal

A - Dowel

Replacement

Replacement of missing tooth structure is achieved with the core

CORE – is the coronal

extension of the dowel

that provide optimal

retention for final

Restoration.

B - CORE

Retention

Is supplied by

1. Dowel for core

2. Core for final restoration

Considerations for anterior teeth

Anterior teeth do not always need complete coverage, except when plastic restorative materials would have limited prognosis in view of the extent of coronal destruction. Many function with composite resin restorations.

when the tooth is loaded, stresses are greatest at the facial and lingual surfaces of the root and an internal post, being only minimally stressed, does not help prevent fracture

protection of anterior teeth?

Coronal coverage does not significantly improve the success of Anterior RCT.

a.Intact marginal ridge

b.Intact cingulum (small access opening)

c.Intact incisal edge

d.1-2 small proximal lesions/restorations

Minimal coronal damage

What is the final restoration of this type of case ?

Restore access opening with a composite resin

significant coronal damage

undermined marginal ridges

loss of incisal edge

coronal fracture/esthetically unacceptable

What is the final restoration of this type of case ?

Post/core-small circular canal acceptable to use prefab post + resin(must have at least 2mm of tooth structure apical to resin core); however, cast post and core best treatment-elliptical/flared canal custom cast post/core

Full coverage crown

do all RCT teeth need “protection”?

Anteriors

Posteriors

YES !!!!!!!!!! (unless not in occlusion)

No, But may need post/core to restore tooth

Considerations for posterior teeth

Endodontically treated posterior teeth are subject to greater loading than anterior teeth are because of their position closer to the insertion of the masticatory mus cles.

Parts of prosthodontic reconstruction compared with chain links

Resin restoration in access opening

Indication Intact anterior tooth with only an access opening or very small class III restoration

ContraindicationsNumerous or large restoration in tooth resulting in extensive desturction most posterior teeth

Resin restoration in access opening

Advantages 1 appointment Cost Preserve tooth structure Esthetics

Disadvantages Potential for microleakage

Amalgam core foundation

IndicationPosterior teeth that are to receive crowns cuspal coverage can be considered for strength as an option to crown

ContraindicationTeeth in which a bulk of amalgam cannot be obtained

TYPES OF POSTS

METALLIC NON-METALLIC

Stainless Steel Titanium Titanium Alloy Gold-Plated

brass

Carbon Fibre Ceramic Glass-fibre

reinforced Composite

Custom cast post and coreAdvantages:

Preservation of maximum tooth structure

Provision of anti-rotational properties

Core retention Less chances of vertical

fractures during preparation High strength

Disadvantages: Less stiff than

wrought Time consuming,

complex procedure

Recommended Use: Elliptical canalsFlared canals

Prefabricated Tapered PostAdvantages: Conserves tooth

structure High strength and

stiffness

Disadvantages: Low retention Longitudinal splitting

of remaining root

Recommended Use:Small circular canals orVery tapered canals

Prefabricated Parallel - Sided Smooth Post

Advantages:

Excellent clinical retention

Minimal stress production within root

Ease of placement Superior rating

Disadvantages: Precious material

post expensive Corrosion of

stainless-steel Less conservative of

tooth structure

Prefabricated Threaded Posts

Advantages:

High retention

Disadvantages: Stresses generated in canal may lead to fracture

Does not conserve coronal and radicular tooth structure

Recommended Use:Only when maximum retention is essential

Fiber Reinforced Post

Advantages: Esthetic

Disadvantages: Low strength High failure rate

Recommended Use:Should not be used where remaining tooth structure is less than ideal or where high occlusal forces are present.

Zirconia Ceramic Post

Advantages: Esthetics High stiffness High modulus of

elasticity

Disadvantages: Expensive Uncertain clinical

performances

Recommended Use:High esthetic demands

Cast metal post and core

IndicationTeeth in which minimal tooth structure remains a tooth that is to be used as an abutment for fixed partial denture.

ContraindicationsTeeth requiring some types of very translucent all ceramic crowns

Cast metal post and core

AdvantagesStrength post and core one unit

Relative easy to incorporate anti rotation feature

DisadvantagesNumerous appointments

Cost

More tooth removal

Ceramic post and core

IndicationTeeth requiring some type of very translucent all ceramic crowns

ContraindicationTeeth for which a metal ceramic crown is planned

Ceramic post and core

AdvantagesEsthetics

DisadvantagesNumerous appointment

Cost

Long term data are limited

Ceramic materials may have a tendency to fracture

Crown placement

IndicationEnhancement of esthetic outcome situation in which existing restoration combined with the endodontic access under mine the structure if crown

ContraindicationAnterior teeth that have only a conservative endodontic access opening

Crown placement

AdvantagesProtection of reaming tooth structure by encirclement

DisadvantagesRemoval of more tooth structure

cost

Crown placement

IndicationEnhancement of esthetics out come situation in which existing restorations combined with the endodontic access undermine the structure integrity of the natural crown

ContraindicationsAnterior teeth that have only a conservative endodontic access opening

metal-ceramic crowns

Metal-ceramic crowns are very strong and resist occlusal loads well. Minimal preparation (0.5 mm) is required on the palatal and approximal surfaces. This may be beneficial in a root-filled tooth with little remaining coronal tooth substance

metal-composite crowns

Metal-composite crowns are often used as

long-term provisional restorations. The composite discolours with time

metal-free crowns -porcelain jacket crown

Porcelain jacket crowns require a buccal tooth

reduction of between 0.8 and 1.3 mm, and can

therefore be more conservative on tooth substance than a metal-ceramic crown. Stained

dentine and metal posts affect the aesthetic

appearance of a porcelain jacket crown. Excessive occlusal loading may be a problem and can result in unpredictable fracture.

Mesio-occlusal cavities

Plastic Restorative TechniquesThe best method of restoring a root-treated

tooth with an existing proximal box depends

on the size and depth of the box and on the

occlusal stresses that are applied during mastication. In a case with a shallow box and no evidence of occlusal loading, an amalgam

restoration could be used

conservative cuspal coveragerestorations

A bevelled margin of I mm depth is prepared

around the circumference of the tooth.

Base metal alloys can be bonded to the etched

occlusal surface of the tooth using a silane

bonding system. Extra retention will be provided

by the internal contours of the access

cavity, the majority of which is packed with

IRM.

Plastic restoration

The cusps are reduced in height and the entire

occlusal surface is rebuilt in amalgam. The technique is technically demanding since the correct occlusal contacts are difficult to achieve, and the material must be thick enough to withstand occlusal forces (2-3 mm). Direct light cured composite materials are not really suitable for use in this situation, and indirect composite or porcelain restorations

Cast restorations

If a metal-ceramic crown is required, significantly more tooth substance will need to

be removed (at least 1-1.5 mm). The clinician

needs to be sure that sufficient tooth substance

will remain after preparation for retention of the restoration to avoid an unnecessarily weakened tooth.

Core Materials - Amalgam

It is strong and easy to use. Added retention can be gained by packing the amalgam into irregularities and undercuts in the pulp chamber and by using grooves, slots and pits in the cavity walls. Self-tapping dentine pins are rarely needed, and they may impart

unwanted stresses within the dentine.

The Nayyar core

The Nayyar core is a useful means of restoring

a molar tooth after root treatment when there is sufficient remaining tooth substance to support the core. Amalgam is packed into the root canals to a depth of approximately 3 mm and into the pulp chamber to give mechanical retention. An adhesive can be used to give extra retention

Composite

Composite cores have the advantage that they can be built up and prepared at the same visit. Chemically activated materials such as Ti Core, have been shown to perform well.

There is some concern in the literature

that there may be risk of microleakage

between the composite core and dentine

Cermets

Although cermets have been recommended as core materials they are not as durable as amalgam or composite. Cermets are easy to use and bond to tooth substance. They should not be used when strength is required, but they could be used as a space filler to reduce the amount of alloy required in a cast restoration

Crowns for Posterior Teeth

Cast Metal CrownsHigh noble metal alloys are considered to be

best since they have the greatest resistance to

corrosion and tarnishing and are easy to work

with. Metal crowns are excellent in situations

where the patient is not concerned with

the appearance of metal. Significantly less

reduction in the tooth is required

Partial Cast Metal Crowns

Partial cast metal crowns may be used when

the buccal surface of the tooth is intact. They

are more conservative of tooth tissue than

complete crowns, but they are more demanding

technically both for clinician and in the

laboratory

Full Cast Metal Crowns

The preparation for a full cast metal crown

is more conservative than for a metal ceramic

crown (0.5-1.0 mm compared with

1.0-2.0 mm).

Metal-Ceramic Crowns

Metal-ceramic crowns are generally used

when a patient requires a more aesthetic

restoration. Porcelain can be used on the visible surfaces, such as the buccal and occlusal surfaces of mandibular teeth. If the clinical crown height is small, then retention grooves are cut in the core to provide added retention

Ceramic Crowns

Occasionally it is reasonable to use a castable or high-strength ceramic crown on a posterior tooth, if occlusal factors are not inhibitive. The amount of tooth reduction is more than with a metal-ceramic crown (occlusal reduction of 2 mm) and may compromise retention, especially in teeth with a short crown height

Temporary crowns

For anterior Polycarbonate and acrylic temporary crown forms Custom-cast temporaries.

For posterior teethMetal shell crown forms

• Custom-cast temporaries

• Long-term temporaries, metal-acrylic and

metal-composite crowns

Full metal veneer crown

Advantages

1. Strong, rigid and wear resistant

2. High resistance & retention

3. Fairly conservative prep

4. Uncomplicated preparation & margins

5. High degree of occlusal accuracy in casting

Disadvantages

Esthetics– Some patients dislike and will strongly

object to the full metal cover– May be limited to upper and lower

molars and lower premolarsGalvanic action

– With other opposing metals (rare)

Advantages of composite fiber post

Can bonded to the tooth with resin cement Modulus of elasticity similar to dentin Ease of removal for retreatment Excellent esthetics Non corrosive

The Role of Posts in the Restorationof Endodontically Treated Teeth

The primary purpose for a post is to retain a core that can be used to support the final restoration.

Posts do not reinforce endodontically treated teeth, and a post is not necessary when substantial tooth structure is present after a tooth has been prepared.

INDICATIONS

Post placement is indicated if both of the following clinical conditions exist: The remaining coronal tooth structure is

inadequate for the retention of a restoration.

When there is sufficient root length to accommodate the post while maintaining an adequate apical seal.

Ideal tooth preparation for post placement

Ferrule Effect

The ferrule is the circumferential ring of sound tooth structure that is enveloped by the cervical portion of the crown restoration. A minimum sound dentine height of 1.5-2 mm is required between the core and crown margins.

ANY QUESTION ?

Thank you all