Dowel core restorations

Dr. Barbara KispélyiAssociate professorDepartment of prosthodontics

Types of the fixed prostetic

appliances

Extracoronal

• Single tooth restoration

• Full coverage crown

• Partial coverage crown

• Venners

• Bridge

• Splint

• Maryland bridge

• Inlay bridge

• CBW bridge

Intracoronal

• Inlay

• Onlay

Intraradicular

• Post and core

• Post

Intraradicular restoration:

Definition:Dowel:

a post, usually made of metal or

fiber reinforced composite material

that is fitted into a prepared root

canal of a tooth that has had

endodontic therapy

Core:

the coronal aspect of the post

foundation

Post and core

Historical background

Various methods of restoring pulpless teeth have been

reported for more than 200 years.

In 1747, Pierre Fauchard described the process by

which roots of maxillary anterior teeth were used for the

restoration of single teeth and the replacement of

multiple teeth

Materials: gold

silver

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Insufficient sound coronal tooth structure due to:

‧Caries

‧Endodontic treatment

‧Previous restorations

Consequences of insufficient coronal tooth structure

‧Retention of subsequent restorations are problematic

‧Increases likelihood of fracture during functional loading

Intraradicular restoration: post

and core:

Indications:

• to retain restoration

• to protect remaining tooth structure

Contraindication:

• malformed tooth

• severe curvatured root

• need for further retreatment

Intraradicular restoration: post

and core:

Conditions:

• Complete root canal filling

• No periapical lesions

• Minimal length of the root is 8-10 mm

• Post is at least as long

as the crown

Disadvantages

• risk of rootfracture

• risk of perforation

• Impossible endodontic retreatment

• higher costs

-

Mean values 8years = 9% clinical failure

Loss of retention & tooth fracture are the most

common causes of post & core failures.

Post and core - Failure:

Turner found – 100 failure

• Loosening (59 )

• Apical Abscess (42 )

• Dental Caries (19 )

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Preparation - post and core

• Conservation of tooth structure

• Retention form

• Resistance form

Conservation of tooth structure

Canal preparation - 1-2 additional file sizes beyond the largest size used

Coronal part preparation-

-removal of undercuts

-ferrule (extension of axial wall of the crown apical to the missing tooth structure)

Ferrule

Jonhson: Color atlas of endodontics

Principles of preparation

Retention form

• Post length

• Post diameter

• Surface texture

• Luting agent

Post length:

• Greater post length=greater retention

• 2/3 length of root / post length should equal crown length

• make the post approximately three-quarters the length of the root when treating long-rooted teeth;

� when average root length is encountered, then post

length is dictated by retaining 3-5 mm of apical gutta-percha

and extending the post to the gutta-percha

� whenever possible, posts should extend at least 4 mm apical to the bone crest to decrease dentin stress.

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Post diameter

Post diameter is to not exceed one-third the

root diameter

A minimum of 1 mm of sound dentin should be

maintained circumferentially

Each millimeter of increase (beyond one-third

the root diameter) causes a sixfold increase in

the potential for root fracture.

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Classification I.-Technique :.:

ChairsideCustom made in the lab:

Classification II.- Custom made in

the lab:

Direct Indirect

Classification III.-Materials:.:

MetalNon-metal Fiber, zirconium

Classification IV.- Retention:.:

1. Direct

2. Active(screw)

1. Indirect

2. Passive(cementation)

Classification V.:.:

Pre-fabricated

Custom-made

Types of post and core

restorations

Metal prefabricatedposts

-Risk of rootfracture high

- Less retention

- Not esthetic

Temporary

Indirect

Direct

Definitive

Indirect dowel core restorations:

Metal casted:

• Individual

• Not esthetic

• Allergy

• Removal of undercutted

tooth structure

• High modulus of elasticity

Zirconium-dioxid:

• Individuális

• Esthetic

• Upper canine or first

incisor

• Rigid

• Removal of undercutted

tooth structure

• High modulus of elasticity

Expensive fiber reinforced posts

Types of post and core

restorations

Metal prefabricatedposts

-Risk of rootfracture high

- Less retention

- Not esthetic

Temporary

Indirect

Direct

Definitive

Direct posts - definitive

Fiber reinforced posts:

• Fiber + epoxi resin (silan)

• polietilen, silica, quartz, zirconium

• Esthetic (frontteeth)

• Easy removal

• Frequent failure

• Root fracture ↓

• Stress ↓

• Techique sensitive cementation

• Ferrule 2-3mm!

• Modulus of elasticity:

FIBER REINFORCED POSTS

Mr. Norman Hicks: Esthetic Fiber Reinforced Composite Posts

Failure

Most often falls

Post fracture

Tooth fracture

Silva et al.: Effect of relining on fiber post retention to root canal

Thank you for your attention!