OBJECTIVES OF RESTORATION ENDODONTICALLY TREATED TOOTH Stated as

OBJECTIVES OF RESTORATION ENDODONTICALLY TREATED TOOTH

Stated as ‘ 3 R’s n n n Reinforcement Replacement Retention

Reinforcement l l Reinforcement of the remaining tooth structure is achieved with dowel and coping DOWEL – post extending approximately 2/3 rd the length of the root canal A - Dowel

l COPING –is a band of metal approximately 1 -2 mm in width surrounding the coronal portion of the dowel to obtain a ‘ferrule’ effect & protect the tooth from fracture Coping

REPLACEMENT Replacement of missing tooth structure is achieved with the core n CORE – is the coronal extension of the dowel that provide optimal retention for final Restoration. n B - CORE

RETENTION Is supplied by 1. Dowel for core 2. Core for final restoration n

n Retention of a dowel (post) is affected by the Ø Ø Ø Preparation geometry The post length Diameter Surface texture Luting agent.

Preparation geometry l parallel-sided posts are more retentive than tapered posts l threaded posts are the most retentive of all, because retention is proportional to the total surface area.

Post length l post length increases retention increases l A post that is too short will fail, whereas if the post is too long may damage the seal of the root canal filling and there is risk of root perforation if the apical third is curved or tapered.

Post diameter l Increasing the post diameter in an attempt to increase retention l but is not recommended because it may unnecessarily weaken the remaining root

Post surface texture l. A serrated or roughened post is more retentive than a smooth one, and controlled grooving of the post and root canal considerably increases the retention of a tapered post.

Luting agent. l The choice of luting agent seems to have little effect on post retention l Zinc phosphate and glass ionomer have similar retentive properties, polycarboxylate and composite resin slightly less.

REQUIREMENT OF CORE & DOWEL

1. Length of the post should be equal or longer than the estimated clinical crown 2. The post must have an occlusal stop to prevent displacement apically 3. They should be resistance to rotational force 4. Post Should be of sufficient thickness resist displacement and assist restoration & stabilization 5. A minimum of 4 mm root canal filling should be there to provide adequate seal

Features Of Successful Design

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