Precious PFM Dental Crown Palladium Silver Dental Post and Core

A post and core is a dental restoration used to sufficiently build-up tooth structure for future restoration i.e crown when there is not enough tooth structure to properly retain the crown.

Post is placed within the body of the root of a tooth that has already treated with root canal treatment. The core is the part of the restoration that shows out in the mouth that help anchor a cap or crown.

Principles of tooth preparation

• Conservation of tooth structure

canal preparation-enlargement of canal should exceed about 1-2 additional file sizes beyond the largest size used.

Coronal part preparation removal of undercuts and ferrule (extension of axial wall of the crown apical to the missing tooth structure) 

• Retention form

Post diameter

Surface texture

Luting agent

Post length

Greater post length=greater retention 2/3 length of root / post length should equal crown length

Maintain 3 – 5mm apical seal

• Post diameter

Shouldn't exceed 1/3 diameter of the root

A minimum of 1 mm of sound dentin should be maintained circumferentially

SURFACE TEXTURE

Serrated or roughened post is greater retentive than smooth post

LUTING AGENT Znpo4,Resin and GIC are greater to other cements 

Resistance form

Post design influences the stress distribution and in turn resistance

post length

parallel posts

threaded posts produce stress conc.

cement layer results in better stress distribution

sharp angles

rotational resistance 

Post and core systems

Custom post and core – mainly used in flared canals,elliptical crossection canals ,multiple canal teeth 

Prefabricated – circular crossection canals