Restoration of endodontically treated teeth م2 Restoration of endodontically treated teeth Composite / amalgam restoration Crown – metal / ceramic

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 Retention form Resistance form

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 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 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

Steps in tooth preparation Removal of RC filling material Enlargement of the canal Preparation of coronal tooth structure

Custom cast post system Direct technique Indirect technique

Direct technique Remove any weak, thin, and/or unsupported tooth structure.

Using progressively larger diameter Pesso reamers remove the gutta percha to the predetermined initial depth Repeat this process as necessary leaving 4-5 mm of gutta percha as an apical seal.

Add a keyway to resist rotation of the post/core Add a keyway to resist rotation of the post/core. Place the keyway in the bulkiest part of the remaining tooth structure.

Try-in the preformed plastic post and be sure it goes all the way down the prepared canal without binding (a totally passive fit). Trim it as necessary. Measure the post relative to the depth of the canal with a periodontal probe

Lubricate the canal with Duralay lubricant Using the "bead brush" technique, fill the canal completely with Duralay resin. Use the bristles of a brush (bent at a 45 degree angle for easier access) to force acrylic down the canal and express any trapped air

Immediately, dip the plastic post in acrylic liquid (to soften post and enhance bond of acrylic) and seat it in the canal to its full depth. Move the post up and down in the canal 1-2 mm (only after the Duralay is nearly set) to avoid getting it "locked in."

Using hemostats, carefully remove the post pattern and inspect it to be sure it is fully formed (with no voids).

Cut off the top of the plastic post so that your patient can close completely

Using a large diameter coarse diamond (high speed handpiece at "near stall" speed with water spray), shape the pattern to ideal preparation form (on the tooth).

Using hemostats (held mesiodistally), remove the pattern from the tooth. The pattern should not be removed (except one time to check that the post portion is fully formed) until it is completed. There is the risk of breakage each additional time the pattern is removed.

Indirect technique of making custom post and core

The completed post is cemented