**12. Post fabrication**

#### **12.1 Pre fabricated posts**


Available materials are pt- au- pd. \ p-g-p,cr-co, s.s, ni- cr-ti and non oxidizing noble alloys.

• Studies reveal that corrosion of these base metal leads to root fracture and this is attributed to the electrolytic action of the dissimilar metals used to the post and core which causes a v olume change that split the root.

*Restoration of Endodontically Treated Teeth DOI: http://dx.doi.org/10.5772/intechopen.98190*

Prefabricated posts have high modulous of elasticity, elongated grain structure which contributes to the physical properties as compared to cast posts and also more rigid.

#### **13. Custom made posts**

These can be cast either by direct pattern or by indirect pattern. In single canals ————direct pattern is used. In multiple canals———indirect pattern is used.

#### **14. Direct pattern**

Lubricate the canal—select a dowel, it should extend full deapth of the canal. Apply resin [bead brush tech,]

Here resin can be applied in two types.

1.Applying at the orifice of the canal only

2.Resin is rolled and placed in canal

Now moisten the dowel with monomer and insert in the canal. Donot allow the resin to set fully and now loosen the dowel and reseat it. repeat this u ntill the resin sets. Remove the dowel. Trim any excess or undercuts on it … . the completed post pattern should not bind the canal.

#### **15. Indirect pattern**

Here a wire reinforcement should be done to prevent distortion and to get an accurate impression of the root canal.

An orthodontic wire cut in J shape is selected. it should be loosely fit in canal and must extend to full depth of the canal. Coat it with an adhesive. Lubricate the canal to facilitate removal of the wire.

Fill the canal with impression material using lentulo spiral. Seat the wire in the canal. Syringe more material around the wire and tooth and place the tray. Now remove the tray along with the post pattern. Evaluate it and pour the cast.

Using this cast take a plastic post or toothpick which extends full deapth, and apply sticy wax to it and seat it in the canal.like this wax pattern is fabricated. Which should completely adapt to post space.

#### **16. Core fabrication**

Replace the missing coronal tooth structure, restoring its original anatomy. It can be shaped either in resin or wax which is added to the post before the assembly is casr in metal. This prevents failure at the post-core interface.

It can be cast on to the prefabricated post system or make the core with a plastic material like amalgam or G I C or composites.

Advantages with plastic materials.


Disadvantages:

