**1. Introduction**

Loss of vitality decreases the physical properties, translucency, and fracture resistance of the remaining tooth structure. A load applied on upper teeth makes them move towards labially i.e. up and outwards having no support from adjacent teeth treated endodontically will have no central core of dentine and so the stresses are mainly absorbed by margins. Unless there is bulk in this region simple restoration of the coronal form may be insufficient to reinforce the tooth. So to reinforce the crown, a post is placed in the root canal. By this, the potential point of fracture from the gingival margin can be shifted towards the root apex. Similarly loads on lower teeth cause down and inward movement which closes the arch and also gains support from adjacent teeth. So here reinforcement with the post is not as important compared to upper teeth. But still, as preparation of access cavity may leave little of dentine placement of post may be desirable. Endodontically treated teeth often require partial or complete coverage restorations according to the amount of remaining tooth structure. Endodontic treatment is usually the consequence of caries followed by pulpal infection or traumatic damage to a tooth. Therefore, these teeth also suffer from loss of structural integrity, necessitating restoration of the tooth for esthetic and functional rehabilitation. It was believed that the insertion of a post into an endodontically treated tooth reinforced and increased fracture resistance [1].

#### • **What is post?** (**Figure 1**)

It is that part of the prosthesis usually made of metal that is fitted into a prepared canal of a natural tooth

**Figure 1.**

*Schematic illustration of an endodontically-treated tooth restored by the post-core system.*

	- 1. round ended
	- 2. tapered ended
	- 3.parallel ended
	- 1. smooth sided
	- 2.serrated
	- 3. threaded posts.

flexi posts, endoposts, plastic impression posts, brasslers ER casting post, weissmans dentatus post, para post, v- lock active post etc.

• Parallel sided posts advantages

Better retention, better distribution of forces.

• Disadvantages are.

Fits only at the apical part of the canal,requires more dentine to be removed.

• Tapered posts advantages are.

Better conforms to the canal, less removal of dentine.

• Disadvantages are.

Less retentive than other posts, causes greater stress concentration and causes wedging affect.

