endo 6 dina

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Dr. Ali Hani Hassan

Root Canal Preparation

2Objectives of Root Canal Preparation

1- To create a tapered funnel.

The final preparation should be a completely tapered funnel,

widest at the orifice & narrowest at the CDJ.


2- To retain all enlarging instrument within the canal.

Instruments used for preparation should be kept withinthe confines of the canal.


3- To develop the apical dentine matrix which is theapical stop.

It developes at the end of the root canal preparationand acts as a barrier (ledge) to prevent the fillingmaterial from moving outside the canal.


4- To retain the original canal shape of theroot canal.

The final prepared canal shape should retainthe same general configuration of the rootcanal.

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1- Intracanal irrigants: Root canal irrigation serves many reasons as:

a- Flushing out the debris: The solution should be able to flush the debris outside (coronally) the canal. Normal

saline is used to flush the debris from the canal

Aids in Preparation of the Root Canal\

7Aids in Preparation of the Root Canal

b- Tissue dissolution: The solution should be able to dissolve the softtissues & hard tissues remnants to permit their removal.

c- Anti bacterial action: The solution should be able to sterilize thecanal or at least eradicate most of the bacteria & toxins inside thecanal.

d- Lubrication: It should aid the instrument to slide down the canal.

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(NaOCl) 2.5-5.25% possesses all the above criteria.

Aids in Preparation of the Root Canal


2- Examination of the instruments: Each instrumentshould be examined each time before insertion inside the rootcanal to verify the presence of any sign of fatigue, stress ordamage,

so any instrument showing such a sign should be discarded.

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3- Precurved instrument: In case of a curvedcanal, the instrument should be curved to estimatethe curvature of the canal.

This is true only in case of stainless steel instrument,but nickel titanium instrument is flexible and does notneed precurve.

Aids in Preparation of the Root Canal


4- Use of instruments insequential order: Root canalpreparation is done gradually by usingsuccessively larger files (never skip anysize of instrument) e.g. size 20 followedby size 25 & then 30 & so on, but not size20 then size 30.

14Modes of action of Intracanal Instruments:

1) Reaming action: It is a repeated clockwise rotation of theinstrument

which will shave the canal walls and give a cross sectionalpreparation approximately round.

Reamers are usually more effective for this function.


2) Filing action: It is a push-pull action without rotationwhich has a great efficiency with files than reamers.

The cross sectional appearance of the prepared rootcanal is irregular with general oval configuration,

so the canal must be filled with gutta percha.


3) Quarter-turn filing: This action is acombination of reaming and filing action.

The instrument is inserted in the root with a quarter turnrotation (90o) then moved with dragging motion toproduce an oval cross section.

K-file and reamer can be used.

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4) Circumferential filing: in this action,filing or quarter turn filing action is used withemphasis placed on the out stroke,

so the file is dragged along different sides of thecanal wall with each withdrawal.

The resultant canal has a wide orifice withgreater taper.

endo 6 dina

Health & Medicine