2. 2
Objectives 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.
3. 3
Objectives of Root Canal Preparation
2- To retain all enlarging instrument within the canal.
Instruments used for preparation should be kept within
the confines of the canal.
4. 4
Objectives of Root Canal Preparation
3- To develop the apical dentine matrix which is the
apical stop.
It developes at the end of the root canal preparation
and acts as a barrier (ledge) to prevent the filling
material from moving outside the canal.
5. 5
Objectives of Root Canal Preparation
4- To retain the original canal shape of the
root canal.
The final prepared canal shape should retain
the same general configuration of the root
canal.
6. 6
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
7. 7
Aids in Preparation of the Root Canal
b- Tissue dissolution: The solution should be able to dissolve the soft
tissues & hard tissues remnants to permit their removal.
c- Anti bacterial action: The solution should be able to sterilize the
canal or at least eradicate most of the bacteria & toxins inside the
canal.
d- Lubrication: It should aid the instrument to slide down the canal.
8. 8
(NaOCl) 2.5-5.25% possesses all the above criteria.
Aids in Preparation of the Root Canal
10. 10
Aids in Preparation of the Root Canal
2- Examination of the instruments: Each instrument
should be examined each time before insertion inside the root
canal to verify the presence of any sign of fatigue, stress or
damage,
so any instrument showing such a sign should be discarded.
11. 11
3- Precurved instrument: In case of a curved
canal, the instrument should be curved to estimate
the curvature of the canal.
This is true only in case of stainless steel instrument,
but nickel titanium instrument is flexible and does not
need precurve.
Aids in Preparation of the Root Canal
13. 13
Aids in Preparation of the Root Canal
4- Use of instruments in
sequential order: Root canal
preparation is done gradually by using
successively larger files (never skip any
size of instrument) e.g. size 20 followed
by size 25 & then 30 & so on, but not size
20 then size 30.
14. 14
Modes of action of Intracanal Instruments:
1) Reaming action: It is a repeated clockwise rotation of the
instrument
which will shave the canal walls and give a cross sectional
preparation approximately round.
Reamers are usually more effective for this function.
15. 15
Modes of action of Intracanal Instruments:
2) Filing action: It is a push-pull action without rotation
which has a great efficiency with files than reamers.
The cross sectional appearance of the prepared root
canal is irregular with general oval configuration,
so the canal must be filled with gutta percha.
16. 16
Modes of action of Intracanal Instruments:
3) Quarter-turn filing: This action is a
combination of reaming and filing action.
The instrument is inserted in the root with a quarter turn
rotation (90o) then moved with dragging motion to
produce an oval cross section.
K-file and reamer can be used.
17. 17
4) Circumferential filing: in this action,
filing or quarter turn filing action is used with
emphasis placed on the out stroke,
so the file is dragged along different sides of the
canal wall with each withdrawal.
The resultant canal has a wide orifice with
greater taper.
