How much larger should be the apical preparation from its original size??

[MHOWAIT]

According to Yared & Bou Dagher 1994 It should be larger by 0.3 to 0.5.

[nehal_sharaf]

http://xs139.xs.to/xs139/09203/scan0001633.jpg.xs.jpg (http://xs.to/xs.php?h=xs139&d=09203&f=scan0001633.jpg)

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[nehal_sharaf]

http://www.4shared.com/file/105185320/6d242f79/A_clinical_method_to_determine_the_optimal_apical_ preparation_size_Part_I_.html

[Khaled Balto]

Dr. Neha....do not you think theses guidlines have been re-vistited now. There are two major additions to our knowledge that might be changing these guidlines. First; the greater tapred preperation and the new avenues in intra-canal irrigation. According to Ove Peters the prefered preparation shape now is the greater taper with small apical diameter.

[suha maddah]

according to my little knowledge the size of the apical preparation will be as the diameter of the tip of master apical file

[Khaled Balto]

you are right Suha...but you are the one who will determine the size of the apical diameter by planing a head your largest apical file...In my opinion; the traditional methods of giving mathematical numbers to what the final size should be is not justifiable...I feel that it should be an intra-operational decision...directed by so many varibles during the procedure

[al-nasser]

According to Yared & Bou Dagher 1994 It should be larger by 0.3 to 0.5.

thanx MHOWAIT
this paper if you really take a deep look at it you will find that the author was trying to give a message which is :-
0.3 to 0.5 mm larger from the first file to bind will give you better microbial elimination by biomechanical aspect point of view
the question is :- what if the root canal is not infected :D i.e if you will do elective R.C.T in responsive pulp with fully defensive capacity :D do you really have to go upto that size ??

http://xs139.xs.to/xs139/09203/scan0001633.jpg.xs.jpg (http://xs.to/xs.php?h=xs139&d=09203&f=scan0001633.jpg)

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thanx nehal for sharing us this paper
I think the author here was trying to tell us that with these suggested sizes you will be able to establish what is called the circular preparation at 1mm from the root apex & thats what Kerkes & Tronstad 1977 JOE told us
and been confirmed by weiger et al 2001 IEJ as well as the same author in 2006 in OOOOE
the question here is :- yes it an excellent Idea to have circular preparation
but in what obturation tech. ??? lateral or vertical
for cold lateral condensation --> definetly you will need circular space in the canal to fit circular cone G.P to have optimal fit & excellent seal .
but do you really need circular prep. in vertical condensation ?? I dont think so
b/c in such tech. optimal fit can be achieved regerdless to the canal shape.

so

I think what dr.balto is trying to say here is absolutely true .
it depend on alot of factors

for example :-
the old trend behind enlarging the canal upto 40 or 45 or whatever size is to completely clean canal from micro-organisms , and this been confirmed by sjogren 1997 IEJ when he published that paper about treatment outcome at time of obturation with or without micro-organisms
he foud that if +ve culture canal then the success was 68%
if the canal culture was -ve then the success was almost 90%
based on that paper one may conclude that he should clean the canal
and what is the best way to do it ??
by physical mean ( ingle 1961 ) now they refere it as biomechanical mean

However
I have critical question :-
How do you explain the 68% success in positivly cultured canals ?????

the answer for question is very very difficult , but if you understad that primary root canal infection live in a very delicate dynamic as well synergetic manner where any disturbance ( preparation + irrigation + medication ) will lead to breaking down that system &
the time needed to recover their system to its narmal ecology i.e (re-growth) can be prevented by a very simple procedure which is a good excellent tight seal at apical as well coronal
so
tight apical seal in cold lateral tech. , you will never ever be sure to achieve it without being so sure that you made a canal the exact -ve picture of your cone i.e you have to have acommodate the shape of the canal to the shape of gutta percha & this cant be achieved without circular preparation which you will never be sure to have it without massive enlargement .
while
in vertical tech. people they have to adapt their cone to the canal i.e ( not at the expense of the root) & this explain why these people never used standard cone , they just fit & cut then re-fit & so on so forth till they get their desire fit for burning & thats it .

any way it is good to share with each other our different thoughts

best regard

[Khaled Balto]

Very Impressive Dr. Abdulrahman.....!!!
Can you tell me what is the fate of residual bacteria in root canals? do they persist? do they fade a way with time?

I think our success is a function of a competetion for intra-canal space.....the less space we leave by the obutration technique that we use; the less the chances for bacterial persistance...and less chances for bacterial survival.

And the lesser the space we have to fill; the more accurate the our 3D filling is...do not you guys think so?