Determination of apical width - Courtesy ROOTS
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From: Randy Hedrick
Sent: Sunday, February 26, 2006
Subject: [roots] recall this week
2. determination of apical width for that particular canal and achieving it
This without a doubt is the most misunderstood part of endodontics for me.
Determining the apical diameter by successively larger files, not only can
move the foramen from its original location, but ellipticizing the foramen,
hence creating an added dimension of difficulty to achieve an apical seal.
Ahmad, Thanks for the detailed response to Sashi's case.
It is very stimulating and hopefully is causing a lot of thought.
I would like to explore your comments under #2 , determination of
apical width. I agree that apical width or apical preparation diameter is
a very misunderstood and more commonly overlooked factor in debridement.
I am a LightSpeed user for over 13 years and I would like to explore the
basis for your statement of concern about larger apical preparation
sizes. I would also like to post a copy of a recent review article in the
Journal of Endodontics on apical preparation size for others to review as
this discussion proceeds.
When you made the statement about transporting and elipiticizing the
foramen with progressively larger instruments were you referring to
tapered instruments only or were you including non-tapered
LightSpeed instruments also? If you were referring only to tapered
instruments I would have to agree with most of your statement. Tapered
rotary NiTi instrument are indeed very stiff, especially with
larger tapers such including .04 tapered instruments and larger tapers.
I would also like to ask how you determine the final apical preparation
diameter in your cases? There is quite an accumulation of anatomic, SEM,
microbiologic culturing studies that support larger apical preparations
for better debridement. Studies using the Bramanti sectional method and
other methods to evaluate canal transportation clearly indicate that
larger apical preparation sizes can be achieved with the more flexible
LightSpeed with little or no transportation.
There are others on ROOTS who base this critical part of the endodontic
procedure on opinion and ignore research. They want to dismiss established,
confirmed research yet offer no legitimate reason for doing so. There was
a time when the literature was weak and very thin on this subject
and small apical preparations could be defended but that is no longer the
case. Proper defense of this position requires scientific substantiation.
I think the review article makes that point very well.
Finally I am enclosing a case I just completed an hour ago. It's #18 please
look at the pre-op distal canal, it is very large even before I initiated the
endo treatment. My final preparation was 45 on the mesials and 80 on the distal.
Notice the wide funnel shaped anatomy of the distal canal orifice also. It is
still in it's original position. When using instruments larger than
#60 LightSpeed they too become stiffer and can cause some transportation.
Yet even though it was necessary to enlarge this to a #80 to properly debride
this large canal, there is minimal transportation. Ultrasonics were used to
insure that the B & L of the distal canal was properly debrided also.
- Randy Hadrick
I ask these questions in the spirit of scientific debate for the benefit of
the members of ROOTS. I'm not looking for a testosterone charged conflict
- Randy Hedrick
Dear Randy ! I have enjoyed the article you have posted. It doesn't show a
solution to the problem and doesn't discuss LightSpeed. I am not a LightSpeed
user, but I can understand the rationale behind it. Your clinical case is also
very nicely done. A great service to the patient - Thomas
Thanks Thomas for the compliment. Just trying to add another piece to the
endodontic puzzle we try to put together everyday in practice - Randy Hedrick
Hi Randy: sorry for the late reply. But, I wanted to read the pdf you attached
and be able to respond intelligently.
It is hard for anyone who does clinical endodontics and recall his patients
to believe : "....mechanical instrumentation in presence of irrigants doesn't
reliably disinfect an infected system."
and yet they concluded with some obvious notions :
"However, these studies are often retrospective or have other factors
(e.g. sample size) Moreover, many of these studies do not specifically
evaluate the impact of a significant enlargement of the
canal or of apical region with regards to clinical success.
They have also shown that larger apical sizes yield cleaner canals that may
promote further success. Failing to clean canals, especially in the apical
region, can result in treatment failure. ".... no disagreement here...
My opinion about the bigger and bigger apical diameter is the lack of
consensus as to what size is actually produces more healing, and more
importantly if it does actually promote healing. Again the
quality of seal in such big sizes is a concern for me. Yes we can take
apical diameter to a size 100 and remove all the substrate infected dentin
from the canal walls apically, but shouldn't we concerned what's happening
to the delicate root as we take more and more dentin away? and when do
we stop? Reducing the bacterial count is only one dimension....
blocking, sealing & preventing their re-occupation of the system is another.
and what about those cases that fail to heal despite our best effort?
how big should we make those apices at retreatment???
Some jokingly say : we might as well take the tooth out for 100% success.....))
A series of carefully bent ss files, 1-2 mm from the tip, in presence of
copious solutions can be quite effective to prep the apical area too....and
there is an added advantage........not only it can be bent to follow the
natural curvature of the canal...it can be effective to look for extra POE
and accessory canals and basically scout the canal.
But I like the LS files as an adjunct to our armamentariums..... I use it by
hand to clear the apical area. I don't dream of spinning it at 2000 rpm
(2500 rpm for LSX) at the apex. Bill Watson, whom I consider one of the best
endodontists in the world, utilizes LS files for determining apical
constriction size, apical diameter, and master LS binding file in his
"Plains Technique" by hand.
In summary, I am not defending a passive # 20 to apex and proceed to
obturation protocol. I never met anyone who does either. Just stating the
obvious, that each case is unique and should be addressed as it own. some
require a size 80 and some a size 35. But my goal is not to take every
apex to size 60 and above.
However, preparing a canal with ss file as mentioned, takes time and
patience, requires deliberate attempts to recapitulate the apical area
through a well shaped & tapered canal to introduce irrigating
solutions and removing debris.
Randy, my knowledge of endodontics is miniscule compared to a Board
certified endodontist such as yourself, but in the spirit of learning
and debate, thanks for allowing me to trespass in your neighborhood - ahmad
PS. Very nice case.
Ahmad, Thanks for responding. And don't feel like you are trespassing,
ROOTS is everybody's neighborhood
who is looking for ways to improve their endodontic technique and
understanding. You are a special person indeed because you are a teacher
and also because you took the time to read the review article with an
open mind instead of simply reciting tired old opinions. Endodontics can
advance and improve only when we realize that we have not reached the end
of the evolution of instrumentation, disinfection and obturation.
New instruments, obturation techniques and materials will continue to come
forth. The question remains will we be able to objectively consider new
innovations or remain locked into the dogma of the past.
I have attached 3 Powerpoint slides that powerfully demonstrate the
importance of proper apical preparation size. It is an incisor that had
been retreated once and was failing again. The patient had enough and
wanted an extraction when another retreatment was recommended. Bill Wildey
extracted the incisor and then sectioned it 1mm from the apex to uncover the
problem. Notice the radiographic length of the obturation is correct and
it is nicely flared. It is a very straight, easy canal to instrument yet
the canal has been transported and is horribly underprepared in the apex.
The final slide is of a typical LightSpeed preparation and Simplifil
obturation. The difference is obvious, no transportation, no overpreparation,
the entire circumference of the canal has been cleaned and obturated.
I agree with you that each case is unique and should be prepared to an
apical diameter that matches the size of the preexisting canal anatomy.
Sometime if you get a chance practice with a LightSpeed at 2000rpm
in an extracted tooth and then do a cross section to see if the canal
is still centered and very clean. You might even try another tooth and
try to intentionally transport the canal by lingering with the
rotating LS instrument in the apex and see if you can detect any
transportation. I bet you won't see much transportation unless it is with
instruments larger than a #50 and in a significantly curved canal.
Use a watch to record the amount of time the instrument was rotating at
length and remember that the LS technique does not require you to be at
the apex with the rotating instrument more than a second or two.
We did a lot of cross-sectional analysis of various techniques in our
preclinical endo lab and no matter who did the preparation, no matter
what technique was used, nothing cleaned the canal more thoroughly and
with less transportation than LightSpeed.
I appreciate the quote you have included and would place equal or
greater emphasis on the first part of the quotation since debridement
is all about achieving cleaner canals. The second sentence is also
They have also shown that larger apical sizes yield cleaner canals that
may promote further success. Failing to clean canals, especially in the
apical region, can result in treatment failure. "....
Thanks again for your comments and dedication to endodontics. It is my
hope that this kind of professional debate will help the many interested
dentists who come to ROOTS improve their technique. In my opinion more
good can be done by helping larger numbers of dentists improve their
endo success rates from 70 to 80 or even 90% than can be done by helping
a few excellent endodontists raise their success rate from 94 to 95%.
They are already doing a good job! - Randy Hedrick
Randy: you may end up replacing terry as our ambassador of goodwill and
fellowship . Love your cases and your communication skills - gary
Randy: great discussion...I have nothing to add to your assertion about
the need to completely and meticulously cleaning a canal system. Be it
with LS, ss files, NiTi, whatever. There is no doubt the cleaning a
system will lead to healing. LS files are great for apical clearing.
I have seen Bill's central case many times and each time I wonder what
went through the mind of the dentists who treated this case......twice!
...lousy length , short anemic preparation and fill....crud at end of
the apex ..etc.. Isn't this Endodontic Insanity? Trying the same crappy
technique over a gain, expecting a different result.
Good solid debate is helpful and very conducive, yet we occasionally
need Attila the Hun or Terry :-) to enforce the law.
Randy, you are a wonderful addition to ROOTS and I sincerely hope you
continue to post cases to stimulate debates in the hope of being able
to serve our patients and our profession at the highest level of care
possible. Thank you - ahmad
Ahmad, I agree, this was a great discussion. I think it is the type
of high level, professional debate that Ken is trying to achieve on
ROOTS. No abrasiveness, no insults. Just a thoughtful debate on the
issues with the intent of education and raising the bar! - Randy Hedrick