From: Randy Hedrick
To: ROOTS
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

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
very important.

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 again, 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