Finding DB Canal - Courtesy ROOTS
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From: J. Terry Frey, D.D.S.
Sent: Tuesday, May 19, 2009 7:14 PM
Subject: [roots] DB canal
Can any of you give me advice on how to find the DB canal?
Can you see it on this radiograph? I could not locate it.
Thanks - Terry
Hi Terry I see it, is almost the same wl that the mb, one that
you open the chamber try to color with methylene blue, with lopes,
and if you don't have ultrasound, with a long neck bur.
Hope it is of help - Georgette
Hi Terry I think there is a DB canal and it is most likely to be
located very close to the orifice of the MB canal if not just
within it. so you may need to remove some of the GP fro
the coronal of the MB to find it. If it isn't there it just
might be close to the orifice of the palatal canal but I think
the first suggestion is much the most likely - Graham
I agree with Grary that in Upper Second Molars the DB canal
orifice can be very close to the MB canal orfice and many a times
within it and the best way is to trough around the MB orfice
and once you have a catch direct vision under a scope is very
helpful to widen the fissure and remove the dentin overhang over
the DB canal ....but here as Graham says you might need
to remove some some GP from the coronal of the MB canal - Sachin
Hi Terry, It's an access problem....access extension is critical
to finding all the anatomy and there are a lot of really bad
suggestions being taught at weekend course all designed to sell
bogus overpriced access burs and cater to a mindset that limits
exploration, adequate debridement, apical shaping, and predisposes
to inside curve perfing. It's not your fault, it's the popular
myth that's being hyped and taught by the duplicitous :):):)
- Terry Pannkuk
Terry et al .. thanks for the information. This happens to be the
dad of my lead assistant and he knows that I had problems and was
posting it to ROOTS. This helps me a lot. Getting back
there for me is a real challenge. Iíll get it and post - Terry F
Good luck!...the other two systems look treated perfectly. Did you
extend out to the mesial marginal ridge to catch an MB2? - Terry Pannkuk
Terry, I get cross eyed with the DB sometimes because it is palatally
located in almost a straight line with the MB. I sort of like Sachinís
example. I can usually determine this by the shape of the crown but
not always. When I get this opened, I use the classical access but
don'ít always look in the classical place. On the case I just posted on
my mother, the DB was easy to find since it had gutta percha in it but
it was palatally located close to a line between the MB and the P.
You probably have seen so many accesses that it jumps out and bites you
on the end of the nose. Hereís where the scope really shines over powerful
loupes. Terry F, do you have a surgical scope. If no, you need to get
one because youíll be placing implants and doing sinus lifts under them
soon - Guy W. Moorman, Jr. DDS
I agree that many a times the shape of the crown helps to determine the
location of the canals ... smaller crowns in upper second molars have the
MB and DB canals close to each other and as you say almost in a straight
line or the DB being very close to the MB orfice and one more thing
I have learned is that there is nothing like a single canal upper second
molar .....at least I am not lucky enough to have them at my clinic ...
as a matter of fact a single canal upper second molar in the radiograph
warns me for hard work ahead.
A Microscope is definitely helpful here but with experience one can
certainly locate this anatomy even without a scope - Sachin
All you have to do is measure the distance from the MB orifice to the
middle of the DB root on a bitewing radiograph. In this case the DB
root is clearly outside the access prep wall. It would be a very bad
decision to keep the extension small on this case and start digging
around next to the MB orifice. Get some better radiographs, expecially
a bitewing and measure out the ideal distal wall extension to the DB
orifice. This one is clearly underextended.
Not fixing the obvious access problem will compound things worse by
digging a furcation perf in the center of the pulp chamber floor working
blind through inadeqate access that fails to give you a perspective of
the pulpal floor map - Terry Pannkuk
Dear Terry, I will share my experience for you to evaluate yourself at
the risk of Guy labeling my advice "dangerous."
In my experience, in molars, both maxillary and mandibular, the mesial
-buccal canal is always directly underneath the mesial-buccal cusp.
I know you're never supposed to say "always." You're never supposed to
say "never," for that matter. But there. I said it. There has even been
an occasion or two when I have completely cut down the mesial-buccal
cusp all the way down to the gumline in order to find the mesial-buccal
canal. Imagine what Dr. Khademi would say about that sacrifice of dentin!!
The distal-buccal canal in maxillary molars is much more variable in
location than is the mesial-buccal canal.
In my experience, the distal-buccal canal is often in the center of the
tooth, and I look at the external outline of the tooth structure to give
me an idea of where that might be. Basically, I think of maxillary molars
as being one of two types -- "fat" or "thin." In a "fat" molar, the three
main canals will often form a triangle. And in a "thin" molar, the three
main canals will usually form more of a straight-line. I've attached two
drawings which illustrate what I am trying to say. But again, there are
no always or nevers when it comes to the distal-buccal canal.
It is certainly possible that you have already uncovered the distal-buccal
canal; it may lie along a line connecting the mesial-buccal and palatal
canals. To enter it, remember to angle your file distally upon entry
- Patrick Wahl
Pat, I tend to agree with the fact that DB canals have a more variable
position, BUT in Terry's case I see the DB root extending beyond his distal
access wall. You won't find that DB anywhere near the line you are talking
The best thing you can do is take multiple angle radiographs and a bitewing,
then "READ" them! In Terry's case I strongly suspect a missed MB2 because
of inadequate mesial extension and a missed DB because of inadequate distal
extension. You have to look at the DB root image on the PA's and bitewings.
In my opinion, it's below the standard of care not to take a bitewing
radiograph before attempting endo treatment - Terry Pannkuk
Dear Terry P., Hopefully Terry F. will know enough to discount anything I say,
and take to the bank anything you say!
I was really commenting generally. I'm not able to interpret the radiograph
as well as you can, and you are no doubt correct as always.
As I am lucky enough to practice within a general practice, I often have
bitewings and even full-mouths. I often find them very helpful, but do not
insist on them, and perhaps I should.
Insisting on an excellent periapical and a bitewing would have saved me a
lot of heartache on Monday, when I worked with just a lousy periapical.
Terry, you've probably done, what -- about 25,000 cases in your career?
It's just a shame that none of those patients are alive today to praise the
fine work you did for them!! - Patty
LOL.....a couple might still be alive but their dementia prevents them from
Simply measure the width from the MB orifice area to where the DB orfice on
Terry's radiograph is, then look at the mesial and distal walls of the access
cavity prep. It is very telling. I think the DB root outline is very clear
and you can simply trace a presupposed root canal system to an area where
you will expect to find the DB.
I'm not particularly clever for figuring that out; I'm pretty good at
measuring small numbers between 1 and 5; anything over 10 confuses me.
:):):):):):):):):) - Terry P