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From: Marga Ree
Sent: Friday, August 05, 2005 5:24 PM
Subject: [roots] Canal projectors a la John Munce
This patient came in with an acute apical periodontitis of
tooth # 37. She was on vacation in Italy when she got a flare-up.
She consulted a dentist, but he told her that he could only
extract the tooth. "An endo was not possible, because of the
presence of the posts and bridge"
She refused to have the tooth extracted and requested the dentist
to prescribe her an antibiotic and a pain killer, which he did.
She decided to go home the same day, and to seek treatment in her
home town in the Netherlands. After a terrible 12 hour drive,
she called our office, because we did a rct on her daughter
some years ago.
Treatment: removal of the bridge with a crown and bridge remover,
removal of the cast build-up and posts with US tips, C&S,
application of Ca(OH)2 and reschedule her for a next visit.
There was not enough tooth structure to recement the bridge
without running the risk that it would come loose, so I did the
canal projector technique of John Munce, which works great in
these situations. Because I had not the original kit, I used the
purple capillary tips of Ultradent.
In summary: Fit the capillary tips in the canals and adjust the
length by clipping them to the right size. After insertion of the
canal projectors, acid etch, apply primer and bonding. Prepare the
inner side of the restoration by applying a separation medium like
vaseline, and make an adhesive build-up of a self cured composite
with the bridge serving as a mold. Apply composite with a needle
tube in the tooth and in the crown, put the bridge back in place,
check the occlusion, and after setting of the composite you will
be able to take it apart from the abutment tooth.
Removal of the cap tips is very easy by screwing in a hedstrom file.
I prefer to connect the preserved canals (see pic) and leave an
outer wall of composite in place. Apply Ca(OH)2, cover the orifices
and pulp chamber with cavit, and recement the bridge with a temporary
From the day of the first treatment, the complaints sudsided.
I finished treatment in the second session. Fiber post in distal
canal and a composite build-up. Although the margins of the bridge
are not 100% perfect, the fit is acceptable, and there was no decay
underneath it. We decided to recement it and monitor for healing.
Which is taking place, see 6 months follow-up rad. - Marga
Very nice. Do they call an amalgam stuffed into the top of the
canals a post in Italy? ;-)- Alan Cady
Marga, excellent as usual. It is always a pleasure to look at your
cases. That's why you are called he "Endofee" - Jörg
Great case! Great tip! Great presentation! APPLAUSE! One tip
that I have found uselful is to paint a *very* thin layer of
Fit-Checker on the inside of the crown before using it to build up the
'retrograde' core. This acts a pseudo die spacer. - Ken Lipworth
Awesome. Do you AE & bond with a dam in place, or do you isolate
with cotton rolls while you place the composite and then quickly
insert the bridge? DougR
Thanks Doug,Yes I always AE & prime and bond with the dam in place.
Then it depends: If the clamp and the rubber dam don't interfere with
the insertion of the bridge then I insert the bridge under rubber dam
and as soon as it is seated, I quickly remove the dam and let the
patient close to check the occlusion. I prefer this situation, and if
possible I take care of this from the start of the treatment when I
place the rubber dam, e.g. by making a slit dam which I cover
during treatment with a light cured secondary isolation material
like opal dam.
If the rubber dam does interfere, I AE & prime and bond with the dam
in place and cover the preparation with a first layer of composite.
Then I isolate with cotton rolls and if necessary, I put a heamostatic
retraction cord in the sulcus. If necessary, I AE & prime and bond again,
and apply the second layer of composite in the prepared tooth and in
the bridge and insert it.
After the setting of the composite, I remove the bridge, and remove
the surplus of composite from the interdental space and below the
outline. Then I clean the bridge with alcohol and a sandblaster,
and recement it either with a temporary or definitive cement. - Marga
Hi Marga, I've heard of the canal projectors, but it's the first time
I see them in action. Thanks. - Hani
Marga, a simply fantastic case. I have wondered about how to do the
Mounce projectors and this is wonderful. Did you have to cut down the
purple tips constantly to make sure that the bridge fit on it again
when you did the buildups .Wonderful treatment, great photos,
educational, and awesome healing. CLAP CLAP CLAP -
Thank you very much for the fine presentation - Glenn
Hi Glenn, You are always so enthousiastic in your comments and remarks,
thanks a lot for your nice feed back! About the length of the tips,
I just estimate this by cutting them at a certain length, and then
try to insert the bridge, which I preferably do under rubber dam,
see my answer to DougR. After I made sure that the bridge fits properly
on them, I apply the self cure composite in the tooth and in the bridge,
like I explained to DougR. - Marga
A truly remarkable effort Marga! You are certainly a master clinician
with amazing skills (and a 'saviour' of many teeth which others would
have definitely condemned to extraction). The technique you have described
(as with many of your other posts) is fascinating and innovative. Some
quick questions about this case: What (realistic) prognosis did you offer
the patient? Are you not concerned about the minimal available natural
ferrule? Will the resin bond have a 'reasonable' long-term survival;
Will it undergo rapid hydrolysis, &/or simply break down soon due to
bond/core flexural fatigue as a consequence of the demanding occlusal
stresses in this region? Why did the case really fail in the first place?
I feel occlusal forces and the lack of 'satisfactory' ferrule may have
being contributory factors towards failure. Lastly, are you not
concerned about possible vertical root fracture of the distal root
(due to presence of a post associated with a very minimal ferrule)?
Peter, Thanks for your compliments, which I appreciate very much.
About your questions:
Are you not concerned about the minimal available natural ferrule?
Will the resin bond have a 'reasonable' long-term survival; Will it
undergo rapid hydrolysis, &/or simply break down soon due to bond/core
flexural fatigue as a consequence of the demanding occlusal stresses
in this region?
Yes, there is a minimal ferrule. That is one of the reasons that
I decided to re-use the current bridge and monitor this case.
If tooth # 37 will fail, then there is always the option of placing
2 implants. And yes, I know that theoretically the chance exists
that the bond will fail due to flexural fatigue. But...., I have
made a lot of these adhesive composite build-ups, for more than
15 years, and to be honest, I don't see them failing frequently,
on the contrary, they function without any problems in the vast
majority of cases.
But I realize that this is a very unscientific statement.......
:-)) I do know that the fabrication of a neat composite filling
or build-up is very technique sensitive, so very dependent on the
operator who is executing the treatment. A poorly performed amalgam
build-up can stillbe an adequate restoration, but a poorly performed
composite will never become a success.
Why did the case really fail in the first place?
In my opinion it failed in the first place because a lousy endo was
Lastly, are you not concerned about possible vertical root fracture
of the distal root (due to presence of a post associated with a very
No, I am not concerned about a possible root fracture, according to
the below mentioned papers, you can reinforce a weakened tooth with
This is in agreement with my clinical experience, for what this is
worth....:-)) Reeh et al. 1989, Trope et al. 1985, 1986, Rabie et al.
1985: Intracoronal acid-etched bonded resins can internally strengthen
endodontically treated teeth and increase their resistance to fracture
Hernandez et al. 1994, Ausiello et al. 1997 : New generation dentin
bonding systems can strengthen rct teeth to levels close to that of
I will keep you informed about the follow-up! - Marga
Marga, thank you for your reply. I'm glad to hear that you've had good
experience with such cases, and above all, it's great that most have
worked over the long-term, at least in your hands. This just goes to
show that clinical experience, good treatment planning and exceptional
skills can successfully salvage even some of the most questionable cases.
I also agree with you that the case most likely failed because of the
lousy endo, but I somewhat suspect that coronal leakage (esp on the
mesial--at least radiographically), may have also contributed
to failure. Again, I wonder if flexure ('bending') of the bridge in
this part of the mouth (where the mandible can flex to a certain degree,
especially with a poorly designed occlusal scheme),also added to the
coronal leakage/breakdown. I guess all this is now irrelevant considering
you've successfully rescued this 'damsel in distress':-)) Thanks too for
providing references to support your anwser to my last question. I agree
with the concept of acid-etched intracoronal (and I guess, intraradicular)
reinforcement, if that's what you were alluding to in your anwser. However,
I am still concerned about the gradual demise of the resin bond or seal
in a shorter time, than a seal created by an amalgam core for example.
Finally, I'm also not sure whether your references specifically considered
the issue of adequate ferrule, but if they did, then you seem to have
provided a good backing for your clinical observations when using this
technique. Thanks again for a great post
and reply. - Peter
Hi Marga, Vaseline provides lubrication only (to all intents and purposes).
I use GC Fit-Checker, which will actually provide space. This is desirable
for the same reasons that the lab applies die spacer to the dies. How do
you accomdate the cememtn thickness with your technique? Do you use air
abrasion or some other means to slightly reduce the size of the core you
have built up? I guess this might work, as well as have the advantage of
getting rid of the Vaseline (which may interfere with the cement bonding).
Would you mind sharing the specifics of the technique that you use? - Ken
Hi Ken, Now I understand what you meant. I do use a sandblaster (in addition
to alcohol), to get rid of the vaseline. You can expect that it will
slightly reduce the size of the core. Moreover, most composites
have a polymerzation shrinkage of approximately 4%. I see your point,
but in practice, I don't have problems with seating the restoration after
I made the build-up. - Marga