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Endo tips    Better Endo    Endo abstracts    Endo discussions

  Canal projectors

The opinions within this web page are not ours. Authors have been credited
for the individual posts where they are. - www.rxroots.com photograph courtesy: Marga

From: Marga Ree
To: ROOTS
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 
cement.

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

canal projector
Canal projector
six month followup

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

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 
done.........

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)? 

No, I am not concerned about a possible root fracture, according to 
the below mentioned papers, you can reinforce a weakened tooth with 
composite.

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 
intact teeth

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
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