Materials, Part II

Hope you are having a good week. I want to talk about root canals and crowns today, so we better get started.

Root canals
First, I want to use a rubber dam every single time I do a pulpectomy or a root canal. Especially after the crazy lady wanted to send me all her medical bills from a file falling in her mouth (see blog history). But I have to admit it is not always easy and I give up.

#10 broken at the gum line, not so easy. Here is where my skittishness comes from. I had a patient I sent over to get a root canal on #10 (there must have been some major complication or I would have done it myself). The endodontist put the clamp on the tissue and, next thing you know, all his tissue is necrotic and then the bone starts to flake off and it was a huge ordeal. Loosing the tooth, tons of bone grafts, an implant, and a very unhappy patient, if you can imagine. Is it the end of the world if I can't get a rubber damn on? No. But it would be ideal to get one on every time.

The first thing I do is gain patency with an 8 file. I want to know right away if this is going to be a problem. I have RC prep on the back of my hand, as well. So it is an 8 file with RC prep on it attached to the Root ZX II going into a canal. Once I get to my desired length, I go into cruise control. I like to bring up most canals to a 25 hand file before I introduce any rotary instrumentation. It is 8,10,15,20, and 25 all with RC prep and straight bleach.

In school we used to call it sodium hypochloride to try to fool the patient. But if you get, "Man, that smells like bleach," enough times, you feel like you are lying to the patient and that doesn't fly. So I say, "This might smell a little like bleach. Oh yeah, because it is bleach."

Once I open the canal up, I use the GT files .04 taper for the finish of my biomechanical prepping. Lots of bleach irrigation and always a swipe of RC prep. After I am done with this, I have a sonic handpiece and put a buzzing file in each canal for one minute. I will then put EDTA in each canal and put a 10 file 1mm past the apex. I might run that 10 files up the wall just to break up any last hanger on-ers. At all times in this process, I have the Root ZX close by. I probably use it 5-10 per canal, attaching it to the hand files and/or the GT files.

I then do a master cone x-ray. I would say 90% of the time I only get a pre-op x-ray and then a master cone x-ray. This may sound like too little, but I have found my Root ZX is like money in the bank. I rely on this thing more than an x-ray. I find when I start to not trust it and try to rely on an x-ray, it usually bites me in the butt. So I get my MC x-ray. I get my master cones from Sybron Endo. They are sized according to the GT files.

PP dry the canal, then obturation. Pretty simple. I use Kerr's pulp canal sealer, put it the MC and put it in. I do a heated vertical condensation with the System B and burn off the MC to 5mm before the apex. Then I use the Obtura II for my back fill.

I think that is it. I hold the files in my hand with this blue plastic holder. It has a ruler on it and a place for a triangle sponge to slide into to hold the hand files, GT files and the sonic file. I think we use the files TWICE and throw them away. I can't remember the last time I broke a file.

Post and Core
I want to talk about the post and core. If and when I do them (which is not often, maybe 10-15 a year,) we have it down pretty good. I cannot recall ever having a post and core come out. I am not saying this to toot my own horn, but if something works, I stick with it.

Speaking of sticking with it, I have been doing the above root canal technique for over 14 years. THE EXACT SAME WAY. So until you can convince me otherwise, I am sticking with it.

Okay, post and core. I drill the post space. I am not enamored by it, but I use the Flexi-post system. I put the post in and take an x-ray of it. Frank Spear says you only need 5mm of a post in a tooth for it to be optimal. My school told me to put it 5mm from the apex. I usually am somewhere in between that.

I am use Panavia to cement the post, but CorePaste as my core. So I kind of blended the two steps. The primer for Panavia is a self-etching primer but the bonding agent for the core is a 4th generation.

So etch goes down on the tooth, then I use ED primer (from Panvia) in the post space. I paper point dry the post space. Then I put my bond on the tooth: I use Photobond® and put on two layers. This is a very old fourth generation, but it has never failed me. This is a dual cured bonding agent, which means that whatever the light doesn't get is going to set up on its own.

I then put in the post with Panavia. Before I put the post in, I have put something called Primer B on the metal. I can't tell you where that came from, but I have always done it. I think it does something to the metal to make a stronger bond (that is what I am going with). Put the post in and right away put on the CorePaste. It is a fast set so I am prepping in less than 30 seconds. I think that is it.

Crowns
My crowns are pretty simple too. I know this is going to sound crazy, but I start my preps with a 330 carbide bur. I do my rough prep with it. It is small and I can get through the contacts without touching the adjacent tooth. Say, on the facial service, if you get the 330 at the interface between the enamel and the dentin it just comes off like butter. That is a $0.15 bur as oppose to a $12 diamond to do most of the prep.

Then I use a diamond chamfer to do the rest. Ninety percent of my preps are these two burs. The majority of my regular crowns are Captek. They call for a circumferential chamfer, so it works out. Not that I am moving away from Captek, but if the person is a grinder they get a regular semi-precious.

If it is on the second molar I try to push gold. If tooth structure can be saved, it is an all porcelain inlay/onlay. If it is gold or an all porcelain restoration, I am usually going with an electrosurge unit to deal with the tissue that is going to make my impression less than ideal.

If it is a PFM or a Captek, I am a two cord kind of guy. I bury a double zero cord and then put a single zero on top of it. I usually will put a band of expasyl on top of that if I think bleeding is going to be an issue. I then pull the second cord off and take the impression with the buried cord still in there. Of course, there are a bunch of variations to this because nothing if very easy. If tissue is just not cooperating, I might just use electrosurge and expasyl.

I use Impregum™ as my impression material, heavy body and light body. It is expensive and it tastes horrible, but it is simply the best and I don't care if it tastes bad. The end justifies the means. We just tell the patient it is going to taste really bad.

Temps
We take an impression of the tooth beforehand with ExaFast™ putty (GC America). We used to use Blue Mouse, but I think this stuff works well and it is less expensive. We keep this impression in a zip lock bag until the crown is seated.

We use TempPhase by Kerr and cement it in usually with Fynal. The best thing about TempPhase is that it shrinks. So if we have an onlay that has this weird shape and is very unretentive, we "lock it on." That is, we put the material on the tooth, in the ExaFast impression, and let it sit until the material hardens. What is left is a perfect temp with excess around the tooth, basically shrink-wrapped on it. I come in and clean off the excess and the patient is out the door.

I know, I know. Too long for a Friday but I was on a roll.

Have a great weekend. Enjoy the Fourth of July. Remember what it means to be an American. Count your blessings, and have a beer.

I love this country.

john