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Dear Dr. DiTolla,

Hello Mike. I’ve been sending my work to Glidewell for 10 years, and I’m really surprised how happy I’ve been. Here’s what’s going on: I cement all my BruxZir® crowns with Fynal® cement (DENTSPLY Caulk; Milford, Del.). I’ve used it for all my PFMs, gold, and now BruxZir crowns, as I can easily remove the crown after cementation as needed if there has been food impaction, a patient complaint, or for a root canal. Using Ceramir® (Doxa Dental Inc.; Newport Beach, Calif.) or RelyX™ (3M™ ESPE™; St. Paul, Minn.) forces me to have to cut off the BruxZir crown if retrieval is needed. I’ve had several debond, and when that happens, I recement them with RelyX. My question is: Is microleakage with BruxZir worse than with PFMs?

Thanks for your help.

– Daniel Birkmire, DDS
Shoreham, New York

Dear Dan,

Fynal, the zinc oxide eugenol cement from DENTSPLY Caulk, is polymer-reinforced. So if you look at the powder, it’s 80 percent zinc oxide and 20 percent methyl methacrylate. The good part about this cement is that it sedates the pulp because of the presence of the eugenol, but the bad thing is that it’s not a really strong bond; in fact, it won’t bond to BruxZir Solid Zirconia at all. You bring up a good point: If you need to remove a BruxZir crown, with Fynal, I’m not surprised you can pop it off and do whatever you need to do. If you put it on with Ceramir or you put it on with RelyX luting cement, you’ll have to cut it off. As far as the microleakage goes, microleakage is bad whether it happens with zirconia or whether it happens with a PFM. There’s really no difference in microleakage between the two materials, or at least not to a degree that you would be able to see. It just comes down to the solubility of the Fynal cement itself. If it’s working for you and you’re recementing crowns with stronger materials any time they come off, I’m good with it.

– Mike

Dear Dr. DiTolla,

In the past, with any type of crown (especially cast crowns), we used a die spacer on the die. It was usually one or two coats of something somewhat like nail polish. Now with BruxZir Solid Zirconia, IPS e.max® (Ivoclar Vivadent; Amherst, N.Y.), Lava™ (3M ESPE) and other CAD/CAM restorations, I don’t see it being used. What happened to allowing room for the thickness of the cement?

Thank you.

– Steven Devins, DDS
Cocoa Beach, Florida

Dear Steve,

For decades, you would see die spacer used; and then all of a sudden, it was gone. First, every crown that we make here today uses CAD/CAM technology — even PFMs — so you will never see die spacer on another die again from us due to the digital design process. When you send in an impression, we pour and articulate the stone model, saw out the die and scan it with a 3Shape™ box scanner (3Shape Inc.; Warren, N.J.), and design the crown virtually. When we do that, there’s a default virtual die spacer of 90 microns that goes across the entire prep surface and stays short of the margin. The big advantage of this is that it’s always 90 microns. A problem in the past was that some technicians would leave the top off of their die spacer, and the acetone would start to evaporate, meaning their two coats of die spacer would be thicker than if they used a new bottle. So there was a lack of consistency from technician to technician based on how fresh their die spacer was. Even though you won’t see any die spacer on your dies from now on, rest assured that there’s a perfect 90 microns designed into the restoration.

Best,

– Mike

Hi Dr. DiTolla,

I have a question regarding the safety of doing a minor gingivectomy around a tooth that has been restored with either an IPS e.max or BruxZir crown. I have a case that has been restored using an e.max crown, and the patient has experienced some tissue growth that has created a tissue height discrepancy with the adjacent tooth. I’d rather not use cold steel, but I’m concerned about using electrosurgery with the possibility of contacting the crown’s surface. Please advise.

– Ernest M. Yamane, DDS, PS
Chehalis, Washington

Hello Ernest,

Cold steel: I like the sound of that for a scalpel. That’s an interesting question, and actually the first time I’ve been asked that. If you look up zirconia on the periodic table, you will see that it is a metal; but when you look up zirconia oxide or zirconia dioxide, the material we use for BruxZir crowns, it is actually a structural ceramic and no longer a metal. So the dioxide or the oxide of almost any metal is in fact a structural ceramic, meaning you are safe to use an electrosurge around them. However, you might consider the purchase of a diode laser; they’ve come down so far in price over the last five to 10 years. The Picasso® Lite (AMD Lasers; Tulsa, Okla.) is selling for less than $2,500, and I’ve been so happy with that device. Like you, I used to have an electrosurge, and I loved how quickly they cut — I mean it’ll just zip right through tissue — but you can’t come anywhere near implants, amalgams or anything metal in the mouth. Whereas with the diode laser, you can come right up to the metal and even touch it, and there won’t be any issues; the downside being they cut a lot slower. If somebody asked me, "Which one should I get?" I would have to say the diode laser just because of the fact that so many implants are being placed and restored today.

Thanks!

– Mike

Dear Dr. DiTolla,

I love "Chairside Live" and watch it religiously; but I was wondering, why do you talk so much about traditional impressions? The wave of the future is obviously digital impressions. I’ve had an iTero® (Align Technology, Inc.; San Jose, Calif.) for two years and could not live without it. Not only does it scan for crown and bridge, but I also use it for Invisalign® (Align Technology, Inc.) cases. Could you talk more about digital impression technology? I think if we all started using it, the prices would go down.

Hope to hear back from you.

– James Beck, DDS
Mayflower, Arkansas

Dear James,

Last month, we got roughly 120,000 impressions for crowns and bridges here at the laboratory, and out of those, right around 4,600 were digital impressions. They are still a very small part of the incoming impressions to our laboratory, even though we’re actually getting more digital impressions than any other lab in the country. So for that reason, I have a tendency to focus on traditional polyvinyl impressions, because that’s what the majority of our dentists are still doing. Are digital impressions the wave of the future? The one thing I do tell any dentist who asks about it is that there are no faster or easier ways to get better as a dentist than to start taking digital impressions. As soon as I started taking digital impressions and blowing up the size of the image on the screen, I could see those little chips out of the margin or those rough spots. And as you see your preps blown up on the screen, then look back at the tooth with your loupes on, you’ll recognize the errors. And the biggest difference is right there: You’re no longer looking at an impression; you’re looking at a virtual model on the screen, and you see it as though it had been poured up. And that’s why you become such a better dentist. Is the future of dentistry digital impressions? I would say yes. I don’t think it’s going to be in the next five years, but rather in the next 10.

– Mike

Chairside Magazine: Volume 9, Issue 2

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