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Dear Dr. DiTolla,

Thank you so much for all you do to educate us wet-glove dentists who do not have the time or resources to do our own research. I appreciate it, and I enjoy working with Glidewell and have had fantastic results. I’m writing today to inquire about an issue I’ve experienced three times so far. One of my patients came back last week with a BruxZir® crown off. I delivered it back in August 2011 with Maxcem Elite™ (Kerr Corp.; Orange, Calif.). I didn’t know about Ivoclean™ (Ivoclar Vivadent; Amherst, N.Y.) and Monobond® Plus (Ivoclar Vivadent) at the time. The crown came off, and the cement came out separate from both the prep’s surface and the crown’s surface. I had cemented a lot of these types of crowns before I started using those two products and am concerned that I will be experiencing this problem again and again.

– Nagib Bahri, DDS, MAGD
Upland, California

Dear Dr. Bahri,

This was an issue that we had early on before we knew about the contamination of zirconia. If a BruxZir crown gets tried in the mouth to check contacts and occlusion, it’ll be contaminated, meaning you’re going to have a difficult time bonding to it. Zirconia oxide is very hydrophilic, and all resin cements (including Maxcem Elite) are very hydrophobic. The two will just never stick together. Hence the need for a zirconia primer like Z-PRIME™ Plus (BISCO; Schaumburg, Ill.). It’s got a hydrophilic binding site on one end of the molecule and a hydrophobic end on the other side. When we launched BruxZir Solid Zirconia, we didn’t know that when you tried the zirconia in the mouth, the phosphates in the saliva get bound down to the zirconia. This means if you apply Z-PRIME Plus after trying it in the mouth, it won’t help at all because those bonding sites have already been taken up by the salivary phosphates. The best way to decontaminate the crown is to sandblast or use Ivoclean. If you are starting with a completely new crown, you can take Z-PRIME Plus and place it inside of the crown before it ever gets in the patient’s mouth. The hydrophilic portion of the Z-PRIME is now bound down to the crown and the hydrophobic end is sticking out waiting for the resin. So when you go to try it in, the saliva that’s on the prep cannot get to the zirconia crown because the Z-PRIME Plus blocks it. You don’t have to worry about contamination of the crown anymore, meaning that as soon as you’re happy with the contacts and the occlusion, you just take the crown out, rinse the inside with water, dry it, and then use your resin cement. That’s actually the easiest way to do this whole procedure. So hopefully you don’t have too many more failures like this; and if you do, you’ll know what to do.

– Mike

Dear Dr. DiTolla,

I’ve been through a few of your videos and courses, and I am impressed with how well your techniques for crown and bridgework have improved my clinical experience. The only question I keep asking myself concerns your material sequence for taking impressions for crown preparation. Is it:

  1. Light body and medium body;
  2. Light body and heavy body/putty;
  3. Or, medium body and putty?

I would be most grateful if you could shed some light on this matter.

– Peter Korpal, BDS
Dublin, Ireland

Dear Peter,

I use heavy body in the tray and syringe medium body around the preps. I’m not a big fan of putty because it’s not as accurate. I use the medium body around the preps instead of the traditional light body because a higher tear strength is needed with the two-cord technique.

– Mike

Dear Dr. D,

I’ve enjoyed every episode of “Chairside Live.” I thoroughly enjoyed your recent all-day seminar in Louisville. You are as educational as you are entertaining. It’s rare that I attend a CE course that not only teaches me many good, usable ideas, but also has me laughing so hard that I’m crying. It was an honor to meet and talk with you.

I have a cementing question that I hope you can answer regarding when to use Ivoclean. We use it with all crowns and all cements. Let me tell you what we do and get your opinion.

The two cements I use are Ceramir® Crown & Bridge luting cement (Doxa Dental Inc.; Newport Beach, Calif.) and RelyX™ Ultimate adhesive resin cement (3M™ ESPE™; St. Paul, Minn.) with Scotchbond™ Universal Adhesive (3M ESPE). We use Ceramir with retentive-prep BruxZir crowns, crowns cemented on implants, and occasionally other crowns. We use Scotchbond adhesive and RelyX with almost all other crowns as well as short-prep BruxZir crowns. Our steps are as follows:

Ceramir: Clean the prep and crown; cleanse crown with Ivoclean; and seat crown with Ceramir.

RelyX Ultimate: Clean the prep and crown; cleanse crown with Ivoclean; etch the prep (optional); place RelyX Ultimate on the prep and in the crown; and seat the crown with RelyX.

So, you see, my steps are cement-dependent rather than crown-dependent. I don’t want to use Ivoclean if I don’t have to use it. I believe the real process should be more crown- and cement-dependent rather than just decided by one factor or the other.

Do you have a rule that will explain the use of both types of cements and all types of crowns — BruxZir zirconia, IPS e.max® (Ivoclar Vivadent), PFM and cast-gold (by the way, we don’t fabricate gold units anymore, but they do require recementing on occasion)?

– Dan Carroll, DMD
Louisville, Kentucky

Dear Dan,

Thanks for your kind words!

Let’s look at Ceramir first. Ivoclean does not need to be used with Ceramir, but it won’t hurt anything if you do use it. As Ceramir does not need phosphates to bond to BruxZir, there is no need to remove the salivary phosphates in order to replace them with the phosphates in the zirconia primer. The same holds true for IPS e.max, PFM and gold: There’s no need for Ivoclean or any sort of silane or primer with Ceramir.

For RelyX Ultimate, we need to use Ivoclean to remove the salivary phosphates from the internal portion of the crown; or with BruxZir, PFM or gold crowns, we can sandblast with a 50-micron alumina oxide particle for 15 seconds instead. Because sandblasting is contraindicated for IPS e.max, we are limited to using the Ivoclean. After removing the phosphates, we are going to place a primer. Use a zirconia primer, such as Scotchbond Universal Adhesive or Z-PRIME Plus, for BruxZir crowns; use a ceramic-silane primer, such as Scotchbond Universal Adhesive or RelyX Ceramic Primer, for IPS e.max crowns; and use Z-PRIME Plus or Monobond Plus as a metal primer. Monobond Plus will also work for both all-ceramic materials because it contains a zirconia primer and a ceramic silane in the same bottle.

As you mentioned, RelyX Ultimate allows you to not etch at all, selectively etch the enamel, or etch the whole prep based on retention needs. Nonretentive preps such as veneers, Maryland bridges, inlay bridges or onlay bridges definitely need the whole prep to be etched.

You are now going to place the primer. For example, with Scotchbond Universal Adhesive, place it on the prep surface with a brush and agitate it for 20 seconds. Use a gentle stream of air for five seconds to evaporate the solvent, and then, because this is an indirect restoration, don’t cure the Scotchbond Universal Adhesive yet. Place the RelyX Ultimate in the crown and seat it. You can either clean it up before curing or place glycerin on the margins while curing to prevent the 50-micron air-inhibited layer. This is more work, but most feel it leads to a more esthetic result. Conversely, you can also spot-cure the cement for a second or two and begin to clean it up that way, as most dentists do.

So, Dan, that’s my long-winded way of telling you that you are doing exactly what you are supposed to be doing. Keep up the good work!

Best,

– Mike

Chairside Magazine: Volume 10, Issue 2

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