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Dear Dr. DiTolla,

I have been hearing that some doctors are routinely using laser gingival troughing, instead of gingival retraction cord, prior to taking a polyvinyl or digital impression. In my mind, laser troughing, particularly in the sensitive anterior area, could cause adverse esthetic gingival recession. In the posterior, recession would not be noticed. What are your thoughts on this? Also, do you have any thoughts on digital impressions?

– Igor Skalsky, DDS
Brunswick, Ohio

Dear Igor,

You have pretty much summed up my thoughts in your question. Any time I have tried to trough an anterior tooth with a diode laser prior to taking an impression, I can see I lose some vertical height of the tissue and slightly expose the margin that I already placed slightly subgingival. Then I have to drop the margin again, trough again and the cycle starts all over. I have not seen anterior recession as a result of the diode; the gingiva appears to tolerate it well. Regardless, I don’t use it for troughing on anterior teeth because of its tendency to expose the preparation margin. I still use the two-cord technique on all anterior teeth, although I will use the diode on anterior gingiva to correct uneven gingival levels.

In the posterior, I am much more likely to use the diode because we are in a noncritical zone for esthetics. If the tissue is healthy on a posterior tooth, I place an Ultrapak® #00 cord (Ultradent Products Inc.; South Jordan, Utah) as part of my Reverse Preparation Technique, and then my assistant packs the #2E cord on top of that one at the end of the prep sequence. If the gingiva is unhealthy, I will prep the tooth without retraction cord and use the diode laser at the end to trough. Retraction cord does not work well on boggy or bleeding tissue in my hands.

Digital impressions continue to evolve, but as of today, there are probably not a lot of good reasons to own a digital impression device that isn’t part of a full system that allows you to make same-day crowns in your office. Digital impressions definitely work, but you do have to keep the tissue in even better condition than if you were using a traditional silicone material. The CEREC® Omnicam (Sirona USA; Charlotte, N.C.) represents the state of the art right now, but it is clear that this technology will continue to get easier to use and more affordable. If you want to position yourself as a high-tech practice, you might want to hop on board. Glidewell gives doctors $20 off on every restoration sent to us via digital impression because we don’t have to make a conventional model, so that’s a great way to save on your lab bill.

Hope that helps!

– Mike

Dear Dr. DiTolla,

I just placed my first BruxZir® crown — no adjustments and perfect margins! Booyakasha! Thanks. May they all go so smoothly.

– Dan Siegel, DDS
Woodbury, N.Y.

Dear Dan,

Sweet! Quit now, and never be disappointed!

Actually, I find that nearly all BruxZir crowns drop into place with fewer adjustments than other crowns, and I am very confident your experience will be the same.

– Mike

Dear Dr. DiTolla,

On page 34 of the last issue of Chairside® magazine (Vol. 8, Issue 1), Figure 43, I think there is a significant error, in that it says BruxZir Solid Zirconia crowns do not have to be cleaned with the Ivoclean® solution (Ivoclar Vivadent; Amherst, N.Y.) before cementation with Ceramir® Crown & Bridge Cement (Doxa Dental; Newport Beach, Calif.). I checked it against information on your website (and what I have been doing for the past year or so). I think what it was meant to say is you do not need to “prime the zirconia” before using Ceramir.

– Michael Conte, DDS
Glenmont, N.Y.

Dear Michael,

Thank you for reading the magazine so closely!

That actually is not a mistake, although it’s very easy to see why you came to that conclusion. This is one of the more confusing areas of dentistry recently, although I will shoulder the blame for this one.

When I initially began using Ceramir, I noticed that it contains phosphates and assumed that was the mechanism through which it bonded to zirconia oxide. Six months later, the company heard me say that and corrected me. Even though there are phosphates in the cement, they are in such a tiny amount that they have nothing to do with how Ceramir bonds to zirconia oxide.

In short, you do not need to use the Ivoclean prior to using Ceramir. Since the mechanism of bonding between the Ceramir and the zirconia oxide is based on hydrophilicity and nanocrystalline formation (as opposed to phosphate groups), the salivary phosphates that attach to the internal aspect of a zirconia oxide crown do not affect Ceramir. If you were to use Ivoclean prior to Ceramir, it would not help anything, nor would it hurt anything — you would just be wasting a dollar or two. Zirconia primers such as Z-PRIME™ Plus (BISCO; Schaumburg, Ill.), however, will cause a large decrease in bond strength if placed on a zirconia oxide crown prior to Ceramir cementation. Ceramir is unique in its ability to be used without any additional treatment (cleaning or priming) of the zirconia oxide crown, and once you see how easy it is to clean up, there is a good chance it will become your everyday cement, like it has for me. I just cemented a BruxZir crown this morning with Ceramir and even had to remind my assistant that she didn’t need to use the Ivoclean and the Z-PRIME Plus.

Any cement with a resin component, such as an RMGI (RelyX™ Luting Plus [3M™ ESPE™; St. Paul, Minn.] and GC FujiCEM™ [GC America Inc.; Alsip, Ill.]), self-adhesive (RelyX™ Unicem [3M ESPE] and Maxcem Elite™ [Kerr; Orange, Calif.]), self-etch (Multilink® Automix [Ivoclar Vivadent] and Panavia™ [Kuraray Dental; New York, N.Y.]) or etch-andrinse (Nexus® [Kerr] and Variolink® [Ivoclar Vivadent]) needs to be cleaned after try-in with either Ivoclean or sandblasting. The internal portion of the zirconia oxide crown then needs to be treated with a zirconia primer, such as Z-PRIME Plus or Monobond Plus (Ivoclar Vivadent).

Lastly, you can also place Z-PRIME Plus inside the crown prior to try-in, make any adjustments, rinse and dry the crown when finished, and then cement it with any resin-containing cement without adding any more Z-PRIME Plus, or using Ivoclean or sandblasting. The hydrophilic end of the Z-PRIME Plus molecule with the phosphate groups attach to the zirconia oxide crown, and the hydrophobic end of the molecule keeps the saliva from interacting with the inside of the crown. That’s why you can simply rinse it off after try-in and go straight to cementation.

Hope that helps!

– Mike

Chairside Magazine: Volume 8, Issue 2

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