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Dear Dr. DiTolla,

I was planning to do a resin-retained (Maryland) bridge on a patient of mine to replace tooth #4. Tooth #3 has an occlusal amalgam and a weak MF cusp, for which I plan to do a MOF onlay preparation. Tooth #5 is virgin, so a distal rest and lingual wing are also planned. I would like to use Prismatik Clinical Zirconia™ or Cercon® (DENTSPLY Caulk; Milford, Del.) for this case, but I need your expertise on preparation design and material choice. I spoke to a lab technician already but want information from the head honcho. Mahalo.

– Todd R. Okazaki, DDS
Haleiwa, Hawaii

Dear Todd,

You have three Maryland bridge choices, none of them great as a permanent restoration.

Your prep design ideas are excellent: Go with the MOF onlay prep on tooth #3 and the distal rest/lingual wing on tooth #5.

Choice 1: PFM with metal wings and ceramic pontic tooth #4. The upside is you can bond to the metal with resin (alloy primer with Kuraray Panavia™ F [New York, N.Y.]); the downside is the MOF on tooth #3 is ugly if you can see it when the patient smiles.

Choice 2: Composite reinforced with fiber (Kerr Premise™ Indirect [Orange, Calif.] with Vectors® [Ivoclar Vivadent; Amherst, N.Y.]). The upside is that any resin cement will bond with it because it is resin; this will give you the best bond strength. The downside is that the bridge is weaker than the PFM Maryland.

Choice 3: Zirconia bridge (3M™ ESPE™ Lava™ [St. Paul, Minn.]). The upside is that the bridge is as strong as the PFM and better looking. The downside is you can’t bond to zirconia, even with Panavia F or Parkell C&B-Metabond® (Edgewood, N.Y.). It might be tough to get the distal rest and the lingual wing to bond to the tooth.

As you can see, there is really no right answer, per se. When my patient declines a single-tooth implant and we decide to use a Maryland bridge, I usually tell them that it is not a permanent restoration like a fixed bridge or an implant. When they agree to that concept, I will usually go with either Choice 1 or Choice 2, based on their esthetic needs and the size of their smile, thickness of their anterior teeth, so on and so forth.

I have tried a zirconia Maryland bridge or two and have not had good luck. Bisco claims its new bonding agent for zirconia, Z-PRIME™ Plus (Schaumburg, Ill.), will bond resin to zirconia, but I haven’t seen any independent confirmation of this yet. We are currently testing it in our R&D Department at the lab to see if we can observe an increase in bond strengths.

I hope that helps!

– Dr. DiTolla

Dear Dr. DiTolla,

Thanks for the input. I’ve decided to go with a resin-retained bridge for the following reasons:

1) The patient cannot afford an implant.
2) The patient is female with no evidence of parafunctional habits.
3) The location of the bridge.
4) Its conservative nature.

I prepped the case today. Tooth #3 ended up being an MOL inlay. The MF cusp appears to be strong. I was wondering, because the weak link appears to be the bond strength to zirconia, is it possible to incorporate female potholes (micro ones) into the internal surface of the zirconia so my cement (C&B-Metabond) can fill in the females and lock in the bridge mechanically? That is, use mechanical rather than adhesive retention to the zirconia. Why use Lava instead of Prismatik Clinical Zirconia or Cercon? Is it because it can be colored? My experience is that Lava is the most esthetic, but your lab tech recommended Prismatik CZ. Also, would you be able to send me a sample of Z-PRIME? By the way, it would be an honor if you used my name in your magazine — only if you send me an autographed copy, though. Thank you for sharing your great practical ideas. Mahalo.

– Todd R. Okazaki, DDS
Haleiwa, Hawaii

Dear Todd,

Typically the wings on a Maryland bridge are too thin to place retentive potholes.

We only have one sample of Z-PRIME at the moment and it’s in the hands of R&D to test how well it works. Perhaps Bisco would be willing to send you one?

I tend to use Lava as an example of a zirconia-based material because it is familiar to most dentists. Our Prismatik CZ is colored the same way.

Thanks for letting us use the letter, and I promise you’ll be receiving a signed copy of the magazine! Take some great before-and-after pictures and they might find their way into Chairside®, too.

– Dr. DiTolla

Dear Dr. DiTolla,

I’ve been in practice since 1971. Recently, I’ve been having issues with missed mandibular blocks. At first I thought it was the anesthetic; then I started to think I was at fault. So I started researching my old anatomy books to see if my technique slipped, and I even got ahold of some CAT scans to study the anatomy again.

But then the article by Dr. William Forbes showed up in Chairside and it was very enlightening! I was giving my blocks too low! The photos and diagrams were very helpful in regaining the proper technique for the mandibular block. Once I started to give them higher, I was back on track to good anesthesia. Thank you for a very educational article.

– Dennis J. Nowak, DDS
Orland Park, Ill.

Dear Dr. DiTolla,

I am concerned with not sealing exposed dentin, even for a short period of time. With dentinal tubules numbering in the tens of thousands per square millimeter and bacteria numbering in the billions in the oral cavity, not sealing this with some sort of temporary luting agent for any period of time seems unwise. Dr. Charlie Cox and others have shown the seal is the deal to prevent pulpitis, whether temps break or not. Do you agree? I am obviously an endodontist. I do a lot of RCTs on previous virgin teeth from “veneers,” 15 out of 20 on one patient — all teeth virgin to start with and then necrotic with radiolucencies within three to six months, with the dentist making her (a 24-year-old) a long-term dental cripple. I see you do try to emphasize that you are not prepping into dentin as much, but most dentists need to have the idea of protecting the pulp jammed into their brains. Remember, whatever you tell them will get applied to almost any restorative situation!

– Anonymous

Dear Dr. DiTolla,

I just wanted to say thanks for the help your clinical videos have provided throughout the years. I just cemented my first BruxZir® crown and it was sweet! The patient loved the combo of high strength and tooth-colored material. Keep up the great work!

– Ray A. Morse, DMD
Panama City, Fla.

Chairside Magazine: Volume 5, Issue 2

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