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Letters to the Editor
“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 ® 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); the downside is the MOF
on tooth #3 is ugly if you can see it
when the patient smiles.
4
www.chairsidemagazine.com
Choice 2: Composite reinforced with
fiber (Kerr Premise Indirect with
Vectris ® ). 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 ). 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 ® . 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,
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