Dear Dr. DiTolla,
First of all, I want to thank you for helping
me with anterior crown preps! I, too, find
that as soon as I begin preparing, I lose
my frame of reference. I have tried various
depth measurement methods, but your
Reverse Preparation Technique is priceless.
Also, your in-depth video demonstration of
its use is outstanding. Thank you so much
for transforming my technique and for my
newly gained confidence in accurately doing
anterior crown preps in a timely manner.
I have a question for you: From the brief
view I got of your dental unit on your video,
it looks like you have an A-dec unit (Continental
style). Also, the electric handpiece,
if I viewed it correctly, is an A-dec/W&H
electric motor. However, I noticed that you
use the KaVo ELECTROtorque high-speed
attachment. I did not know that KaVo electric
handpieces were capable of connecting
to A-dec/W&H electric motors. Do you
need a special coupling/adaptor, or are you
able to simply snap it on the same way you
would if you used an A-dec/W&H electric
handpiece? Also, I have the same A-dec
unit plus A-dec/W&H electric motor, but
I use the A-dec/W&H electric handpieces. I
find them to be very good, but I must admit
I have never tried the KaVo ELECTROtorque
electric handpiece. Have you used or tried
the A-dec/W&H electric handpiece? If so,
how does it differ from the KaVo electric
handpiece that you use?
Thank you very much for your time. Again, I
enjoy watching and reviewing your instructional
videos!
- Larry Kolar, DDS
Chicago, Ill.
Dear Larry,
Thanks for the kind words!
The KaVo electric handpieces do snap
directly onto the A-dec motor; no
adapter is needed. I have never used
anything but KaVo handpieces, even
going back to my air turbine days, so
I guess that means I've been pretty
satisfied with KaVo.
I know KaVo is doing a special promotion
where, if you go to www.trykavo.com, they will send you an electric
handpiece at no charge that you can
snap on for a few days, prep some
teeth and see which one you like better.
Let me know what you think!
Best,
- Mike
Dear Dr. DiTolla,
I was wondering which is the strongest
anterior bridge material besides monolithic
zirconia? I have had failures with IPS
Empress® II and IPS e.max® (Ivoclar
Vivadent). Fractures usually occur when
patients unknowingly bite into a hard bone
(meat that is supposed to be boneless), or
forget they need to be cautious with the
restorations and chomp on something like
a hard baguette. The bridges in these cases
have had solid, broad connectors. Could
you comment on IPS e.max versus zirconia
with layered porcelains (e.g., 3M™ ESPE™
Lava™)? Is it possible to make the lingual
occlusion of an anterior maxillary bridge
in zirconia and layer just the facial with
porcelain, using the same concept of metal
occlusion in a PFM? I am sitting on a case,
so a quick response would be appreciated.
Mahalo for your input.
- Dr. Todd Okazaki, DDS
Haleiwa, Hawaii
Dear Todd,
Good question! First of all, you are
correct in thinking that monolithic zirconia,
such as BruxZir® Solid Zirconia
(Glidewell Laboratories), is the strongest
all-ceramic bridge material that we
have. This time last year, I would have
hesitated to recommend that a dentist
prescribe BruxZir Solid Zirconia
for an anterior bridge. The esthetic
nature of BruxZir restorations has
really improved over the last year, although
it hasn't quite caught up with
its monolithic brethren, such as IPS
e.max. An anterior PFM bridge is probably
the strongest solution, although
the ceramic material can certainly
chip off the metal understructure, and
the esthetics can be compromised by
the lack of translucency and possibly
exposed metal margins.
I am not sure I would want to go with
the zirconia-layered-with-ceramic option
you mention, as we have noticed
more chipping with that combination
of materials than we have with porcelain
fused to metal. In fact, porcelain
fused to zirconia would probably be
my last choice after BruxZir Solid Zirconia,
IPS e.max and PFM.
You also asked about making the lingual
of the bridge in solid zirconia,
similar to a metal lingual on a PFM
restoration. While we do fabricate
bridges like that on request from dentists,
we don't get many requests for it.
Perhaps the reason is that the strength
of BruxZir Solid Zirconia comes from
its monolithic nature – the fact that
it doesn't have any ceramic material
fused to it. As a result, it fractures and
or chips less than any other restoration
in the lab (except cast gold, of course).
When we do make a BruxZir restoration
like that, we typically place the ceramic material on the facial and
carry it from the gingival down to the
incisal edge, without wrapping the
incisal edge. We want to allow the
patient to function in protrusion on
the zirconia, rather than the porcelain.
But doing this takes it from being a
monolithic BruxZir restoration to a
bilayered restoration, which is more
prone to chipping.
While there are no absolutes, my first
choice today is IPS e.max for a 3-unit
bridge in the anterior on a patient
who does not show a lot of wear. For
that same bridge in a patient who
does show signs of wear, my choice is
BruxZir Solid Zirconia, especially if the
patient has previously chipped a PFM
restoration. As the size of the bridge
increases beyond 3 units, I begin to consider PFM as my choice because
of the superior strength of the metal
connectors when compared to any allceramic
system, especially when there
is a lack of room for the connectors.
As always, your mileage may vary.
Hope that helps!
- Mike
