Page 69 - CEREC Q4|2012

quarter 2 | 2013 | cerecdoctors.com | 65
Thomas Kauffman | Atlanta, Ga.
I think your preparation design needs some
refinement. Here is an example of a first molar
prepped last week.
Preparation smooth-
ness leads to easy
scanning and great
fit. It is not so much
dependent upon what
burs you use but how
you use it. There
are many very good techniques for polishing anything,
including dentin and enamel. I am not convinced that
low speed is any better than high speed, mid-speed or
moderate speed. Just remember that the slower the RPM,
the more heat is generated. Sometimes it is easier to apply
a small layer of RelyX resin or other material at the pulpal
floor or other areas to provide that glass-like smoothness.
This photo was prior to final margination and scanning.
At this point, I give the preparation on the bicuspid and
second molar a C+, first molar a B+. At least it will give
you a comparison. Diamond, carbide, hand instrumenta-
tion, disc, clockwise, counterclockwise, et al. There are
many paths to the resultant image data being gathered.
Best margins in the world, tooth surface as smooth as glass
with no roughness or irregularities. That is, and always
will be, the key to a great result with CEREC.
James Kim
[In response to Gregory Mark] Thanks for the bur
info! My last five have seriously dropped in with
zero adjustments! Is there a bur that is in between the KS6
and KS0? Because the KS6 is almost too wide for my pref-
erences. I looked on Brasseler's website but couldn't find
anything.
Sameer Puri (cerecdoctors.com Founder)
#6 or a #8 round bur on a slow speed handpiece.
Kevin Potts
Barely noticed that this thread got resurrected.
So, I feel that I should give an update on my
personal progress.
ITWAS MY PREP!
That led to the fact that my margins were hard to define
virtually. The first thing I switched to was using a #6 or #8
round bur inmy slowspeed set at 30kRPM. It's very smooth
and requires very little pressure ... as in darn near no pres-
sure. Only touching the very edge of the prep to ensure no
enamel lip and keeps heat transfer down. Gotta use sharp
burs to make that work.
Second thing I needed to work on was axial wall regu-
larity more than smoothness. Easy enough to focus on.
Third was getting the axial-occlusal angle to a rounded
edge around the whole prep. I tried a number of egg/
football shaped diamonds but got faceting that didn't
satisfy as often. So, I started using a bur that I had plenty
of from years in the past. It's a weird bur. I believe it was
intended to create the shape of marginal ridges for inter-
prox composites. It's like a cone with a gradual inverted
curve. Works like a champ for me more often than other
solutions. I wish I knew the name of the bur so I didn't
sound like a moron.
Then, since the prep is somuch cleaner, I fixed the wonky
margination I was doing by:
1. Using only manual mode
2. Initial margination from occlusal
3. Revising margin line at a 45-degree angle or so, and
4. Making sure that I have a regular and smooth surface
that I am ending my crown on
So, in review, it was purely user error. The machine is
what it is: a machine. A highly sophisticatedmachine with a
newbie user. Might as well handme a Lambo to take around
a track at top speed. It has humbled me as a clinician. And
has made me better for it.
I now consider my use of CEREC as 90 percent fun and
rewarding and 10 percent maddening. But that 10 percent
is other stuff that I need training on or need to be better at.
And this forum has been unbelievably helpful in that
process!
Sameer Puri (cerecdoctors.com Founder)
Awesome Kevin!