Dear Dr. DiTolla,
I am a fourth year dental student at the University of Florida and I love watching your clinical videos from Glidewell. I am interested in trying out your Reverse Preparation Technique bur block. Roughly how many uses can you get out of each bur on typical crown and bridge cases before it starts getting dull and need to be replaced?
- Anis Elkhechen, Dental Student, University of Florida
Dear Anis,
Nice to hear from you! Well, the workhorse bur is the 856-025 and I probably get three or four preps out of it. If I do the occlusal reduction with the football bur instead of the 856-025, I can get more uses out of the 856-025. I order the 856-025 in batches of 100 and just rotate it into the Reverse Preparation Kit as needed. I use the depth cutters slowly with light pressure to keep them from clogging and dulling quickly. I hope that helps!
- Dr. DiTolla
Dear Dr. DiTolla,
I'm not sure if I've come to right place to contact you on an educational level. I'm
graduating this year and have recently
been watching your clinical videos, which
I love! They are outstanding and very educational.
I wanted to ask you a couple of
questions. If you find the time to answer
them, I would appreciate it.
1) For porcelain (non-metal) restorations
I've been taught a shoulder margin is required.
Should I use a flat end bur for the
90-degree shoulder or is it appropriate to
use a rounded torpedo bur?
2) You use a round bur in one of your videos
to prepare the finish line for a veneer.
Is it ok if I stick with a round-ended taper
bur?
3) We work with light body and heavy body
silicone two-stage impression for preps.
After the putty impression, my teachers
make grooves and channels in the impression.
Is this necessary and what is the
point really? Why do you take both phases
at once?
4) With regards to the retraction cord, will
we leave the retraction cord for the first
stage and remove it for the light body
stage? I'm not really sure when to leave
the retraction cord in or take it out. I always
assumed to leave it in for however
long was required, then take it out and take the impression whether it's one stage
or two. What are your views?
Thank you very much, and if you manage
to answer any I am grateful.
- Alidad Daftari, Dental Student, London, United Kingdom
Dear Alidad,
Thanks for your kind words! To answer your questions…
1) For porcelain restorations, it is
preferable to have a rounded internal
line angle rather than a 90-degree
shoulder. The KR burs will achieve
this, and my favorite, the 856-025,will
do it as well. Both of these burs are
not quite as pointed as a torpedo
bur.
2) Yes, of course you can use a round
end taper bur for your margin formation.
I just find it really fast and
easy to use the 801-021 bur and then
use the round end taper (856-025) to
blend the margin with the rest of the
axial reduction.
3) The relief that your teachers are
having you put in the putty material
is to ensure the entire preparation
is surrounded with light body material
from the tray being able to seat
completely. I don't use putty at all,
actually; I use medium body as my
syringe material and heavy body in
the tray. Using putty is simply a costsaving
method that leads to more
problems than it is worth. Taking a
simultaneous impression where both
materials set together prevents several
different problems from occurring
and is the preferred method for
taking quality impressions, although
they may be slightly more expensive.
4) I refuse to take two-stage impressions.
It makes no sense to me. I
pack two different retraction cords:
a size 00 cord goes in the sulcus first
while I am preparing the tooth, and
the second cord (size 2 typically)
goes in when I am done with the
preparation. The size 2 cord stays in
for eight to 10 minutes and then is
removed, leaving the 00 cord in the
sulcus while I syringe the medium
body material around the tooth. At
the same time my assistant expresses
heavy body material into the tray
and then I seat that in the patient's
mouth. The 00 cord is removed either
after the impression or after the
temps are cemented.
- Dr. DiTolla
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 Anonymous,
I am concerned with not sealing exposed
dentin as well; it has always
been a shortcoming to the prepped
veneer/shrink-wrap temp technique.
As time went on, I began to apply a bonding agent to the dentin prior to
temporization, even though I knew
it could theoretically affect fit. I personally
have a case where I prepped
10 virgin teeth for veneers into the
dentin as I was taught, and three of
them ended up needing endodontic
therapy. After that case, I drew a
mental "line in the sand" and decided
not to expose dentin unless I
could care for it properly. Fortunately,
at the same time we introduced
Prismatik ThinPress™ ceramic material,
which made 0.3 mm veneers a
reality and made it unnecessary to
remove all of the facial enamel.
Are we really being conservative if
we are able to prepare teeth less, but
protect them less during provisionalization
and subject them to possible
pulpal death? Conservatism needs to
apply to the pulpal tissues as well as
the enamel, and today I believe that
by removing only enamel for my veneers
(and many times no enamel on
half the teeth), I may make a small
sacrifice in the pursuit of ultimate esthetics
to protect the long-term health
of the teeth. I doubt many patients
would say they want lobe development
and incisal translucency in their
veneers, even if it meant that some of
their teeth might need endo.
- Dr. DiTolla
