Howdy all! I'm writing from my Dad's computer in the Big City. It is
attached to the Videotron network, and so, even using Web based Google
Groups to spy on all o' youse, it goes fast. That's why I'm answering
you here.

In unrelated news, I saw one guy on veneers today at the ODQ/FDI
congress and I found him quite good: Gerard Kugel (sp?) at Tufts U. One
of the things he said was to not ignore the effects of DRY MOUTH on the
longevity of our hard-won restorations. In fact this is one factor
which seems to be coming up in some of the lawsuits ovah theah in USofA
land.

He also says that if you have to prep for a three quarter crown to get
decent esthetics, do a crown instead and save the headaches. Remember
that when one of those thick preped veneers fails (eg: Ivoclar stuff),
often the only recourse is full coverage, and the patient has to
understand this before any preps are done.

I asked him if there is any decent book description of the type of
preps one wants to have, and he said that there probably were, but the
Proctor and Gamble (!) website will undoubtedly have refrences to good
dental preps for veneers. So, what does Proctor and Gamble make that
puts them in the position of being recommended by a (supposed) unbiased
educator?

Other things: ideal preps often wrap the incisal, but should not end on
a centric occlusive stop (wear/Fx); Try to not wrap the incisal of an
upper canine unless there is no alternative and if this is the case,
consider good ol' porcelanine fused to metal crown;

use LIGHT CURE adhesive systems in the anterior and do your veneers two
by two so that the same bonding/esthetic conditions exist for both (ie:
if you did the UL central/lateral, and then did the UR central/lateral
subsequently, the esthetics could come out not the same, especially for
the centrals, especially if you're using dual cure stuff). Another
advantage of light cure stuff is that you can take your time and
reposition if it didn't sit down properly the first time, and clean up
before blasting it with the light. This is also indespensible for
checking for voids in the bonding material. If found, TAKE IT OFF AND
START AGAIN: where there is a void, there will be a crack. He likes
CLEAR light cured adhesives wherever possible, as they don't change the
look of the veneer. He spot cures the CERVICAL AREA FIRST, as  that is
where the problems will arise, and so it makes sense to start there, so
the stuff doesn't contract out of the area.

He likes the bis-acryl stuff as temp material, and he usually doesn't
have to bond or cement it: the natural contraction will hold it in
place, especially if you're doing the upper six anteriors, say, with
incisal coverage. You do the temp out of a silicone matrix made from
the waxup and leave them all together. He gives them an Endo syringe
with chlx in it and asks them to run it around the cervical but to try
not to get it on the temps. (I would give them microbrushes for this).

You make a silicone impression of the wax-up and cut it horizontally at
the junction of the incisal, middle and cervical thirds of the
centrals. These strips of material will show you as you prep if you
have the required reduction, especially in difficult areas (just
eyeball it, I guess).

For those of us who don't do many veneers, use depth reduction
indicator burs such as the ones that Brassler (who else?) makes. He
likes the Brassler LVS-3 and LVS-4 for completion after depth
indication prep.

His preferred try-in paste? Water (di-hydrous monoxide; or at the
limit: H3O+).

Preps should not need to be more than 0.8 to 1.0 mm deep, and should
ALWAYS end in enamel.

There are situations where the occlusion/inter-arch relation will not
permit you to veneer... Tough titties.... Crown 'em. Speaking of
occlusion, he likes the Dawson school. I asked about Okeson, but he
didn't really know it well and said so.

Anyway, I told him it was a good lecture and that a further education
for his students after they got out of jail is to get on the newsgroup
called 'sci.med.dentistry' and read and contribute. (Perhaps some of
youse have heard of it....). I wrote it down for him and he said he had
heard reference to it. But of course, his caveat emptor was that all of
those things were only anecdotal. That may indeed be true, but the
anecdotes from highly experienced wet-finger dentists adds up to more
that just chest pounding. I repeated to him how advice asked for and
gotten here had often saved cases from being referred out of this
little office.

Re the bis-acryl stuff as temp material: I went downstairs to the
slaughterhouse and stopped at the Kerr booth. I asked to try their
FILL-IN material (crowns, veneers, in/onlays) and she whipped out a
prepped model and an acrylic temp matrix. I took the double syringe
contraption and syringed it into the temp and placed it on the model.
You want ten seconds working time and 25 seconds on the tooth. Well,
after about thirty seconds or so, I took it off and placed the matrix
loaded with FILL-IN up to the corner of my eye (the skin is very
sensitive to heat there).

I can tell you from that experience that bis-Acryl temp materials (at
least FILL-IN) DO exhibit an EXOthermic reaction on hardening, and so
those of us who feel that these materials will circumvent heat damage
to teeth while making temps are perhaps not exactly right. The best
test would be to do one of those FILL-INs and then do one exactly the
same with SNAP or TRIM.

Now, that's enough, already. Since I'm on my Dad's rocket-driven
computer with the ultra-quick connection, I feel it is only fitting
that I go see the QuickTime Trailers on the Apple site.

Thanks youse, and good nicht to all o'youse.  ;-)

SP