Re: New trend - CNC in Dentistry

[I read this article with interest. But one thing puzzles me. It refers to a
"small porcelain block" as the material carved to be used as a crown. But
this doesn't make a lot of sense to me. Is it fired porcelain, like toilets
are made from? This, besides being rather difficult to carve, would be
rather brittle in use, no? Or is it carved in the green state and quickly
fired? As far as I know (and my knowledge may be dated) crowns are cast in
gold first, then coated with "porcelain" enamel, a glass powder which is
carefully matched to the color of adjacent teeth, and fired onto the metal
to form an opaque and impervious coating. It seems more likely that a metal
tooth was actually carved by this machine, and the enamelling was done
before showing it to the patient, although the time-frame seems short for
that. No URL was attached for futher reference - is there a little more
detail on this anywhere?]

Andrew Werby
www.computersculpture.com


"jjfear" <jjfear@...> wrote:
Subject: New trend


I haven't posted for months, since my vision has deteriorated to the
point I no longer do shop work. But I ran across this post from
Andrew Tobias, author and investment, "expert?" But I immediately
thought of this group. So here it is:


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Daily Column

Ah, Brave New World of Dentistry
(And with this ring . . . )
Published on February 07, 2005

How I cracked half my molar eating a slice of tomato will go down in
The Annals of Dental Mystery as its own separate chapter. But when I
settled into his chair, my dentist announced that I needed a new
crown, which I always modestly accept, being the King of Patience.
Because we dental patients know the drill: First visit is for
preparing the tooth and making that delicious and oddly cold playdough
impression to send to the lab, and for installing the awful ill-shapen
and bad-tasting aluminum "temporary." The following week is for
getting that awful biting-the-inside-of-your-cheek deal going. Second
visit is for finding out that the lab didn't make the crown quite
right. Third visit is for - ta-da! - successfully fitting the crown
and handing over $1,000, give or take, for your regality.



No more.



Without even bragging, my dentist (who - a little journalistic probing
revealed once I was allowed to talk - is just one of 40 out of 7,000
in Florida to have this technology) wheeled over a cart with a control
panel and computer screen, displaying the 3D image of my tooth and
designing the crown right in front of me, like Leonardo Da Dentist.
Then, when it was perfect - get this - he clicked GO and sent the
instructions to a milling machine in the backroom, which set about
sculpting a small porcelain block into the precise crown that had been
specified.



Anyone under 30 will know this as "CAD/CAM" - computer-aided design /
computer-aided manufacture. But instead of milling the prototype for
a new carburetor, they were milling my tooth #14 (which I call Herbie).



(As you probably know, your teeth are numbered. You start with the
top right wisdom tooth way in the back, which is #1, and go all the
way around to #16; then drop down to #17, the wisdom tooth right under
#16, and back around to the right. Those of us whose wisdom teeth now
hang on leather bands around our necks [to intimidate potential
adversaries] count from #2 to #31, skipping #16 and #17. William "the
Refrigerator" Perry, who needs nothing around his neck to intimidate,
and is available to appear at your next event, seems to be missing #6
thru #11 and #22 thru #27.)



Within a second or two of my dentist's clicking GO, the computer
reported that milling would take 17 minutes - the way your browser
estimates the length of a download - which gave me time to return some
phone calls ("I'm at the dentist, but I have 13 minutes and 12 seconds
left to talk") and my dentist time to go out for a beer, or whatever
dentists do in these circumstances. (Call their brokers, more likely.)



In he came 17 minutes later, bing, bang, boom . . . and then . . .
after the ritual "bite down, chop-chop" so many of us are familiar
with ("No, it's still too high," you say, ten or twelve consecutive
times, feeling increasingly embarrassed and guilty for being so
difficult, when, really, what have you done wrong? But what if he
keeps drilling deeper and deeper to make the fit and goes all the way
through the crown to your nerve or - worse - breaks the crown and you
have to start all over again? Could it be you are just being
difficult? Or are setting your bite funny because of the Novocain?) .
.. . it was perfection.



A crown in a single visit.



To find a dentist near you who's made the $100,000 investment and
taken the training to master this system, click here. (The link's in
the box at lower right.) Despair not if you don't find one; the
listing is incomplete. Your own dentist may be off at CAD/CAM school
as we speak. Thank you, Dr. Nassery.