Message-ID: <003f01bebed5$a1d11be0$bded85c6@2thman>
From: "Barrett/Burns" <2thman@olympus.net>
To: "Lancair List" <lancair.list@olsusa.com>
Subject: Preparing for bonding
Date: Thu, 24 Jun 1999 23:39:46 -0700
Mime-Version: 1.0

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Mr. Seay wrote,

"Roughing up the surface does in fact INCREASE surface area.  The higher the
peaks
and valleys the more the surface area, hence the courser the sandpaper, the
rougher the
surface, thus the more the surface area. "

I used to believe the same thing - early titanium implants (dental) had
coarse threads and the devices were screwed into the bone for attachment.  I
stands to reason (I thought) that those threads would really hold the post
in place.  If all you've got is mechanical interlock, that is probably true.
A non threaded bolt won't stay in a hole the way a threaded one will.  But
when you begin to think about retention through a bond - chemical
ordinarily - surface area is the key to success.  That's why many of the
dental implants now are plasma coated with titanium - this gives a surface
similar to a micro etched surface - .  The guys that know say this provides
a much greater surface area than any deep grooves or cuts.  It's never been
explained to me in a way I can understand it, but I've come to believe and
know that it's true.  I'd bet that some decent theoretical mathematicians
could all agree on a formula to show this.  Whether the formula would mean
beans to me is another story entirely.

Regards,
John Barrett


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