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  1. #1

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    Photosensitive dental composite

    A few weeks ago I chipped a tooth. I had it repaired today by my dentist, who is always happy when I chip a tooth--I think I paid for his new set of ping irons.

    Anyway, he applied a glob (technical term) of stuff (another technical term) to my tooth. I assumed it was an epoxy which would have to cure for quite a time before he could grind it down to match the old tooth. I was surprised when he pulled out a special light and the glob hardened in about 60 seconds.

    That's right, he used a photosensitive dental composite. According to the Teck who was working with it, it hardens in proportion to the amount of light it receives (I drove her crazy with questions.). This got me thinking (always a dangerous thing), could this be used to make photographs? After reading all I could about the material on the net, I assume it could be used to make a plate like making line drawings on circuit boards. The dental composite may turn out to be more interesting, however, because it can be molded into any shape.

    Any ideas?

  2. #2

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    The light generates free radicals that get the polymerization reaction going. I'll stick with silver for photography!

  3. #3
    Akki14's Avatar
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    "Free radicals" nice buzzword there. Most dental stuff uses UV light to cure, as far as I'm aware.
    ~Heather
    oooh shiny!
    http://www.stargazy.org/

  4. #4
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    Sounds remarkably like how Niepce made the world's first photograph, using bitumen of judea (asphalt, basically). I just wonder 1. if the amount of light coming through an aperture would be enough to selectively harden it, let alone in the right places, without any hardening of the wrong places, 2. what happens to the areas that receive some light, but not enough to fully harden it (in short, could it render continuous tone, or only half tone?), 3. if the undried portion will wash away cleanly, and 4. what sorts of colorants would mix with it.

    Oh yeah...and 5. How much does it cost?
    Last edited by 2F/2F; 07-29-2008 at 03:36 AM. Click to view previous post history.
    2F/2F

    "Truth and love are my law and worship. Form and conscience are my manifestation and guide. Nature and peace are my shelter and companions. Order is my attitude. Beauty and perfection are my attack."

    - Rob Tyner (1944 - 1991)

  5. #5
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    UV cure is quite common now. Most of our screen printed graphic inks are UV cure as is the encapsulant we put around components placed on flexible polyester circuits.

    To me, the most amazing use of UV cure I have seen is in the finishes applied to acoustic guitars. With traditional methods, the finish was applied then left for days or weeks to harden before polishing. With UV cure it can be sprayed, exposed to UV for a short while then polished immediately.


    Steve.
    "People who say things won't work are a dime a dozen. People who figure out how to make things work are worth a fortune" - Dave Rat.

  6. #6
    Akki14's Avatar
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    Quote Originally Posted by 2F/2F View Post
    Sounds remarkably like how Niepce made the world's first photograph, using bitumen of judea (asphalt, basically). I just wonder 1. if the amount of light coming through an aperture would be enough to selectively harden it, let alone in the right places, without any hardening of the wrong places, 2. what happens to the areas that receive some light, but not enough to fully harden it (in short, could it render continuous tone, or only half tone?), 3. if the undried portion will wash away cleanly, and 4. what sorts of colorants would mix with it.

    Oh yeah...and 5. How much does it cost?
    Physautotypes are a bit more like Niepce although that's technically the second process he tried out. I occasionally print phyautotypes in a more modern way using violin rosin for the bitumen element. They're a cheap and "easy" process to start out with but you need fan-cooled UV light for 5-6hours (and a positive instead of a negative to contact print).
    ~Heather
    oooh shiny!
    http://www.stargazy.org/

  7. #7

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    There are dental resins that change color when cured. The purpose of the color change is to confirm that the material is cured. The only colors I am aware of are pink and blue. Also, there is no way to arrest the process, as any of the visible wavelengths will eventually cure the material.

  8. #8

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    "To me, the most amazing use of UV cure I have seen is in the finishes applied to acoustic guitars. With traditional methods, the finish was applied then left for days or weeks to harden before polishing. With UV cure it can be sprayed, exposed to UV for a short while then polished immediately."

    BASF's 'Glasurit' line has a rather high-end polyurethane automotive clear coat in spray cans that can be buffed in 90 seconds IF you use the right UV lamp, goggles required.

    Welcome to the 21th century.

  9. #9

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    I hope someone will post a list of materials and sources. They may be interesting and useful in many ways not intended.

  10. #10

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    Quote Originally Posted by Akki14 View Post
    "Free radicals" nice buzzword there. Most dental stuff uses UV light to cure, as far as I'm aware.
    Buzzword, or not. That's how it works. I was trained as a chemist - before I got sidetracked by finance.

    http://en.wikipedia.org/wiki/Radical_polymerization

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