Forums Erbium Lasers General Erbium Discussion Hydrokinetics Article

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  • #2928 Reply

    Glenn van As
    Spectator

    Hi folks: I have recieved in PDF format the article from ESOLA that is 1.8mb large and I am willing to send it to people which came out from Hibst which says that Hydrokinetics isnt possible for ErCrYSGG

    IF you want the article emailed to you, please email me.

    I will forward it to those people requesting it Until this weekend….

    Feb 22nd is the last day.

    Glenn

    Reach me at glennvanas@shaw.ca

    You need Adobe Acrobat to open it and in addition it is 1.8 mb large.

    Adobe Acrobat is free and can be downloaded from

    Glenn” target=”_blank”>http://www.adobe.com

    Glenn

    #7311 Reply

    Swpmn
    Spectator

    Glenn:

    Wow that’s a big one! Go ahead and forward:

    dral@clearwatersmiles.com

    Al

    #7286 Reply

    lagunabb
    Spectator

    Glenn, received my copy of the paper. thanks. The pictures did not come through as you said. I would be interested in your PDF version if the pictures are clearer. Thanks again.

    #7306 Reply

    Robert Gregg DDS
    Spectator

    Perhaps Tom Haney can put his “clean copy” into a PDF file for all us interested folks?

    Tom?

    Bob

    #7299 Reply

    Glenn van As
    Spectator

    Bob: I sent it to you by email……….

    Glenn

    #7291 Reply

    lagunabb
    Spectator

    Glenn, thanks for emailing a cleaner copy of the article.

    It is a nice state-of-the-art review although no new experimental data were shown.  From the date of the article, it looks like Daniel Fried’s experimental observations were not yet available to Prof Hibst.  I think the mechanistic study by Fried is more relevant in terms of the effect of water on ablation rate.  Quoting Fried’ “The addition of water increased the rate of ablation and produced a more desirable surface morphology during enamel ablation with all the erbium systems.”   Futhermore, Fried’s numerical measurements of the size of the conical craters with and without water showed that ablated volume with water is about 10X (I screwed up on the math here, the number is actually 135X assuming conical shapes for the craters and that volume is proportional to r**2*h, 3/14/03) that of that without water.  Neither Fried nor Hibst offer any explanation of why that would be the case if the role of water is just cooling and cleaning.  

    I am optimistic that the ablation mechanism with water will be better understood in the near future as better 3D computational models of shock wave induced boundary layer separation become available.  I just wish these experimental research folks will attack these measurements more directly.  It is frustrating to see them try to solve for three unknowns (cooling, cleaning, ablation) with one equation.

    (Edited by lagunabb at 7:47 am on Mar. 14, 2003)

    (Edited by lagunabb at 9:09 am on Mar. 14, 2003)

    #7300 Reply

    Glenn van As
    Spectator

    Hi Ray……..I am trying to tone down my remarks regarding water accleration and other assorted issues with various mechanisms of action. The water definitley seems to wash the debris away, cool the pulp and apparently it also is needed to rehydrate the tooth.

    I am glad you enjoyed the article and it was a fun read for me as well.

    All the best and I will keep my eye out for anything like this in the future.

    Glenn

    #7303 Reply

    Robert Gregg
    Participant

    Glenn,

    Thanks for the article!

    No need to tone down what you are saying, especially when you are right.

    I don’t believe for a second that water is doing the cutting with an Er:YAG or Er,Cr:YSGG.

    Turn the water and air off an Er,Cr:YSGG, like I did in Phoenix last Friday. SOMETHING sure as hell cut that extracted tooth! And it wasn’t water! Maybe it was……..no I’m not gonna go there, I promised Ray.

    My two cents.

    Bob

    #7301 Reply

    Glenn van As
    Spectator

    My pleasure Bob for the article. I am glad that things are calmer these days.

    Gonna post a couple of cool ones for you today.

    Glenn

    #7287 Reply

    lagunabb
    Spectator

    Bob: You went there. I can’t believe you actually played with a Waterlase ……. How dare you! If Del finds out, he is going to want a divorce and half the biz.

    I am with Glenn on this one as most are tired of this non-issue (why bother if erbiums cuts enamel faster with water as advertised and as Fried measured) although I am strictly interested from a technical point of view. Cheers.

    #7312 Reply

    Swpmn
    Spectator

    Hi Guys:

    A couple of weeks ago Glenn and I were discussing the “hydrokinetic” theory. This was prior to Glenn sending me Dr. Hibst’s article.

    I ran some tests in my office on extracted teeth using an Er,Cr: YSGG laser. Turned off the water but not the air. I found that the Erbium laser ablated enamel and dentin efficiently without a water spray.

    However, I did not feel that the ablation rate was as rapid as what I see in the mouth using a water spray on vital teeth. Is it possible that my observations could be explained by the presumption that a vital tooth in the mouth would have a higher water content than extracted teeth sitting in a jar of water?

    Please feel free to rip me apart as you guys are so far ahead of me on basic laser science.

    Has a study ever been conducted comparing ablation rate with an Erbium laser on vital vs. endodontically treated teeth?

    Al

    #7304 Reply

    Robert Gregg
    Participant

    Allen,

    QUOTE
    Is it possible that my observations could be explained by the presumption that a vital tooth in the mouth would have a higher water content than extracted teeth sitting in a jar of water?

    I think you hit the nail on the proverbial head!!

    Bob

    #7297 Reply

    Glenn van As
    Spectator

    Hi Allen , what I see clinically with the scope at high mag, is that the tooth starts to char because if you dont have water to rehydrate the tooth the water gets eliminated after a few pulses and then it stops cutting.

    If you keep stopping, put a little water on the tooth and then cut dry it will cut at the rate you are used too.

    Glenn

    #7310 Reply

    Swpmn
    Spectator

    Thanks for your help Bob and Glenn. I think I’m starting to get the picture.

    Glenn, I’ve seen the charring you mentioned when playing around with different water settings. That’s a good idea you proposed.

    Al

    #7292 Reply

    lagunabb
    Spectator

    All,  According to Joseph Neev (formerly of Beckman Laser Institute and former editor of Lasers in Surgery and Medicine) charring a is direct consequence of the ablation rate not being high enough.  When that happens, the material (tooth in this case) heats up faster than material removal and charring occurs.  Water cooling doesn’t buy you much in this case unless it speeds up the ablation rate to the point where the hot material is removed faster than it can build up.  He gives a very nice and detailed description of the mechanism in US patent 6,156,030.  See equations 38 – 45 and Figures 5a – 5d.  I will give a quiz on the paper next week and I will treat you to lunch if you get 90%+ on the quiz.  Who will take the challenge?

    ps I can’t believe I am doing this on a Saturday night.

    (Edited by lagunabb at 8:51 pm on Mar. 1, 2003)

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