unfilled resins...

Discussion in 'NBDE Exams & Licensure Exams' started by jassy08, May 26, 2008.

  1. jassy08

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    it is said that unfilled resins have a very high coff of thermal expansion... and low thermal conductivity... so it changes very slowly in response to hot and cold..... then how come it shows the maximun marginal leakage.. RELATED TO TEMP...
    I DONT GET IT...
     
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  3. dentheartthrob

    dentheartthrob DreamDMDweaver

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    a high coef of expansion means it expands more
     
  4. aphistis

    Moderator Emeritus

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    Thermal conductivity refers to the transmission of heat through the material, not the degree to which it distorts as it changes temperature. Unfilled resins are highly susceptible to thermal distortion. You're a dentist?
     
  5. ItsGavinC

    Dentist Moderator Emeritus

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    It's okay for dentists to ask questions, you know. :)
     
  6. aphistis

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    Better than not asking, I suppose.
     
  7. jassy08

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    yup i am d dentist... but that doesnt mean i can ask if i have a doubt.. after all this web site is to discuss doubts..I SUPPOSE....:rolleyes:
     
  8. mesha

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    Jassy 08 I agree with you nothing wrong with asking questions I am a dentist I find it very hard to understand the difference between thermal conductivity and co-offecient of thermal expansion it doesn't seem to be the same
    aphistis YOUR COMMENT IS NOT APPROPRIATE you would better take it back and apologize, we all make mistakes.
     
  9. aphistis

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    1) You're right, they aren't the same thing at all.

    2) Inappropriate? I answered the question fully, and I'm as entitled to ask questions as anyone else.
     
  10. jassy08

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    lets chill man... we are not here to fight... all is cool...
     
  11. ivorinedust

    ivorinedust Senior Member

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    Coefficient of thermal expansion and thermal conductivity are two different things. The first one deals with dimensional changes in the material with regard to temperature variations and the other one deals with how quickly a material transmits heat. Marginal leakage of a resin restoration, whether filled or unfilled, is more likely a result of the CTE, not thermal conductivity.

    Unfilled resins distort with temperature changes because of its high CTE relative to that of the tooth structure's. This distortion occurs when a patients eats a hot pizza and then follows it with an ice cold drink, for example. The resin expands with heat and then contracts as it comes in contact with cold, while the tooth structure remains relatively stable. This phenomenon is known as percolation. As this is occurs repeatedly, the marginal integrity of a restoration collapses and you have a leak.

    Anyway...who would fill a tooth with unfilled resin nowadays?

    Ivorinedust

    "Apolonia! You relieved my toothache!!!!"
     
    #10 ivorinedust, Jun 4, 2008
    Last edited: Jun 6, 2008

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