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Troubles of heating cd

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Troubles of heating cd for Dr mohammed Elkhodary

Troubles of heating cd for Dr mohammed Elkhodary


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  • 1. Dr/ Mohamed Elkhodary Asso. Prof. of prosthodontic www.elkhodary.net [email_address]
  • 2. بالأمس .. yesterday و اليوم .. Today
  • 3. العقل البشري
    • عدد الخلايا 1000000000000 خلية
    • مجموع الوصلات 10000000 كيلومتر
    ماذا يعني ذلك ؟ !
  • 4. استراحة
  • 5. استراحة
  • 6. Troubles of heating CD: Processing errors
  • 7.  
  • 8. 1-Porosity:
    • a)Too rapid rise of temperature in the initial stage of curing
    • b)Thick denture bases heated too rapidly.
    • c)Lack of dough in the mold at the time of final closure.
    • d)Lack of adequate pressure during polymerization.
    • e)Packing the resin in a sticky rather than doughy stage.
  • 9. 2-Tooth movements
    • a) The use of plaster instead of stone in investing the trial denture .
    • b) Incomplete closure of the flask .
    • c) Excessive and rapid pressure during trial closure .
    • d) Over packing of the mold with resin material before final closure .
    • .
  • 10. 3 . Denture base and teeth breakage during Deflasking
    • a) Careless flasking( knife blade hit teeth when removing stone cap) .
    • b) Hammer used to tap denture out of the flask .
  • 11. 4 . Fractured or cracked teeth :
    • causes :
    • a) Improper Deflasking( use hammer)
    • b) Packing the dough in the rubbery stage the material too stiff .
    • c) Excessive and rapid application of pressure during trial packing .
    • d) Setting the teeth directly on the stone cast .
  • 12. 5 . Crazing of acrylic resin base or acrylic teeth :
    • crazing of resin consists of the formation of small cracks which may vary in size from microscopic dimension to the visible size it indicates beginning of fracture .
    • causes :
    • a) Stresses induced by the contraction of the resin around the tooth by rapid cooling .
    • b) The use of solvents to remove wax from the mold before packing .
    • C) Application of separating medium just before packing
  • 13. 6 . Bleaching of acrylic resin
    • causes :
    • a) Contamination of the acrylic resin with some acrylic solvents .
    • b) under cured acrylic resin due to incorrect time and temperature of curing .
    • c) incorporation of the tin foil substitute with the acrylic resin .
    • d) incorporation of the jelly like material of wet cellophane into the resin .
  • 14. استراحة
  • 15. استراحة
  • 16. 7 . color streaks in the resin material:
    • causes:
    • a) improper mixing of the monomer and polymer .
    • b) contamination of the resin mix with dirty hands or instrument .
    • c) adding resin material in layers during trial packing .
  • 17. 8 . Sandy appearance of the resin material :
    • Causes ;
    • a) Too much delay in curing after packing [ more than 12 hour ] .
    • b) Evaporation of the monomer liquid.
    • c) Insufficient monomer in the mix (packing of a dry mix) .
  • 18. 9 . Stone adhere to the surface of the denture:
    • Causes ;
    • a) Insufficient separating medium on the mold before packing .
    • b) The application of separating medium contaminated with stone .
    • c) Incomplete elimination of wax during washing out thus rendering separating medium ineffective .
  • 19. 10 . Space between the teeth and resin base:
    • Causes :
    • a) Delayed curing leaving the flask without curing for a long time .
    • b) The application of separating medium on the teeth
  • 20.  
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