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DIE MATERIALS AND DIE SYSTEMS

DIE MATERIALS AND DIE SYSTEMS. Die :POSITIVE REPLICA OF A SINGLE TOOTH the positive reproduction of the form of a prepared tooth in any suitable substance.

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DIE MATERIALS AND DIE SYSTEMS

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  1. DIE MATERIALS AND DIE SYSTEMS

  2. Die :POSITIVE REPLICA OF A SINGLE TOOTH • the positive reproduction of the form of a prepared tooth in any suitable substance. • Working cast: is a master cast that reproduces the entire arch including the prepared and unprepared teeth, relevant soft tissues, and edentulous areas. Die spacer : an agent applied to a die to provide space for the luting agent in the finished casting. Optimum thickness-20-40 micro meter Die hardner- cyanoacrylate resins • Die/ dowel pin : a metal pin used in stone casts to remove die sections and replace them accurately in the original position

  3. Various die materials 1. Gypsum Products (type IV and type V) 2. Metallic dies a) Electroplated dies b) metal sprayed dies c) silver amalgam

  4. 3. Resin dies a) Epoxy resins b) Acrylic resin 4) Die stone-investment combination 5) Flexible die material 6) Silico -phosphate cement 7) Ceramic dies

  5. GYPSUM PRODUCTS

  6. ADA specification No. 25 5 types • Type 1. Impression plaster • Type 2. Model plaster / plaster of paris • Type 3. Dental stone / Hydrocal • Type 4. Dental stone, high-strength / Densite/ Die stone • Type 5. Dental stone, high-strength, high-expansion

  7. Advantage of gypsum as die material • Compatibility with all impression materials • Easy to use • Dimensionally stable • Inexpensive Disadvantage of gypsum dies • Susceptibility to abrasion • Brittle prone to fracture

  8. Methods to increase abrasive resistance • Substitution of colloidal silica for water. • Treat surface with resin (epoxy, acrylic, styrene or cyanoacrylate) • Impregnating acrylic resin into stone die.

  9. ELECTROPLATED DIES Electro deposition of metal on the impression Metals generally used: Copper, silver

  10. Advantages: • Hard and abrasion resistant • Dimensionally accurate • Reproduce finer details • Prevent cuspal wear due to repeated contact with opposing cast

  11. Disadvantage • Difficult to trim • Not compatible with all impression materials • In Silver electroplating, hydrogen cyanide release can occur • Wax pattern cannot be as easily adapted as on stone. • Plating can some times tear from the cast during separation.

  12. Resin dies • They are self curing polymeric materials with fillers • eg: Epoxy resin dies Acrylic resin die Polyester resin dies • Not compatible with –Hydrocolloid or impression compound • Compatible with elastomeric impression materials

  13. Advantages • Reproducibility of details is excellent • Good abrasion resistance • Stronger than die stone • Compatible with most rubber base impression material • Easy to use & economical compared to electroplated dies

  14. Disadvantages • Viscous and does not flow readily • Not dimensionally stable & when kept beyond 24hrs, unsuitable for precision fixed prosthodontic procedure • Setting reaction is slow • Can not be used with water containing impression materials like agar and alginate

  15. DIE STONE –INVESTMENT COMBINATION DIES • Eg: Divestment (Whipmix corp)

  16. Advantage • Eliminates possibility of distortion of pattern on removal from the die. Disadvantage • Divestment gypsum bonded material not recommended for high fusing alloys

  17. Divestment phosphate (DVP) • Phosphate bonded investment • Used in same manner like divestment • Suitable for high fusing alloys.

  18. Die Separator Easy removal of wax pattern without damaging margins. Applied with brush excess to be removed with tissue paper Eg: Dielube wax sep (Dentecon Inc.)

  19. Die systems Working cast with separate dies Working cast with removable dies

  20. Working cast with separate die Simplest method of fabrication • Impression is poured twice • First only prepared teeth are poured • Then a full arch pour is done • First the wax pattern is fabricated on the die • Then transferred to the cast for checking contour, contact and occlusion.

  21. Advantages: • Easy to fabricate • Keeps relation between abutments fixed • better contours and emergence profile while wax pattern fabrication.

  22. Disadvantages • Wax pattern must be transferred from die to cast  destroy internal adaptation of wax • Some times difficult to seat wax pattern on the cast - Different impressions - Second pour –impression damaged - Different thickness of spacers

  23. WORKING CAST WITH REMOVABLE DIE The die is an integral part of the working cast and can be removed and refixed accurately back on to the cast.

  24. Advantage: • Convenient to use • Wax pattern need not be removed from die and transferered to the working cast Disadvantage: • Risk of introducing error in the pattern if die does not seat accurately in the working cast

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