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Processing

Processing . Ideal denture base material: No trial packing needed Good shade match with surrounding tissues Dimensionally stable Complete polymerization Easily polished. Processing. Note: Master cast must be recovered from flasking for laboratory remount. Techniques Compression

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Processing

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  1. Processing • Ideal denture base material: • No trial packing needed • Good shade match with surrounding tissues • Dimensionally stable • Complete polymerization • Easily polished

  2. Processing • Note: Master cast must be recovered from flasking for laboratory remount. • Techniques • Compression • Microwave • Injection

  3. Processing Technique • Compression molding • Conventional method • More than 60 years • Time consuming

  4. Master cast Mounting (with casts already indexed on the bases) * Trim base of cast to the dimension that will fit in the processing flask prior to indexing

  5. 2 1 3 Split mold • Denture flask (ejector-type, three piece) • The drag (bottom) • The cope (middle) • The cap (thin top)

  6. Split mold

  7. Maxillary denture with the index in place and embedded in the flask Soap, or a gypsum separator, is used between the two pours of dental stone in the lower and upper portions of the flask.

  8. The surface of the third layer is left slightly rough to hold the fourth investment layer in • position. • Tinfoil separating medium is painted on the third layer. • The fourth investment layeris used to fill the remainder of the flask. The lid of the flask • is pressed into place while the investing stone is still soft. The flask is set aside for • min. 1 hr. before the wax elimination.

  9. Second pour (upper half of flask)

  10. Flask press

  11. Boil-out When the wax and shellac record base are completely warmed, the flasks can be opened. The teeth remain in the lower portion of the flask (left). The record base is soft and can be easily removed in one piece, along with any remaining wax (right). Both flask halves are thoroughly cleaned by rinsing with boiling water. The teeth are removed and also cleaned with boiling water. Ensure that the wax is completely removed by using a detergent.

  12. Placed in boiling water for 5 mins to soften the wax • Stiff, bladed instrument is used to open the flask.Upper portion of the flask is lifted as • vertically as possible to avoid fracturing the investment layers. • The softened wax is removed from the mold. Remaining wax is flushed from the mold • with a stream of boiling water. The mold is then cleaned with a soft brush and a • powdered detergent. Detergent is removed by flushing the mold with clean boiling water.

  13. Smooth all sharp edges and create an escape groove Feathered stone edges must be removed because they break off easily and can become embedded in the acrylic resin base material. A groove is made completely around the master cast for the purpose of allowing excess acrylic resin to escape (right). The surface of the dental stone in both halves of the flask is coated with a gypsum separating medium. Each tooth is carefully placed in its original position. Make under cuts in the acrylic resin teeth similar to the diatorics in porcelain teeth.

  14. Packing Mixing the acrylic resin I and packing the dough The autopolymerizing acrylic resin is mixed to a kneadable dough according to the manufacturer’s instructions (powder to liquid volume ratio usually 3:1) and placed in the cold flask halves in which the denture teeth are positioned.

  15. Trial packing (3000-4500 lbs over the entire flask area) • Use two sheets of cellophane between • two layers of resin dough to allow • opening of the flask without pulling • acrylic resin. • Trim excess acrylic and flash • Repeat until no excess is visible • Final closure of the flask halves is • accomplished without the intervening • sheets of cellophane • Heat cure in water bath with temp. set at • 160-165°F for at least 8 hrs. with constant • pressure

  16. 8 hrs 160-165 F

  17. Occlusal correction Laboratory Remount • to eliminate the processing error • depends on • Jaw relation technique • instrumentation

  18. Processing Technique Microwave System (GC America Inc.3737 W. 127th Street, Alsip, IL 60803) Use the split mold technique to form molds ACRON MC microwave cured acrylic Need special flask (resin + small metal screws) One minute microwaved to soften wax Eliminate wax from mold Three minute curing in microwave Leave 15-20 mins before opening flask Less VDO increase?? Easy to use Low water absorption

  19. Microwave system • Three minute curing in microwave • Fast, easy to use • Allows more efficient use of time • Produces denture in short processing time • Denture repair • Interim partial

  20. Processing Technique 3. Injection 3.1 Ivocap injection system, Ivoclar, Vivadent, Inc, Amherst, NY) • In Mid 1970 • VDO is more stable compare with conventional • Flask is closed during the procedure

  21. Processing Technique 3. Injection 3.2 Success System (Dentsply, International, Inc, York, PA) • PMMA Lucitone 199 • 90 PSI, use heat-polymerized resin

  22. Success Flasking or Investing After Boil out Flask is closed Divesting

  23. Flask in injecting unit Insert plastic nozzle De-flasking Master cast Recovery

  24. Master cast removed from invest material Finished denture

  25. Eclipseä Prosthetic Resin System (Dentsply) • Light-cured composite resin • New indirect build-up method for making dentures  • Flask-free and monomer-free • Conditioning Oven to warm models and materials • Melting Pot to prepare and melt Contour Resin • Electric Spatula to apply Contour Resin • Hot Air Gun to replace flaming • Eclipse Processing Unit to polymerize materials • Resin materials and supplies • Eclipse Bonding Agent            

  26. Dimensional change in CD fabricated by injected molding and microwave processing. Keenan, Radford, and Clark. J Prosthet Dent 2003;89:37-44.

  27. Deflasking Remove the flasking stone The denture can be deflasked as shown without damage. The silicone index can be easily removed. Denture after deflasking Because the denture was carefully waxed and a silicone index was used, finishing around the teeth can be readily accomplished.

  28. Remounting and Occlusal Equilibration After the dentures have been deflasked they are mount ed in the articulator without removing them from their casts. Small errors can now be seen that occurred during the flasking and polymerization procedures. Although there is very little shrinkage during autopolymerization, occlusal contacts may have been slightly altered. For this reason, the first occlusal equilibration is performed so that a clear cusp-to-fossa relation can be obtained

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