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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 l.jpg
Processing

  • Ideal denture base material:

    • No trial packing needed

    • Good shade match with surrounding tissues

    • Dimensionally stable

    • Complete polymerization

    • Easily polished


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Processing

  • Note: Master cast must be recovered from flasking for laboratory remount.

  • Techniques

    • Compression

    • Microwave

    • Injection


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Processing Technique

  • Compression molding

    • Conventional method

      • More than 60 years

      • Time consuming


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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


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2

1

3

Split mold

  • Denture flask (ejector-type, three piece)

  • The drag (bottom)

  • The cope (middle)

  • The cap (thin top)



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  • 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.


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  • 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.


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Second pour (upper half of flask) hold the fourth investment layer in


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Flask press hold the fourth investment layer in


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Boil-out hold the fourth investment layer in

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.


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Placed in boiling water for 5 mins hold the fourth investment layer in

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.


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Smooth all sharp edges and create an escape groove hold the fourth investment layer in

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.


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Packing hold the fourth investment layer in

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.


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  • Trial packing hold the fourth investment layer in (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


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8 hrs 160-165 F hold the fourth investment layer in


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Occlusal correction hold the fourth investment layer in

Laboratory Remount

  • to eliminate the processing error

  • depends on

    • Jaw relation technique

    • instrumentation


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Processing Technique hold the fourth investment layer in

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


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Microwave system hold the fourth investment layer in

  • 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


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Processing Technique hold the fourth investment layer in

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


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Processing Technique hold the fourth investment layer in

3. Injection

3.2 Success System (Dentsply, International, Inc, York, PA)

  • PMMA Lucitone 199

  • 90 PSI, use heat-polymerized resin


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Success hold the fourth investment layer in

Flasking or Investing

After Boil out

Flask is closed

Divesting


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Flask in injecting unit hold the fourth investment layer in

Insert plastic nozzle

De-flasking

Master cast Recovery


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Master cast removed from invest material hold the fourth investment layer in

Finished denture


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Eclipse hold the fourth investment layer in ä 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            


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


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Deflasking microwave processing. Keenan, Radford, and Clark. J Prosthet Dent 2003;89:37-44.

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.


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Remounting and Occlusal Equilibration microwave processing. Keenan, Radford, and Clark. J Prosthet Dent 2003;89:37-44.

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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After all centric contacts are established, the eccentric excursions are equilibrated and the protrusive and retrusive movements are ground free from interferences. The occlusion is then refined with carborundum paste. Only now should the dentures be separated from the casts.

Post-processing remount

The dentures are not yet separated. Dentures and master casts are remounted in the articulator.


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Checking the condylar guidances excursions are equilibrated and the protrusive and retrusive movements are ground free from interferences. The occlusion is then refined with carborundum paste. Only now should the dentures be separated from the casts.

The condylar guidances are still set at the patient’s individual condylar path angle.


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Equilibrating the occlusion in centric relation excursions are equilibrated and the protrusive and retrusive movements are ground free from interferences. The occlusion is then refined with carborundum paste. Only now should the dentures be separated from the casts.

Premature centric contacts

Polymerization shrinkage has caused a slight shift in the original cusp-to-fossa relations. Initial contacts are now premature or deflective, and must be selectively eliminated in order to restore proper intercuspation.

Below left: The occlusion is corrected with a round diamond stone. Avoid grinding the centric supporting cusps, which in complete dentures are primarily the maxillary palatal cusps and the mandibular buccal cusps.


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