Denture Processing Overview

Denture Processing Overview

• Denture processing involves replacing a trial denture base and waxed portions with a final denture material, typically heat-cured acrylic resin.
• Successful processing requires satisfaction from both the dentist and the patient regarding the trial denture.
• The complete process involves steps like waxing up, flasking, wax elimination, packing, curing, cooling, deflasking, and finishing/polishing.

Waxing Up

• Waxing-up is the process of contouring the trial denture base by adding or carving wax to achieve a natural appearance.
• It aims to replicate the original form of the tissues in the patient's mouth.
• Proper contouring of waxed surfaces and the positioning of artificial teeth are essential for denture stability, aesthetics, phonetics, and support for the cheeks, lips, and tongue.

Flasking

• Flasking is the process of surrounding the cast and trial denture with stone or plaster inside a metal flask.
• The purpose is to create a mold for packing and processing the acrylic material.
• The flask should be larger than the casts.

Wax Elimination

• After flasking, the wax is removed by placing the flask in boiling water for a short period to soften it.
• The softened wax is then removed meticulously.
• Incorrect timing (longer than 3-5 minutes) can result in molten wax penetrating the plaster and causing problems later.
• Thorough cleaning of the flask halves after wax removal is crucial.

Packing and Curing

• The mold created by the flasking process is filled with acrylic resin, either by open flask or injection methods.
• The acrylic resin is mixed according to the manufacturer's instructions and packed in its dough stage.
• There are different curing cycles for the acrylic. These include short, long (slow), and rapid cycles, each with specific durations and temperatures for various thickness and desired results.

Cooling

• Cooling is essential to prevent distortion in the denture.
• The flask is removed from the curing chamber and cooled slowly to room temperature.

Deflasking

• Carefully removing the stone surrounding the dentures from the flask is called deflasking.
• This step requires gentle and controlled techniques to prevent breakage.
• Dentures are usually kept on their casts for laboratory remounting.

Laboratory Remounting and Grinding

• Remounting dentures on an articulator ensures proper occlusal relationships with teeth.
• Grinding procedures adjust the occlusion for centric, lateral, and protrusive movements.

Polishing and Finishing

• Abrasive stones are used to remove any excess stone.
• Finishing procedures smooth surfaces, edges, and frenal notches.
• Polishing smooths any edges and defects with brush wheels and wet pumice.
• The dentures are soaked in fresh water to leach out any remaining monomer.

Common Laboratory Errors

• Porosity: Incorrect packing, high temperatures, or lack of metal-to-metal contact.
• Crazing: Improper mixing, temperature fluctuations, or rapid cooling.
• Sandy appearance: Dry mixes, monomer evaporation, or delayed curing.
• Denture base/tooth breakage/nodules during deflasking: Improper techniques (knife blades, hammering), rapid curing/cooling.
• Stone adhering to the surface: Insufficient separating medium, medium contamination with stone or incomplete wax removal.

Specific Methods (Injection, Open flask)

• Injection method uses a fluid resin, allowing easier injection into the mold.
• Open-flask method requires packing the resin into the mold.

Curing Cycles

• Short cycle: Flask is in water for 2 hours, then 1 hour at higher temp. Faster, but risks porosity for thick dentures.
• Long cycle: Flask in water for 9 hours (overnight), followed by higher temp. Reduces porosity in thick dentures.
• Rapid cycle: Flask heated to a fast temperature rise in boiling water for 20 minutes. Faster option.

Materials

• Heat-cured acrylic resin is made with a powder (polymethylmethacrylate) and liquid (methyl methacrylate) components.
• Separating media and waxes are used in procedures to prevent sticking and damage during processing.

This quiz covers the essential steps involved in denture processing, including waxing up, flasking, and the materials used. It highlights the significance of achieving patient satisfaction and the final aesthetic result. Ideal for dental students and professionals looking to enhance their understanding of denture fabrication.