Fabrication of the Record Base

The record base is used:

• To establish jaw relations
  
• As a guide in setting teeth
  
• To simulate occlusal and esthetic aspects of the completed prostheses
  

• Withstand biting force
  
• Accurately represent the denture base
  
• Be dimensionally stable when placed on the cast
  

• Autopolymerizing resin, sprinkle-on
  
• Autopolymerizing resin, dough
  
• Light-cured resin

Preparing the Master Cast for Either of the Two Autopolymerizing Resin Techniques

All undercuts must be blocked out to prevent breakage and other damage to the master cast. Undercuts greater than 2-3 mm should be blocked out with pink baseplate wax; shallower undercuts can be blocked out with modeling clay or soft-curing resin.

To prevent the formation of air bubbles that can cause voids and resulting weakness in the resin base, the master casts should be immersed in water for at least 10 minutes following blockout of the undercuts.

A separating solution must be painted on the wet master cast and allowed to dry fully, in order to prevent the resin from bonding to the stone surface. Petrolatum is not an appropriate substitute for alginate-based separating media ("tin-foil substitute") as the final denture base may not cure properly if an oil-based lubricant is used.

Application of Autopolymerizing Resin

The polymer and monomer (powder and liquid, respectively) can be employed to fabricate the baseplate by one of two techniques:

• Sprinkle method
  
• Finger-adapted dough method