An injection molding device, improving the existing injection system for acrylic denture fabrication

Abstract

Introduction: The advantages of injection molding system (IMS) are precise adaptation of acrylic to master cast, continuous compensation of acrylic shrinkage, low porosity and better physical properties of dentures. Traumatic, toxic and allergic complications are reduced.

The existing IMS produces only one denture at a time. Using standard capsules leads to waste of material. Removable partial acrylic dentures (RPAD) with wire clasps haven`t been fabricated yet.

Materials and methods: The objective is to construct a device for serial injection fabrication of acrylic dentures optimizing both working time and cost of restoration.

The device should:

• provide a precise adaptation of material to master cast
• reduce residual monomer
• fabricate a lot of dentures for a short time
• fabricate RPAD with wire clasps
• optimize the amount of material

A prototype of the device is designed and constructed.

Results: The new device is based on the existing IMS.

The following improvements are applied:

• The serial fabrication is achieved by dividing the injection and polymerization process by including a specially designed cap which is fixed on the flask after acrylic injection. It provides continuous pressure during the polymerization process. This allows fabrication of large number of dentures at the same time, injected by a single pneumatic cylinder.
• RPAD with wire clasps are fabricated by fixing the clasps with cold-cured acrylics and mechanical retention in the master mast.
•  Capsules for multiple fabrication are  used.                                                                                               

Conclusion: A serial injection of large number of dentures as well as separate processing of each of them is possible at a time. The waste of material is reduced. Fabrication of RPAD with wire clasps is achieved.