Abstract:
Background: Polymethyl meth acrylate (PMMA) resin has been the most commonly used material for
denture bases, despite its popularity, PMMA resin is far from ideal. Polymerization shrinkage and release of
thermal stresses are the major disadvantages exhibited by the material. In an attempt to overcome dimensional in
accuracies of PMMA resin, new thermoplastic resins and alternative processing techniques have been
developed. Purpose: The purpose of this study was to evaluate and compare the adaption accuracy of two
commercial heat cured resins and an injection molded resin. Materials and Methods: a total of 21 accurate
denture bases with the same dimension were fabricated, 14 denture bases were made using conventional
compression molding technique (Acrostone, WHW plastic, England and Vertex regular, Zeist, Netherlands), and
7 dentures were processed using injection molding technique (Crystal, Bredent, Germany). The adaptation
accuracy was examined using universal measuring microscope. The gap between the resin base and stone cast
was measured at canine region and posterior palatal area at five points at 5 points, corresponding to the right and
left residual ridge crests, the midline, and the right and left marginal limits of the flanges. Results: The least total
gap score measured was for Bre-Crystal followed by Vertex- regular while the highest gap score was for
Acrostone group. However, there was no statistically significant difference between the Vertex- regular and
Acrostone groups. Conclusion: injection moulded PMMA resin showed superior dimensional accuracy
compared to conventional pressure packed PMMA resin.
