Evaluation of the Effect of Addition of Poly Vinyl Pyrrolidone on, Dimensional Changes of Heat Cured Acrylic Resin Denture Base Material

Abstract

The most common materials used for fabrication of denture bases are poly methyl methacrylate (PMMA). Preparation of modified heat cured denture base acrylic resin was carried out by preparing of (PMMA)(80%) and poly vinyl pyrrolidon (PVP)(20%) and the liquid part composed of methyl methacrylate (MMA) monomer. A(10) specimens for each experimental group were tested . All specimens were cured by using short curing cycle (90 min.at 74C° followed by 30 min .at 100C°).Evaluation was made by measuring dimensional stability and accuracy of the prepared denture base material in comparison with the control denture base material . The dimensional accuracy of acrylic resin denture base is the main necessity ,where it effects the retention and stability of the denture .A silicon mold was used to prepare a(40) stone mandibular master casts (control and experimental). Acrylic dough was prepared and packed for processing ,the flask were closed with pressure technique and placed in clamps after final closure .Distances were measured between (3) points marked on denture bases before and after thermocycling for both control and experimental groups. For AB and BC distances the PVP had improved the dimensional stability and accuracy before and after thermocycling while for AC distance the control group material before and after thermocycling improved the dimensional stability and accuracy.