An In vitro Study to Evaluate and Compare the Dimensional Accuracy of Poly (Methyl Methacrylate) by Injection Molding and Conventional Molding Technique

Introduction Poly(methyl methacrylate) is widely used as denture base material due its better physical properties, ease to fabricate, and repair. Despite being the material of choice for the denture fabrication, dentures made from poly(methyl methacrylate) may exhibit dimensional changes due to volumetric shrinkage. This further affects the retention of the denture. Various methods have been used to overcome this problem. One such method is the use of injection molding technique. So, a study was planned to evaluate the efficacy of dentures processed by injection molding technique in reducing the volumetric shrinkage. Objective To evaluate and compare the dimensional accuracy of poly(methyl methacrylate) resin processed by conventional and injection molding technique. Materials and Methods A total of 90 samples were made. Half of the samples (45) were fabricated by compression molding and half (45) by injection molding technique. Dimensional change was studied at three equidistant points in posterior region with the help of digitized travelling microscope. Statistical analysis was done using student’s t-test. Result Dimensional accuracy of injection molded poly(methyl methacrylate) resin was greater than that of compression molded poly(methyl methacrylate).