Comparison of Water Sorption of Two Injection Acrylic Resins with a Conventional Pressure-Packed Acrylic Resin

Background and Aim: Water sorption is one of the most important properties that affects the quality of a prosthesis, and subsequently, the quality of treatment, and patient’s quality of life. The aim of this study was to determine and compare the water sorption of two types of poly methyl methacrylate (PMMA) using the injection-molding systems with a traditional acrylic resin base material. Materials and Methods: In this in vitro, experimental study, three groups of PMMA (n=10), consisting of two groups of injection molded PMMA samples (Vertex Castavaria and Ivo-Base High-Impact) were used for two different injection molding techniques and one group of conventional pressure-packed PMMA (Meliodent Heat Cure) was used for the conventional pressure-packed technique. After processing, 30 specimens were stored in distilled water at 37°C for 30 days. The water sorption test was then performed. Statistical analysis was carried out using SPSS version 23.0 via the Kruskal-Wallis and Mann-Whitney tests (α=0.05). Results: The mean value of water sorption was 17.88±1.08 μg/mm3 for IvoBase specimens, 28.45±2.19μg/mm3 for Vertex specimens, and 21.76 ±3.26 μg/mm3 for Meliodent specimens (P<0.001 for Ivobase-Vertex, P <0.007 for Ivobase-Meliodent, and P<0.001 for Vertex-Meliodent). Conclusion: Water sorption of IvoBase was significantly lower than that of other materials. Despite such a significant difference, all of them completely fulfilled the requirements of EN ISO 20795-1:2008.