Curing process modification of a ‘self-cured’ injection molding material: Effect on surface hardness
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Abstract
Objectives: The objective of this study was to compare the surface hardness of a self-cured injection-molding denture base material, which its curing process was modified from that recommended by the manufacturer, when stored in water at 7 days and 30 days.
Materials and Methods: Ten rectangular specimens (10 mm x 64 mm x 2.5 mm) in three groups of injection-molding denture base materials were prepared from separate mix. The first group contained SR Ivocap® High Impact heat-cured specimens which were polymerized in water at 100°C according to the manufacturer’s instruction (Ivocap wet curing). The second group was IvoBase® Hybrid self-cured injection-molding specimens which were polymerized via the injection machine at 40°C up to120°C (IvoBase dry curing). The third group was IvoBase® Hybrid specimens which were mixed according to the manufacturer’s instruction but the processing method was the same as Ivocap wet curing. The Vickers hardness of the specimens were measured at 7 and 30 days of water storage. Split-plot ANOVA was used to analyze the data at α=0.05.
Results: The surface hardness of IvoBase® Hybrid when polymerized according to the manufacturer’s instruction and when polymerized with a modified method were not significantly different at both 7 days and 30 days storage in water. The surface hardness of IvoBase® Hybrid was significantly higher than that of SR Ivocap® High Impact. The hardness of IvoBase® Hybrid significantly increased when they were stored in water for a longer time from 7 days to 30 days. The surface hardness of SR Ivocap® High Impact significantly decreased with water storage from 7 days to 30 days.
Conclusions: The modified curing technique of IvoBase® Hybrid did not alter the surface hardness characteristics of the material. Time of storage in water had an effect on the material’s hardness differently. The hardness of the self-cured material increased with increasing storage time from 7 days to 30 days, whereas the hardness of the heat-cured material decreased.
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References
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