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Objective: To investigate color stability of a heat-cure, a self-cure, and a modified curing self-cure injection-molding denture base materials after immersing in distilled water and coffee for 7 days and 30 days.
Materials and Methods: Three groups of injection-molding denture base materials were fabricated as the disk specimens (diameter 50 mm and thickness 0.5 mm). Heat-cure SR Ivocap® High Impact were wet cured following the manufacturer instruction (100 oC for 35 min - Ivocap wet curing). Self-cure IvoBase® Hybrid were dry cured in an automated instrument, which the curing temperature started from 40 OC up to 120 OC for 35 min (IvoBase dry curing). The IvoBase® Hybrid material were also wet cured at 100 OC for 35 min (IvoBase wet curing). Ten specimens of each group were measured for baseline color (T0) using a spectrophotometer. Five specimens of each group were immersed in distilled water and the other five in coffee. The color values of the specimens were remeasured at the 7th day (T7) and at the 30th day (T30). The mean color differences (∆E) for the experiment groups were compared statistically by using Split-plot ANOVA, followed by Tukey’s honest significant difference (HSD) test at 5% level of significance.
Results: Color differences (∆E) of each experiment group were not significantly different when compared at the same immersion period within the same immersion solution (p>0.05). However, the color differences were significantly different between 7 days and 30 days of immersion for both immersion solution (p<0.05). The color differences were also found between the materials immersed in coffee and distilled water at the same periods of immersion time (p<0.05). Modified curing technique of IvoBase Hybrid material did not cause any significant color changes.
Conclusions: Longer immersion time and different immersion solutions resulted in color changes of Ivocap High Impact and IvoBase Hybrid. Modified curing of IvoBase Hybrid did not result in color changes.
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