Modification of curing technique of a ‘self-cure’ injection molding denture base materials: Effect on flexural strength
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Abstract
Objectives: This study compared the flexural strength of a self-cure 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: Twenty rectangular specimens (10mm x 64mm x 3.3mm) were prepared according to ISO 20795-1:2013 for each experiment group. SR Ivocap® High Impact were wet cured at 100 OC for 35 min (Ivocap wet curing). 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). IvoBase® Hybrid were also wet cured at 100 OC for 35 min (IvoBase wet curing). Ten specimen in each group were immersed in 37oC distilled water for 7 days and the other 10 specimens at 30 days. At the end of the storage periods, three-point bending flexural strength test with a 5 mm/min crosshead speed was carried out using a universal testing machine. Nonparametric test (Kruskal Wallis and Mann-Whitney) was used to compare the flexural strength data.
Results: The median, 25th percentiles and 75th percentiles values of flexural strength of SR Ivocap® High Impact wet curing, IvoBase® Hybrid dry curing and IvoBase® Hybrid wet curing and were 61.5(61.2,63.1), 78.9(75.6,81.7) and 68.0(61.4,70.2) MPa, respectively for 7 days immersion; and, 62.6(59.2,63.6), 68.3(66.4,72.5) and 64.4(50.7,67.2) MPa, respectively for 30 days immersion. The flexural strength of Ivocap High Impact was significantly lower than that of IvoBase Hybrid (p<0.05). The flexural strength of IvoBase® Hybrid dry curing was significantly higher than that of IvoBase Hybrid wet curing. (p<0.05). The flexural strength of IvoBase Hybrid decreased when immersion in water up to 30 days.
Conclusion: Flexural strength of IvoBase® Hybrid was higher than that of SR Ivocap® High Impact but decreased for water storage up to 30 days. Alternative curing of IvoBase Hybrid did not improve its flexural strength.
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References
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