Effecf of thermal cycling on flexural strength and microhardness of the novel composite resin with alkaline filler in self-cured and dual-cured modes

Abstract

Background Different materials, such as amalgam and a variety of composites and glass ionomers, are used to repair caries, which require newer materials to be tested to determine their use. The new substance Cention N has been introduced as an alternative to amalgam restorations. Therefore, the aim of this study was to investigate the flexural strength and microhardness of this material in both self-cure and dual cure conditions before and after thermocycling.

Material and Methods For determination and comparison of Microhardness, 40 specimens of Cention N with 8mm diameter and 2mm thickness were prepared. Half of the samples were set by self-cured method and the other half were set by dual-cure method. The Vickers Microhardness test was performed once 24 hours later and again after 10,000 thermocycling. Three-point bending test was used to determine and compare the flexural strength of 52 specimens of 2×2×25 mm bar-shaped specimens. Half of the samples were prepared by self-cure method and the other half by dual-cure method. From 26 specimens of each group, 13 specimens were randomly selected and three point bending test was performed after 24 hours and for another 13 specimens after 10,000 thermocycling. Data were analyzed using two-way ANOVA and paired samples T test tests. (P < 0.05)

Results Statistical analysis showed that there was a statistically significant difference between the mean of microhardness in both of curing methods and at both evaluation stages and the mean of Dual-cure method’s microhardness was higher than the self-cure and microhardness after 24h was higher than after the thermocycling stage (P˂0.001). There was no statistically significant difference between the mean of flexural strength in the two curing method) P˃0.05), but there was a statistically significant difference between the two modes of storage and the mean of flexural strength after 24h was higher than the mean in the thermocycling method. (P˂0.001)

Conclusions According to the results the microhardness of cention N in dual cure mode was higher than the self-cure mode, But the flexural strength in dual-cure mode was not significantly different from the self-cure mode. Ten thousand thermocycles significantly affected microhardness and flexural strength.