Effect of Different Curing Time on Degree of Conversion for Three Different Bulk-fill Composite Materials.

Abstract

This in vitro study was carried out to assess and compare the effect of different curing time (10, 20, 30, and 40 seconds) on the degree of conversion oftop and bottom surfaces of three different bulk-fill flowable resin based composite materials (FiltekTM, X-trabase® and SDR®). A total of 60 bulk-fill flowable resin composite samples were prepared for this study using specially constructed split-Teflon mold.They were divided intothree main groups (n=20) according to type ofbulk-fill resin composite used. Each group was further classified into four subgroups (n=5) according to curing time (10, 20, 30 and 40 seconds). Each subgroup was further subdivided into two classes (n=5) according to the surface assessed for the degree of conversion; the top surface and the bottom one of the cured specimen. The samples were then stored in a lightproof container for 24 hours at room temperature. Degree of conversion (DC) assessment of the tested samples was performed utilizing Fourier Transform Infrared Spectrometer apparatus (FTIR). Moreover, depth of cure was evaluated through assessing the DC of both the top and bottom surfaces of each sample. Statistical analysis was carried out using IBM® SPSS® program. The results of this study showed that all the three variables tested had statistical significance on the degree of conversion of bulk-fill composites. SDR® showed the highest statistically significant difference DC (%) value compared to Xtra-base® and FiltekTM.The 40 seconds curing time showed the highest statistically significant difference DC (%) value in relation to (10, 20 and 30 seconds) curing time. Regarding the assessed surface, the top surface showed the highest statistically significant mean DC (%) value in relation to the assessed bottom surface.