Investigation of nanohardness values of dual-cure, bulk-fill composite resins at different time intervals

Abstract

Aim: The aim of this study was to evaluate the surface hardness of dual-cure, bulk-fill composite resins at different depths and time intervals using nanoindentation.
 Methodology: In the study, a comparison was conducted of the nanohardness values of Fill-Up, HyperFIL, and Cention N dual-cure, bulk-fill composite resins in the experimental group and Reveal HD, a light-cured, bulk-fill composite, in the control group. The dual-cure, bulk-fill composites used in the experimental group were divided into two subgroups. The first group was polymerized with an LED light source, and the second group was chemically polymerized in line with the manufacturer's instructions. The dual-cure composite resins were prepared in two different depths, 5 mm and 10 mm. In the control group, specimens with a depth of 5 mm were prepared, and their polymerization was provided by an LED light source. The nanohardness values of the lower and upper surfaces of the samples were measured using the Hysitron TI 950 Triboindenter 24 hrs and 7 days after polymerization.
 Results: Following statistical evaluations, no statistically significant difference was found between the nanohardness values measured 24 hrs and 7 days after light or chemical polymerization of the dual-cured, bulk-fill composite resins. It was observed that light polymerization of HyperFIL and Fill-Up dual-cure, bulk-fill composite resins had no effect on nanohardness values. When Cention N dual-cure, bulk-fill composite resin was polymerized with a light source, higher values of nanohardness were obtained.
 Conclusion: It was determined that the investigated dual-cure, bulk-fill composites reached their final hardness after 24 hrs. In all groups, it was observed that the highest nanohardness values belonged to Cention N for both polymerization methods.
 
 How to cite this article: Bolgül B, Özdemir E. Investigation of nanohardness values of dual cure bulk-fill composite resins at different time intervals. Int Dent Res 2021;11(Suppl.1):19-25. https://doi.org/10.5577/intdentres.2021.vol11.suppl1.4
 
 Linguistic Revision: The English in this manuscript has been checked by at least two professional editors, both native speakers of English.