Depth of Cure of Nanohybrid Composite Resins

When composite resins are light-cured, they undergo polymerization up to a certain depth.  This can be clinically significant, leading to marginal discrepancy, microleakage, sensitivity, and debonding. It has been conjectured that the new category of nanohybrid (nono-filled hybrid) composites may have greater depth of cure.  Objective: to compare the depth of cure of four nanohybrid composite systems, TetricEvo Ceram (Ivoclar-Vivadent, shade A3), Herculite Ultra (Kerr, shade A3), Filtek Supreme Ultra (3M-ESPE, shade A3) and Ceram-X Mono (Dentsply-Caulk, shade A3). Methods: Composite resin was cured with a halogen curing light @ 650 mW/cm2 intensity for 20 secs. The samples were then subjected to ISO 4049 scrape test and curing depth measured with a Boley gauge. Four groups of 10 samples each were tested:  TetricEvo Ceram (Group 1), Herculite Ultra (Group 2), Filtek Supreme Ultra (Group 3) and Ceram-X Mono (Group 4).  Results: The mean depth of cure for Group 1 was 4.80 mm, Group 2 was 4.00 mm, Group 3 was 3.95 mm, and Group 4 was 3.90 mm. The one-way ANOVA and Student-Newman-Keuls tests were used for statistical analysis. At p<0.05, there was no significant difference between groups 2, 3 and 4, but there was a significant difference between groups 2/3/4 and group 1. Conclusions: There was no significant difference in depth of cure of three of these nano-filled nanonybrid composite resins, but there was a significant difference from the other resin, with TetricEvo Ceram > [Herculite Ultra = Filtek Supreme Ultra = Ceram-X Mono].