Objective: To evaluate depth of cure (DOC) of bulk-fill resin-based composites (BFRBCs) with various photo-initiators cured by monowave and polywave light curing units (LCUs).
Methods: Two commercially available BFRBCs were used; Filtek One Bulk Fill Restorative (3M ESPE) (FOBF) which contains Camphorquinone (CQ) photo-initiator system only and Tetric N-Ceram Bulk Fill (Ivoclar Vivadent AG) (TNBF) which contain CQ and Ivocerin photo-initiator systems. LCUs utilized were two light-emitting diodes (LED) LCUs; a monowave LED LCU (BlueLEX LD-105, Monitex Industrial CO) and a polywave LED LCU (Twin Wave GT-2000, Monitex Industrial CO). Twenty cylindrical specimens (4 mm diameter and 10 mm thickness) were prepared from each BFRBC. Ten specimens light cured by monowave LCU and the other ten specimens cured by polywave LCU according to the manufacturer's recommendations (n=10). The International Organization for Standardization (ISO) 4049 method (Scraping test technique) was used to assess DOC. Statistical analysis was performed using two -way ANOVA and Tukey's post-hoc tests (p< 0.05).
Results: There were no statistically significant differences in DOC between LCUs within each BFRBC (p> 0.05). However, there was a statistically significant difference in DOC between composite types within each LCU (p< 0.05), and there was no interaction between them (p> 0.05). FOBF with CQ photo-initiator system only showed particularly high DOC mean values.
Conclusion: When a BFRBC has a variety of photo-initiators, the type of LCU has no effect on DOC. BFRBC with Ivocerin photo-initiator has lower DOC as ivocerin needs shorter violet wavelength which is scattered by filler particles.