Bulk-Fill Composites: Effectiveness of Cure With Poly- and Monowave Curing Lights and Modes.

This study compared the effectiveness of cure of bulk-fill composites using polywave light-emitting diode (LED; with various curing modes), monowave LED, and conventional halogen curing lights. The bulk-fill composites evaluated were Tetric N-Ceram bulk-fill (TNC), which contained a novel germanium photoinitiator (Ivocerin), and Smart Dentin Replacement (SDR). The composites were placed into black polyvinyl molds with cylindrical recesses of 4-mm height and 3-mm diameter and photopolymerized as follows: Bluephase N Polywave High (NH), 1200 mW/cm(2) (10 seconds); Bluephase N Polywave Low (NL), 650 mW/cm(2) (18.5 seconds); Bluephase N Polywave soft-start (NS), 0-650 mW/cm(2) (5 seconds) --> 1200 mW/cm(2) (10 seconds); Bluephase N Monowave (NM), 800 mW/cm(2) (15 seconds); QHL75 (QH), 550 mW/cm(2) (21.8 seconds). Total energy output was fixed at 12,000 mJ/cm(2) for all lights/modes, with the exception of NS. The cured specimens were stored in a light-proof container at 37 degrees C for 24 hours, and hardness (Knoop Hardness Number) of the top and bottom surfaces of the specimens was determined using a Knoop microhardness tester (n=6). Hardness data and bottom-to-top hardness ratios were subjected to statistical analysis using one-way analysis of variance/Scheffe's post hoc test at a significance level of 0.05. Hardness ratios ranged from 38.43% +/- 5.19% to 49.25% +/- 6.38% for TNC and 50.67% +/- 1.54% to 67.62% +/- 6.96% for SDR. For both bulk-fill composites, the highest hardness ratios were obtained with NM and lowest hardness ratios with NL. While no significant difference in hardness ratios was observed between curing lights/modes for TNC, the hardness ratio obtained with NM was significantly higher than the hardness ratio obtained for NL for SDR.