Ability of low-cost generic and reference light-cure a bulk-fill resin-based composite

Abstract

The Knoop hardness (KH) of OPUS Bulk Fill APS (FGM) resin-based composite (RBC) was compared after it had been light-cured using four different light-curing units (LCUs). The VRNVAFU Black and VRN-VAFU Purple (Guilin Veirun Medical Technology Co., Ltd.) were classified as generic low-cost LCUs and were compared to the VALO Grand and VALO Cordless, (Ultradent). The RBC specimens (n = 10) were light-cured for 20 s in standard mode or 3 s in the high-power mode. Power, energy, and emission spectra were measured using an integrating sphere attached to a fiber optic spectrometer. Irradiance was calculated, and beam profiles were obtained. The KH was measured at the top and bottom surfaces. Data were analyzed using two-way ANOVA and the Tukey test (α = 0.05). The irradiance and power were higher in the high-power 3 s mode, but the radiant exposures delivered to the RBCs were significantly higher in the standard mode, irrespective of LCU. The generic LCU's beam profile was heterogeneous and lacked violet light (400 nm). Both curing modes and LCUs produced similar top KH values, >52 in Opus Bulk fill (FGM), but there was a significant reduction in the KH at the bottom in the high-power 3 s mode for all four LCUs. The high-power 3 s mode delivered less energy and produced lower KH values at the bottom surfaces. Thus, short exposure times with high irradiance should not be used with this brand of RBC.