IADR Abstract Archives
Localized Irradiance From LCUs Influence on Resin-matrix Composite Cross-link Density
Objectives: To investigate the relationship between the characteristic light-beam-irradiance profiles from multiple light-curing units (LCUs) and the curability of a resin-matrix-composite (RMC). This was explored by comparing localized cross-link density (CLD) values throughout RMC samples that were cured at two different light-tip distances with the beam profiles collected for the respective LCUs at the respective distances.
Methods: Light-beam-irradiance profiles were generated from one quartz-tungsten-halogen and multiple single-peak and multi-peak light-emitting-diode (LED) curing-units (Table1) using a camera-based beam profiler system combined with power measurements of the LCUs obtained using an integrating-sphere/spectrometer assembly. A mapping approach was used to investigate CLD throughout nano-hybrid RMC (Tetric-EvoCeram bleaching shade XL) samples (5×5×2mm) on the top and bottom surfaces and at the following depths: 0.5, 0.7, 0.9, 1.1, 1.3 and 1.5mm. The samples were cured at light-tip distances of 2 and 8mm. CLD was assessed indirectly by an ethanol-softening method (%KHN reduction) using automated microhardness-testing. ANOVA was used to analyze the effect of the LCU and distance on the %KHN reduction by depth for each measurement. Linear mixed models and Pearson correlation coefficients were used to calculate correlations across multiple locations, and calculate associations between beam inhomogeneity from the LCUs with corresponding %KHN reduction in RMC samples.
Results: Inhomogeneous beam profiles corresponded with localized %KHN reduction at the depths assessed on the RMC samples ranging between 26-58% and 28-57% when cured at 2 and 8mm distances, respectively. The values of %KHN reduction were significant at various locations and depths within the samples that did not follow a specific pattern. Furthermore, samples cured with the multi-peak LCUs demonstrated a gradual increase in %KHN reduction values from the top to the bottom of the RMC unlike the single-peak LED LCUs.
Conclusions: The inhomogeneous light-beam-irradiance profiles from the LCUs resulted in corresponding localized CLD discrepancies throughout the RMC samples regardless of curing distance.
Methods: Light-beam-irradiance profiles were generated from one quartz-tungsten-halogen and multiple single-peak and multi-peak light-emitting-diode (LED) curing-units (Table1) using a camera-based beam profiler system combined with power measurements of the LCUs obtained using an integrating-sphere/spectrometer assembly. A mapping approach was used to investigate CLD throughout nano-hybrid RMC (Tetric-EvoCeram bleaching shade XL) samples (5×5×2mm) on the top and bottom surfaces and at the following depths: 0.5, 0.7, 0.9, 1.1, 1.3 and 1.5mm. The samples were cured at light-tip distances of 2 and 8mm. CLD was assessed indirectly by an ethanol-softening method (%KHN reduction) using automated microhardness-testing. ANOVA was used to analyze the effect of the LCU and distance on the %KHN reduction by depth for each measurement. Linear mixed models and Pearson correlation coefficients were used to calculate correlations across multiple locations, and calculate associations between beam inhomogeneity from the LCUs with corresponding %KHN reduction in RMC samples.
Results: Inhomogeneous beam profiles corresponded with localized %KHN reduction at the depths assessed on the RMC samples ranging between 26-58% and 28-57% when cured at 2 and 8mm distances, respectively. The values of %KHN reduction were significant at various locations and depths within the samples that did not follow a specific pattern. Furthermore, samples cured with the multi-peak LCUs demonstrated a gradual increase in %KHN reduction values from the top to the bottom of the RMC unlike the single-peak LED LCUs.
Conclusions: The inhomogeneous light-beam-irradiance profiles from the LCUs resulted in corresponding localized CLD discrepancies throughout the RMC samples regardless of curing distance.