IADR Abstract Archives
Color and translucency of composites related to the refractive indices of unfilled resins and filled polymer
Objectives: To evaluate the effect of refractive indices (RIs) of unfilled resins and filled polymer on color and translucency of model composites.
Methods: Resin mixtures were prepared using bisphenol-A-glycidyl methacrylate (BisGMA), urethane dimethacrylate (UDMA), a modified UDMA resin (FIT) and triethyleneglycol-dimethacrylate (TEGDMA) as BisGMA/TEGDMA, UDMA/TEGDMA and FIT/TEGDMA in 3:1, 2:1, 1:1, 1:2, 1:3 ratios. The RIs of unfilled resins were measured using an ABBE refractometer. Model composites, based on 2:1 and 1:1 resin mixtures, contained 70wt% of silanated Ba-glass fillers (0.7 μm average size, RI=1.553) and 30wt% of resin matrix including 1wt% of photoinitiator. Samples, 20 mm in diameter and 2 mm thick, were polymerized using a LEDition light-curing light (Ivoclar Vivadent). Color was determined using an AvaSpec-2048 fiber-optic spectrometer (Avantes BV). Translucency was determined using the same spectrometer against a black and white background. The RIs of cured composites, i.e. filled polymer, were determined by the Becke-line method using a series of index matching oils. Data were analyzed using Pearson’s correlation coefficient and regression analysis (α=0.05).
Results: The RIs of unfilled resins were 1.4970-1.4745 (BisGMA/TEGDMA), 1.4765-1.4655 (UDMA/TEGDMA) and 1.4800-1.4675 (FIT/TEGDMA). The RIs decreased with increasing amounts of TEGDMA. Increased RIs of filled polymer, compared to unfilled resins, were found in all groups: 1.5262-1.5268 (UDMA-based composites), 1.5310-1.5314 (FIT-based composites) and 1.5396-1.5442 (BisGMA-based composites). BisGMA-based composites were more translucent and showed significantly lower L* values than FIT- and UDMA-based composites. Positive correlation was found between the RIs of unfilled resins and filled polymer (p=0.001), as well as between the RIs and translucency and color (p=0.001 and p=0.008, respectively).
Conclusions: Higher RIs of unfilled BisGMA/TEGDMA resins and filled polymer i.e. BisGMA-based composite were associated with higher translucency and greater deviation from ‘ideal white’ of BisGMA-based composite compared to UDMA- and FIT-based materials.
Methods: Resin mixtures were prepared using bisphenol-A-glycidyl methacrylate (BisGMA), urethane dimethacrylate (UDMA), a modified UDMA resin (FIT) and triethyleneglycol-dimethacrylate (TEGDMA) as BisGMA/TEGDMA, UDMA/TEGDMA and FIT/TEGDMA in 3:1, 2:1, 1:1, 1:2, 1:3 ratios. The RIs of unfilled resins were measured using an ABBE refractometer. Model composites, based on 2:1 and 1:1 resin mixtures, contained 70wt% of silanated Ba-glass fillers (0.7 μm average size, RI=1.553) and 30wt% of resin matrix including 1wt% of photoinitiator. Samples, 20 mm in diameter and 2 mm thick, were polymerized using a LEDition light-curing light (Ivoclar Vivadent). Color was determined using an AvaSpec-2048 fiber-optic spectrometer (Avantes BV). Translucency was determined using the same spectrometer against a black and white background. The RIs of cured composites, i.e. filled polymer, were determined by the Becke-line method using a series of index matching oils. Data were analyzed using Pearson’s correlation coefficient and regression analysis (α=0.05).
Results: The RIs of unfilled resins were 1.4970-1.4745 (BisGMA/TEGDMA), 1.4765-1.4655 (UDMA/TEGDMA) and 1.4800-1.4675 (FIT/TEGDMA). The RIs decreased with increasing amounts of TEGDMA. Increased RIs of filled polymer, compared to unfilled resins, were found in all groups: 1.5262-1.5268 (UDMA-based composites), 1.5310-1.5314 (FIT-based composites) and 1.5396-1.5442 (BisGMA-based composites). BisGMA-based composites were more translucent and showed significantly lower L* values than FIT- and UDMA-based composites. Positive correlation was found between the RIs of unfilled resins and filled polymer (p=0.001), as well as between the RIs and translucency and color (p=0.001 and p=0.008, respectively).
Conclusions: Higher RIs of unfilled BisGMA/TEGDMA resins and filled polymer i.e. BisGMA-based composite were associated with higher translucency and greater deviation from ‘ideal white’ of BisGMA-based composite compared to UDMA- and FIT-based materials.