A fluorescent whitening agent [FWA, 1,4-double-(benzoxazole-
group-2-group)naphthalene] was added with the concentration of 0.01–0.1%. To determine
the difference by the resin matrix, two resin composites (60wt.% Bis-GMA or UDMA with
40wt.% TEGDMA) with the same filler content were made, and the FWA was added