Characterization of Esthetic Orthodontic Wires Made from Glass-Fiber-Reinforced Thermoplastic Containing High-Strength, Small-Diameter Glass Fibers

Table 6

Color differences measured in ΔE and NBS units after immersion in coffee solution.

	24 hours		1 week		2 weeks		4 weeks
	ΔE	NBS units	ΔE	NBS units	ΔE	NBS units	ΔE	NBS units
GFRTP-13	1.47 ± 0.52	1.36 ± 0.48	1.05 ± 0.46^a	0.97 ± 0.42^a	1.10 ± 0.59^a	1.01 ± 0.54^a	0.83 ± 0.52^a	0.77 ± 0.48^a
GFRTP-7	1.34 ± 0.39	1.23 ± 0.36	1.11 ± 0.23^b	1.02 ± 0.21^b	1.00 ± 0.36^b	0.92 ± 0.32^b	0.84 ± 0.36^b	0.77 ± 0.33^b
GFRTP-5	1.84 ± 0.62	1.70 ± 0.57	2.20 ± 0.51^a,b	2.02 ± 0.47^a,b	2.07 ± 0.43^a,b	1.90 ± 0.39^a,b	1.94 ± 0.48^a,b	1.79 ± 0.45^a,b

ΔE values were converted to NBS units using the following equation: NBS units = ΔE × 0.92; mean values with the same superscripts are significantly different from each other (); for each GFRTP, there were no significant differences in color change data across all immersion periods ().