Color changes of esthetic elastomeric ligatures evaluated with the Commission Internationale d'Éclairage color system

ABSTRACT Objective: The aim of this study was to assess and compare color changes in esthetic elastomeric ligatures after 30 days in situ using a spectrophotometer and the Commission Internationale d'Éclairage (CIE) color system. Materials and Methods: The sample comprised elastomeric ligatures of four color groups (n = 42): blue pearl (BP); colorless; white pearl (WP); and pearl. Four samples from each group were allocated in for quadrants of seven patients in a split-mouth model. Color measurements were performed with a spectrophotometer in the elastomeric ligatures as received (T0) and after 30 days in situ (T1). Variables L*, a*, and b* were compared between times (T1–T0) with Wilcoxon paired ranks; color changes were compared between groups with Kruskal–Wallis test; Dunn's test was used for multiple comparisons. Spearman's correlation was applied between CIELAB and CIEDE2000 calculations. Results: All groups showed color changes (T1–T0) in a* and b*, but only the Group BP had a change in L* (P < 0.01). Group C showed the greatest lightness decrease (ΔL = −2.49 ± 0.47) (P < 0.05), the smallest yellowing (Δb = 3.17 ± 0.88) (P < 0.05), and the smallest total color change (ΔE2000 = 3.19 ± 0.85), which had no statistical difference from Group WP (ΔE2000 = 3.36 ± 0.53). Correlation between ΔEab and ΔE2000 was moderate (r = 0.59; P < 0.01). Conclusions: Esthetic elastomeric ligatures became yellowish after 30 days in situ, and there were color differences between them.

Ionic Liquid-Assisted Synthesis of C@ZrSiO4 Ceramic Inclusion Pigment

An innovative two-step route was successfully applied to the ionic liquid-assisted synthesis of C@ZrSiO4 ceramic pigments, which is able to reduce the reflux time from many hours to a few minutes. The structure and morphology of the inclusion pigments were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). And the chromatic value of the pigments was measured by the CIE color system. The results show that the pigment in the absence of ionic liquid (IL) exhibited homogeneous single t-ZrO2 phase, while the samples in the presence of IL showed coexistence of two crystal phases (m-ZrO2 and ZrSiO4). The CIE coordination L* value decreased with the increase of TEOS amounts due to the pure zircon formation. The as-prepared pigment showed high tinting ability, as L*=37.16, a*=0.71, b*=0.3, making it promising candidate for ceramic decoration.

Preparation and Chromatic Properties of Encapsulated Carbon Black Pigment via Layer-by-Layer Self-Assembly Method

Encapsulated carbon black pigment was prepared by layer-by-layer self-assembly method. The RX8002 carbon black particles were well coated by a SiO2 layer, which makes it has good connection with ZrSiO4 layer. Meanwhile, dense ZrSiO4 layer was coated on the C@SiO2 particles surface to prevent the corrosive effects of glaze. The structure and morphology of samples were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The chromatic value of the pigments was measured by the CIE color system. The results show that the carbon black particles can be well coated by SiO2 and ZrSiO4 layer. When the TEOS/H2O ratio is 0.002 and the ZrSiO4/C ratio is 0.71, the chromatic value of the encapsulated carbon black pigment is 42.55, and the pigment has a good stability in glaze.

Preparation of C@ZrSiO4 Inclusion Pigment Using Compound Colorants via Non-Hydrolytic Sol-Gel Method

C@ZrSiO4 inclusion pigment was prepared by using commercial carbon black RX8002C and phenolic resin (PF) as compound carbon source via non-hydrolytic sol-gel (NHSG) process. The RX8002C carbon could well disperse in phenolic resin solution, which developed a compound carbon source after calcination. Dense ZrSiO4 layer was coated on the carbon surface as a protector. The structure and morphology of samples were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The chromatic value of the pigments was measured by the CIE color system. The results show that the compound colorants can be well coated by ZrSiO4 dense layer to develop a black inclusion pigment. When the compound proportion is 1:4 and the compound colorants amount is 4wt.%, the chromatic value of the C@ZrSiO4 inclusion pigment is 27.54.