The Thickness and Opacity of Aesthetic Materials Influence the Restoration of Discolored Teeth

SUMMARY Objectives: This study aimed to evaluate the influence of thickness and opacity on the ability of composite resin and ceramic veneer restorations to mask discolored teeth. Methods: Ninety veneers were made of lithium disilicate ceramic, shades BL1 and 0 (IPS e.max Press, Ivoclar Vivadent), and 60 were made of composite resin, shade BL-L (IPS Empress Direct, Ivoclar Vivadent). The veneers measured 4 mm in width x 4 mm in length and had a thickness of 0.7, 1.0, or 1.2 mm. One hundred and fifty human premolars were selected to obtain 150 dental fragments with the following dimensions: 4 mm x 4 mm x 3 mm (width x length x thickness). The fragments were discolored, submitted to color measurement and randomly assigned to 15 groups (n=10) according to the type and opacity of the restorative material (IPS e.max Press: high translucency [HT], low translucency [LT], and medium opacity [MO]; IPS Empress Direct: dentin and enamel) and thickness of the veneers (0.7, 1.0, and 1.2 mm). After cementation of the ceramic or composite resin veneers using a translucent resin cement (RelyX veneer, 3M), a final color measurement was taken from each specimen and the total color variation (ΔE) was calculated by subtracting the initial and the final color measurement. The final lightness (L*) of the restored dental fragments was also calculated. Results: The highest ΔE values were observed for the LT and MO ceramic groups, followed by dentin composite resin. Regarding the different thicknesses of ceramic veneers, every 1.2-mm–thick group had higher values of ΔE, considering their respective opacities (p<0.05). The highest lightness values were found for the LT and MO ceramic veneers (thickness of 1.2 mm). Dentin-shade composite resins showed similar lightness values in all groups. Conclusion: The best thickness/opacity combinations for masking discolored dental substrates were LT and MO ceramic veneers with 1.2-mm thickness. Dentin-shade composite resin veneers with a thickness of 0.7–1.0 mm showed good ability to mask discolored dental substrates.

Effect of Different Bleaching Methods on Optical Behaviors of CAD/CAM Ceramics

Background: The present study aimed to survey the influence of two different bleaching techniques on changes of color, translucency, and whiteness of the four CAD/CAM materials. Methods: The monolithic blocks of Vita Suprinity, Vita Enamic, IPS e.max CAD, and Katana Zirconia were sectioned to discs with thickness of 2 mm (n=30 / each group). Samples from each type of ceramic were assigned to three subgroups: 1) the 40% hydrogen peroxide for 20 minutes; 2) the 16% carbamide peroxide for three hours/day for 2 weeks; and 3) the control. Then CIELab coordinates of each sample were evaluated before and after the intervention by a spectrophotometer. Final color change (ΔE), Whiteness (ΔWI D), and Translucency Parameter (ΔTP) were calculated. Two-way ANOVA test was adopted to analyze the data (α=0.05). Results: Type of ceramic, bleaching subgroups, and interaction between them had a statistically significant influence on mean values of ΔE, ΔWID. The influence of bleaching subgroup on the mean value of ΔTP was also significant (P<0.001). Conclusions: Carbamide peroxide 16% for three hours/day and for two weeks caused the most considerable changes in final color, whiteness, and translucency of the all tested CAD/CAM materials. Maximum color change and whiteness were detected in the Vita Enamic, which were clinically unacceptable.

De novo transcriptome sequencing and anthocyanin metabolite analysis reveals leaf color of Acer pseudosieboldianum in autumn

Background Leaf color is an important ornamental trait of colored-leaf plants. The change of leaf color is closely related to the synthesis and accumulation of anthocyanins in leaves. Acer pseudosieboldianum is a colored-leaf tree native to Northeastern China, however, there was less knowledge in Acer about anthocyanins biosynthesis and many steps of the pathway remain unknown to date. Results Anthocyanins metabolite and transcript profiling were conducted using HPLC and ESI-MS/MS system and high-throughput RNA sequencing respectively. The results demonstrated that five anthocyanins were detected in this experiment. It is worth mentioning that Peonidin O-hexoside and Cyanidin 3, 5-O-diglucoside were abundant, especially Cyanidin 3, 5-O-diglucoside displayed significant differences in content change at two periods, meaning it may be play an important role for the final color. Transcriptome identification showed that a total of 67.47 Gb of clean data were obtained from our sequencing results. Functional annotation of unigenes, including comparison with COG and GO databases, yielded 35,316 unigene annotations. 16,521 differentially expressed genes were identified from a statistical analysis of differentially gene expression. The genes related to leaf color formation including PAL, ANS, DFR, F3H were selected. Also, we screened out the regulatory genes such as MYB, bHLH and WD40. Combined with the detection of metabolites, the gene pathways related to anthocyanin synthesis were analyzed. Conclusions Cyanidin 3, 5-O-diglucoside played an important role for the final color. The genes related to leaf color formation including PAL, ANS, DFR, F3H and regulatory genes such as MYB, bHLH and WD40 were selected. This study enriched the available transcriptome information for A. pseudosieboldianum and identified a series of differentially expressed genes related to leaf color, which provides valuable information for further study on the genetic mechanism of leaf color expression in A. pseudosieboldianum.

Masking of High-Translucency Zirconia for Various Cores

Clinical Relevance Various core materials with different shades affect the final color of high-translucency monolithic zirconia restorations. The blue core shows the greatest color difference in final zirconia restorations followed by metal, A3 dentin-shade resin core, and white core.

Discoloration of Bulk-Fill Versus Conventional Composites: A Spectrophotometric Evaluation

Purpose: The purpose of this study was to evaluate the discoloration of a dual-cure bulk-fill (DCBF) and light-cure bulk-fill (LCBF) composites relative to conventional composites (CC) after water and coffee immersion. Methods: One-hundred disc-shaped specimens (8mm in diameter × 4mm thickness) were prepared using five commercially available composites (n=10); two LCBF (XB-X-trafil Voco, FB-FiltekTM Bulk Fill), one DCBF (FU-Fill-upTM Coltene), and two CC (CE-Clearfil Majesty ES2, EQ-Estelite ΣQuick). Initial and final color readouts were measured with a spectrophotometer (Easyshade,Vita) according to the CIELAB color system. Statistical analyses were performed using 2-way ANOVA with Bonferroni adjustment to evaluate ∆E, ∆L, ∆a, and ∆b parameters (p<0.05). Results: Significant interactions were noted among the material types and immersion solutions for all evaluated parameters (p=0.00). ∆E values were observed in the order of FU>FB≥XB>EQ≥CE in water immersion groups and XB>FB>EQ≥FU≥CE in coffee immersion groups. Conclusion: Within the limitations of this study, DCBF composite is more susceptible to intrinsic discoloration compared to LCBF and CC. However, DCBF exhibited lower extrinsic discoloration than LCBF and comparable with CC after coffee immersion. Depending on their chemical and structural compositions, composites will exhibit color change, which compromises the esthetic performance of composite restorations.

De novo transcriptome sequencing and anthocyanin metabolite analysis reveals leaf color of Acer pseudosieboldianum in autumn

Background Leaf color is an important ornamental trait of colored-leaf plants. The change of leaf color is closely related to the synthesis and accumulation of anthocyanins in leaves. Acer pseudosieboldianum is a colored-leaf tree native to Northeastern China, however, there was less knowledge in Acer about anthocyanins biosynthesis and many steps of the pathway remain unknown to date. Results Anthocyanins metabolite and transcript profiling were conducted using HPLC and ESI-MS/MS system and high-throughput RNA sequencing respectively. The results demonstrated that five anthocyanins were detected in this experiment. It is worth mentioning that Peonidin O-hexoside and Cyanidin 3 5-O-diglucoside were abundant, especially Cyanidin 3 5-O-diglucoside displayed significant differences in content change at two periods, meaning it may be play an important role for the final color. Transcriptome identification showed that a total of 67.47 Gb of clean data were obtained from our sequencing results. Functional annotation of unigenes, including comparison with COG and GO databases, yielded 35,316 unigene annotations. 16,521 differentially expressed genes were identified from a statistical analysis of differentially gene expression. The genes related to leaf color formation including PAL, ANS, DFR, F3H were selected. Also, we screened out the regulatory genes such as MYB, bHLH and WD40. Combined with the detection of metabolites, the gene pathways related to anthocyanin synthesis were analyzed. Conclusion Cyanidin 3, 5-O-diglucoside played an important role for the final color. The genes related to leaf color formation including PAL, ANS, DFR, F3H and regulatory genes such as MYB, bHLH and WD40 were selected. This study enriched the available transcriptome information for A. pseudosieboldianum and identified a series of differentially expressed genes related to leaf color, which provides valuable information for further study on the genetic mechanism of leaf color expression in A. pseudosieboldianum.