A randomized controlled study on color stability of tetracycline teeth restored with ceramic veneer / 华西口腔医学杂志

OBJECTIVES@#This study aimed to evaluate the color stability of tetracycline teeth restored with ceramic veneers of different thicknesses combined with different resin cement systems after aging.@*METHODS@#Twenty patients with tetracycline teeth, including two maxillary central incisors, were selected clinically. The patients were randomly divided into four groups and restored with 0.5 and 0.75 mm ceramic veneers by using a veneer adhesive system, either with light-cured or dual-cured reaction. The color difference (ΔE) values after cementation and 1, 6, 12, and 24 months of use were obtained by quantification of L*, a*, and b* values with a colorimeter. The results were analyzed statistically with two-way ANOVA and Student's @*RESULTS@#The ΔE values of ceramic veneers detected after aging were less than 2.25. The 0.5 mm groups exhibited greater color change than the 0.75 mm-thick veneers (@*CONCLUSIONS@#Resin cements and veneer thickness influence the color of ceramic veneers after aging. Cementation of veneers with either dual- or light-cured resin cements does not affect the long-term color stability of tetracycline teeth differently.

Chemical constituents from Calystegia sepium / 中草药

Objective To study the chemical constituents from Calystegia sepium. Methods The compounds were isolated and purified by silica gel column chromatography, Sephadex LH-20, ODS column chromatography, preparative HPLC and so on. Their structures were determined on the basis of physicochemical properties and their spectroscopic data, as well as literatures. Results A total of 20 compounds were separated and identified as tyrosol (1), quercetin-3-O-β-D-glucopyranoside (2), scutellarein-7-O-β- glucopyranoside (3), kaempferol-3-O-β-D-glucopyranoside (4), kaempferol-3-O-galactoside (5), kaempferol-3-O-β-robinobioside (6), nicotiflorin (7), rutin (8), uridine (9), tachioside (10), 2-methoxy-4-(2’-hydroxyethyl)-phenyl-1-O-β-D-glucopyranoside (11), 4-hydroxyphenethylol-4-O-β-D-glucopyranoside (12), polybotrin (13), pyridine-3,5-dicarboamide (14), skimmin (15), benzylalcohol-β-D-glucopyranoside (16), 5-hydroxyl-2-hydroxymethylpyridine (17), picein (18), 5-hydroxymethyl-furaldehyde (19), and sessiline (20). Conclusion Compounds 1-20 are isolated from Calystegia sepium for the first time.