The aim of this study was to verify the match between 5 shades of composites from different manufacturers with a shade guide and among the systems using a portable spectrophotometer.

Shade measurements were performed on specimens of Z350 XT (3M ESPE), Charisma Diamond (Heraeus Kulzer GmbH), Esthet X-HD (Dentsply Caulk), and Empress Direct (Ivoclar-Vivadent) for shades A1, A2, A3, B1, and C3 using a Vita Easyshade spectrophotometer (Vita Zahnfabrik) against a white background. Corresponding shades of Vitapan Classical (Vita Zahnfabrik) guide were measured likewise and shade variation (ΔE) was calculated based on International Commission on Illumination L*a*b* parameters. The ΔE of the composites in each shade was compared by one-way analysis of variance and Tukey's post hoc test (α = 0.05).

All composites presented ΔE > 3.7 compared with the shade guide. Variation in shades A3, B1, and C3 was significantly different for all composites. ΔE of Z350 XT was significantly lower for A1 than for the other shades, whereas ΔE of Z350 XT and Charisma Diamond were significantly lower for A2 than for the other shades.

No composite shade matched with the shade guide. Equivalent shades of the restorative composite from different manufacturers may show clinically noticeable ΔE.

This study evaluated the effects of a bleaching agent on the composition, mechanical properties, and surface topography of 6 conventional glass-ionomer cements (GICs) and one resin-modified GIC.

For 3 days, the specimens were subjected to three 20-minute applications of a 37% H₂O₂-based bleaching agent and evaluated for water uptake (WTK), weight loss (WL), compressive strength (CS), and Knoop hardness number (KHN). Changes in surface topography and chemical element distribution were also analyzed by energy-dispersive X-ray spectroscopy and scanning electron microscopy. For statistical evaluation, the Kruskal-Wallis and Wilcoxon paired tests (α = 0.05) were used to evaluate WTK and WL. CS specimens were subjected to 2-way analysis of variance (ANOVA) and the Tukey post hoc test (α = 0.05), and KH was evaluated by one-way ANOVA, the Holm-Sidak post hoc test (α = 0.05), and the t-test for independent samples (α = 0.05).

The bleaching agent increased the WTK of Maxxion R, but did not affect the WL of any GICs. It had various effects on the CS, KHN, surface topography, and the chemical element distribution of the GICs.

The bleaching agent with 37% H₂O₂ affected the mechanical and surface properties of GICs. The extent of the changes seemed to be dependent on exposure time and cement composition.