Surface treatments affected the flexural strength and optical properties of CAD/CAM restorative materials. Er,Cr:YSGG laser irradiation with 2 W energy level may be an alternative surface treatment method for CAD/CAM materials.

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The aim of this study was to evaluate color stability of 3 restorative materials, discoloration ability of different solutions, efficacy of 2 office bleaching agents, and surface roughness and topography. Sixty specimens for Clearfil Majesty Esthetic (CME), Lava Ultimate (LU), and Vita Enamic (VE) were prepared. They were immersed into 3 staining solutions for 2 weeks and then they were bleached. According to the measured L⁎, a⁎, and b⁎ parameters described by CIELAB system, color changes (ΔE00), translucency parameters (TP), whiteness index values (W⁎), and changes in closeness to pure white (ΔW⁎) were calculated. Then 3 specimens from each group were scanned with an atomic force microscope for surface analysis. After staining, CME groups and control groups of LU and VE showed clinically acceptable color changes (ΔE00 < 1,8). After bleaching, while a reverse effect on color was observed, VE showed the furthest color values to pure white. There was no statistically significant difference between whiteness index values of LU and CME. LU was the most translucent material during the study and TP values of materials showed minimal differences. Most of the VE groups and a control group of LU showed surface roughness (Ra) values higher than critical value for biofilm accumulation (0,2 μm).

Purpose To evaluate the effect of in‐office and at‐home bleaching agents on color changes (ΔE00), translucency (TP00), whiteness (WID), surface roughness (Ra), and surface topography (Rsk and Rku) of a resin nano‐ceramic and a polymer‐infiltrated ceramic network CAD/CAM material. Materials and Methods Sixty specimens (6 mm × 7 mm × 1.3 mm) were prepared from Lava Ultimate (LU) and Vita Enamic (VE). The specimens were divided into 6 groups according to the bleaching agents applied (n = 10/group): control, Perfect Bleach Office + (PBO), Opalescence Boost (OB), Perfect Bleach (PB) with 10% and 16% carbamide peroxide and Whiteness Perfect (WP). ΔE00 values were calculated before and after bleaching procedures with a spectrophotometer using the CIEDE2000 formula. ΔTP00 and ΔWID values were calculated for each material. Ra, Rsk, and Rku values of the specimens were evaluated with an Atomic Force Microscope. Two‐way ANOVA was used for statistical analyses of the parameters measured after bleaching. For pairwise comparisons, Tukey test was performed. Results For LU, no statistically significant difference among the ΔE00 values of the groups was observed (p = 1.000). For VE, only WP group presented significantly higher values (2.12 ± 2.66) than the other groups (p < 0.001). For both materials; ΔTP00 values of at‐home bleaching groups were significantly higher than in‐office bleaching groups and control group (p < 0.001). For VE, ΔWID values did not demonstrate statistically significant difference (p = 1.000); however, for LU, PBO applied group showed statistically higher ΔWID values (3.00 ± 2.38) (p = 0.010) and WP applied group showed lower ΔWID values (0.47 ± 0.31) than the other groups (p = 0.030). For both LU and VE, there was no statistically significant difference among the groups regarding Ra (F = 4.544), Rsk (F = 2.369), and Rku values (F = 2.391) (p = 1.000). All of the VE groups presented Ra values higher than 0.2 µm. Conclusions The optical properties of LU and VE after bleaching applications were affected by the contact time with bleaching agents rather than concentration. Bleaching procedure had no effect on the surface properties of these materials.

Background The structure of bulk-fill resin composites differs from that of their conventional counterparts, but how this difference affects the color stability of the former after staining and bleaching is unclear. Accordingly, this study was aimed at investigating color change in nine bulk-fill resin composites and one nanohybrid resin composite treated with hydrogen peroxide and carbamide peroxide after staining with tea, coffee, and red wine. Methods Eighty specimens were prepared from each resins [Clearfil Majesty Posterior (CMP), SDR flow+ (SDR), FiltekTMBulk-Fill Flowable Restorative (FBF), Reveal HD Bulk (RHD), Beautifil-Bulk Restorative (BBR), Tetric EvoCeram® Bulk Fill (TEC), SonicFill™2 (SF2), everX Posterior™ (eXP), X-tra base (XB), and Venus® Bulk Fill (VBF)]. Following baseline color measurements, the specimens were randomly divided into 4 groups according to immersion solutions and distilled water as the control. At the end of a 30-day test period, color measurements were repeated, and color change values (∆E00) were calculated. Each resin group was then divided into 2 subgroups (with 10 specimens per group) on the basis of bleaching agent (Opalescence Boost 40%, Opalescence PF 16%). Following bleaching application, ∆E00 and changes of whiteness (∆WID1 = WIDbleaching-WIDbaseline, ΔWID2 = WIDbleaching-WIDstaining) values were recorded. Two- and three-way analyses of variance and Tukey’s post hoc test were performed, with a P < 0.05 regarded as indicative of significance. Results After immersion in distilled water, tea, and red wine, the highest ΔE00 values were observed in eXP (P < 0.05). Resin materials immersed in coffee and tea exhibited statistically higher ∆E00 values than those immersed in red wine except for eXP, TEC, and FBF (P < 0.05). For eXP, the highest ∆E00 values were recorded in distilled water. For TEC and FBF, there was no statistically significant difference among the immersion solutions and distilled water (P > 0.05). For all the resins and staining beverages, no statistically significant difference in ∆WID1 and ∆WID2 values were detected between bleaching agents (P > 0.05). All the ΔWID1 values were above the whiteness perceptibility threshold. Conclusion The bulk-fill materials were more resistant to discoloration and bleaching procedures than the conventional resin composites. Coffee and tea caused more staining than distilled water and red wine generally. The type of bleaching procedure had no effect on the whiteness of the tested materials.

The purpose of this study was to evaluate the color difference of nanohybrid and ormocer-based composite resins with different thicknesses when 4 different shades of resin luting cement were used. 56 disc specimens of each composite resin (Aelite aesthetic enamel, Ceram-X mono) with 0.5 and 1 mm thicknesses were fabricated. Baseline color measurements were performed using a clinical spectrophotometer. The specimens of each thicknesses of each resin were randomly divided into 4 groups according to the shades of resin luting cement (white/A1, yellow/universal/A3, transparent and white opaque) (n = 7). Mixed resin cement was applied onto the resin specimens using a Teflon mold in 0.1 mm thickness. Color measurements of cemented composite resin specimens were repeated and color difference (∆E) between baseline and after cementation measurements was calculated. ANOVA and Tukey's test were used for statistical analysis. The opaque shade had significantly increased ∆E values as compared to the other shades (p < 0.05). For all shades except white opaque in both thicknesses, ∆E values of aelite aesthetic enamel were higher as compared to Ceram-X mono. There is no significant difference between 2 thicknesses for both resins in terms of ∆E values. The shade of resin cement and the type of the resin affected the final color; however, the thickness of composite resin had no influence on the final color of restoration. Selecting the shade of resin luting cement before cementation of indirect composite laminate restoration is important to achieve final color match.

The purpose of this study was to evaluate the effect of Er,Cr:YSGG laser irradiation and/ or acid etching on the micro-shear bond strength (µSBS) of two different dual-cured resin cements to human enamel. 24 intact, extracted molars were sectioned longitudinally and randomly divided into three subgroups according to three surface pretreatment methods:(1) Er,Cr:YSGG laser (Waterlase MD, Biolase) irradiation was used with a power setting of 2 W (55% water and 65% air), and a repetition rate of 20 Hz for 10 s; (2) 37% phosphoric acid application for 20 s;(3) Re-etching with phosphoric acid for 20 s after the Er,Cr:YSGG laser irradiation as in group1.12 enamel discs for each of the resin cements (Panavia F2.0 and Variolink N) were prepared and three cylinders of resin cements were bonded to each enamel surface (n = 12). A microshear bond test (EZ-test-500 N) was used at a cross-head speed of 1 mm min −1 to determine the µSBS. One-way analysis of the variance and Tukey post-hoc tests at the 95% confidence level were used to analyze the µSBS values. Panavia F2.0 verified significantly higher µSBS values than Variolink N (p < 0.05) for all the tested surface pretreatment methods. The combination of laser and acid etching on enamel produced higher µSBS values for bonding both resin cements than the use of acid or laser irradiation alone. The combination of the Er,Cr:YSGG laser and phosphoric acid etching of the enamel for the cementation of indirect restorations with Variolink N and Panavia F2.0 produced better µSBS values to enamel than the use of phosphoric acid or Er,Cr:YSGG laser etching alone, holding the potential to become a highly attractive method for routine use.

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