Objective: To evaluate the translucency and effects of different cement colors on the final shade of lithium disilicate ceramics (LDS) and zirconia-reinforced lithium silicate ceramics (ZLS) over an A1 and A3 tooth-shaded background. Materials and Methods: Eighty-eight rectangular-shaped specimens were sliced from LDS and ZLS blocks. The final thickness of the specimens was set at 0.8 ± 0.01 mm. Spectrophotometric measurements for the translucency were taken against black and white backgrounds. Composite resin tooth-shaded background disks were fabricated in two shades (A1 and A3), as were resin cement disks (opaque and translucent) (n = 11). Next, the ceramic specimens and tooth-shaded backgrounds were connected with glycerin, and baseline measurements were taken. These measurements were used as a reference. Then, the ceramic specimens, cement specimens, and tooth-shaded backgrounds were connected together with glycerin, and a second set of measurements was taken. The CIEDE2000 (ΔE 00) color formula was used to calculate the translucency and color differences. A Mann-Whitney U test was also performed for the translucency, and a three-way ANOVA (analysis of variance) test was performed for the ΔE 00 values (α = .05). Results: The LDS and ZLS groups had similar translucency (P = .055). The ΔE 00 values of the specimens were significantly affected by the cement color and tooth-shaded backgrounds in the LDS and ZLS groups (P < .05). Using the opaque cement color resulted in statistically significant differences against the light and dark (A1 and A3) tooth-shaded backgrounds in both the LDS and ZLS groups (P = .022 and P = .006). Conclusions: The material type did not affect the translucency or final color. However, the cement color did affect the final shade when thin ceramic restorations were used. Clinical Significance: It should be noted that the cement color and tooth-shaded background used may change the final color of thin high translucency ceramic restorations that contain lithium disilicate and zirconia-reinforced lithium silicate.

Purpose To compare the marginal and internal fit of cobalt‐chromium (Co‐Cr) alloy copings fabricated by with lost wax technique (LW), computer‐aided design and computer‐aided manufacturing (CAD/CAM), and direct metal laser sintering (DMLS). Materials and Methods Thirty‐six tissue level, straight titanium abutments were screwed onto implant replicas. All specimens were embedded in acrylic resin and randomly divided into 3 subgroups according to the fabrication of metal coping: LW, CAD/CAM, and DMLS. In total, 36 (n = 12/group) Co‐Cr implant‐supported metal copings were prepared. Marginal, intermarginal, axial, and occlusal fits of each coping were measured using the silicone replica technique. The data were evaluated statistically using one‐way ANOVA and Bonferioni post‐hoc test (α = 0.05). Results The CAD/CAM group showed significantly lower marginal fit than the LW group and DMLS groups (p < 0.001). The marginal fit of the LW group was not significantly different from the DMLS group (p = 0.721). No significant difference found among the fabrication methods in terms of intermarginal fit (p = 0.913). The CAD/CAM group showed lower axial fit than the LW group (p = 0.026), but there was no statistical difference between the DMLS group and the LW (p = 0.999) and CAD/CAM groups (p = 0.247). No significant differences found among the fabrication methods in terms of occlusal fit (p = 0.158). Conclusions The LW and DMLS groups showed better marginal fit compared to the CAD/CAM group; however, the CAD/CAM group was better than the LW group in terms of axial fit. All fabrication methods demonstrated similar intermarginal and occlusal fit.

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This study evaluated the effect various surface conditioning methods on the surface topography and adhesion of luting cements to zirconia. Zirconia blocks (N = 25) were randomly assigned to five groups according to the surface conditioning methods: (a) No conditioning, control (CON), (b) tribochemical silica coating (TSC), (c) MDP-based zirconia primer (ZRP), (d) coating with nano aluminum nitride (ALN) (e) etching with Er: YAG laser (LAS). The conditioned zirconia blocks were further divided into five subgroups to receive the luting cements: (a) MDP-based resin cement (Panavia F2.0) (PAN), (b) 4-META-based cement (Super Bond) (SUB), (c) UDMA-based (GCem) (GCE), (d) bis-GMA based (Bifix QM) (BIF) and (e) polycarboxylate cement (Poly-F) (POL). Cements were applied in polyethylene moulds (diameter: 3 mm; height: 2 mm). The bonded specimens were first thermocycled for 5500 cycles (5-55°C) and then adhesive interface was loaded under shear (0.5 mm/min). The data (MPa) were analyzed using 2-way ANOVA, Tukey's and Bonneferroni tests (alpha = 0.05). Regardless of the cement type, TSC resulted in significantly higher bond strength (p 0.05) (13.3 ± 4.35-25.3 ± 6.3) compared to other conditioning methods (2.96 ± 1.5-5.4 ± 5.47). Regardless of the surface conditioning method, no significant difference was found between MDP, 4-META and UDMA based cements (p > 0.05) being significantly higher than those of bis-GMA and polycarboxylate cements (p 0.05). Failure types were frequently adhesive in all groups. Tribochemical silica coating provided superior bond results compared to other conditioning methods tested on zirconia especially in conjunction with UDMA-and 4-META-based resin cements.

Purpose To compare MEP which is originally manufactured for increasing bond strength between organic resins and ceramic with conventional surface treatment methods in preparation of leucite-reinforced FC surfaces regarding shear bond strength (SBS) of stainless steel brackets and the mode of bond failure. Materials and Methods Forty specimens that were fabricated from FC material and glazed were randomly assigned to four surface conditioning methods: (1) CoJet Sand; (2) MEP; (3) HF acid etching followed by silane coupling agent; (4) Diamond bur followed by silane coupling agent. The SBS was determined using universal testing machine. Bond failure sites were classified according to Adhesive Remnant Index (ARI). Results No statistically significant difference (p>0.05) was found in SBS between the groups while significant intergroup differences were detected concerning ARI scores (p<0.001). Group 1 had ARI score 1 and 2 indicating mode of failure at the adhesive interface with greater percentage of the adhesive left on bracket base. The other groups had higher frequency of ARI score 3 and 2. The quantity of the ARI retained on the ceramic surface was highest in Group 3, followed by Group 4 and Group 2. Conclusion MEP can be a suitable alternative for bonding metal brackets to FC surface.

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