Objectives To compare the strength and translucency of CAD/CAM zirconia blocks, with traditional and high‐speed sintering, to lithium disilicate. Materials and Methods Three zirconia materials (Katana STML Block, Prettau Anterior, and Zpex Smile) were tested with either traditional (7 hours) or high‐speed (18 or 30 minutes in a SpeedFire furnace) sintering. A lithium disilicate material (IPS e.max CAD) was tested as a reference. Three‐point bend flexural strength specimens (16 mm × 4 mm × 1.2 mm, n = 10) were tested on 14‐mm‐separated supports and loaded to failure at 1 mm/min. Specimens (1 mm thick, n = 10) were measured in a Color‐i7 spectrophotometer against a black and white background to calculate translucency parameter. Zirconia specimens were thermally etched and a grain structure was observed with scanning electron microscopy. Data were analyzed with 1‐way ANOVA and Tukey's post hoc analysis (α = 0.05). Results There were significant differences between materials for flexural strength, translucency parameter, and grain size (P < .001). Grains became significantly larger and pores were present when two of the zirconia materials (Prettau Anterior and Zpex Smile) were sintered with a high‐speed sintering program. Conclusions Two of the zirconia materials (Prettau Anterior and Zpex Smile) became less translucent and less strong using a high‐speed sintering program, whereas another (Katana STML Block) was unaffected.

Zirconia first gained attention as an engineering ceramic in the 1970s and began to be used in prosthodontics in the late 1990s. [1][2][3] Zirconia exhibits polymorphism, existing in cubic, tetragonal, and monoclinic forms. A martensitic phase transformation from tetragonal to monoclinic (t/m) zirconia forms is accompanied by a 4% increase in volume. However, a small amount of controlled expansion can decrease crack propagation, thereby making a material tougher through a process called transformation toughening. 4,5 The addition of stabilizing oxides, typically yttria (Y 2 O 3 ), can create tough multiphase partially or fully stabilized zirconia materials. 1,2 Zirconias that are capable of undergoing transformation toughening do not exhibit a proportional relationship between toughness and strength. 5,6 A wide variety of zirconia formulations are possible, each having their own distinctive physical properties. 6,7

Objective: This article describes a practical, predictable, and reliable method to select shades for direct composite restorations using custom shade guides made of resin composite at hand using a process of elimination Clinical Considerations: Esthetics in direct resin composite restorations depends on the clinician's ability to reproduce the shape and shade of natural teeth, thus appropriate shade selection is a must. This method presented in this article simplifies the process of shade selection for direct resin composite restorations. The use of custom shades tabs made of commecially available resin composites, its arrangment and a process of elimination of tabs during shade selection allows the practitioner to obtain the best possible resin composite shade available for every case. Conclusions:The use of custom shade guide tabs and an elimination protocol facilitates and expedites the process of shade selection for direct resin composites Clinical Significance: The article presents a practical, predictable, and reliable method to select shades for direct resin composite restorations for daily practice.