The aim of the study was to assess the effect of staining and bleaching on CAD/CAM materials with high (HT) and low translucency (LT or T). Samples were stored in coffee and subsequently bleached. CIELAB parameters were recorded at baseline, after coffee immersion, after bleaching. Translucency parameter (TP), whiteness index (WID) and color changes were calculated (ΔE00). Influence of staining and bleaching was analyzed with repeated-measures ANOVA and color differences between materials were analyzed with one-way ANOVA (α=0.05). Staining and bleaching significantly affected CIELAB parameters and WID for all materials (p<0.001). TP was significantly influenced by staining and bleaching for Crios and Enamic (p<0.05). Mean color differences were significantly different between materials (p<0.001). The greatest color changes due to staining were observed for Lava Ultimate while the lowest for e.max CAD. Both coffee staining and bleaching induced greater color changes for HT materials of the same brand compared to LT.

Objectives To assess the effect of material, thickness and glazing upon the color, translucency, and roughness of monolithic zirconia. Materials and methods Sixty discs (0.8, 1.5, and 2 mm thickness) were fabricated from A1 translucent zirconia (IPS e.max ZirCAD/MT, Katana/HT, Vita YZ/HT, Cercon/HT) and glazed. Roughness (Ra) was assessed with a profilometer and color coordinates were measured with a spectrophotometer on a black, white, and tooth‐shaded background before and after glazing. Relative translucency parameter (RTP), color differences (CIEDE2000) and differences in translucencies between materials, before and after glazing were calculated. RTP, Ra, color differences were statistically analyzed using ANOVA. Any significant interaction between factors was further analyzed using Tukey's HSD. Results RTP values were significantly different between materials (P < .001) and thicknesses (P < .001), with the interaction effect between material type and thickness, also significant (P < .001). However, glazing did not have a significant effect on RTP values (P = .782). Color differences resulted after glazing were significantly different between materials (P < .001), and thicknesses (P < .001) with the interaction effect also significant (P < .001). Glazing influenced roughness, Ra decreasing for all materials (P < .001). Conclusions As a result of glazing, only color changes were statistically significant. Translucency varied among brands of precolored monolithic zirconia; the differences increased for greater thicknesses. Clinical significance Glazing is an important step in the technological process of ceramic restorations; however, it can influence the final optical appearance of the restoration as color changes could be expected after the application of the glaze.

Translucent monolithic zirconia is the newest option of zirconia-based ceramics, which aimed to substitute the opaque classic yttria-stabilized tetragonal zirconia polycrystal (Y-TZPs) in more demanding esthetic cases. The aim of this review was to assess the available literature regarding the optical, chemical and mechanical properties of translucent zirconia ceramics. This systematic review was developed according to the PRISMA (Preferred Reporting Items for Systematic Review and Meta-analysis) guidelines. An electronic literature search was undertaken through Medline (National Library of Medicine) via PubMed to identify relevant articles, published in the interval 2010-2018. The search was limited to the English language publications, in vitro studies of color and microstructure of translucent zirconia material. Yttria-stabilized tetragonal zirconia polycrystals (Y-TZPs) has excellent mechanical properties, but its intense white color and high opacity represent an esthetic limit. Cubic zirconia represents a new generation of dental ceramics with molecular structure and physical properties different from the conventional zirconia. Dental manufacturers created new formulations of this restorative material, introducing new cubic varieties of zirconia with improved optical properties. Translucent monolithic zirconia provides a new restorative option that combines strength with improved esthetics, due to its increased translucency. Translucent zirconia is indicated for anterior and posterior restorations but should be used carefully for discolored teeth, because the background color can affect the final esthetic appearance of the restoration.

In the current orthodontic and prosthodontics practice, study models made of plaster are being used to provide a three-dimensional view of the patient’s occlusion and allow the clinician to analyze, diagnose, or monitor anomalies. With the introduction of intraoral and extra oral digital impressions, it is now possible to obtain digital study models of the patients’ dental arches. Digital models can be obtained in a physical hardcopy via 3D printing or rapid prototyping. Although, professional 3D printers require a high initial set-up cost, low cost 3D printers can provide similar quality products. The aim of this study is to investigate the accuracy of physical dental models reconstructed from digital data by two rapid prototyping techniques. For this purpose twenty mandibular and maxillary conventional plaster models from randomly chosen subjects were selected and served as the gold standard. The casts were digitized using a 3D scanner and .stl surface models were acquired; the virtual model was adjusted for reconstruction using dedicated software, thus obtaining the CAD model of the casts. The CAD models were reconstructed using a 3D fused deposition modeling (FDM) printer, a RepRap FDM printer and an inverted stereolithography printer. The reconstructed models were digitized using a laboratory 3D scanner and the resulting Mesh datasets were compared with the CAD model using inspection software. The mean systematic differences for the 3D comparison of the reconstructed models were 0.207 mm for the stereolithography models, 0.156 mm for the FDM models, and 0.128 mm for the RepRap models. Although a technology proved the ability to manufacture a dental model with accentuated morphology, the results demonstrate that replicas of plaster casts are influenced by problems linked to the size of the detail to be reproduced, which is often similar to or finer than the fabrication layer.

Highly translucent ceramics should be wisely used for restoring the appearance of dental structures since background color has a large effect upon these materials. The more recently introduced pressable ceramics showed high levels of translucency.