Objective. Zirconia ceramics for frameworks of fixed partial dentures can be color shaded to better match the shade of veneering porcelain. The aim of this study was to evaluate the effect of color shading the green-stage zirconia ceramic on some mechanical properties. Material and Methods. Zirconia disks (diameter 19 mm, thickness 0.8 mm) were divided into 10 groups of 10 disks each according to the color shade of the zirconia ceramic. The disks were shaded with the same color liquid using either the recommended shading time (3 s) or prolonged shading time (60 s). Nine control disks were tested without color. Composition of the color liquids was determined with EDX analysis. All the disks were sintered at 1500°C and their biaxial flexural strength was measured dry and at room temperature. Surface Vickers microhardness was measured. Data were evaluated using ANOVA analysis. Results. Disks of shade D4 (Vita Classic-scale) revealed the highest strength (1007 MPa) of the shaded disks, but the strength did not differ statistically from that of the control group (1132 MPa). Other color shades had values of A3: 898 MPa, B1: 918 MPa, C4: 885 MPa, and D2: 897 MPa. Prolonging the shading time from 3 s to 60 s lowered the strength even more. Shading time had no effect on microhardness, but there were some differences among the different color shade groups (p<0.05). EDX analysis showed slight differences between compositions of different color liquids. Conclusions. Some variation was found in strength and surface hardness of zirconia that had been color shaded to different shades.

Objective: To systematically review the dental literature for clinical studies reporting on production time, effectiveness and/or costs of additive and subtractive computer‐aided manufacturing (CAM) of implant prostheses.Materials and methods: A systematic electronic search for clinical studies from 1990 until June 2020 was performed using the online databases Medline, Embase and Cochrane. Time required for the computer‐aided design (CAD) process, the CAM process, and the delivery of the CAD‐CAM prostheses were extracted. In addition, articles reporting on the effectiveness and the costs of both manufacturing technologies were included.Results: Nine clinical studies were included reporting on subtractive CAM (s‐CAM; 8 studies) and additive CAM (a‐CAM; 1 study). Eight studies reported on the s‐CAM of prosthetic and auxiliary components for single implant crowns. One study applied a‐CAM for the fabrication of an implant bar prototype. Time was provided for the CAD process of implant models (range 4.9–11.8 min), abutments (range 19.7–32.7 min) and crowns (range 11.1–37.6 min). The time for s‐CAM of single implant crown components (abutment/crown) ranged between 8.2 and 25 min. Post‐processing (e.g. sintering) was a time‐consuming process (up to 530 min). At delivery, monolithic/veneered CAD‐CAM implant crowns resulted in additional adjustments chairside (51%/93%) or labside (11%/19%).Conclusions: No scientific evidence exists on production time, effectiveness and costs of digital workflows comparing s‐CAM and a‐CAM. For both technologies, post‐processing may substantially contribute to the production time. Considering effectiveness, monolithic CAD‐CAM implant crowns may be preferred compared to veneered CAD‐CAM crowns.