The aim of this study is to compare the hardness of Co–Cr metal alloy specimens made by different methods and how it is influenced by multiple temperature changes. Fifty-four samples are made by three different methods and are accordingly divided in three groups – group M (Milling), group LP (Laser Printing) and group LW (Lost Wax), with 18 samples each. All of them contain three subgroups with six samples – metal samples with no thermal cycles (subgroup 1), metal samples with one thermal cycle (subgroup 2) and metal samples with two thermal cycles (subgroup 3). Their Vickers hardness is evaluated by a weight of 1 kg applied for 20 s. The results are presented in tables. The average hardness is the highest for group LP – 509, followed by group M – 440, and for group LW it is 401. For the subgroups, the best results are exhibited by the samples of subgroup 2 – 430, followed by subgroup 3 – 457, and subgroup 1 – 450.

The aim of this in vitro study was to compare the quality of the data obtained by intraoral and by laboratory 3D scanners. An artificial jaw with an acrylic tooth prepared for a full metal ceramic crown was used as a master model of the prosthetic field. A reference model was created by scanning this field by a coordinate measuring machine (CCM). The acrylic master model was scanned by four scanners using three different methods and six digital models were obtained. They were divided in three groups - direct intraoral scanning (DIS), laboratory stone scanning (LSS) and laboratory conventional impression scanning (LCIS). Each scan was saved in the STL file format. Using a computer program, each of the six digital models were compared with the reference model created by the CCM and the results were displayed as color maps. The minimal acceptable deviation was defined as the deviation from the digital standard within the ± 0.02 mm limits. Thus, the LSS group exhibited an average of 13.5% points within these limits, followed by the LCIS group with 17.25%. The result for the DIS group was 44.75%.