Abstract
Background and Aims The aim of this study was to investigate the effect of computer-aided design/computer-aided manufacturing (CAD/CAM) procedures on the overall fit of metal copings. Materials and Methods A standardized die was made in die stone of an upper right molar prepared for a full crown. The die was digitalized by an Identica Blue Light Scanner, and the coping substructure was designed using CAD software. Ten milled specimens and ten laser-sintered specimens were manufactured by Renishaw plc based on the generated file by the software. All twenty copings were digitized by the Identica scanner, and the data were superimposed with the original premanufacturing data file of the prepared full crown. Using the Geometric Modelling Library (GML) package, the fit discrepancies were displayed as colour maps showing discrepancies in three dimensions. Each map was made up of thousands of data points carrying numerical error values allowing detailed analyses. Results The milled group displayed a mean of fit discrepancies of 42.20 μm (SD 3.04 μm), while the laser-sintered group showed a mean of 42.24 μm fit discrepancies (SD 2.94 μm). Thus, a small difference of 0.04 μm between the two groups was detected. Conclusions The evaluated manufacturing systems can be used in dental practice as a small and insignificant discrepancy of fit between the two manufacturing methods was detected.
Highlights
Ceramometal crowns are the most common type of restoration used in dentistry [1]
direct metal laser sintering (DMLS) images appeared to have a greater range of fit deviations to computer numerical control milling (CNCM) as indicated by the colour spectra. e occlusal aspect of the fitting surface of the restorations was the area mainly affected with blue colour patches, indicating negative deviations over the occlusal aspects underlying cusps while showing positive deviations mesiodistally
Total mean of discrepancies for the CNCM group was found to be 42.20 μm with an standard deviation (SD) of 3.04 μm. e DMLS group showed a mean discrepancy of 42.24 μm with an SD of 2.94 μm
Summary
Ceramometal crowns are the most common type of restoration used in dentistry [1]. Recently, types of restoration are commonly produced by various -aided design/computeraided manufacture (CAD/CAM) systems rather than the conventional lost-wax technique introduced in 1907 by Taggart [2]. e advantages of using digital systems include the introduction of new and improved materials, reduced labor and time, increased cost efficiency, and more uniform, high quality [3]. e term “CAD/CAM” has come to be mostly associated with milling [2]. There are two possible ways of computer-assisted manufacturing (CAM): computer numerical control milling (CNCM) and direct metal laser sintering (DMLS) [4]. Both methods may use identical CAD technology to scan and design the restoration. Direct metal laser sintering called “3D printing” is a relatively new technique [12] It is a process of building up dental frameworks by a high-powered laser beam focusing onto a bed of the Co-Cr alloy powder and welding it together into subsequent, thin solid layers on cooling [13]. E aims of this study are to evaluate and compare the overall fit of metal copings fabricated by two different methods: CNCM (computer numerical controlled milling) and DMLS (direct metal laser sintering)
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