THE MANUFACTURING PRECISION OF DENTAL CROWNS BY TWO DIFFERENT METHODS IS COMPARABLE

Abstract

Like all production areas the production of dental replacements, either prosthetic or aesthetic, has recently undergone great advancement due to computer-aided design of dental parts and their computer aided manufacturing. CNC milling, which belongs to the group of subtractive production methods, is very well established in dental production. For the last several years, methods of additive manufacturing, such as Selective Laser Melting (SLM), Selective Laser Sintering (SLS) and Direct Metal Laser Sintering (DMLS), have gone mainstream. In general, both additive and subtractive methods have their technological pros and cons; therefore, the aim of this paper is to determine how accurate in terms of tolerance of production of ± 50 μm both technologies are and afterwards to determine which of the technologies is more accurate. Given that nowadays the most commonly used material in the dental area is cobaltchromium (Co-Cr) alloy, this alloy was chosen for the experiment. Thirty Co-Cr dental crowns were manufactured for analysis according to the referential CAD model, 15 by CNC milling and 15 by SLM. The crowns were subsequently scanned using a dental 3D scanner, and their inner areas were extracted and compared to the nominal CAD model. The percentage agreement of production is on the level of approximately 94% with both devices, and the average value of agreement as well as the standard deviation and range variation are better with additive production.