Challenges of Co–Cr Alloy Additive Manufacturing Methods in Dentistry—The Current State of Knowledge (Systematic Review)

Abstract

Complex dental components which are individually tailored to the patient can be obtained due to new additive manufacturing technology. This paper reviews the metallic powders used in dental applications, the fabrication process (build orientation, process parameters) and post-processing processes (stress relieving, surface finishing). A review of the literature was performed using PubMed, ScienceDirect, Mendeley and Google Scholar. Over eighty articles were selected based on relevance to this review. This paper attempts to include the latest research from 2010 until 2020, however, older manuscripts (10 articles) were also selected. Over 1200 records were identified through the search; these were screened for title and/or summary. Over eighty articles were selected based on relevance to this review. In order to obtain a product which can be used in clinical applications, the appropriate manufacturing parameters should be selected. A discussion was made on optimal selective laser melting (SLM) parameters in dentistry. In addition, this paper includes a critical review of applied thermal treatment methods for Co–Cr alloys used in dentistry.

Reliability of Metal 3D Printing with Respect to the Marginal Fit of Fixed Dental Prostheses: A Systematic Review and Meta-Analysis

“…The final misfit of 3D-printed prostheses represents the summation of the errors involved in all the steps from the image acquisition to the post-treatment process. Compared to conventional methods, although the digital workflow allows the elimination of inherent inaccuracies related to laboratory manual works, different devices and parameters can highly influence the dimensional accuracy of outcome products [9]. The quality of optical scanners and scan protocols also affect the accuracy of digitization.…”

“…During the procedure of powder bed fusion, a high-powered laser beam is directed at the layer of metal powder following the design of an object and fuses the powder particles sequentially until the 3D object is completely formed [8]. The main differences between the metal 3D printing technologies are operational parameters and post-treatment processes [9,10].…”

“…These alloys demonstrate good tensile strength, elasticity, fatigue resistance, or corrosion resistance [11]. The major constituents of the powder are cobalt and chromium; however, molybdenum, tungsten, silicon, manganese, niobium, cerium, iron, and carbon are also included to improve the properties of the material [9]. Chromium increases corrosion resistance by forming a passivation film; molybdenum influences the grain size and decreases the susceptibility to pitting corrosion; tungsten causes solid solution strengthening with molybdenum; silicon and manganese are inserted to enhance the alloy's fluidity; and niobium affects the intermetallic phase formation and solution strengthening.…”

Dental 3D-Printing: Transferring Art from the Laboratories to the Clinics

“…Yet, research on their use has been limited due to the cost of titanium alloys, turning the focus to CoCr alloy, which present numerous advantages. Compared to other metallic materials, CoCr alloy presents lower density, higher hardness and good corrosion resistance and bonding characteristics to porcelain [ 26 , 46 , 47 , 48 , 49 ]. A study by Barazanchi et al (2020) demonstrates that CoCr materials fabricated by SLS have a higher bonding capacity with porcelain compared to CoCr materials fabricated by soft milling.…”

Thin Films Deposition of Ta2O5 and ZnO by E-Gun Technology on Co-Cr Alloy Manufactured by Direct Metal Laser Sintering

“…Common methods used to characterize biomaterial surfaces are SEM, EDS, XRD, contact angles, ESCA (XPS), auger electron spectroscopy, SIMS, FTIR-ATR, and STM. The direct metal laser sintering (DMLS) process has been developed for industrial and medical applications due to its remarkable capabilities, such as building complex parts that are otherwise difficult to manufacture by conventional methods [4][5][6][7][8]. DMLS is a layer-by-layer automated fabrication process used for producing three-dimensional physical scaled objects directly from 3D CAD data without utilizing part-dependent implements [9].…”