Citation: Reimann, L.; Brytan, Z.; Jania, G. Inﬂuence of Filler Metal on Electrochemical Characteristics of a Laser-Welded CoCrMoW Alloy Used in Prosthodontics. Materials 2022, 15, 5721. https://doi.org/10.3390/ ma15165721 Academic Editors: Antonio Riveiro and S. Joseph Poon Received: 18 July 2022 Accepted: 12 August 2022 Published: 19 August 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional afﬁl- iations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). materials Article Inﬂuence of Filler Metal on Electrochemical Characteristics of a Laser-Welded CoCrMoW Alloy Used in Prosthodontics Lukasz Reimann 1, * , Zbigniew Brytan 2 and Grzegorz Jania 3 1 Materials Research Laboratory, Faculty of Mechanical Engineering, Silesian University of Technology, Konarskiego St. 18a, 44-100 Gliwice, Poland 2 Department of Engineering Materials and Biomaterials, Faculty of Mechanical Engineering, Silesian, University of Technology, 44-100 Gliwice, Poland 3 Dental Engineering Laboratory Grzegorz Jania, 48-200 Prudnik, Poland * Correspondence: lukasz.reimann@polsl.pl Abstract: This paper sought to determine corrosion resistance changes in the artiﬁcial saliva of a CoCrMoW-based alloy used for dental prostheses under Nd:YAG laser welding with CoCr alloy and stainless steel wire ﬁller metals. The paper presents the corrosion characteristics of such joints, including the next stage of porcelain-fused-to-metal (PFM) ﬁring. Corrosion tests were performed by electrochemical methods registering anodic polarization curves and electrochemical impedance spectroscopy (EIS). The microstructures were assessed by scanning microscopy (SEM) and chemical composition analysis (EDS) at the connection and heat-affected zones. Welding CoCrMoW alloy with and without a ﬁller material increased the open circuit potential of the samples by 40–100 mV compared to unwelded base alloy. At the same time, a potentiodynamic test showed a polarization resistance R pol reduction in welded samples, both for CoCr and stainless steel wires, as compared to the base CoCrMoW material. On the other hand, when comparing the current density and polarization resistance between materials welded with two different ﬁller metals, better results were obtained for samples welded with stainless steel wire. The polarization resistance R pol for the base alloy was 402 kΩ·cm 2 , for the CoCr wire weld it was 436 kΩ·cm 2 , and the value was 452 kΩ·cm 2 for stainless steel wire welds. Comparing polarization resistance R pol from the Tafel analysis and the total charge transfer resistance from Rp (EIS) from EIS, the CoCrMoW alloy welded with a stainless steel wire after heat treatment equaled or even slightly exceeded the corrosion resistance of the base alloy and alloy welded with dedicated CoCr wire after heat treatment. These results indicated the possibility of using stainless steel wire for the laser welding of CoCrMoW alloys dental prostheses, including the next stage of PFM, without sacriﬁcing the corrosion resistance of such connections, and this was conﬁrmed by most electrochemical parameters. Keywords: CoCrMoW alloys; CoCr alloys; stainless steel; LBW; corrosion resistance; EIS; dentures; prosthodontic; biomaterials 1. Introduction Welding technology has been known in prosthodontia for many years. Most prosthet- ics laboratories use it successfully with nonprecious alloys (titanium alloys, cobalt alloys, and nickel alloys) and noble metal alloys. That method repairs broken ﬁxed dentures and attachment dentures, and connects long prosthetics (bridges) and dental implants— fabricated in part because it minimizes potential distortion problems that may occur after welding, relative to casting technology [1,2]. There are many joining technologies employed in prosthodontia for preparing den- tures, including soldering, TIG (tungsten inert gas) welding with or without a ﬁller metal (autogenous TIG), and laser beam welding (LBW). Presently, the most promising welding method in dental engineering is LBW because it does not require a unique ﬁller material; Materials 2022, 15, 5721. https://doi.org/10.3390/ma15165721 https://www.mdpi.com/journal/materials