Trueness of removable partial denture frameworks additively manufactured with selective laser melting

Statement of problem: Although studies have reported on selective laser melting (SLM)-fabricated removable partial dentures (RPDs), research addressing the trueness of SLM-fabricated RPD metal frameworks is sparse. Purpose: The purpose of this in vitro study was to evaluate the trueness of powdered cobalt-chromium (Co-Cr) or titanium-6 aluminum-4 vanadium (Ti-6Al-4V) alloy frameworks for RPDs fabricated by SLM. Material and methods: A digital scan of a Kennedy class II mandible typodont was obtained to design an RPD framework by using a computer-aided design (CAD) software program (denoted as CRF). Two experimental groups of frameworks were fabricated from the CRF by using SLM in alloys of Co-Cr (SLM-Co-Cr, n=6) and in Ti-6Al-4V (SLM-Ti-6Al-4V, n=6) while a control group was fabricated by using traditional lost-wax casting following stereolithography (CA-Co-Cr, n=6). In total, 18 RPD frameworks were digitally scanned (denoted as CRF), with each scan then superimposed on the CRF and evaluated for discrepancies by using a 3D analysis software program. A nonparametric Kruskal-Wallis test was performed to determine differences in trueness among groups (α=.05). Results: The CA-Co-Cr group showed the highest discrepancy between CEF and CRF. Statistically significant differences were found between the CA-Co-Cr and SLM-fabricated groups (P=.03 for Co-Cr, and P=.016 for Ti-6Al-4V). However, no significant difference was found between the SLM-Co-Cr and SLM-Ti-6Al-4V groups (P=.787). Conclusions: SLM-fabricated RPD frameworks exhibited higher trueness than CA-Co-Cr fabricated ones, indicating the potential of selective laser melting to produce the geometric shapes required for accurate dental restorations.