Comparative evaluation of maxillary partial denture frameworks additively manufactured with different 3D printing techniques

Abstract

To compare the accuracy of fit, surface roughness, and microstructure of cobalt chromium (Co-Cr) maxillary removable partial denture (RPD) frameworks fabricated using direct metal laser melting (DMLS) and selective laser melting (SLM). A custom Kennedy Class II maxillary partial edentulous resin model was digitally scanned, and a virtual RPD framework was designed. Frameworks were fabricated using DMLS (Co-Cr, n = 8) and SLM (Co-Cr, n = 8), while a control group was produced using a hybrid digital-conventional protocol by lost-wax casting (CAST-Co-Cr, n = 8), in total 24 frameworks. Overall and point comparison adaptation was assessed using Geomagic Control X software program, surface roughness and microstructure were analyzed using scanning electron microscope (SEM). Group comparisons were performed using one-way ANOVA, with Tukey HSD post-hoc tests (significance at p ≤ 0.05). Quantitative analysis revealed significant differences in 3D accuracy among fabrication techniques ( p < 0.001). DMLS frameworks demonstrated superior overall fit (170 ± 1μm) and rest seat adaptation (144.9 ± 87.0 μm) compared to CAST (194 ± 17 μm and 392.6 ± 166.1 μm, respectively, p ≤ 0.003), with SLM showing intermediate values (182 ± 14 μm and 237.4 ± 151.6 μm). Surface topography analysis indicated DMLS had significantly lower roughness (54.1 ± 8.0 μm) than SLM (87.3 ± 9.8 μm) and CAST (83.4 ± 10.4 μm, p ≤ 0.003), with no SLM-CAST difference ( p = 0.734). DMLS 3D printing method produced Co-Cr RPD frameworks with superior fit accuracy and smoother surfaces compared to SLM 3D printing and traditional casting techniques. conclusion The comparison between DMLS and SLM 3D printing techniques for the fabrication of RPD frameworks offers significant insights for clinical practice in prosthodontics. Both techniques present a promising alternative to traditional metalworking methods, with potential improvements in precision, customization, and material strength. • DMLS produced superior fit (170 ± 16 μm) vs. SLM/Cast frameworks (p < 0.05). • DMLS showed lowest surface roughness (54.1 ± 8.0 μm) among all groups. • SLM frameworks had intermediate accuracy but higher roughness than DMLS. • 3D-printed frameworks outperformed cast in adaptation and surface quality. • Build orientation and support structures critically influence 3D printing accuracy.