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TiO 2 nanotubes (NTs) obtained via electrochemical anodization (EA) on conventionally machined titanium surfaces are reported to be promising for achieving mucointegration in dental implant therapy. Dental abutments, manufactured by selective laser melting (SLM), combined with thermal post-treatment, present a promising alternative to conventionally machined titanium. Based on an original protocol, this study aims to investigate how the characteristic microstructure of the α + β phases in post-heated SLM Ti6Al4V can influence the growth of NTs and the resulting physical and chemical surface properties. Ti6Al4V-SLM discs were fabricated, heat post-treated and mechanically polished. The samples were then subjected to EA under different voltage conditions (10, 20 and 30 V). The specimens' surfaces were characterized at the same location, before NTs formation by electron backscatter diffraction (EBSD), and after by scanning electron microscopy (SEM). Then, roughness and wettability were studied to determine how EA affects surface properties compared to conventionally machined and polished titanium surfaces without NTs (reference). Surface reactivity was evaluated through chemical analysis and collagen binding capacities. The self-organized TiO 2 layer was developed on the α phase only and the β phase was preferentially dissolved. The characteristic dimensions of the nanotubes (diameter, length and wall thickness), measured by SEM image analysis, increased proportionally with the rise in voltage but were not affected by the crystallographic orientation of the underlying α grain. Micro-roughness was the same for nanotubular and reference surfaces. Wettability was improved, as was surface reactivity towards collagen, which may contribute to improved bioactivity of titanium surfaces in dentistry.

Mechanical properties of polylactic acid (PLA), which is a biopolymer obtained via 3D-printing, were compared with conventional resins for the realization of interim prosthesis. A PLA built by fused deposition modeling and traditional interim resins (Unifast ® , Integrity ® , Temporary CB ® ) were divided into 4 groups (n=10). Each group was investigated for Young modulus, flexural strength, microhardness and analysis of the fractured surface. Data were analyzed by Kruskal-Wallis and ANOVA (α=0.05). The porosity of the PLA was calculated from the crystallinity degree and density. PLA-group showed an elastic modulus and flexural strength in the same range than Integrity ® -group, better than Unifast ® -group and inferior to Temporary CB ® -group (p<0.05). PLA-group microhardness was equivalent to Unifast ® -group and inferior to Integrity ® and Temporary CB ® groups (p<0.05). Due to mechanical properties similar to conventional resins and the low porosity rate, this biocompatible 3D-printed polymer may be an interesting alternative to conventional polymer to build temporary prosthesis.

Purpose: To mechanically characterize and assess the biological properties of Ti6Al4V surfaces obtained by Selective Laser Melting in order to determine whether this process is conceivable for production of implant-supported prostheses and particularly trans-gingival components. As-built and polished surfaces were studied in comparison with components obtained by computer numerical control machining technology in order to consider whether the properties are in the same range as the conventional method currently used., Materials and Methods: Cylindrical specimens of Ti6Al4V (n = 6) were built with Selective Laser Melting for the characterization of mechanical properties according to ISO 22674 and discs (n = 12) were fabricated in the same conditions for cytotoxicity evaluation. Discs (n = 12) of Ti6Al4V were also obtained by computer numerical control machining as control. Half of the number of discs (n = 6) from each process were polished, to simulate the laboratory protocol for polishing of transmucosal components and half of the discs remained unaltered (as-built). Surface roughness measurements of disc specimens (as-built and polished) were compared with computer numerical control milling specimens (as-built and polished). Proliferation of human gingival fibroblasts on Ti6Al4V surfaces was also assessed for each condition. Viability and cell morphology were then evaluated qualitatively. Ra and Sa data were compared using Student's t-test (α = 0.05) and metabolic activity data were compared using Kruskal-Wallis statistical test (α = 0.05)., Results: Selective Laser Melting specimens showed elongation at break greater than 2% and 0.2% yield strength better than 500MPa which complied with ISO 22674 standards. Although Selective Laser Melting samples displayed significantly increased roughness on as-built surfaces compared to computer numerically controlled milling samples (p < 0.05), no statistically significant difference was observed after mechanical polishing (p = 0.279). Regarding metabolic activity, no statistical difference was observed between groups at day 3 (p > 0.05) and fibroblasts showed a viability higher than 97% on all discs. Cell shapes on polished samples suggested moderate adhesion compared to unpolished samples., Conclusion: With the manufacturing parameters selected in this study, Selective Laser Melting of Ti6Al4V appeared to be compatible with a prosthetic application type 4 according to ISO 22674. Surfaces obtained, followed by recommended postprocessing provided components with equivalent biological properties compared to computer numerical control machining technology., (© 2021 by the American College of Prosthodontists.)

Purpose: To determine whether selective laser melting (SLM) is suitable for the fabrication of dental superstructures., Materials and Methods: Mechanical properties of Ti-6Al-4V, manufactured with SLM or numerically controlled milling, were evaluated and compared., Results and Conclusion: Both groups showed a mechanical strength greater than 500 MPa and an elongation greater than 2%, as required by the International Organization for Standardization 22674 standard. However, a reduced ductility was observed for SLM samples.