Feasibility of Selective Laser Melting additive 3D printing technology for the fabrication of implant-supported partial fixed dental prostheses: dimensional precision and physicochemical characterization

Author(s)

Anna Gabriella Camacho Presotto

• Document type: Doctoral Thesis
• Press: Piracicaba, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Odontologia de Piracicaba
• Defense date: 2020-02-20

Examining board members

Marcelo Ferraz Mesquita; Aldiéris Alves Pesqueira; Ricardo Armini Caldas; Flavio Henrique Baggio Aguiar; Vanessa Cavalli

• Advisor: Marcelo Ferraz Mesquita; Valentim Adelino Ricardo Barão

Abstract

The aim of this study was to verify whether Selective Laser Melting (SLM) additive manufacturing technology provides better dimensional precision for implant-supported 3-unit fixed dental prosthesis (FDPs) frameworks than subtractive manufacturing with Soft Metal Block (SMB) milling and the standard casting technique. Also, the physicochemical properties (superficial, microstructural, mechanical, and electrochemical) of specimens made by all evaluated technologies were characterized and compared. For dimensional precision evaluation, 3-unit FPDs frameworks were made by the casting, SMB, and SLM technologies with their respective commercially available Co-Cr alloys. For physicochemical investigations, specimens with specific dimensions for each analysis were fabricated by the same technologies with the same Co-Cr alloys. The marginal fit between prosthesis cylinder-to-abutment was evaluated with photoelastic and strain gauge models. Stress and strain were quantitatively investigated by PH and SG analyses after prosthetic screw tightening. Several techniques were carried out to characterize the specimens in terms of surface morphology, chemical composition, microstructure, surface free energy, and mechanical properties. Metal-ceramic bond strength was evaluated with the 3-point bend test. Standard electrochemical tests were performed in artificial saliva (pH of 6.5). All data were evaluated at a significance level of 5%. The SLM group showed the best values of marginal fit (µm) in comparison with SMB and casting (p < 0.05). SLM presented lower mean ±standard deviation stress and strain values when compared with SMB and casting (p < 0.05). A positive correlation was observed between fit and stress or strain for all evaluated groups (p < 0.05). Similar microstructure patterns ('gama'-phases and 'épsillon'-phases), surface morphology, roughness, and surface free energy were found among groups (p > 0.05). Energy-dispersive spectroscopy confirmed the elemental composition provided by manufacturer¿s information of the alloys used. SLM technology provided a fine-grained homogeneous and less porous microstructure on specimens. X-ray photoelectron spectroscopy suggested a thicker oxide film on SLM specimens¿ surfaces. Highest values of Vickers microhardness, flexural strength, elastic modulus, and metal-ceramic bond strength were found for the SLM group (p < 0.05). The SLM group exhibited superior electrochemical stability with higher values of polarization resistance (Rptot), corrosion potential (Ecorr), and pitting potential (Epit) values (p < 0.05). SLM technology revealed 3-unit implant-supported FPD frameworks with superior dimensional precision and greater physicochemical properties, and can be a promising option for the fabrication of dental prostheses (AU)

• FAPESP's process: 16/23490-1 - Using Selective Laser Melting additive CAD/CAM technology (3D printing) for the fabrication of implant-supported partial fixed dental prosthesis: biomechanical, structural and electrochemical analysis
• Grantee: Anna Gabriella Camacho Presotto
• Support Opportunities: Scholarships in Brazil - Doctorate