Molding Quality and Biological Evaluation of a Two-Stage Titanium Alloy Dental Implant Based on Combined 3D Printing and Subtracting Manufacturing.

Metal 3D printing has been used in the manufacturing of dental implants. Its technical advantages include high material utilization and the capacity to form arbitrarily complex structures. However, 3D printing alone is insufficient for manufacturing two-stage titanium implants due to the limited precision in printing titanium alloy parts. In this study, 3D printing was employed to create the implant structure, subsequently complemented by mechanical processing to refine the implant abutment connection and neck. Additionally, the mechanical properties of 3D-printed titanium alloy implants were evaluated through tensile and dynamic fatigue testing. The MTT assay was employed to assess the cytotoxicity of 3D-printed titanium alloy dental implants. The impact of bone union and osteogenesis from 3D-printed titanium alloy dental implants was investigated through in vivo experimentation. The results demonstrated that combining 3D printing with subsequent machining constitutes a viable method for the manufacture of two-stage titanium dental implants. Test results for mechanical properties indicated that heat-treated 3D-printed titanium alloy dental implants possess significant tensile strength and fatigue resistance and are capable of withstanding the robust chewing forces in the oral cavity. In vitro findings revealed that sandblasted and acid-etched 3D-printed titanium alloy exhibited negligible cytotoxicity, with osteoblast differentiation of hMSCs being more pronounced compared with the control group. In vivo studies indicated that no significant differences were observed in bone volume fraction, bone-implant contact rate, and unscrewing torque between 3D-printed titanium alloy dental implants and commercial SLA surface implants at both 1 and 3 months postimplantation.