Build orientation optimisation and truss-cone hybrid support structure generation for additive manufacturing of implant-supported fixed complete denture metal frameworks

Laser powder bed fusion (LPBF) enables efficient manufacturing of implant-supported fixed complete dentures (ISFCD) Ti–6Al–4V frameworks, essential for rehabilitating edentulous patients. Yet these frameworks can suffer from accuracy and complication issues due to inadequate strength and improper appearance of supports on critical surfaces (abutment interfaces and screw channels). To address these issues, this study proposed an integrated approach combining build orientation (BO) optimisation and hybrid support generation. Specifically, a GPU-accelerated multi-objective particle swarm optimisation was developed to minimise overhang areas of the overall and critical surfaces, enabling near or complete support-free fabrication of critical surfaces. Furthermore, a novel truss-cone hybrid support based on truncated cube truss was designed to balance lightweight and mechanical performance. Through analysing frameworks’ distortion under different supports, the influence mechanism of supports on the distortion was clarified. Experimental results showed that the algorithm determined the optimal BO within 10 s, reducing the median supported critical surface area to 0.03% and eliminating support on critical surfaces in one-third of cases; frameworks with new supports exhibited smaller median distalmost gaps (all below the clinically acceptable 150 μm) and a 0.49 g reduction in support mass. This work facilitates the production of more accurate LPBF-built ISFCD frameworks, promoting their clinical application.