Design and validation of Offset Split-P porous titanium implants for mandibular defect repair

• An integrated evaluation of specific surface area, transport properties, and mechanical performance identified the optimal TPMS structure for mandibular repair. • A wall-offset strategy reduced the maximum stress in the Split-P lattice by 58.6% under compression, effectively overcoming its stress concentration. • A biomimetically graded design reduced the equivalent elastic modulus by 8.5% while maintaining permeability. • For the first time, small-scale Ti-6Al-4V Offset Split-P structures (5 × 5 × 5 mm unit cell, 0.5 mm minimum strut diameter) were additively manufactured, demonstrating favorable mechanical properties and biological compatibility; these structures were then successfully implemented in a patient-specific mandibular implant model that withstood simulated physiological masticatory loads. Mandibular defects from tumor resection and trauma are increasing, while autograft and allograft resources remain limited. Here, we developed and fabricated a mandibular implant based on an offset-optimized, gradient-designed Split-P lattice. The feasibility of the porous implant was systematically assessed through mechanical simulations, fluid dynamic analyses, compression testing, in vitro cell culture, and corrosion immersion experiments, employing small-scale Ti-6Al-4V Offset Split-P structures (unit cell: 5 × 5 × 5 mm; strut diameter: 0.5 mm). The results demonstrate that this structure exhibits superior mass transport performance compared with four common topologies (Gyroid, Schwarz, Diamond, and Neovius). At porosities consistent with the human mandible (60 %–90 %), its elastic modulus (3.83–18.89 GPa) and yield strength (28.51–171.90 MPa) that match the characteristic range of human mandibular bone, while maintaining good biocompatibility. Moreover, it promotes cell proliferation, directional migration, and osteogenic differentiation, and shows outstanding corrosion resistance, ensuring long-term structural stability.