Biomimetic ceramic-resin dental restorations with graded TPMS structures

Natural teeth achieve exceptional performance through their graded structures and inorganic/organic composite composition-a principle that has long inspired the design of dental restorations. Ceramic‑resin interpenetrating phase composites (IPCs) have emerged as promising biomimetic materials that replicate this hybrid composition. However, current IPC‑based dental restorations lack the graded architectures analogous to those found in natural teeth, and therefore fail to emulate their gradient‑dependent mechanical behavior. To address this limitation, this study proposes a design and fabrication strategy for biomimetic dental crowns using graded triply periodic minimal surface (TPMS) structures. Schwarz‑P and Gyroid architectures with longitudinally graded and dual‑graded (both radial and longitudinal) porosity distributions were designed and 3D‑printed in zirconia. The printed scaffolds were then infiltrated with resin to form the final IPCs, which subsequently underwent mechanical and tribological testing. Results revealed that dual-graded structures exhibited superior compressive strength, elastic modulus, energy absorption capacity and wear resistance compared to longitudinally graded structures, which in turn outperformed uniformly porous structures. Comparing Gyroid and Schwarz-P configurations, Gyroid structures demonstrated significantly higher energy absorption (by 40.1%-63.9%) across all groups. Longitudinally graded and uniform Gyroid structures showed 8.7% and 23.7% greater compressive strength than their Schwarz-P counterparts, respectively. Meanwhile, dual-graded and uniform Schwarz-P structures exhibited 7.8% and 29.4% higher elastic modulus than corresponding Gyroid structures. The dual-graded Schwarz-P structure also demonstrated 50% better wear resistance than its Gyroid counterpart. Based on these results and the distinct biomechanical demands of incisors and molars, crown designs were tailored accordingly: a longitudinally graded Gyroid IPC was selected for incisors due to its higher compressive strength and energy absorption, while a dual-graded Schwarz-P structure was adopted for molars, leveraging its isotropic mechanics, higher stiffness, and superior wear resistance. These findings confirm the feasibility and potential of the proposed TPMS-based gradient design strategy for creating customized, high-performance biomimetic dental restorations.