3D-printed strong hybrid materials with low shrinkage for dental restoration

Flowable photocurable resins can be printed effectively by stereolithographic 3D printing for dental applications; however, the 3D-printed objects’ mechanical properties cannot meet the requirements for the dental restorative materials. In this study, a strong customized crown for tooth repair was first prepared via direct ink writing 3D printing from a high-viscosity hybrid paste of acrylic monomer and multi-scale inorganic particles. The results showed that the hybrid resin-based composites (RBCs) could be printed successfully and smoothly through a metal nozzle with a gradually shrinking channel. The theoretical simulation of finite element methods was consistent with the experiment results. The printed objects were preliminarily cured incrementally and exhibited a low shrinkage ratio of only 2.58 ± 0.11%. The printed samples with criss-crossed layers by interrupting crack propagation exhibited superior mechanical properties (a flexural strength of 120.8 ± 4.1 MPa and a compressive strength of 323.6 ± 5.6 MPa) than their traditional molding counterparts. Since the deposited layers exhibited improved resistance to bending forces, the flexural strength of the sample with a print orientation in adjacent layers (45–135°) even reached 145.5 ± 8.7 MPa. The RBCs were successfully used to print strong, high-performance and biocompatibility dental crowns, expected to provide a customized component for the clinical restoration of teeth.