Hybrid resin-based composites useful in printing efficient dental crowns: Study

Hybrid composites were introduced in the 1980s and are more commonly known as resin-modified glass ionomer cements (RMGICs). Initially, resin-based composite restorations in dentistry were very prone to leakage and breakage due to weak compressive strength.

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 group of researchers from China prepared 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 of this study 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 crisscrossed 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 moulding 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.

Thus, the researchers concluded that the hybrid resin-based composites (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.

Reference:

A study titled, "3D-printed strong hybrid materials with low shrinkage for dental restoration" by Zhao M et. al published in the Composites Science and Technology.

https://doi.org/10.1016/j.compscitech.2021.108902