PICN Nanocomposite as Dental CAD/CAM Block Comparable to Human Tooth in Terms of Hardness and Flexural Modulus

Abstract

Polymer infiltrated ceramic network (PICN) composites are an increasingly popular dental restorative material that offer mechanical biocompatibility with human enamel. This study aimed to develop a novel PICN composite as a computer-aided design and computer-aided manufacturing (CAD/CAM) block for dental applications. Several PICN composites were prepared under varying conditions via the sintering of a green body prepared from a silica-containing precursor solution, followed by resin infiltration. The flexural strength of the PICN composite block (107.8–153.7 MPa) was similar to a commercial resin-based composite, while the Vickers hardness (204.8–299.2) and flexural modulus (13.0–22.2 GPa) were similar to human enamel and dentin, respectively. The shear bond strength and surface free energy of the composite were higher than those of the commercial resin composites. Scanning electron microscopy and energy dispersive X-ray spectroscopic analysis revealed that the microstructure of the composite consisted of a nanosized silica skeleton and infiltrated resin. The PICN nanocomposite block was successfully used to fabricate a dental crown and core via the CAD/CAM milling process.

Castable polymer-infiltrated ceramic network composite for training model tooth with compatible machinability to human enamel

“…Such PICN structure provides unique mechanical properties including machinability. In fact, the mechanical properties of the PICN composite, such as hardness and elastic modulus, are reportedly similar to that of enamel and dentin rather than those of conventional resin composite 13,15) . From a materials science perspective, a key factor for mimicking the enamel properties is the microstructure; thus, the PICN structure contributes to mimicking the unique machinability of enamel.…”

“…The present PICN model teeth were formed in the steps which involved the precursor slurry casting to the tooth-shaped mold followed by light curing. This light-curable precursor slurry was prepared as indicated in our previous studies 13,14) . The slurry contains silica nanoparticles, alcohol solvents (PrOH and POE), resin monomers (HEMA and TEGDMA), and the photo-initiator (BAPO).…”

“…Subsequently, the body was shrunk by the sintering of the silica nanoparticles. The porous silica body had nanosized continuous pores with a silica skeleton 13) . Therefore, mixture of UDMA and TEGDMA monomers infiltrated into the porous silica body through the continuous pores and were polymerized by heat treatment.…”

“…The PICN model tooth was prepared via the slip-casing method, which was the partially modified method reported in our previous study on PICN composite for the CAD/CAM block 13) . The flowchart of the preparation process is described in Fig.…”

Printable PICN Composite Mechanically Compatible with Human Teeth

“…The chemical composition of the precursor slurry used in this study was slightly modified from the PICN composite used with CAD/CAM blocks reported in our previous study (Kawajiri et al 2021). The present composition contained a high silica loading (49.5 wt%) and exhibited excellent printing ability.…”