A Functionally Graded PICN Material for Biomimetic CAD-CAM Blocks

• Published in: Journal of dental research Vol. 97; no. 12; pp. 1324 - 1330
• Main Authors: Eldafrawy, M., Nguyen, J.F., Mainjot, A.K., Sadoun, M.J.
• Format: Journal Article Web Resource
• Language: English
• Published: Los Angeles, CA SAGE Publications 01-11-2018; SAGE PUBLICATIONS, INC
• Subjects: bioengineering; biomaterial(s); Ceramics; Composite materials; Crack initiation; Data analysis; Dental enamel; Dental prosthetics; Dental restorative materials; Dentin; Dentisterie & médecine buccale; Dentistry; Dentistry & oral medicine; Enamel; Energy; Ethyl carbamate; High temperature; Human health sciences; Lithium; Manufacturing; materials science(s); Mechanical properties; Optical properties; Porosity; Prostheses; prosthetic dentistry/prosthodontics; Prosthetics; Scanning electron microscopy; Sciences de la santé humaine; Slurries; Stress concentration; Teeth; Zirconia; ceramics; biomaterial(s); prosthetic dentistry/prosthodontics; materials science(s); composite materials; bioengineering
• ISSN: 0022-0345; 1544-0591; 1544-0591
• DOI: 10.1177/0022034518785364

The objective of this study was to introduce a functionally graded (FG) polymer-infiltrated ceramic network (PICN) block, characterized by a gradient of mechanical properties, as a biomimetic material for computer-aided design and manufacturing (CAD-CAM) prostheses. FG-PICN blocks were manufactured from a slurry of glass-ceramic powder, which was subsequently centrifuged and sintered. The ceramic network was infiltrated with urethane dimethacrylate and polymerized under high temperature-pressure. Blocks were sectioned into 9 layers, and each layer was subsequently cut into 3 samples. Samples were loaded into a 3-point bending device and tested for flexural strength, flexural load energy, and flexural modulus. The volume percentage of glass-ceramic, hardness, and brittleness index were also measured and scanning electron microscopy (SEM) observations were performed. Katana translucent zirconia (HT-ZIR) and e.max-CAD (EMX) were tested for comparison. Flexural strength, flexural load energy, and Weibull modulus of FG-PICN were shown to increase from the first (enamel-like zone) to the ninth layer (dentin-like zone), while, on the contrary, flexural modulus, hardness, brittleness index, and ceramic volume percentage decreased. SEM characterization highlighted a higher porosity in layer 9 than in layer 1. Flexural strength of the dentin-like zone (372.7 ± 27.8 MPa) was similar to EMX and lower than HT-ZIR. Flexural modulus was shown to vary from 41.9 ± 5.1 to 28.6 ± 2.0 GPa from surface to depth. Flexural load energy in the dentin-like zone (27.1 ± 4.9 mJ) was significantly superior to EMX and HT-ZIR. Hardness gradient was shown to be close to tooth tissues. This work introduces FG-PICN blocks, with a gradient of mechanical and optical properties through the entire thickness of the block designed to mimic dental tissues. FG-PICN demonstrated a favorable gradient of flexural strength, elastic modulus, and, most of all, flexural load energy and hardness compared to other CAD-CAM materials, which can promote the biomechanical behavior of single-unit restorations on teeth and implants.