Enhancing the Hydrophobicity and Antibacterial Properties of SiCN-Coated Surfaces with Quaternization to Address Peri-Implantitis

Abstract

Peri-implantitis is a major cause of dental implant failure. This disease is an inflammation of the tissues surrounding the implant, and, while the cause is multi-factorial, bacteria is the main culprit in initiating an inflammatory reaction. Dental implants with silicon carbonitride (SiCN) coatings have several potential advantages over traditional titanium implants, but their antibacterial efficiency has not yet been evaluated. The purpose of this study was to determine the anti-bacterial potential of SiCN by modifying the surface of SiCN-coated implants to have a positive charge on the nitrogen atoms through the quaternization of the surface atoms. The changes in surface chemistry were confirmed using contact angle measurement and XPS analysis. The modified SiCN surfaces were inoculated with Streptococcus mutans (S. mutans) and compared with a silicon control. The cultured bacterial colonies for the experimental group were 80% less than the control silicon surface. Fluorescent microscopy with live bacteria staining demonstrated significantly reduced bacterial coverage after 3 and 7 days of incubation. Scanning electron microscopy (SEM) was used to visualize the coated surfaces after bacterial inoculation, and the mechanism for the antibacterial properties of the quaternized SiCN was confirmed by observing ruptured bacteria membrane along the surface.

Keywords: peri-implantitis; quaternization; silicon carbonitride (SiCN).

Figure 1

Schematic drawings of sample testing configuration for bacterial culture.

Figure 2

Contact angle images of (a) Si and (b) quaternized SiCN surface with 5% nitrogen content.

Figure 3

High-resolution XPS spectra of N1 peak analysis of SiCN and QSiCN surfaces with (a) 0°- and (b) 45°-tilted coating surfaces and (c) the peak separation of 45°-tilted QSiCN spectra.

Figure 4

Colony-forming unit (CFU) per mililiter of S. mutans culture on Si, SiC, SiCN, and quaternized SiCN substrates with different nitrogen contents after 24 and 48 h of incubation time.

Figure 5

Fluorescence microscopy images of S. mutans cultured for three days on quaternized SiCN surface with (a) 5%, (b) 10% and (c) 15% nitrogen content and (d) Si as the control group; and seven days culture time on SiCN surface with (e) 5%, (f) 10% and (g) 15% nitrogen content and (h) Si as the control group.

Figure 6

The optimization of nitrogen concentration range in quaternized SiCN using Pearson IV and Edgeworth–Cramer Peak Function.

Figure 7

SEM images of the surface of (a) Si, (b) SiC, (c) SiCN, and quaternized SiCN with (d) 5%, (e) 10% and (f) 15% nitrogen content. (g) With a larger magnification image of quaternized SiCN with 5% nitrogen content. Note yellow arrow pointing to the ring-shaped pattern and red arrow pointing to irregular outline of bacterial cell.