Antibacterial and preventive effects of newly developed modified nano-chitosan/glass-ionomer restoration on simulated initial enamel caries lesions: An in vitro study.

Abstract

Background: Despite the superiority of glass-ionomer cements (GICs) over composites in treating white spot lesions (WSLs), there is still a concern about their preventive and antibacterial properties. Efforts have been made to improve the strength of their bond to demineralized enamel, fluoride release and antibacterial properties by adding nanoparticles of chitosan, which seems to be a promising method.

Objectives: The aim of the present study was to assess the antibacterial effect, the microshear bond strength (μSBS) to enamel at the WSL area, and the fluoride and nano-chitosan release after modifying the polyacrylic acid liquid phase of a traditional GIC with different nano-chitosan volumes.

Material and methods: A total of 120 samples were prepared, and then divided into 4 groups (n = 30): G1 - non-modified GIC, which served as a control group, while G2, G3 and G4 were modified with different nano-chitosan volumes (50%, 100% and 150%, respectively). Microshear bond strength was assessed using a universal testing machine (UTM) after storage in distilled water for 24 h. Fluoride and nanochitosan release was measured with the use of spectrophotometers at different time points (initially, and at 1 h, 24 h, 48 h, 72 h, 1 week, 2 weeks, 3 weeks, and 6 weeks) after storage in distilled water. The antibacterial effect against the Streptococcus aureus strain was assessed with the agar diffusion test. The data was statistically analyzed.

Results: After 24-hour storage, G2 recorded a slight, yet non-significant, increase in the μSBS values (4.1 ±0.94 MPa) as compared to G1 (3.9 ±1.30 MPa). With regard to fluoride release, the amount recorded for G1 was significantly greater at the end of the 24-hour storage period (0.70 ±0.30 μmf/cm2) than modified nano-chitosan GIC groups; G1 was followed by G4 (0.54 ±0.34 μmf/cm2). The highest amount of nano-chitosan release after 24-hour storage was noted for G3 (0.85 ±0.00 μmf/cm2). The highest inhibition zone value was recorded for G2.

Conclusions: Glass-ionomer cement modified with 50% nano-chitosan was shown to positively affect μSBS and the antibacterial effect, while modification with 150% nano-chitosan significantly increased fluoride release.