Microhardness and Fluoride Release of Glass Ionomer Cement Modified with a Novel Al(+3) Complex to Enhance Its Antimicrobial Activity

OBJECTIVES: To synthesize and characterize a novel Al(+3) complex with 2-(2-hydroxyphenyl)-1H-benzimidazole (HL) to be added to a restorative glass ionomer cement (GIC) to enhance its antimicrobial activities and to evaluate the Vickers microhardness (HV) and fluoride release (FR) of the modified GIC. MATERIALS AND METHODS: Al(+3) complex was synthesized by the addition of 1 mmol (0.210 g) of HL to 1 mmol (0.342 g) of aluminum sulfate in ethanol. The resulting solution was then refluxed under stirring for 24 h and then collected by filtration and dried in a vacuum desiccator over an anhydrous CaCl(2). Characterization of Al(+3) complex was carried out by Fourier transform infrared spectroscopy (FTIR), elemental microanalysis, thermal gravimetric analysis (TGA), molar conductance, (1)H NMR spectra, and electron impact-mass spectrometry. The antimicrobial activity of Al(+3) complex-modified GIC (Al-GIC) was studied by the “cut plug method” against Gram-negative bacteria (Acinetobacter baumannii) and Gram-positive bacteria (Staphylococcus aureus, Enterococcus, and Streptococcus mutants) and fungi (Candida albicans). HV was evaluated by a digital microhardness tester (Zwick/Roell, Indentec, ZHVμ-S, West Midlands, England). Fluoride levels in ppm were obtained using the ion-selective electrode connected to a digital meter. A one-way ANOVA and Bonferroni test were used to analyze the data with the significance level established at p ≤ 0.05. RESULTS: Synthesis of Al(+3) complex was confirmed by FTIR, elemental microanalysis TGA, molar conductance, (1)H NMR spectra, and electron impact-mass spectrometry. Al-GICs exhibited an enhanced antibacterial activity against all studied microorganisms as confirmed by the growth of inhibition zones compared to control GIC (C-GIC). Though there was a slight reduction in HV and FR with increasing the added percent of Al(+3) complex, no significant differences were found between the studied groups. CONCLUSIONS: Addition of Al(+3) complex to GIC powder enhanced the antimicrobial activity of GIC materials. As there was a negligible insignificant reduction in HV and FR upon the addition of Al(+3) complex, Al-GICs can be used with a guaranteed degree of clinical success.