Biological evaluation of resin-modified glass ionomer cement containing coumarin derivatives for dental application

To evaluate the cytotoxic effects of resin modified glass ionomer cement (RMGIC) incorporated with coumarin derivatives 3-acetylcoumarin (AC) and coumarin thiosemicarbazone (CT) on human periodontal ligament fibroblast (HPdLF) cells and the antibacterial activities thereof against cariogenic bacteria.

RMGIC-AC and RMGIC-CT were synthesized by incorporating AC and CT, respectively, in RMGIC at compositions 0.5 %, 1.0 % and 1.5 % by weight. The chemical functional groups in RMGIC-coumarins were identified by Fourier Transform Infrared (FTIR) spectroscopy. The cytotoxicity effects of RMGIC-coumarins were evaluated in the HPdLF cell line using MTT assay for 72 h. Broth macrodilution assay was used for the antibacterial evaluation of RMGIC-coumarins against Streptococcus mutans. Bacterial growth was monitored by measuring the changes in absorbance each hour for 22 h with a densitometer. The morphological features of the treated bacteria were investigated by field emission scanning electron microscopy (FESEM).

FTIR spectra of the RMGIC-coumarin derivatives detected a lactone group (C[bond, double bond]O) at 1678-1716 cm-1 and an imine stretching (C[bond, double bond]N) at 1602 cm-1. At concentrations of 50 mg/ml or lower, the cytotoxicityof RMGIC-coumarins resulted in more than 70 % cell viability, except for RMGIC-CT at1.5 %. Significant differences in cell viability were observed at concentrations of 50,100, and 200 mg/ml (p < 0.05). Treatment with RMGIC-coumarins significantly affected the antibacterial performance (p < 0.05) compared with the untreated control group. FESEM images showed that bacterial cells treated with coumarins were distorted and aggregated in clusters.

RMGIC incorporated with coumarin derivatives at 0.5 % exhibited the most favorable biological performance, achieving an optimal balance between cytotoxicity and antibacterial properties compared with concentrations of 1.0 % and 1.5 %. RMGIC-CT at 0.5 % appeared to be more effective than RMGIC-AC at 0.5 %, as shown by the stronger inhibition of S. mutans.