Antimicrobial properties, compressive strength and fluoride release capacity of essential oil-modified glass ionomer cements—an in vitro study

This study was designed to investigate the antimicrobial properties, compressive strength and fluoride release capacities of high-viscous glass ionomer cements (GICs) after incorporation of cinnamon and thyme essential oils. Experimental-modified GICs were prepared by incorporation of thyme and cinnamon essential oils into the liquid phase of the cement at 5 and 10% v/v. Antimicrobial activity against selected microorganisms (Streptococcus mutans and Candida albicans) was done using direct contact test. Compressive strength of the four new formulations and control group was tested using a universal testing machine while fluoride ion release was measured by ion-selective electrode at 1, 7, 14 and 28 days. Data analysis and comparisons between groups were performed using factorial and one-way ANOVA and Tukey’s tests. All newly formulated GICs exhibited significantly higher inhibitory effects against both Streptococcus mutans and Candida albicans growth when compared to conventional GIC (p < 0.05). Compressive strength of 5% cinnamon-modified GIC (MPa = 160.32 ± 6.66) showed no significant difference when compared with conventional GIC (MPa = 165.7 ± 5.769) (p value > 0.05). Cumulative fluoride-releasing pattern at days 7, 14, and 28 were 10% cinnamon-GIC > 5% thyme-GIC > 5% cinnamon-GIC > 10% thyme GIC > conventional GIC. Incorporation of 5% cinnamon oil into glass ionomer resulted in better antimicrobial effects against S. mutans and C. albicans and increased fluoride-release capacity without jeopardizing its compressive strength. The 5% cinnamon-modified GIC appears to be a promising alternative restorative material in ART technique.