Enhancing glass ionomer cement with Citrus aurantium L. extract: a combined in vitro and in silico investigation of antimicrobial and mechanical properties

Recurrent caries remains a significant challenge in restorative dentistry. While various antimicrobial agents have been incorporated into restorative materials, their efficacy and impact on mechanical properties remain a concern. This study investigates the potential of incorporating Citrus aurantium L. seed extract into glass ionomer cement (GIC) to enhance its antimicrobial activity while maintaining mechanical integrity comparable to conventional GIC. Additionally, in silico molecular docking and bioactivity predictions were performed to elucidate the mechanistic basis of its antimicrobial effects and broader pharmacological potential. The aqueous extract of Citrus aurantium L. was incorporated into the liquid component of a commercially available conventional GIC at two concentrations (10% and 20% by weight), forming two modified groups. Antimicrobial activity against S. mutans was evaluated using the agar diffusion assay. Molecular docking was conducted to predict interactions between key phytocompounds and S. mutans glucosyltransferase B (GtfB). Mechanical properties, including flexural strength and microhardness, were evaluated according to ISO 9917-1 and ASTM E-384:1999, respectively. Modified GIC demonstrated significantly enhanced antimicrobial activity, with the 20% concentration showing the strongest effect (27.2 ± 0.6 mm inhibition zone) compared to the control (16.2 ± 0.6 mm). Molecular docking confirmed strong binding affinities between key bioactive compounds and GtfB. A minor but significant reduction in flexural strength was observed in modified GICs. Additionally, both modified GIC groups demonstrated improved surface microhardness (10% CA: 32.2 VHN; 20% CA: 42.4 ± 2.1 VHN) compared to the control (33.5 ± 2.0 VHN). The incorporation of C. aurantium L. extract into GIC significantly enhanced its antimicrobial properties against S. mutans while maintaining satisfactory mechanical performance. Molecular docking provided mechanistic insights into the antimicrobial effects, reinforcing the potential of integrating natural bioactive compounds with computational approaches in dental material development.