Enhancement of mechanical and antibacterial properties of glass ionomer cement using oyster shell-derived TiO2-hydroxyapatite nanorods for dental restoration application

Abstract

Glass ionomer cement (GIC) is widely used in restorative dentistry due to its capability to form a chemical bond with tooth tissue and its biocompatibility. Nevertheless, its limited mechanical strength and antibacterial capabilities hinder its long-term success in dental restorations. In the current study, TiO 2 -Hydroxyapatite (TiO 2 /HAp) nanorods have been synthesized using an economical, simple precipitation method from waste oyster shells. TiO 2 /HAp nanorods of different weight percentages (0, 2, 4, 8, 10, and 15%) are used to enhance the mechanical and antibacterial properties of GIC. Both GIC and incorporated samples were analyzed by XRD, FTIR, FE-SEM, along with EDAX, HR-TEM, and SAED. The mechanical properties, including compressive strength (ranging from 136 to 192 MPa) and microhardness (ranging from 49 to 63), were evaluated using a Universal Testing Machine (UTM). The antibacterial activity of the samples was assessed against Escherichia coli and Staphylococcus aureus . Characterization results confirm the incorporation of TiO 2 /HAp nanorods into the GIC matrix. The mean crystallite sizes for 8% and 15% TiO 2 /HAp with GIC are 19.74 nm and 18.78 nm, respectively. GIC + TiO 2 /HAp reveals a predominantly rod-like (needle-shaped) morphology with significant agglomeration. Furthermore, the influence of TiO 2 /HAp nanorods on the microstructure and reinforcing behaviour of the GIC matrix was systematically investigated. The results revealed that incorporating TiO 2 /HAp nanorods significantly enhanced both the mechanical and antibacterial properties of GIC, owing to improved nanorod dispersion and their strong interfacial interactions with the cement matrix. This is the first successful study to employ oyster shell-derived TiO₂/HAp nanorods as a multifunctional reinforcement in GIC and, to the best of our knowledge, to systematically correlate their structural characteristics with improvements in mechanical and antibacterial performance under in vitro conditions.