Developing a novel glass ionomer cement with enhanced mechanical and chemical properties

Objective: To develop a novel glass ionomer cement (NGIC) with enhanced mechanical and chemical properties and assess its biocompatibility, mechanical strength, and ion release. Methods: Nanosilver doped bioactive glass (NanoAg BAG) was synthesized by sol-gel method and characterized by scanning electron microscopy with energy-dispersive X-ray spectroscopy and transmission electron microscopy. The NanoAg BAG, together with poly(vinylphosphonic acid) (PVPA), alumino-fluorosilicate glass and poly-acrylic acid were used to synthesize NGIC. The optimal PVPA concentration for NGIC was determined by PVPA modified GIC's biocompatibility and mechanical properties and used to prepare NGIC specimens. NGIC specimens with NanoAg BAG at 0%, 1%, 2%, and 5% were allocated into Groups NGIC0, NGIC1, NGIC2, and NGIC5, respectively. The biocompatibility, surface morphology, elemental composition, surface topography, chemical properties, compressive strength, diametral tensile strength, and ion release of the NGIC were assessed. A conventional glass ionomer cement (GIC) was used as a control. Results: A granular BAG with nano silver particles attached on its surface were found, indicating the successful synthesis of NanoAg BAG. PVPA at 10% presented the best effect in enhancing the biocompatibility and mechanical properties of PVPA modified GIC and was used to prepare NGIC specimens. NGIC1 showed similar biocompatibility, surface morphology and topography to GIC. Chemical properties results showed that NGICs showed the same adsorption peaks to GIC. The compressive strength (mean +/- SD in MPa) was 168.1 +/- 29.7, 205.5 +/- 29.5, 221.8 +/- 46.8, 216.6 +/- 59.3 and 167.7 +/- 36.4, and the diametral tensile strength (mean +/- SD in MPa) was 14.1 +/- 1.7, 18.3 +/- 4.9, 21.2 +/- 2.2, 17.2 +/- 3.8 and 13.3 +/- 3.3 for GIC, NGIC0, NGIC1, NGIC2 and NGIC5 respectively. NIGC0, NGIC1 and NGIC2 showed higher compressive and diametral tensile strength than GIC (p < 0.01). NGIC2 and NGIC5 showed higher release of fluoride, calcium, phosphate and silver ion than GIC and NGIC0 (p < 0.05). Conclusion: A biocompatible NGIC with enhanced mechanical properties were developed. It presented enhanced fluoride, calcium, phosphate and silver ion release compared to conventional GIC.