Thesis (Ph.D.)--Chulalongkorn University, 2011

Objectives. To develop a novel glass ionomer cement (GIC) with improved physical properties and in vitro biological response to human pulp cells. Method. Magnesium carbonate apatite (MgCO₃Ap) was synthesized by precipitation method and characterized by Scanning Electron Microscopy, Fourier Transformed-Infrared Spectroscopy and X-ray Photoelectron Spectroscopy. The test cement was prepared by adding 2.5% by weight of MgCO₃Ap to Fuji IX GP® (control) and encapsulated mixing with the liquid (P/L=3.6:1). Setting time, compressive strength, fracture toughness, shear bond and microleakage tests were performed according to international standards (ISO 9917-1, ASTM E399-90 and ISO/TS 11405). Inductive Couple Plasma Optical Emission Spectroscopy and Fluoride Ion Electrode were used to determine calcium, magnesium and fluoride ion release respectively. WST-1 cell proliferation, Alkaline Phosphatase (ALPase) assay, Real Time-PCR and Alizarin red staining were used to evaluate biological responses. Results. The test cement had significantly improved fracture toughness, less microleakage at dentin interface (p<.05) and exhibited higher cell proliferation, improved ALPase activity, early expression of COL1A1, DMP-1 and DSPP compared to the control. Conclusion. 2.5% MgCO₃ApGIC demonstrated improved physical properties and biological response to human pulp cells compared to Fuji IX GP®. This finding indicated a potential of MgCO₃ApGIC to be a restorative material for higher clinical performance and pulp-dentin regeneration.