IADR Abstract Archives
Novel Resin-modified Glass Ionomer Cement for Repairing Defective Tooth-restoration Complexes
Objectives: Ethylene glycol methacrylate phosphate (EGMP) is a proton-conducting electrolyte with highly reactive polar groups. The aim is to formulate and evaluate a new restorative cement based on inclusion of EGMP into a commercially available resin-modified glass ionomer (RMGIC) for its potential application as a reparative material for failed tooth-restoration complexes (TRCs).
Methods: EGMP monomer (0-40%wt) was incorporated into the liquid phase of a commercial hand-mixed RMGIC (Fuji II LC, GC Corp.). The setting kinetics of varying monomer concentrations using the recommended powder: liquid ratio (2.7:1) did not interfere with cement working/setting times. Physical properties of specifically selected formulations were then characterised. 320 cylindrical specimens (n=8/group) were tested for compressive strength and microhardness, 160 discs for biaxial flexural strength (BFS), water uptake and fluoride release were also assessed. The mechanical properties were tested after sample storage: 1 day, 14 days, 28 days, 6 months. Data was analysed statistically using one-way ANOVA and Tukey’s post-hoc test (p> 0.05).
Results: Experimental EGMP cements showed higher compressive strength and modulus, microhardness and a two-fold increase in BFS compared to control specimens up to 6 month storage (p<0.001). Ageing had a significant effect on the mechanical properties of the tested groups (p<0.05). The inclusion of EGMP encouraged the formation of reinforcing complexes within the RMGIC, thus improving the physical properties. The microstructure exhibited a reduced porosity, integrated structure that could account for the increased stiffness and BFS with increasing EGMP content. The phosphate groups accounted for hydrophilicity whilst the interaction with the matrix decreased solubility and fluoride release.
Conclusions: The incorporation of phosphate moieties into the RMGIC matrix provides a basis for the development of physically improved cements, potentially useful for repairing defective TRCs.
Methods: EGMP monomer (0-40%wt) was incorporated into the liquid phase of a commercial hand-mixed RMGIC (Fuji II LC, GC Corp.). The setting kinetics of varying monomer concentrations using the recommended powder: liquid ratio (2.7:1) did not interfere with cement working/setting times. Physical properties of specifically selected formulations were then characterised. 320 cylindrical specimens (n=8/group) were tested for compressive strength and microhardness, 160 discs for biaxial flexural strength (BFS), water uptake and fluoride release were also assessed. The mechanical properties were tested after sample storage: 1 day, 14 days, 28 days, 6 months. Data was analysed statistically using one-way ANOVA and Tukey’s post-hoc test (p> 0.05).
Results: Experimental EGMP cements showed higher compressive strength and modulus, microhardness and a two-fold increase in BFS compared to control specimens up to 6 month storage (p<0.001). Ageing had a significant effect on the mechanical properties of the tested groups (p<0.05). The inclusion of EGMP encouraged the formation of reinforcing complexes within the RMGIC, thus improving the physical properties. The microstructure exhibited a reduced porosity, integrated structure that could account for the increased stiffness and BFS with increasing EGMP content. The phosphate groups accounted for hydrophilicity whilst the interaction with the matrix decreased solubility and fluoride release.
Conclusions: The incorporation of phosphate moieties into the RMGIC matrix provides a basis for the development of physically improved cements, potentially useful for repairing defective TRCs.