The Effect of Coating Glass Ionomers with a Nanofilled Resin

Objectives: Surface protection may change mechanical properties of glass ionomer cements (GIC). A new generation of nanofilled resin coating for GIC is supposedly capable to improve GIC's mechanical properties. The objective of this study was to investigate the effect of a nanofilled resin coat on the flexural strength and the wear of Fuji IX Extra and Ketac Molar Aplicap. Methods: Flexural strength (n=10) was evaluated using a 3-point bending test (ISO 9917-2; stored in parafine 37ºC, 24h) on a universal testing machine and wear (n=20) was evaluated after 1 and 4 days with the ACTA wear machine. Ketac Molar Aplicap and Fuji IX Extra specimens were prepared and half of these specimens coated with G-Coat plus. The uncoated specimens were used as controls. For the wear experiments at 4 days the coat was reapplied before the experiment. One-way and two-way ANOVA and Tukey post hoc tests were used to analyze differences in flexural strength and wear. Results: For Fuji IX Extra the coat significantly increased the flexural strength (p<0.01) (20.2 MPa without coat and 34.9 MPa with coat) and the wear (p<0.05) along the two time spans (93 µm without coat and 54 µm with coat after 200,000 cycles@1day; 70 µm without coat and 46 µm with coat after 200,000 cycles@4days). Ketac Molar Aplicap did not show a significant diference in flexural strength with the coat (44.1 MPa without coat and 36.1 MPa with coat). Improvements were observed only at 1day wear experiment (83 µm without coat and 72 µm with coat after 200,000 cycles@1day). Conclusions: Based on these results, it is concluded that the new GIC coat is indicated for use in association with Fuji IX Extra with the aim to improve the mechanical properties of the former.