The effects of nanofilled resin-based coatings on the physical properties of glass ionomer cement restorative materials

Objectives To determine the effect of two resin-based coatings on the water sorption/solubility and colour change of three conventional and two resin modified glass ionomer cement restorative materials. Methods Five glass-ionomer cement (GIC) restorative materials and two nanofilled resin-based coatings were studied. Disc-shaped specimens of each material were prepared and divided into three groups, uncoated and coated with either of the two coatings tested (n = 8). Water sorption and solubility were measured in accordance with ISO 4049 and ISO 6876 instructions, respectively. For colour change, the specimens were immersed in distilled water for 24 h, then immersed for another 24 h and an extra week in the three solutions of lactic acid, coffee, and distilled water. The specimens were subjected to colour measurements, using a spectrophotometer after 24 h and 7 days of immersion. The colour change (ΔE) was calculated using a specific formula. ANOVA tests were used for data analysis. Results Two-Way ANOVA revealed a significant interaction between materials and coatings for the water sorption/solubility values. Fuji Bulk showed the lowest water sorption/solubility and the coated groups showed a lower mean sorption/solubility and ΔE. The ΔE varied depending on the materials and the solutions. Conclusions Coating of GIC restoratives reduced the water sorption/solubility and ΔE of almost all materials with a significant decline in most of the materials. Clinical significance Coating of GIC restorations in the oral environment with resin-based coating may protect the restorations from early water sorption/solubility and discolouration.