In vitro wear and fracture toughness of an experimental light-cured glass-ionomer cement

Objective: The objective of this study was to evaluate the in vitro wear and fracture toughness (FT) of an experimental resin-modified glass-ionomer cement (RMGIC) formulated with the newly synthesized 6-arm star-shape poly(acrylic acid) and Fuji II LC glass fillers and investigate the effects of several important formulation parameters on wear-resistance and FT of the cement. Materials and Methods: The in vitro abrasive and attritional wear as well as FT of the newly developed RMGIC were evaluated. The resin composite P-60 and RMGIC Fuji II LC were used as controls. The effects of glycidyl methacrylate (GM)-grafting ratio, powder/liquid (P/L) ratio, polymer/water (P/W) ratio and aging in water were investigated. All the specimens were conditioned in distilled water at 37 °C for 1 day prior to testing, unless specified. Results: The optimized experimental cement exhibited almost the same high initial wear-resistance to abrasion as P-60 and much higher than Fuji II LC. The experimental cement showed 1.4 times higher in resistance to attritional wear than Fuji II LC but 6 times lower than P-60. After 1-month aging, the cement can compete with P-60 in resistance to attritional wear by showing only 1.3 times more in wear depth. The experimental cement also showed a significantly higher FT value than Fuji II LC but a similar value to P-60. Conclusions: It appears that this novel experimental cement may be potentially used for high wear and high stress-bearing site restorations such as Class I and II.