Fracture Toughness, Hardness, and Microstructure of Ceramic Modified Versus Resin Modified Glass Ionomer Restorative Materials

The aim of this study was evaluation and comparison of fracture toughness, hardness and microstructure of ceramic-modified versus resin-modified glass ionomer restorative materials. For fracture toughness, 20 specimens from both materials were fabricated in a stainless-steel split mold (25mm length, 2.5mm thickness and 5mm width). Fracture toughness was measured using Lloyd universal testing machine with cross head speed 2 mm/min. For hardness testing, 20 specimens from both materials were fabricated in a disc-shaped stainless-steel mold (5mm diameter and 2mm height). All specimens were stored in distilled water at 37°C for 24 hours. Hardness was measured using Vickers micro hardness tester with 50 g load. The microstructure of both materials was examined using scanning electron microscopy. The results of this study showed there wasn’t significant difference between both materials in fracture toughness. The hardness of ceramic-modified glass ionomer was higher than that of the resin-modified type. The addition of ceramic filler to the glass ionomer didn’t improve its fracture toughness. The microstructure of resin-modified glass ionomer showed tight packing between the matrix and the resin filler, while the ceramic-modified glass ionomer showed separated matrix from the ceramic filler.