Microenergy dispersive X-ray fluorescence (μ-EDXRF) spectroscopy and scanning electron microscopy (SEM) were used to test the hypothesis that zirconia modified glass ionomer cement (GIC) could improve resistance to erosion-abrasion to a greater extent than conventional cement.Bovine enamel (n = 40) and dentin (n = 40) samples were prepared with cavities, filled with one of the two restorative materials (GIC: glass-ionomer cement or ZrGIC: zirconia-modified GIC). Furthermore, the samples were treated with abrasion-saliva (AS) or abrasion-erosion cycles (AE). Erosive cycles (immersion in orange juice, three times/day for a duration of 1 min over a 5 day period) and/or abrasive challenges (electric toothbrush, three times/day for a duration of 1 min over a 5 day period) were performed. Positive mineral variation (MV%) on the enamel after erosion-abrasion was observed for both materials (p < 0.05), whereas a negative MV% on the dentin was observed for both materials and treatments (p < 0.05). The SEM images showed clear enamel loss after erosionabrasion treatment and material degradation was greater in GIC_AE compared to those of the other groups. Toothbrush abrasion showed a synergistic effect with erosion on substance loss of bovine enamel, dentin, GIC, and ZrGIC restorations. Zirconia addition to the GIC powder improved the resistance to abrasive-erosive processes. The ZrGIC materials may find application as a restorative material due to improved resistance as well as in temporary restorations and fissure sealants. K E Y W O R D Sglass ionomer cement, micro energy dispersive X-ray fluorescence spectroscopy, scanning electron microscopy, teeth erosion, zirconia

Glass-ionomer cements (GICs) are used as restorative dental materials due to their capacity to chemically adhere to enamel and dentin, low thermal expansion coefficient, and compatibility with dental structures. However, these materials have low resistance to wear and fracture. In this work, zirconia-reinforced GICs were prepared to evaluate the influence of particle size as well as ZrO2 content on their properties. All evaluated composites presented compressive strength values above the pure GIC strength. The highest compressive strength values were obtained with the addition of 8.5 wt% ZrO2. The average roughness obtained was not significantly changed compared to commercial GIC and the lowest value was for the composite with 10 wt% ZrO2 (50 mesh). In the microhardness test, the highest values were obtained with the addition of 8.5 wt% of ZrO2. Therefore, the results indicated that the addition of ZrO2 to GIC is an effective alternative to improve the quality of dental restorations.