Hertzian load-bearing capacity of a ceramic-reinforced glass ionomer cement stored wet and dry

ObjectiveTo investigate the development of the load-bearing capacity of a ceramic-reinforced glass ionomer cement (GIC), stored dry or wet, using Hertzian indentation.MethodsGIC discs 2 mm thick and 10 mm in diameter were made (Amalgomer CR, Advanced Healthcare, Tonbridge, Kent, UK), randomly divided into 8 groups and stored at 37 °C in air or artificial saliva (AS) for 1, 7, 30 and 90 days. Discs were tested by loading centrally using a 20 mm diameter hard steel ball while resting freely on a filled-nylon substrate (E: 10 GPa), at 23 °C in air. The failure load at the first bottom-initiated radial crack was detected acoustically.ResultsAll the failure loads of air-stored specimens were higher than those of AS-stored specimens. The failure load was relatively stable for air-stored specimens but showed a significant decreasing tendency for AS-stored specimens.SignificanceZirconia-reinforced GIC is sensitive to moisture. Artificial saliva storage has a detrimental effect on the failure load of ceramic-reinforced GIC that may indicate long-term deterioration in service.