Compressive fatigue comparison of a 3M glass ionomer core build-up material to Ketac-Silver, Z-100, and Amalgam

This research was designed to compare the in vitro fatigue performance of posterior teeth restored with Ketac-Silver, Amalgam, and Z-100, and experimental reinforced glass ionomer (EXL-292, 3M) core build-ups and gold crowns subjected to compressive fatigue forces 45/spl deg/ to the occlusal surface. Fatigue was utilized to simulate the intra-oral function on a gold crown placed over a pin-retained core build-up. Microleakage at all interfaces was evaluated and the structural integrity of the fatigued material, the build-up/tooth interface and build-up/cement/gold crown system were evaluated by light microscopy. Analysis of the microleakage using the Mann-Whitney U-test, revealed no statistically significant difference (p<0.05) between the Amalgam and the Z-100 groups, between the EXL-292 and the Ketac Silver groups, or between the Amalgam and EXL-292 groups, A significant difference existed between the following groups: (1) Amalgam and Ketac Silver, (2) Ketac Silver and Z-100 and (3) EXL-292 and Z-100. These results indicate that the EXL-292 material is equal to or better than three other commonly used materials in maintaining an adhesive seal preventing the influx of materials with a radius greater than Ca/sup 45/ after 1/spl times/10/sup 6/ cycles. Results of examination using light microscopy showed interfaces between the gold crowns, buildup material, and dentin, and porosity and cracking in the EXL-292 probably caused by air incorporation during mixing.