Mechanical properties of compomer restorative materials

The purpose of this study was to measure the compressive strength, flexural strength, microhardness, and surface roughness of three compomers (Compogl ass, Dyract, and Hytac) and compare the values to the ones obtained for a r esin-modified glass-ionomer cement (Vitremer) and a resin composite (Z100). All materials were handled according to the manufacturers' instructions. T here was a significant difference (P < 0.01) among Vitremer, Hytac and Z100 composite with regard to yield strength. Vitremer values were lower than f or Hytac, which were lower than for Z100, The yield strength values for Com poglass and Dyract were significantly lower than for Hytac and Z100 composi te and significantly higher than for Vitremer (P < 0.01). There was no sign ificant difference in the strain at yield among Vitremer, Hytac, and Z100, but their values were significantly higher than for Compoglass and Dyract ( P < 0.01). The flexural strength data displayed a significant difference be tween Vitremer and Hytac (P < 0.05). Z100 was significantly stronger than t he other products tested. The values of strain at break for Vitremer, Hytac , and Z100 were significantly lower than for Compoglass and Dyract (P < 0.0 1). The compressive strength results showed significantly higher values for Dyract, Compoglass, and Hytac than for Vitremer (P < 0.01), Z100 displayed higher values than the other products tested (P < 0.01). Hytac strength wa s significantly higher than for Dyract (P < 0.01). The microhardness of Com poglass and Dyract was not significantly different (P < 0.05). Hytac displa yed microhardness values higher than for Vitremer, Compoglass, and Dyract ( P < 0.01). However, all products tested showed values significantly lower t han for Z100 (P < 0.01). The surface roughness values for Compoglass, Dyrac t, Hytac, and Z100 were not significantly different. Vitremer displayed a s ignificantly higher value than Dyract, Hytac, and Z100 (P < 0.05).