COMPARISON OF THE WET AND DRY FATIGUE PROPERTIES OF ALL CERAMIC CROWNS

The purpose of this paper was to investigate the influence of fatigue on the fracture strength of In ceram, optimal pressable ceramic (OPC(T M)) and IPS Empress in both wet and dry environments. Twenty-six crown shapes 8 mm in diameter and 8.5 mm in height were fabricated for each ceramic system. For each ceramic system, ten specimens were tested fo r fracture strength without fatiguing. The second group was submitted to a fatigue and fracture test in a dry (eight specimens) and a third group in a wet (eight specimens) environment using an Instron testing machine. The results were statistically analysed using a Mann-Whitney test. The results indicated that: (i) the fracture strength for In cer am was significantly stronger than OPC(TM) and IFS Empress (p < 0.05) - no difference was found between OPC(TM) and IFS Empress; (ii) fatigu ing and fracture testing showed a significant decrease in the fracture strength for In ceram and IFS Empress in the wet environment and no d ifference was found in the dry environment - no difference was found f or OPC(TM); and (iii) when fatigued in a dry environment, In ceram cro wn shapes were significantly stronger than OPC(TM) and IPS Empress (p < 0.05) - the same statistical differences were found when fatigued in a wet environment.