Effect of ion-exchange temperature on mechanical properties of a dental porcelain

The objective of this study was to determine the influence of different ion-exchange temperatures on the biaxial flexural strength ( σ f ), hardness (HV) and indentation fracture resistance ( K IF ) of a dental porcelain. Disk-shaped specimens were divided into five groups ( n = 10) and submitted to an ion-exchange procedure using KNO 3 paste for 15 min in the following temperatures (°C); (I) 430; (II) 450; (III) 470; (IV) 490; (V) 510; and control (no ion exchange). The value of σ f was determined in artificial saliva at 37 °C. The values of HV and K IF were obtained using 3 Vickers indentations in each specimen (19.6 N). Results showed that ion exchange increases significantly the properties of the material as compared to the control and no significant differences were found among the temperatures tested for any of the properties studied.