THE STRENGTH OF A HEAT-PRESSED ALL-CERAMIC RESTORATIVE MATERIAL

A heat-pressed technique (IPS Empress(R), Ivoclar) has been described to construct single unit crowns, inlay/onlays and veneers using precer ammed and precoloured glass-ceramic ingots, The aim of the study was t o evaluate the strength of materials obtained using this technique. St rengths were determined by means of shell (disc rupture) tests. Seven groups of 10 specimens each were prepared with different combinations of core, incisal and glaze firing. Shell strength values of these seve n groups varied between 167 +/- 18 and 81 +/- 9 MPa. After analysis, r esults showed that there was no statistical difference between groups when the core porcelain was in tension. However, there was a significa nt difference between those groups in which the lower surface was eith er core or incisal porcelain. The component thicknesses of the core an d incisal materials did not change the strength of the complete specim en.