![]() | Only 14 pages are availabe for public view |
Abstract The application of ceramic materials for the fabrication of dental restorations is a focus of interest in esthetic dentistry. Zirconia holds a unique place amongst oxide ceramics due to its excellent mechanical properties. The two main techniques used for fabrication of zirconia crowns, conventional firing and CAD/CAM techniques, were assessed in the light of their possible clinical implications and consequences on the long-term performance of zirconia. With the advent of this new ceramic material, it has become imperative to evaluate its strength in order to select the appropriate processing technique. The purpose of this in vitro study was to compare the marginal and internal fit; and fracture resistance; of a CAD/CAM versus conventionally fabricated zirconia all-ceramic crowns. A stainless steel die was machined to simulate a mandibular right first molar and prepared as an abutment for crown coverage, from which 16 epoxy resin dies were reproduced. The sixteen epoxy dies were randomly allocated into two equal groups (I and II). Each group received 8 zirconia all-ceramic crowns. Eight Cercon Zirconia crowns were milled using Cercon Smart Ceramic (CAD/CAM) system and eight In-Ceram Zirconia crowns were fabricated by conventional firing that involved slip-casting and glass-infiltration. All crowns were adhesively luted with composite resin-bonded cement (Multilink Cement system). Subsequently, three specimens from each group were embedded completely in transparent acrylic resin and sectioned into four quarters then viewed under stereomicroscope to evaluate the precision of fit, while the remaining five specimens from each group were loaded until fracture using universal testing machine to indicate the fracture resistance for each zirconia crown then statistical analysis was carried out. The results showed significant difference between CAD/CAM and conventionally fired zirconia crowns in precision of fit, where CAD/CAM-milled zirconia crowns had significantly better fit. There was no significant difference in fracture resistance between the two groups. |