Clinical, Cosmetic and Investigational Dentistry (Mar 2022)
Fracture Resistance and Fracture Behaviour of Monolithic Multi-Layered Translucent Zirconia Fixed Dental Prostheses with Different Placing Strategies of Connector: An in vitro Study
Abstract
Nada Heidari,1 Rasha Amawi,1 Przemek Seweryniak,2 Fahad Bakitian,3 Per Vult von Steyern1 1Department of Materials Science and Technology, Malmö University, Malmö, Sweden; 2Commercial Dental Laboratory, Malmö, Sweden; 3Department of Restorative Dentistry, Umm Al-Qura University, Makkah, Saudi ArabiaCorrespondence: Fahad Bakitian, Department of Restorative Dentistry, Faculty of Dentistry, Umm Al-Qura University, Makkah, 21511, Saudi Arabia, Tel +966500507661, Email [email protected]: To evaluate the effect of different placing strategies performed in the connector area on fracture resistance and fracture behaviour of monolithic multi-layered translucent zirconia fixed dental prostheses (FDPs).Materials and Methods: Thirty 3-unit monolithic FDPs were produced and divided into three groups (n = 10) based on the different strategies for placing the connector area of FDPs in multi-layered zirconia blank with varying contents of yttria ranging from 4 to 5 mol%. The groups were as follows: FDPs with connectors placed in dentin layer with 4 mol% yttria content, FDPs with connectors placed in gradient layer, and FDPs with connectors placed in translucent layer with 5 mol% yttria content. A final group (n = 10) of conventional monolithic zirconia with a monolayer of yttria content (4 mol%) has been used as a control group. The specimens were artificially aged using thermocycling and pre-loading procedures and subsequently loaded to fracture using a universal testing machine. Fracture loads and fracture behaviour were analyzed using one-way ANOVA and Fisher’s exact tests and statistically evaluated (p ≤ 0.05).Results: There were no significant differences in fracture loads among the groups based on the placing strategies of the connector area of the FDPs in the multi-layered translucent zirconia blank (p > 0.05). There was no significant difference in fracture loads between monolithic multi-layered translucent zirconia and conventional monolithic translucent zirconia materials (p > 0.05). Fracture behaviour of FDPs with connector area placed in translucent layer differed significantly compared to FDPs with connector area placed in dentin layer and FDPs in control group (p = 0.004).Conclusion: The placing strategies of the connector used in the computer aided design and manufacturing procedures do not considerably affect fracture resistance of monolithic FDPs made of multi-layered translucent zirconia. Monolithic FDPs made of multi-layered translucent zirconia show comparable strength to FDPs made of conventional translucent zirconia, but with different fracture behaviour.Keywords: all-ceramic restorations, computer-aided design\manufacturing, fracture load, multi-layered zirconia, Y-TZP
