Supervisor : Ashraf Hassan Mokhtar, Hanaa Hassan Zaghloul.Hassan, Radwa Hamdy,2022-01-172022-03-272022-01-172022-03-272019.EG-CaMIUThs332https://iorep.miuegypt.edu.eg/handle/20.500.13071/62DISSERTATION NOTE-Degree type M.Sc.DISSERTATION NOTE-Name of granting institution Misr International University, Faculty of Oral and Dental MedicineIncludes Arabic Summary.Includes bibliographic references (pages 86-109)Esthetics and biocompatibility are crucial factors that increased the demand for metal free restorations among patients. Zirconia-based ceramics are a rapidly growing type of esthetic restorations. They are characterized by superior mechanical properties and superior resistance to fracture. The use of zirconia ceramics has increased rapidly with the evolution of computer- aided design and computer-aided manufacturing (CAD/CAM) technology. This technology improved the marginal fit, mechanical durability and predictability of the final restorations. Veneering of zirconia-based ceramic restorations with feldspathic ceramics is mandatory as they suffer from deficient translucent properties. The introduction of monolithic zirconia “translucent zirconia” offers improvement in the esthetic appearance and durability of the final restorations without fracture compared to veneered zirconia. Clinical longevity of translucent zirconia full coverage restorations is a multi-factorial. The marginal fit and microleakage are critical factors in determining the durability of the final restoration. Any marginal gap reflects the quality of the marginal adaptation and can influence the amount of leakage which may be one of the main causes of failure of monolithic zirconia full coverage restorations. The proper selection of luting agent considered to be the key factor for long-term success of any fixed dental prosthesis. Different luting agents were analyzed and only those containing organophosphate ester monomer groups have shown a significant durable bond to zirconia. In the dental field, bioactive materials were recently introduced and referred to a property of new cements to form hydroxy- apatite when immersed in a simulated body fluid (SBF) and saliva. Ceramir bioactive cement is a modification of glass ionomer cement with addition of calcium aluminate which has a remineralizing characteristic. Such limited number of studies were found using Ceramir as a luting agent with monolithic zirconia, therefore the aim of the present study was to evaluate the marginal fit and microleakage of monolithic zirconia crowns cemented by bio-active cement (Ceramir).109 pages : illustrations, photo ; 29 cmtextapplication/pdfengFixed Prosthodonticstext