Thesis (M.Sc.) - Cairo University - Faculty of Oral and Dental Medicine- Department of Prosthodontic

The success of dental restorations is determined by four main factors: biocompatibility, aesthetic value, resistance to fracture and marginal adaptation. An inadequate marginal fit may compromise the longevity of the restoration since cement film exposure to the oral environment can lead to its dissolution.The consequent plaque accumulation increases the risk of secondary caries, micro leakage, endodontic inflammation and periodontal diseases causing the failure of the restoration. Marginal and internal fit can be influenced by several factors, starting from the impression phase to the final cementation process. In general dental practice impressions using elastomeric materials are a conventional procedure. These can be made with monophase or multiphase consistencies as well as one- or two-step technique. Although high quality impressions are achievable by these impression techniques and workflows, several mistakes associated with the intraoral phase or laboratory procedures may occur, leading to inaccuracies. The computer aided design/computer aided manufacturing (CAD/CAM) techniques for dental restorations have been developed to optimize the quality of the restorations as well as the efficiency of the workflow. Another target is the production of high resistance ceramic restorations which, up to date, can only be produced with these techniques. This randomized clinical study was done to compare the marginal fit and internal adaptation of the ceramic zirconia fixed restorations obtained from two impression techniques: Conventional technique dual mix two step technique and Digital Intra-oral technique. Thirty two monolithic zirconia single crowns were fabricated using in Coris TZI C zirconia blocks. The patients were selected according to eligibility criteria and divided into two groups according to the impression technique Group 1 (control group) Conventional impression technique. Group 2 (intervention group) intra-oral digital impression techniques

Issued also as CD