Comparison of Zirconia Copings Marginal Fitness Made from a Conventional Impression Technique and Gypsum Cast Technique by CAD/CAM

Document Type : Original Article


Department of Operative and Esthetic Dentistry, Faculty of Dentisty, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.


Background and Objectives:One of the most important factors in restorations durability is their marginal integrity. Contradictory results are witnessed in previous studies; some find the conventional methods more accurate and others believe that the CAD-CAM is better. In this study, ma l fitness of zirconium copings that made from conventional impression and gypsum cast were compared.
Subjects and Methods: In this study, ten healthy premolar teeth were used. The teeth were prepared with a round edge shoulder bur. An impression was taken from each tooth and the impression was scanned with the scanner. The information obtained from the impression were transferred to software, and the computer sent the fabrication command to the milling device. While restoration milling is being started, the cast was made by special dye plaster. The obtained cast was scanned. The collected information of the cast was transferred to the software and the rest of the stages were done similar to the cast. The copings gained by the first and second methods are placed on the shaped tooth separately and the marginal gap was measured by direct observation using the SEM microscope in two Bucall/lingual and mesial/distal areas and five random points in each area were measured.
Results: There was significant difference in marginal gap dimensions between the tested groups (P<0.01). However,  there was no meaningful difference between the marginal dimensions between the two tested areas (Bacall/lingual and mesial/distal) (P>0.05).
Conclusion: Zirconia-based copings marginal accuracy depends on digital impression techniques although all of restorations did not have acceptable marginal accuracy and making copings from cast showed higher accuracy.


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