Yi-hong Liu1, Yong Wang2, Qing-hui Zhang3, Yuan Gao1, Hai-lan Feng4. 1. Department of General Dentistry, Peking University School and Hospital of Stomatology, Beijing 100081, China. 2. National Engineering Laboratory for Digital and Material Technology of Stomatology, Peking University School and Hospital of Stomatology, Beijing 100081, China. 3. Department of Dental Technician, Peking University School and Hospital of Stomatology, Beijing 100081, China. 4. Department of Prosthetics, Peking University School and Hospital of Stomatology, Beijing 100081, China.
Abstract
OBJECTIVE: To study the fracture resistance and characteristics of the bi-layer zirconia all ceramic crowns according to the zirconia coping design using various experimental methods and to compare the results of the in vitro test with the clinical evaluation. METHODS: The bi-layer zirconia all ceramic crowns were fabricated by the same method as used in clinical practice. Two different coping designs with/without zirconia marginal collar were used. All the samples were cemented onto corresponding resin dies. All the specimens were tested in the 2 groups with/without zirconia collar. The fracture load test was performed on 10 crowns from each group. Fracture strength was tested with a universal testing machine. The fracture modes and features of the failed crowns were observed with an integrated microscope and a field emission scanning electron microscope. RESULTS: The zirconia collar group showed higher fracture load than the group without zirconia collar. All the zirconia crowns failed with porcelain failure and without zirconia coping broken. The porcelain fracture modes were crack, chipping and delamination. The distribution of the different fracture modes in the groups was the same. CONCLUSION: The bi-layer zirconia crown with 2 mm zirconia marginal collar showed more fracture strength under once load. The fracture modes of the test specimens were the same as the clinical fracture bi-layer zirconia crowns, showing porcelain chipping and delamination.
OBJECTIVE: To study the fracture resistance and characteristics of the bi-layer zirconia all ceramic crowns according to the zirconia coping design using various experimental methods and to compare the results of the in vitro test with the clinical evaluation. METHODS: The bi-layer zirconia all ceramic crowns were fabricated by the same method as used in clinical practice. Two different coping designs with/without zirconia marginal collar were used. All the samples were cemented onto corresponding resin dies. All the specimens were tested in the 2 groups with/without zirconia collar. The fracture load test was performed on 10 crowns from each group. Fracture strength was tested with a universal testing machine. The fracture modes and features of the failed crowns were observed with an integrated microscope and a field emission scanning electron microscope. RESULTS: The zirconia collar group showed higher fracture load than the group without zirconia collar. All the zirconia crowns failed with porcelain failure and without zirconia coping broken. The porcelain fracture modes were crack, chipping and delamination. The distribution of the different fracture modes in the groups was the same. CONCLUSION: The bi-layer zirconia crown with 2 mm zirconia marginal collar showed more fracture strength under once load. The fracture modes of the test specimens were the same as the clinical fracture bi-layer zirconia crowns, showing porcelain chipping and delamination.
Authors: Sanath K Shetty; Tharammal Fayaz; Mohammed Zahid; Karkala S Suhaim; Mallikarjun Ragher; Mohammed S Hasan Journal: J Pharm Bioallied Sci Date: 2020-08-28