Abstract

The fracture of all ceramic restorations due to the occlusal and lateral forces is one of the major problems these days. This problem arises mainly due to high intensity of masticatory forces in the molar and premolar area along with the brittle nature of ceramic restorations. The aim of this present in-vitro study is to compare the fracture resistance of chamfer and shoulder margins under a cyclic load of Inceram crowns. Materials and methods:First maxillary premolar without any cracks and caries extracted for orthodontic purposes were included in the present study. Using appropriate burs, 50 in. chamfer and 90 in. shoulder margins were prepared on the tooth. 10 impressions were taken using a polyvinylsiloxane and then dies were fabricated by pouring with epoxy resin.Again 10 polyvinylsiloxane impressions were made and ten epoxy resin dies were created from these impressions. After setting the stone dies were coated with a space liner and were sent to a dental laboratory where the alumina cores with 0.5 mm thickness were fabricated (Vita, Germany). The t of each alumina core on their respective epoxy resin was veried under a 2.5stereomicroscope. Using a universal testing machine called Instron, mechanical testing was carried out. Result: The mean ± standard deviation for the resistance of fracture came out to be 610.1880±58.79526 N for chamfer margin and 502.7270±105.83233 for that of shoulder margin. The difference between the two groups was statistically signicant as revealed by Student's t-test (p = 0.011). Conclusion: Fracture caused by the occlusal and lateral masticatory forces seems to be one of the main problems of all ceramic restorations. These restorations can sometimes lead to unesthetic appearance and many biologic problems because of the metal present in these restorations

Description