172AN IN VITRO COMPARATIVE EVALUATION OF COMPRESSIVE STRENGTH OF THREE DIFFERENT PERFORATION REPAIR MATERIALSThe aim of this study was to evaluate the compressive strength of MTA and two novel tricalcium silicate-based endodontic materials, Biodentine and Bioaggregate. The compressive strength of the test materials were determined using the Universal Testing Machine. Each material was mixed and placed in a split stainless steel mold (6 mm in diameter and 4 mm in height) within 2 minutes after the start of mixing. The materials were divided into 3 experimental groups and the compressive strength of each group was measured at 1 hour, 1 day, 1 week, 2 weeks, 3 weeks and 4 weeks. The maximum load required to fracture each specimen was determined. The ultimate compressive strength (USC) was calculated in megapascals (MPa) by using the following formula: UCS = 4F/ D² where F = maximum applied load in Newton and D = mean diameter of specimens in millimetres. The compressive strength of Bioaggregate was significantly lower than that of MTA and Biodentine. Within the limitations of this study, it was concluded that Biodentine have superior strength than MTA and Bioaggregate.amitharaj321@gmail.comResearch722017Bioaggregate,Biodentine,Compressive strengthYadav Chakravarthy,Amitha M RajDepartment of Endodontics, Vinayaka Mission Sankarachariyar Dental College, Salem, Tamil Nadu, India.,Department of Endodontics, Vinayaka Mission Sankarachariyar Dental College, Salem, Tamil Nadu, India.