Retention evaluation of two methods of implant prosthesis reconstruction after abutment screw fracture and damaged fixture threads

Abstract

Background: In the abutment-implant connection system, the abutment screw plays a central role for mechanical stability and fatigue resistance. In this study, we investigated the determination of the retention rate of two reconstruction methods, after the failure of the abutment screw and the damage of the threads inside the fixture. Methods: In this laboratory-experimental study, 34 Analogs were mounted inside the resin block. In order to prepare the index from compression silicone, a direct abutment was closed on one of the samples and then the index was prepared by silicon from the abutment to make the next copings. After separating the abutment from the Analog, the threads inside all the Analogs were smoothed with the help of carbide mill and plenty of water and the samples were divided into two groups. In the first group, each Analog was reconstructed from a Ni-cr alloy with a casting post and blind. In the second group, after removing the threads, the abutment was placed directly on the Analog and the abutment screw was cemented by Calibra resin cement. Tensile strength measurements of all samples were recorded by Universal testing machine at a force of five hundred kg at a speed of 0.5 cm per minute. SPSS 24 software and independent t-test were used for data analysis Results: The mean variable of tensile strength in the group of "post and blind Analog" with the value of 245.95 64 64.77 is significantly higher than the average in the group of "cementing the avant-garde screw" with the value of 173.05 41 41.91. Conclusion: The tensile strength of the "post and blind Analog" method was higher than the "cement screw avant-garde" method.