Comparative evaluation of screw loosening and joint integrity across different implant-abutment connection types utilizing stock and CAD/CAM abutments under cyclic loading

Screw loosening is a common complication in dental implants, compromising their long-term stability and success. Implants with internal connection play a critical role in maintaining the structural integrity of implants by reducing the possibility of screw loosening. To study torque loss in two different types of internal implant-abutment connections utilizing stock & custom-made abutments under application of cyclic loading. Two groups were used; each group had sixteen epoxy-resin blocks divided into eight block in each subgroup. Implants with an internal implant abutment connection (hexagonal & trilobe) were installed in the epoxy-resin blocks, after abutment installation scanning was done and the crown was fabricated via CAD/CAM technology. After cementation of the crowns, the initial removal torque value was recorded via a digital torque gauge, and each block was prepared with an acrylic base to fit in the chewing simulator to apply dynamic cyclic loading. After the application of cyclic loading, the post load removal torque value was recorded. The removal torque loss ratio of the abutment screw before and after dynamic cyclic loading was subsequently calculated to evaluate the screw joint stability via removal torque measurements. There was a significant difference in the amount of torque loss between the two types of internal connections. There was removal torque loss in both types of internal implant-abutment connections, demonstrating that the internal hexagon connection exhibited significantly lower torque loss compared to the internal trilobe connection in the tested groups. Stock abutments offer superior mechanical stability and a significantly lower incidence of screw loosening under occlusal loading compared to custom-made alternatives. Furthermore, the hexagonal internal connection demonstrates enhanced structural integrity over the trilobe configuration, making it the preferred choice for long-term prosthetic success and reduced maintenance in high-load dental restorations.