Evaluation of abutment screw torque for internal/external hexagonal implant

Objectives: Evaluate the torque applied to the abutment screws in dental implants with external hexagonal and internal hexagonal connections, to verify the presence of the same torque after a number of loosening and tightening cycles, and to evaluate the efficacy of a counter-torque device in reducing the torque load transmission to the implant and to the surrounding bone.Methods: Twenty-eigh dental implant specimens were tested, 14 with external hexagonal shape and 14 with internal hexagonal shape. Each group of 14 implants was divided in two subgroups, where in the S subgroup, the counter-torque device was not used and in the C subgroup, the counter-torque was used. In this manner, there were four groups: SEH - external hexagonal without counter-torque device, CEH - external hexagonal with counter-torque device, SIH- internal hexagonal without counter-torque device, CIH - internal hexagonal with counter-torque device. Results: A digital torque gauge registered the tightening and the loosening in each cycle and the load transmission to implant specimens in N.cm. According to linear analysis (P=0.001), a torque loss occurred in the abutment screws after the loosening and tightening cycles, mean of 34%, 39.62% and 12.24% to the SEH, SIH and CIH groups, respectively. Conclusions: The counter-torque device limited the torque transmission to the external hexagonal implant in 48.56% and to the internal hexagonal implant in 53.55%. Financial support: Fapesp: 03/06702-5