Evaluation of the External Hexagon Dental Implants after Simulating Surgical Placement and the Rotational Freedom of Implant Components

Currently, there are several possibilities of abutments connections in dental implants. The most common design in use is the external hexagon connection, which, besides the function of transmitting torque at surgical placement, also works as an antirotational mechanism and orientation of the abutment for single tooth prostheses. Several researchers have suggested that screw joint stability is directly correlated with rotational freedom between implant and abutment. This work aimed at evaluating rotational freedom and integrity of two types of implants (Neodent Implante Osteointegrável): a conventional external hexagon implant (EH) and a new implant system called internal torque (IT). In this system, the implant is inserted by means of internal torque, without the need of a mount. A device was designed and made to measure rotational freedom angles of the two systems, after different torque applications. Parallel, rotational freedom values were determined by an analytical model. These values were compared with the experimental results. There have been verified different behaviors between the implants analyzed in relation of rotational freedom for different torque applications. Furthermore, the external hexagon (EH) deformed after 80 Newton cm torque, differently from the internal torque (IT), showing that clinical placement of IT implants does not influence the integrity of implant–abutment interface.