Dental implant and piece to be connected to a dental implant are provided. Both the implant and the piece are capable of being connected to each other by an internal connection to the dental implant. The internal connection principally comprises an anti-rotational part and a cylindrical part, with the anti-rotational part being formed by the repetition of a series of anti-rotational components, each of them formed by a series of arcs tangent to each other. This design of the anti-rotational part enables better performance to be obtained than with known anti-rotational designs.