An internal hex, connection type in dental implants is more stable than an external hex and helps resist abutment loosening especially in friction fit abutments. A hex or similar anti-rotation device is necessary,  otherwise occlussal force may cause a friction fit abutment to rotate on top of the implant. This will break the cold weld and taper lock causing the abutment to dislodge. This situation is particularly likely to occur in the upper anterior region of the mouth if angled friction fit abutments have been used.

Combining a hex with a taper lock produces an abutment range with infinite three dimensional angular corrections freeing the technician from the restorative constraints imposed by limited abutment choice.

Combi abutments have  an offset hex, this means that there are 12 positions that the abutment can fit into the implant giving the greatest flexibility to the laboratory, ensuring the most aesthetic design.