The disclosure relates to a fastening system for fastening a dental prosthesis (1) to a dental implant (2) having a ball shaped portion (3), wherein the fastening system comprisesan external sleeve (10) , a manoeuvring member (20) and a gripping member (30), wherein a seat portion (30b) of the gripping member (30) is provided with a circumferentially extending wall (32) extending around the seat (31),wherein the wall is provided with at least two slits (33a, 33b), each slit having a transverse extension (T) through the wall (32) from an inner surface (31') of the seat (31) to an outer surface (32’) of the seat portion (30b) and each slit having a longitudinal extension (L) with a major extension along the bore axis (A) from a mouth portion (m) of the seat (31) towards the body portion (30a),wherein the slits (33a, 33b) divide the wall (32), as seen along the circumference of the wall (32), in at least two wall portions (32a, 32b), which wall portions are interconnected via the body portion (30a), thereby allowing the wall portions (32a, 32b) to resiliently flex towards each other when subjected to an inwardly directed force.
