A molding element of a mold for molding and vulcanizing a tire tread, this tread comprising a tread surface intended to come into contact with the ground when the tire is running. The molding element comprises a molding surface intended to mold part of the tire tread surface and a blade of length L and of height H intended to mold a sipe or a groove in the tread. This blade comprises a rounded end extending along the length of the blade in a direction of extension X. The molding element further comprises two cutting means positioned on either side of the blade at a certain distance from this blade. Each cutting means comprises a cutting edge extending in the direction of extension, this cutting edge making an acute angle in a cutting plane perpendicular to this direction of extension, the height of this cutting edge being greater than or equal to the height of the blade.