An abutment assembly includes an abutment, an adjustable buffer member and an adhesive. There is an angle between an extending direction of the abutment and a Z-axis direction, and the angle is greater than or equal to 0 degrees and smaller than or equal to 30 degrees. The adjustable buffer member is closely connected to the abutment having a positioning structure. The adjustable buffer member includes an engaging structure, an inner side wall, a base portion and a grinding portion. The engaging structure is engaged with the positioning structure. The inner side wall has at least one inner annular groove corresponding to the engaging structure. The base portion has a base thickness which is smaller than or equal to 4 mm. The adhesive is connected between the abutment and the adjustable buffer member, and contained in the inner annular groove. The grinding portion is manufactured by the instrument.
