The invention relates to a device (1) for machining a virtual 3D model (2) of teeth (2.1, 2.2, 2.3, 2.4), arranged in a dental arch (9, 11), by means of a virtual tool (21, 22, 23, 24, 25, 26, 27, 28, 50). The tool (21, 22, 23, 24, 25, 26, 27, 28, 50) can be used on a first tooth (2.1, 2.3) of the 3D model (2), wherein the corresponding use is mirrored, in respect of a plane of symmetry (12), on a second tooth (2.2, 2.4) which is contralateral to the first one, i.e. on the tooth on the other side of the plane of symmetry (12), which tooth is a mirror image of the first tooth (2.1, 2.3) in respect of the plane of symmetry (12).
