Abstract: The jaw of a person and a model thereof is represented with a series of steps. A device for positional determination, which has marking points, is inserted into the oral cavity of the person, at least one picture of the jaw of the person is taken with an imaging process, such as X-ray, CT, MRI or the like, including the marking points in the picture. The picture is stored as a data set and the marking points are identified. After an impression is taken of the jaw, a model is created. The representation itself includes the following steps: a further 3D sensor is brought to the model of the jaw. Next, the device for positional determination is reinserted into the model of the jaw in the same position as when the picture was taken. The positional relationship is determined between a 3D sensor on the device and the 3D sensor on the model of the jaw. After the device has been removed, a further 3D sensor is brought to the model of the jaw and inserted in the same position as when the picture was taken.