the face bow has the task of the dental technician "show" the patients horizontal or horizontal position .
With larger edentulous restorations where no tooth guidance more present, we recommend a face-bow. Only when the ear inputs are at the same height, then we can in conformity with the patient, the models, in the articulator mount.
If he does not have this info, there is a risk that later your prothesis are crooked, based on the ear or eye plane / nose axis are therefore not arranged harmoniously.