Feedback data useful in prosthodontic procedures associated with the intra oral cavity is provided. First, a 3D numerical model of the target zone in the intra oral cavity is provided, and this is manipulated so as to extract particular data that may be useful in a particular procedure, for example data relating to the finish line or to the shape and size of a preparation. The relationship between this data and the procedure is then determined, for example the clearance between the preparation and the intended crown. Feedback data, indicative of this relationship, is then generated, for example whether the preparation geometry is adequate for the particular type of prosthesis.