Modeling system and method of reducing interproximal tooth

computerized system for modeling IPR a patient's teeth to facilitate orthodontic treatment, said computerized system comprising: a microprocessor comprising a plurality of algorithms; a memory device; and wherein said computer system for modeling IPR is configured to: determine if the polishing for a tooth between any adjacent teeth is necessary; generating a three dimensional model of IPR tooth based on potential collision with any adjacent tooth; and using said model IPR tooth to facilitate treatment planning, so that the generation of a model of IPR tooth to said tooth comprises the construction of a grinding plane (202, 302, 626) for said tooth, and wherein said computer system is configured to construct said grinding plane for said tooth determining the normal direction of said grinding plane based on local coordinate systems for the tooth or other appropriate references and at least an adjacent tooth and determine a point lens between contours associated with said tooth and said at least one adjacent tooth, said plane being constructed to pass through polishing said target point and said normal.