METHOD AND SYSTEM FOR FINDING TOOTH FEATURES ON A VIRTUAL THREE-DIMENSIONAL MODEL
A method and system are disclosed for finding virtual tooth features on virtual three-dimensional models of the teeth of patients. The tooth features comprise marginal ridges, cusp tips, contact points, central groove and buccal groove. Tooth axes system plays a key role in identifying the tooth features. An iterative method is disclosed for improving the accuracy of the tooth axes system. A virtual three-dimension model preferably obtained by scanning the dentition of a patient forms the basis for determining the tooth features. Tooth features are derived for all categories of teeth including molars, premolars, canines and front teeth. Tooth features are very helpful and used in planning orthodontic treatment. The tooth features are determined automatically using the computerized techniques; and can be manually adjusted when necessary.
1 - 12 . (canceled)
13 . A method of correcting positioning of a tooth axes system on a virtual tooth using a workstation, comprising the steps of:
(a) placing said tooth axes system on a digital model of said tooth in said workstation, wherein said tooth axis system comprises an origin, an x-axis in mesial and distal directions of said tooth, a y-axis in buccal and lingual directions of said tooth and a z-axis in occlusal and gingival directions of said tooth; and
(b) if said tooth has two cusp tips, then rotating said tooth axes system around an axis, wherein said axis passes through said origin of said tooth axes system and is perpendicular to said z-axis and to a vector connecting said two cusp tips of said tooth, by an angle such that z-coordinates of said two cusp tips are equal; or
(c) if said tooth has three cusp tips, then rotating said tooth axes system in such a way that said three cusp tips have same z-coordinate; or
(d) if said tooth has more than three cusp tips, then rotating said tooth axes system in such a way that differences between z-coordinates corresponding to said cusp tips is minimized.
14 . The method of claim 13 , wherein said tooth axes system is created for each individual tooth.
15 . The method of claim 13 , wherein said tooth axes system for any tooth moves with said tooth.
16 . The method of claim 15 , wherein position of said tooth axes system is determined by position of said tooth.
17 . The method of claim 13 , wherein when said tooth axes system is corrected, said cusp tips for said tooth are determined again in order to improve accuracy of features for said tooth.
18 . The method of claim 13 , wherein when said tooth axes system is corrected, ridges and marginal ridges for said tooth are determined again in order to improve accuracy of features for said tooth.
19 . The method of claim 17 , wherein subsequently said tooth axes system is also refined and entire process of refining said tooth features is repeated.
20 . The method of claim 19 , wherein iterative process of refining said tooth axes system and said tooth features may be stopped when (a) a limit is reached in said angle of rotation for correction applied to said tooth axes system, or (b) a maximum iteration count is reached.