Method and apparatus for digitally evaluating insertion quality of customized orthodontic arch wire
A method and apparatus is provided for digitally checking the insertion quality of a target customized virtual arch wire designed during treatment planning prior to actually manufacturing the target arch wire. The method includes the steps of digitally simulating the insertion of the customized target virtual arch wire into the virtual brackets placed up on virtual teeth of a patient in an initial state of interest for checking if the arch wire could be inserted into the virtual brackets without conflicts or collisions. The initial state may be a malocclusion state or any intermediate treatment state of the patient. In the event the target virtual arch wire would cause conflicts, then the simulation optimizes the arch wire design in an attempt to eliminate the conflicts. In another aspect, a method is provided for selecting the recommended starting point for inserting the customized arch wire in the brackets placed on the dentition of the patient in the initial state.
1. A method of digitally evaluating the insertion quality of a target custom virtual arch wire, comprising the steps of:
(a) obtaining a model of a set of virtual of brackets placed up on virtual teeth of a patient in a jaw in an initial state; wherein each of said set of virtual brackets has a slot;
(b) obtaining a virtual model of a target custom arch wire designed to be inserted into said virtual brackets; wherein said custom arch wire comprises alternating sequence of straight segments and bent segments; wherein each of said straight segments is designated to be inserted into the slot of a specific virtual bracket from said set of virtual brackets;
(c) selecting a first virtual bracket from said set of virtual brackets;
(d) inserting the first straight segment of said target custom arch wire into the slot of said first virtual bracket; wherein said first straight segment is designated for insertion into the slot of said first virtual bracket;
(e) selecting a second virtual bracket from said set of virtual brackets; wherein said second virtual bracket is the neighbor of said first virtual bracket;
(f) inserting the second straight segment of said target custom arch wire into the slot of said second virtual bracket; wherein said second straight segment is designated for insertion into the slot of said second virtual bracket;
(g) calculating deformation of said second straight segment;
(h) evaluating the quality of insertion of said second straight segment into the slot of said second virtual bracket; and
(i) optimizing said target custom arch wire if a collision is detected at said second virtual bracket, where by a portion of a bent segment gets inserted into the slot of said second virtual bracket.
2. The method of claim 1 , wherein said jaw is the upper jaw of said patient.
3. The method of claim 1 , wherein said jaw is the lower jaw of said patient.
4. The method of claim 1 , wherein step (d) further comprises ligature tying said first straight segment into the slot of said first virtual bracket.
5. The method of claim 1 , wherein in step (f), an incremental measured force is iteratively applied to said second straight segment while inserting said second straight segment into the slot of said second virtual bracket.
6. The method of claim 1 , wherein said step of optimizing said target custom arch wire comprises modifying the length of said second straight segment, thereby modifying the design of said target arch wire, so as to attempt to remove said collision at said second virtual bracket.
7. The method of claim 1 , wherein the geometry of said target custom arch wire is non-planar in three-dimensions.
8. The method of claim 1 ,wherein said initial state comprises the patient's dentition in malocclusion.
9. The method of claim 1 , wherein said initial state comprises the patient's dentition in an intermediate state during the course of the treatment.
10. The method of claim 1 , further comprising step (j) of displaying said target custom arch wire and said virtual brackets to a user.
11. The method of claim 1 , wherein said deformation in step (g) is expressed in terms of moment decomposed into three parts: a torsional moment and two bending moments.
12. The method of claim 1 , wherein said deformation in step (g) is expressed using three angles representing moment of cross section of said target custom arch wire.