Method of forming orthodontic brace

• US 5,395,238 A
• Filed: 10/22/1993
• Issued: 03/07/1995
• Est. Priority Date: 01/19/1990
• Status: Expired due to Term

• Current Assignee: Ormco Corporation (Envista Holdings Corporation)
• Original Assignee: Ormco Corporation (Envista Holdings Corporation)
• Inventors: Payne, Mark A., Andreiko, Craig A.
• Primary Examiner(s): O'Connor, Cary E.
• Application Number:
  US08/141,376
• Time in Patent Office: 501 Days
• Field of Search: 433/24
• US Class Current: 433/24
• CPC Class Codes: A61C 13/097 characterised by occlusal profiles , i.e. chewing contact surfaces
• CPC Class Codes: A61C 2007/004 Automatic construction of a set of axes for a tooth or a plurality of teeth
• CPC Class Codes: A61C 7/00 Orthodontics, i.e. obtaining or maintaining the desired position of teeth, e.g. by straightening, evening, regulating, separating, or by correcting malocclusions
• CPC Class Codes: A61C 7/002 Orthodontic computer assisted systems
• CPC Class Codes: A61C 7/146 Positioning or placement of brackets; Tools therefor
• CPC Class Codes: A61C 7/16 specially adapted to be cemented to teeth
• CPC Class Codes: A61C 9/008 Mechanical means or methods, e.g. a contact probe moving over the teeth
• CPC Class Codes: A61C 9/0093 Workpiece support

Abstract

Contours of a patient'"'"'s teeth are digitally determined from individual teeth of a model of the patient'"'"'s mouth provided by an orthodontist, preferably by scanning individual teeth in a lingual-facial plane on the model with a mechanical probe. Tooth prominence parameters including tooth-gum intersections, mesial cusp tips or lingual and facial incisal edge points, and groove/ridge locations are selected on the contours. Tooth long axes are derived therefrom in the contour plane through the gum intersection and incisal edge/cusp tip midpoints and the contours are oriented to in the plane to predetermined inclination angles. From these, calculations are made to locate brackets on the contours and determine geometry of slots to cut in the brackets for disposition of a curved archwire in a horizontal plane so as to incline the axes and position the tooth parameters as desired relative to each other when the brace is installed as calculated, using a mold of the brace and model and/or written instructions provided with the brace, and without the need for the orthodontist to bend the archwire. The bite resulting preferably places lower buccal cusps in upper marginal ridges on bicuspids and molars.

Claims

1. A method of forming an orthodontic brace for positioning teeth of a patient, the method comprising the steps of:

digitally representing individual teeth of the patient each by a contour in a vertical labial-facial plane;

simplifying the contours by selecting parameters of prominences of each of the respective teeth, including parameters representing each selected prominence by coordinate data, including vertical and horizontal-lingual-facial components of the prominences on the contour, of;

a lingual tooth gum intersection point and a facial tooth gum intersection point,

for posterior ones of the teeth, a mesial-buccal cusp tip, a mesial lingual cusp tip, and, additionally for at least the upper posterior teeth, a mesial marginal ridge point, and,

for anterior ones of the teeth, a lingual incisal edge point and a facial incisal edge point;

selecting an arcuate shape for an orthodontic brace;

digitally calculating with a processor positions of contours and of the coordinate data for the parameters of individual teeth relative to the arcuate shape of the brace to place the parameters of the teeth in desired positions relative to the parameters of others of the teeth;

digitally calculating with a processor locations on the contours of the individual teeth for connection of the orthodontic brace thereto;

digitally calculating with a processor geometry, including dimensional parameters, of the orthodontic brace for connection at the locations on the teeth such that, when the brace is attached to the respective tooth at the calculated location thereon, the brace will exert forces on the teeth to move the teeth to the desired relative positions; and

fabricating the brace in accordance with the calculated geometry.

2. A method of forming an orthodontic brace for positioning teeth of a patient, the method comprising the steps of:

digitally representing individual teeth of the patient by digital data defining a contour in a vertical labial-facial plane;

digitally deriving for each of the teeth, from the digital data, additional parameters including a crown long axis of the tooth;

digitally representing orientations of the derived crown long axes of the teeth in their respective lingual-facial planes to desired torque angles;

digitally calculating, with a processor, geometry, including dimensional parameters of an orthodontic brace for connection at locations on each of the teeth relative to the contours thereof such that, when the brace is attached to the respective teeth at the locations, the brace will exert forces on the teeth to move the crown long axes of the teeth to the desired torque angles; and

fabricating an orthodontic brace in accordance with the calculated geometry.

3. The method of claim 2 wherein:

the contour defining data includes vertical horizontal-lingual-facial coordinate data including;

a lingual tooth gum intersection point, a facial tooth gum intersection point,

for posterior ones of the teeth, a mesial-buccal cusp tip and a mesial lingual cusp tip, and

for anterior ones of the teeth, a lingual incisal edge point and a facial incisal edge point;

the crown long axes deriving step includes;

for posterior teeth, constructing a line through a midpoint between the tooth gum intersection parameters and through a midpoint of between the cusp tip parameters on the contour, and

for anterior teeth, constructing a line through a midpoint between the tooth gum intersection parameters and a midpoint between the incisal edge point parameters on the contour.

4. The method of claim 3 wherein:

the crown long axis orienting step includes the step of mathematically orienting the axis of each tooth in accordance with a predefined set of values for the teeth.

5. The method of claim 4 wherein:

the axis orienting step includes the step of orienting each crown long axis to a predefined set of angles relative to the horizontal approximately equal to;

for lower centrals, 63°

,

for lower laterals, 68°

,

for lower cuspids, 72°

,

for lower first bicuspids, 86°

,

for lower second bicuspids, 86°

,

for upper centrals, 73°

,

for upper laterals, 73°

,

for upper cuspids, 80°

,

for first bicuspids, 97°

, and

for second bicuspids, 100 °

.

6. The method of claim 5 wherein:

the axis orienting step includes the step of orienting the crown long axes for molars to angles, relative to the horizontal, that set the mesial cusp tips thereof level.

7. A method of forming an orthodontic brace for positioning teeth of a patient, the method comprising the steps of:

digitally representing individual teeth of the patient by digital data defining a contour in a vertical labial-facial plane;

simplifying the contour by defining coordinate data locating points thereon including;

for each tooth, a lingual tooth gum intersection point and a facial tooth gum intersection point,

for posterior ones of the teeth, also a mesial-buccal cusp tip and a mesial lingual cusp tip, and

for anterior ones of the teeth, also a lingual incisal edge point and a facial incisal edge point;

digitally deriving, with a processor from the digital data, a crown long axis of individual teeth;

for posterior teeth, through a midpoint between the tooth gum intersection parameters and through a midpoint of between the cusp tip parameters on the contour, and

for anterior teeth, through a midpoint between the tooth gum intersection parameters and a midpoint between the incisal edge point parameters on the contour;

digitally calculating, with a processor, geometry, including dimensional parameters, of the orthodontic brace for connection at locations on the contours of the individual teeth such that, when the brace is attached to the respective teeth, the brace will exert forces on the teeth to relatively position the teeth with respect to the derived crown long axes of the teeth; and

fabricating the brace in accordance with the calculated geometry.

8. A method of forming an orthodontic brace for positioning teeth of a patient, the method comprising the steps of:

digitally representing individual teeth of the patient each by a counter that includes coordinates of parameters corresponding to prominences of the tooth;

digitally defining a generally horizontal archwire plane;

digitally representing the vertical position of the archwire plane relative to of at least one of the prominences of a selected one of the teeth such that the plane intersects the contour;

digitally deriving vertical positions, relative to at least one of the prominences of the respective teeth, of the intersections of the archwire plane with the contours of a plurality of the teeth other than the selected one of the teeth that will vertically locate the prominences of the respective teeth relative to the prominences of the selected one of the teeth;

digitally calculating with a processor, for the selected one of the teeth and each of the teeth of the plurality, the geometry of a bracket to be mounted at an attachment position at the intersection of the archwire plane and the contour of the tooth, for connecting the tooth to an archwire disposed in the archwire plane so that, when the brackets are attached at the attachment positions on the respective teeth and connected to the archwire, forces will be exerted on the teeth to move the teeth to desired relative positions; and

fabricating brackets in accordance with the calculated bracket geometries.

9. The method of claim 8 further comprising the step of:

establishing the bracket attachment positions at the intersections of the contours of the teeth with the archwire plane.

10. The method of claim 9 further comprising the step of:

selecting an archwire having an arcuate shape;

the bracket geometry calculating step including the step of calculating the dimensions of a slot in the brackets such that, when the brackets are mounted on the teeth at the attachment positions, the slot will lie in the archwire plane and have a depth extending to an archwire positioned in the archwire plane.

11. The method of claim 8 wherein:

the selected tooth is a molar;

the parameter coordinate defining step for the molar includes the step of defining the coordinates of the location of the mesial marginal ridge of the molar with respect to the contour of the molar; and

the archwire plane locating step, for the molar, includes the step of mathematically locating the vertical position of the archwire plane relative to the contour of the molar at a predetermined height with respect to the mesial marginal ridge point thereof.

12. The method of claim 11 wherein:

the molar is an upper molar;

the plurality of other teeth include at least one upper bicuspid;

the parameter coordinate defining step for the bicuspid includes the step of defining the coordinates of the location of the mesial marginal ridge of the bicuspid with respect to the contour thereof; and

the archwire plane locating step, for the bicuspid, includes the step of mathematically locating the vertical position of the archwire plane relative to the contour of the bicuspid at a height with respect to the mesial marginal ridge point of the bicuspid that is related to that of the molar.

13. The method of claim 8 wherein:

the selected tooth is a lower molar;

the parameter coordinate defining step for the molar includes the step of defining the coordinates of the location of the mesial buccal cusp tip of the molar with respect to the contour of the molar; and

the method further comprises the step of calculating a vertical distance from the archwire plane to the mesial buccal cusp tip of the molar.

14. The method of claim 13 wherein:

the plurality of other teeth include at least one lower bicuspid;

the parameter coordinate defining step for the bicuspid includes the step of defining the coordinates of the location of a mesial buccal cusp tip with respect to the contour thereof; and

the archwire plane locating step for the bicuspid includes the step of mathematically locating the vertical position of the archwire plane a vertical distance relative to the buccal cusp tip of the bicuspid that is related to that of the molar.

15. The method of claim 13 wherein:

the plurality of other teeth include at least one lower anterior tooth;

the parameter coordinate defining step for the anterior tooth includes the step of defining the coordinates of the location of an incisal peak with respect to the contour thereof; and

the archwire plane locating step for the anterior tooth includes the step of mathematically locating the vertical position of the archwire plane a vertical distance relative to the incisal peak of the anterior tooth that is related to the distance of the mesial buccal cusp tip of the molar relative to the archwire plane.

16. The method of claim 15 further comprising the step of:

digitally deriving for the anterior tooth an extension of the contour containing a pre-attrition peak of the tooth prior to wear thereof;

the parameter coordinate defining step for the anterior tooth includes the step of defining the coordinates of the location of the incisal peak as the pre-attrition peak.

17. A method of forming an orthodontic brace for positioning teeth of a patient, the method comprising the steps of:

digitally representing individual teeth of the patient by a contour that includes coordinates of parameters corresponding to prominences of the tooth, including the coordinates corresponding to a mesial marginal ridge point on a selected posterior tooth;

digitally defining the vertical position of a bracket attachment location relative to the contour of the selected posterior tooth at a predetermined vertical distance from the marginal ridge point thereof;

digitally deriving, with a processor, vertical positions of bracket attachment locations relative to the contours of a plurality of the teeth other than the selected posterior tooth at vertical distances relative to parameters thereof that have a specifically defined relationship to the predetermined vertical distance for the selected posterior tooth;

digitally calculating, for the selected tooth and each of tooth of the plurality, the geometry of a bracket to be mounted at the attachment position on each respective tooth, for connecting the teeth to an archwire so that, when the brackets are attached to the attachment positions on the respective teeth and connected to the archwire, forces will be exerted on the teeth to move the teeth to desired relative positions; and

fabricating brackets in accordance with the calculated bracket geometry.

18. The method of claim 17 further comprising the steps of:

defining a generally horizontal archwire plane;

establishing the positions of the bracket attachment locations at the intersections of the contours of the teeth with the archwire plane.

19. The method of claim 18 further comprising the step of:

selecting an archwire having an arcuate shape;

the bracket geometry calculating step including the step of calculating the dimensions of a slot in each of the brackets such that, when the brackets are mounted on the teeth at the respective attachment locations, the slots will lie in the archwire plane and have depths extending to an archwire positioned in the archwire plane.

20. The method of claim 17 wherein:

the selected tooth is a molar;

the parameter coordinate defining step for the molar includes the step of defining the coordinates of the location of the mesial marginal ridge with respect to the contour thereof; and

the bracket attachment location deriving step for the molar includes the step of mathematically locating the vertical position of the bracket attachment location thereof relative to the contour of the molar at a predetermined height with respect to the mesial marginal ridge point thereof.

21. The method of claim 20 wherein:

the molar is an upper molar;

the plurality of other teeth include at least one upper bicuspid;

the parameter coordinate defining step for the bicuspid includes the step of defining the coordinates of the location of the mesial marginal ridge with respect to the contour thereof; and

the bracket attachment location deriving step for the bicuspid includes the step of mathematically locating the vertical position of the bracket attachment location relative to the contour of the bicuspid at a height with respect to the mesial marginal ridge point of the bicuspid that is related to that of the molar.

22. The method of claim 17 wherein:

the selected tooth is a lower molar;

the parameter coordinate defining step for the lower molar includes the step of defining the coordinates of the location of the mesial buccal cusp tip with respect to the contour thereof; and

the method further comprises the step of calculating a vertical distance from the mesial buccal cusp tip of the lower molar to the bracket attachment location thereof.

23. The method of claim 22 wherein:

the plurality of other teeth include at least one lower bicuspid;

the parameter coordinate defining step for the lower bicuspid includes the step of defining the coordinates of the location of a mesial buccal cusp tip with respect to the contour thereof; and

the bracket attachment location defining step for the bicuspid includes the step of mathematically locating the vertical position of the bracket attachment location at a vertical distance relative to the buccal cusp tip thereof that is related to that of the molar.

24. The method of claim 22 wherein:

the plurality of other teeth includes at least one lower anterior tooth;

the parameter coordinate defining step for the anterior tooth includes the step of defining the coordinates of the location of an incisal peak with respect to the contour thereof; and

the bracket attachment location defining step for the anterior tooth includes the step of mathematically locating the vertical position of the bracket attachment location thereof at a vertical distance relative to the incisal peak thereof that is related to the distance of the mesial buccal cusp tip of the molar relative to the bracket attachment location thereof.

25. The method of claim 24 further comprising the step of:

digitally deriving for the anterior tooth an extension of the contour containing a pre-attrition peak parameter of the tooth representing an incisal peak thereof prior to wear;

the parameter coordinate defining step for the anterior tooth including the step of defining the coordinates of the location of the incisal peak as the pre-attrition peak.

26. A method of forming an orthodontic brace for positioning teeth of a patient, the method comprising the steps of:

digitally representing individual teeth of the patient each by a contour that includes a representation of prominences of the tooth, the contour for anterior ones of the teeth including a representation of an incisal peak on the anterior tooth;

digitally modifying, for at least one of the anterior teeth, the contour thereof to include a pre-attrition peak of the tooth as the incisal peak thereof;

digitally calculating with a processor, for each of the individual teeth, the geometry of a bracket to be mounted at an attachment position relative to the contour thereof, for connecting the teeth to an archwire so that, when brackets are attached to the attachment positions on a plurality of the teeth and connected to the archwire, forces will be exerted on the teeth to move the teeth to desired relative positions relative to the pre-attrition peak of the at least one anterior tooth; and

fabricating brackets in accordance with the calculated bracket geometries.

27. The method of claim 26 further comprising the steps of:

establishing the position of the bracket attachment location on the anterior tooth relative to the pre-attrition peak thereof.

28. The method of claim 27 further comprising the step of:

selecting an archwire having an arcuate shape and establishing an archwire plane in which the archwire is to be positioned relative to the contours of the teeth;

the bracket geometry calculating step including the step of calculating the dimensions of a slot in each of the brackets such that, when the brackets are mounted on the teeth at the attachment locations, the slots have depths extending to an archwire positioned in the archwire plane.

29. A method of forming an orthodontic brace for positioning teeth of a patient, the method comprising the steps of:

digitally representing each of a plurality of individual teeth of the patient by a contour that includes prominences of the tooth, the contours for upper molars and bicuspids including a horizontal facial-lingual coordinate corresponding to a mesial marginal ridge point thereon and the contours for lower molars and bicuspids each including a horizontal facial-lingual coordinate of a mesial buccal cusp tip thereon;

defining bracket attachment locations relative to the contours of a plurality of the teeth including molars and bicuspids;

selecting an archwire having an arcuate shape;

determining the positions of upper and lower archwires in respective generally horizontal archwire planes;

digitally calculating with a processor, for upper molars and bicuspids, the geometries of brackets to be mounted at the attachment locations relative to the contours of the respective teeth, for connecting the teeth to the upper archwire so that, when the brackets are attached at the attachment locations to the respective teeth and connected to the upper archwire at its position in the upper archwire plane, forces will be exerted on the teeth to move the upper molars and bicuspids to desired relative positions at which their mesial marginal ridge points are at related horizontal distances from the upper archwire;

digitally calculating with a processor, for lower molars and bicuspids, the geometry of a bracket to be mounted at the attachment locations on the contours of the respective teeth, for connecting the teeth to the lower archwire so that, when the brackets are attached to the attachment locations on the respective teeth and connected to the lower archwire at its position in the lower archwire plane, forces will be exerted on the teeth to move the lower molars and bicuspids to desired relative positions at which their mesial buccal cusp tips are at related horizontal distances from the lower archwire and at the horizontal positions of the mesial marginal ridge points of the corresponding upper molars or bicuspids; and

fabricating brackets in accordance with the calculated bracket geometry.

30. A method of forming an orthodontic brace for positioning teeth of a patient, the method comprising the steps of:

digitally representing each of a plurality of individual teeth of the patient by a contour that includes prominences of the respective tooth, the contours for upper first bicuspids including a horizontal facial-lingual coordinate corresponding to a mesial buccal cusp tip thereof, and the contours for upper anterior teeth including a horizontal facial-lingual coordinate corresponding to an incisal peak thereof;

defining bracket attachment locations relative to the contours of a plurality of the teeth including upper anterior teeth and first bicuspids;

defining a generally horizontal upper archwire plane;

selecting an upper archwire having an arcuate shape;

determining the position of an upper archwire in the upper archwire plane;

digitally calculating with a processor, for individual upper first bicuspids and anterior teeth, the geometries of brackets to be mounted at the attachment locations relative to the contours of the respective teeth, for connecting the teeth to the upper archwire so that, when the brackets are attached at the attachment locations to the respective teeth and connected to the upper archwire at its position in the upper archwire plane, forces will be exerted on the teeth to move the upper anterior teeth and first bicuspids to desired relative positions at which the incisal peaks of the upper anterior teeth are at horizontal distances from the upper archwire that are related to the horizontal distances of the mesial buccal cusp tips of the first bicuspids from the upper archwire; and

fabricating brackets in accordance with the calculated bracket geometry.

31. The method of claim 30 further comprising the step of:

digitally modifying for at least one of the upper anterior teeth the contour thereof to include a pre-attrition peak of the tooth as the incisal peak thereof;

the forces exerted on the teeth being those that will move the teeth to desired relative positions such that the pre-attrition peak of the upper anterior tooth will be spaced from the upper archwire at a distance related to the distance of the mesial buccal cusp tip of an upper first bicuspid from the upper archwire.

32. A method of forming an orthodontic brace for positioning teeth of a patient, the method comprising the steps of:

digitally representing each of a plurality of individual teeth of the patient by a two dimensional contour in a vertical labial-facial plane, the contour including parameters of prominences of the tooth spaced in three dimensions over the surface thereof, the contour being generated by;

providing a three dimensional physical model of the patient'"'"'s upper and lower jaws, the model including representations of individual teeth of the patient, including posterior teeth including molars and first and second bicuspids, and including anterior teeth including cuspids, laterals and centrals, and

mechanically scanning individual teeth of the model with a mechanical probe and generating coordinate signals, including vertical coordinate data and horizontal, lingual-facial coordinate data of a plurality of prominences on the surface of the tooth;

digitally calculating with a processor, for each tooth, in response to the coordinate signals and in accordance with the coordinate data, the geometry of a bracket to be mounted at an attachment position located relative to the contour of the tooth, for connecting the teeth to an archwire so that, when brackets are attached to the attachment locations on a plurality of the teeth and connected to the archwire, forces will be exerted on the teeth to move the teeth to desired relative positions; and

fabricating brackets in accordance with the calculated bracket geometry.

33. A method of forming an orthodontic brace for positioning teeth of a patient, the method comprising the steps of:

digitally representing individual teeth of the patient by a two-dimensional contour in a vertical labial-facial plane, the contour including parameters of prominences of a corresponding tooth, the contour being generated by;

providing a physical model of the patient'"'"'s upper and lower jaws, the model including representations of individual teeth of the patient, including posterior teeth including molars and first and second bicuspids, and including anterior teeth including cuspids, laterals and centrals,

mechanically scanning individual teeth of the model with a mechanical probe and generating coordinate signals, including vertical coordinate data and horizontal lingual-facial coordinate data thereby;

digitizing from the coordinate data, with respect to respective ones of the contours, a lingual tooth gum intersection point, a facial tooth gum intersection point, and;

for posterior ones of the teeth, a mesial-buccal cusp tip, a mesial lingual cusp tip, and a mesial marginal ridge point, and

for anterior ones of the teeth, a lingual incisal edge point and a facial incisal edge point;

digitally deriving with a processor, from the digitized parameters, additional parameters including;

a crown long axis of individual teeth, the axes being;

for posterior teeth, a line through a midpoint between parameters of tooth gum intersections and through a midpoint between parameters of cusp tip positions on the contour, and

for anterior teeth, a line through a midpoint between parameters of tooth gum intersections and an incisal edge midpoint on the contour, and

digitally representing orientations of the contour of each tooth in a respective vertical lingual-facial plane such that the crown long axis forms a long axis torque angle LAXTQ in accordance with a predefined criterium for the tooth, the LAXTQs being approximately equal to;

for lower centrals, 63°

,

for lower laterals, 68°

,

for lower cuspids, 72°

,

for lower first bicuspids, 86°

,

for lower second bicuspids, 86°

,

for upper centrals, 73°

,

for upper laterals, 73°

,

for upper cuspids, 80°

,

for first bicuspids, 97°

, and

for second bicuspids, 100°

;

selecting upper and lower archwires, each lying in an archwire plane and each having an arcuate shape;

for each of the upper and lower archwires;

digitally defining the vertical position of the corresponding archwire plane relative to respective upper and lower molars wherein the plane is approximately horizontal and intersects each contour, as inclined, at two points spaced vertically from the parameter of the marginal ridge,

for lower bicuspids, digitally defining the buccal cusp tips relative to the lower archwire plane a vertical distance that is derived from the distance between the buccal cusp tip and lower archwire plane for the lower molars,

determining bracket attachment locations on the teeth at an intersection of the respective archwire plane with the contour;

digitally calculating, with a processor, for each tooth, the geometry of a bracket, including the position, depth and inclination of a slot therein, such that, when the bracket is mounted at the respective attachment location on a contour of the respective tooth, the slot lies in the archwire plane and has a depth extending;

for molars, to a predetermined horizontal distance from attachment location, and defining thereby a horizontal reference distance from the marginal ridge for the upper molars, and a horizontal reference distance from the buccal cusp tips for the lower molars,

for lower bicuspids, to a distance from the buccal cusp corresponding to the reference distance of the lower molars,

for upper bicuspids, to a distance from the marginal ridge corresponding to the reference distance of the upper molars, and further defining thereby a horizontal reference distance from the buccal cusp tips for the upper bicuspids,

for lower anteriors, to a distance from the incisal tip thereof corresponding to the reference distance for the lower molar,

for upper anteriors, to a distance from the incisal tip thereof corresponding to the reference distance for the upper bicuspid; and

cutting slots in bracket blanks in accordance with the calculated geometries;

whereby, when the brackets are attached to the attachment locations relative to the contours of the respective teeth and the archwires are mounted in the slots of the brackets, a brace is formed that will exert forces on the teeth to move the teeth to desired positions at which the crown long axes thereof are at predetermined inclinations in the respective vertical lingual-facial planes, the mesial cusp tips of the molars are level, the mesial buccal cusps of the lower posterior teeth align vertically and horizontally with the marginal ridges of the corresponding upper posterior teeth, incisal edges of anterior teeth align by the prewear attrition points thereof.