Method for designing orthodontic apparatus
OwnerPascal Baron, Christophe Gualano +1inventors
InventorsPascal Baron, Christophe Gualano, Laurent Sempe
Life of this patent
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Abstract
A method of producing a customized orthodontic appliance (1), including brackets (12) fixed to teeth (13) of a dental arch of a patient and an orthodontic archwire (11). Each bracket (12) is fixed to a surface of a tooth (13) of the dental arch by a bracket bonding pad (121) of the bracket, and the orthodontic archwire (11) is fixed to the brackets in a housing (123) of a bracket body (122) of each bracket. The bracket is produced with a blank (50) having at least two volumes (51, 52), one volume representative of an envelope volume of a bracket bounding pad and an envelope volume of a bracket body.
Claims19
1- Method of producing a customized orthodontic appliance (1), the said orthodontic appliance comprising:
- brackets (12) fixed to teeth (13) of a dental arch of a patient, each bracket (12) being fixed to a surface of a tooth (13) of the dental arch by a bracket bonding pad (121) of the said bracket,
- an orthodontic archwire (11) fixed to the said brackets in a housing (123) of a bracket body (122) of each bracket,
- the said method comprising a step of constructing a numerical representation (12n) of each bracket from a numerical representation of the desired end-of-treatment dental arch, known as the dental arch final numerical representation, the said method being characterized in that the step of constructing the numerical representation (12n) of each bracket comprises the steps of:
- a) positioning a numerical representation (11n) of the orthodontic archwire with respect to the dental arch final numerical representation, then
- b) for each tooth (13n) of the dental arch final numerical representation, positioning a numerical representation (52n) of a volume representative of an envelope volume of a bracket body, known as a second volume, of a bracket blank (50n) such that it interferes with the orthodontic archwire (11n) and in close proximity to the relevant tooth, and
- c) for each tooth (13n) of the dental arch final numerical representation, positioning a numerical representation (51n) of a volume representative of an envelope volume of a bracket bonding pad, known as a first volume, of the bracket blank (50n) such that it interferes with the second volume (52n) and with the volume of the relevant tooth, then,
- d) determining, for each tooth (13n) in the first volume (51n) and in the second volume (52n), volumetric exclusion zones, which volumetric exclusion zones contain all of the volumes that interfere with the tooth for the first volume and all of the volumes that interfere with the orthodontic archwire for the second volume,
- the numerical representation of the bracket (12n) of one tooth (13n) being determined by the volume of the bracket blank (50n) minus the volumetric exclusion zones.
2- Method according to claim 1, in which the volumetric exclusion zones of the first volume (51n) are defined in such a way as to determine a substantially constant thickness of the numerical representation of the bracket bonding pad (121n).
3- Method according to claim 1, in which the blank (50n) is chosen from a database comprising at least two models of numerical representation of blanks.
4- Method according to claim 1, in which the blank (50n) is chosen in relation to the shape of the relevant tooth (13n) so as to minimize the volume of the exclusion zones while at the same time keeping a sufficient aerial contact between a bearing surface (124n) of the bracket bonding pad (121n) and the surface of the tooth (13n).
5- Method according to claim 1, in which the numerical representation of the orthodontic archwire (11n) is positioned in such a way that a distance d, for each tooth (13n) of the dental arch final numerical representation, between the numerical representation of the orthodontic archwire (11n) and the surface of each tooth (13n) is greater than a minimum distance dmin that corresponds to a minimum thickness of the numerical representation of the brackets (12n) at their bracket bodies (122n).
6- Method according to claim 1, in which, for each tooth (13n) of the dental arch final numerical representation, the numerical representation of the second volume (52n) is positioned in such a way that a reference point of the said second volume corresponds to a point of intersection between the numerical representation (11n) of the orthodontic archwire and an orthogonal projection of a centre (132n) of the relevant tooth (13n).
7- Method according to claim 1, in which housings (123) are produced, for certain sectors of the dental arch, with a cross section appreciably larger than a cross section of the orthodontic archwire (11) so that the orthodontic archwire can slide naturally along the dental arch in the said housings as the teeth (13) of the said dental arch move.
8- Method according to claim 1, in which the orthodontic appliance is produced from a flat orthodontic archwire.
9- Method according to claim 1, in which the numerical representations of the brackets (12n) are placed on lingual surfaces (131n) of the teeth (13n) of the dental arch final numerical representation.
10- Method according to claim 1, in which the numerical representations of the brackets (12n) are placed on vestibular surfaces of the teeth (13n) of the dental arch final numerical representation.
11- Method according to claim 1, in which the exclusion zones of the second volume determine a housing (123n) in the form of an open slot in the numerical representation of the bracket body (122n) to accommodate the numerical representation of the orthodontic archwire (11n) and, if appropriate, a numerical representation of orthodontic archwire self-ligating means.
12- Method according to claim 1, in which the exclusion zones of the second volume determine a housing (123n) in the form of a tube in the numerical representation of the bracket body (122n) to accommodate the numerical representation of the orthodontic archwire (11n).
13- Method according to claim 1, in which volumetric exclusion zones are determined in a numerical representation of at least one volume representative of an envelope volume of an ancillary accessory, known as a third volume, of the bracket blank (50n), and are then subtracted from the blank (50n).
14- Method according to claim 1, in which the final numerical representation of the dental arch desired at the end of the treatment of the patient is produced from a numerical representation of the dental arch of the patient prior to treatment.
15- Method according to claim 1, in which the brackets are produced from a biocompatible material in accordance with the numerical representations.
16- Bracket (12) of an orthodontic appliance, characterized in that the said bracket is produced according to the method of claim 1 using a blank (50), the said blank comprising at least two imbricated volumes (51, 52) constituting an envelope of at least two elements that are to be produced, one volume representative of an envelope volume of the bracket bonding pad (121), known as the first volume (51), machined on a first side, known as the bearing surface (124), to conform to the surface (131) of the tooth (13), and one volume representative of an envelope volume of the bracket body (122), known as the second volume (52), machined on an opposite side of the first volume to a bearing surface (124), to form the housing (123).
17- Bracket (12) according to claim 16, characterized in that the second volume (52) of the blank from which the said bracket is produced is substantially spherical.
18- Bracket (12) according to claim 16, characterized in that the first volume (51) of the blank from which the said bracket is produced is a body that is convex on the tooth side.
19- Bracket (12) according to claim 16, characterized in that the first volume (51) of the blank from which the said bracket is produced is a body that is concave on the tooth side.