|Publication number||WO2005107628 A1|
|Publication date||17 Nov 2005|
|Filing date||12 May 2005|
|Priority date||12 May 2004|
|Publication number||PCT/2005/679, PCT/AU/2005/000679, PCT/AU/2005/00679, PCT/AU/5/000679, PCT/AU/5/00679, PCT/AU2005/000679, PCT/AU2005/00679, PCT/AU2005000679, PCT/AU200500679, PCT/AU5/000679, PCT/AU5/00679, PCT/AU5000679, PCT/AU500679, WO 2005/107628 A1, WO 2005107628 A1, WO 2005107628A1, WO-A1-2005107628, WO2005/107628A1, WO2005107628 A1, WO2005107628A1|
|Inventors||David Hynd, Geoffrey Hall|
|Applicant||E-Brackets Pty Ltd|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (11), Referenced by (1), Classifications (3), Legal Events (7)|
|External Links: Patentscope, Espacenet|
PLACEMENT OF ORTHODONTIC BRACKETS
FIELD OF THE INVENTION
The present invention relates broadly to a method for accurate placement of orthodontic brackets together with configurable bracket pads used in the placement and attachment of orthodontic brackets.
BACKGROUND OF THE INVENTION
Orthodontic treatment for the manipulation of tooth position, rotation and orientation often involves the use of brackets indirectly or directly bonded to teeth, and an archwire connected to the brackets. The archwire is elastically deformed when initially installed on the brackets. The resiliency of the archwire to deformation causes the brackets attached to the teeth to be subject to rotational and/or translational force, thereby moving the teeth over time to a desired final tooth position. The design (prescription) of the slots in the bracket also produce a torqueing force on the tooth (that is, a rotational force along an axis perpendicular to the length and breadth of the tooth).
In this conventional method, the placement of brackets on teeth is an important step. Incorrect placement of brackets can result in movement of teeth in undesired directions, requiring subsequent correction. Conventionally, correct bracket placement is difficult or impossible where the tooth to which the bracket is to be attached is severely maloccluded (ie an adjacent or opposing tooth is blocking the placement of the bracket in the desired position on the tooth).
SUMMARY OF THE INVENTION
According to a first aspect of the invention there is provided a method for placement of an orthodontic bracket on a tooth, said method comprising the steps of: obtaining a digital three-dimensional representation of the tooth; calculating a desired final tooth position for the tooth from the digital representation; and calculating an optimum position on the tooth for an orthodontic bracket using the desired final tooth position.
According lo second aspect of the invention there is provided a method for placement of an orthodontic bracket on a replica of a tooth, said method comprising the steps of: obtaining a digital three-dimensional representation of the tooth or the replica of the tooth; calculating a desired final tooth position for the tooth from the digital representation; calculating an optimum position on the tooth for an orthodontic bracket using the desired final tooth position; attaching a configurable bracket pad to a pad-facing side of the bracket; and placing the bracket on the replica of the tooth in a position on the replica corresponding to the optimum position.
Preferably the method also comprises the step of designing the configurable bracket pad having a bracket-facing surface and an opposing tooth-facing surface being shaped to conform to the surface of the tooth a the optimum position.
Preferably the step of placing the bracket on the replica of the tooth includes instructing or programming a robot to effect this placement step.
According to a third aspect of the invention there is provided a method for determining an optimum position for placement of a configurable bracket pad on the surface of a tooth, said method comprising the steps of: obtaining a digital three-dimensional representation of the tooth; calculating a desired final tooth position for the tooth from the digital representation; and calculating an optimum position on the tooth for the bracket pad using the desired final tooth position.
According to a fourth aspect of the invention there is provided a configurable bracket pad being adapted for placement on a tooth or a replica of a tooth at an optimum position , calculated from a desired final position for the tooth derived from a three-dimensional representation of the tooth, said bracket pad having a tooth-facing surface being shaped to conform to the surface of the tooth at the optimum position.
BRIEF DESCRIPTION OF THE FIGURES
Figure 1 depicts the current technology limitation of prior art orthodontic brackets in which the base of the bracket is required to be perpendicular to the archwire in the final tooth position.
Figure 2 depicts an application of the preferred embodi ent of the present invention in which the configurable bracket pad of the preferred embodiment enables the bracket to be placed anywhere on the tooth surface,
Figure 3 depicts the current technology limitation of prior art orthodontic brackets in which a bracket cannot be placed on the centreline of maloccluded teeth.
Figure 4 depicts an application of the preferred embodiment of the present invention in which pff-ccntrc bracket positioning enables maloccluded teeth to be rotated in one step.
DETAILED DESCRIPTION OF THE INVENTION
The invention in its preferred embodiment is primarily directed to facilitating the optimum position of orthodontic brackets in an automated, cost-effective and time-effective manner. In one aspect of the invention there is provided a method for placement of an orthodontic bracket on a tooth, said method comprising the steps of; obtaining a digital three-dimensional representation of the tooth; calculating a desired final tooth position for the tooth from the digital representation; and calculating an optimum position on the tooth for an orthodontic bracket using the desired final tooth position.
In a preferred embodiment, the method also comprises the step of designing a configurable bracket pad for attaching to a pad-facing side of the bracket, the pad having a bracket-facing surface an an opposing tooth-facing surface, wherein the tooth-facing surface of the pad is shaped to conform to a surface of the tooth at the optimum position. The configurable bracket pad enables the bracket lo be placed in the oplimum position in relation to the teeth, providing significantly more flexibility in the positioning of the bracket.
Preferably, the method according to the first aspect further comprises the step of attaching the configurable bracket pad lo the pad-facing side of the bracket. It is also preferable that the method further comprises placing the bracket in the optimum position on the tooth.
ϊn order to facilitate a better understanding of the invention, the following general steps of this and other aspects of the method will now be described in more detail but by way of example only.
1 , Obtaining a three-dimensional digital representation of the tooth This step is usually achieved by taking a mould or impression of the patient's teeth (generally of the teeth in a single jaw) and filling that mould with a plaster or stone- like substance that will harden within the mould to form a cast. Once the cast has hardened, the mould is removed. The cast takes the form of the patient's teeth and comprises replicas of each of the patient's teeth. The cast is then scanned in three dimensions using a laser or Computer Aided Tomography (CAT) scanner. Software is then utilised to produce a three- dimensional, digital representation of the teeth to be treated.
Alternatively, if a high quality impression is made (most usually from a polyvinylsiloxanc material) it is possible to directly scan the impression using a CAT scanner. In this case it is not necessary to make a cast.
It is also possible to obtain a three-dimensional representation of a patient's tooth by intra-oral scanning of the tooth. In this case it is also not necessary to make a cast.
2. Calculating and displaying a desired final tooth position
Conventionally, the final positions r the teeth are estimated by the treating orthodontist, cither by a manual means of by means of a computer. Errors in the estimation process require adjustments as treatment progresses, resulting in lengthy treatment times. In a prefen-ed embodiment of the invention, the final tooth position is automatically calculated by means of a computer. The tooth in its post-treatment or final position is displayed on a display means (for example a computer monitor or printer) for verification. It is important to note that the desired final position of any given tooth may be dependent on the position of one or a number of other teeth, to maintain symmetry and aesthetics. Accordingly, modification of the final position of any tooth may affect the final position of one or a number of other teeth. The operator is able to manually adjust the computer-calculated position of the teeth to obtain this adjusted desired final tooth position. Accordingly, in a preferred embodiment of the invention, the desired tooth position automatically calculated by means of a computer is manually adjusted by an operator.
3. Verification of final tooth position
After the final position of the teeth are displayed, this is verified by the treating orthodontist or dentist.
4. Calculation of optimum bracket position
Once the final tooth position is verified, the required movements of each tooth to reach its final position are calculated. From the results of this calculation, the magnitude and direction of the force required to be applied to the tooth is calculated. Using known characteristics of the bracket and the material used to form the archwire, and given the restraint that the archwire must remain on the bracket, the optimum position of the bracket is calculated. In a preferred embodiment, the optimum position for placement of the bracket is calculated by means of a computer.
Conventionally, the optimum position for the bracket is constrained by at least the following factors:
(a) the base of the bracket must be in contact with the tooth;
(b) the archwire must remain in intimate contact with the bracket; and (c) the bracket must be able to be positioned on the tooth - that is, there must be sufficient clearance above the surface of the tooth to enable the bracket to be installed and not interfere with other teeth.
Additionally, brackets conventionally have a specific base curvature. The specific curvature of the base of the brackets means that that a bracket will only tit snugly on a relatively small area of a tooth, generally around the centre line of the tooth ( the centre line bisecting the breadth of the tooth and running from the gum line to the tooth tip).
These constraints have meant that in many cases brackets have not been able to be installed in the optimum position on the tooth, and accordingly alterations of the archwire and/or brackets have needed to be made during treatment.
The preferred embodiment of the present invention involves the use of a configurable bracket pad on the base of the bracket to alleviate the aforementioned constraints. The configurable bracket pad can be of any height, and has its bottom surface moulded to the surface of the tooth at the optimum placement position. This greatly increases the area of the surface of the tooth on which the bracket is able to be placed.
The effect of this part of the preferred embodiment invention may be described by example. Conventionally, in the final tooth position the base of the bracket is required to be perpendicular to the archwire. If the tooth is to be rotationally aligned with the archwire, this requires the bracket to be placed on the centreline of the tooth, as shown in Figure 1.
If for any reason the bracket cannot be placed on the centreline of the tooth, it wil I have lo be replaced on the tooth a number of times during treatment in order lo achieve the desired final tooth position.
If the configurable bracket pad of the preferred embodiment of the present invention is used, the bracket may be placed anywhere on the toolh surface, as shown in Figure 2, including in an optimum position offset from the centre line of the tooth. The advantages of this flexibility are most clearly demonslraled in relation to maloccluded teeth, where a bracket cannot be placed on the centreline of the tooth. Conventionally, bracket placement is impossible, as shown in Figure 3.
By enabling off-centre bracket positioning, the preferred embodiment of the present invention allows correct rotation of maloccluded teeth in one step, as shown in Fi ure 4.
5, Placing the brackets (i n uding the configurable bracket pad) on the cast
Having calculated the optimum bracket position for each bracket (including the shape of the configurable bracket pad or composite base), the brackets must be positioned on the patient's teeth. In accordance with the preferred embodiment of the present invention, the brackets may be placed on a replica of the teeth (for example a cast) by means of a robot, and subsequently joined by an archwire. As indicated above, the optimum bracket position is calculated from the original scan of the patient's teeth. The computer uses its calculations of the optimum bracket position to instruct a robot to place the brackets on the replica or cast in a position on the replica or cast corresponding to the optimum position on the teeth. The use of three-dimensional modelling, calculation of optimum bracket position, and the use of a robot to place the brackets on the cast based on the calculations results in highly accurate bracket placement. Once the brackets have been placed on the replica or cast, the brackets are connected by an archwire to fo i an orthodontic appliance. This appliance is removed from the replica and placed in the patient's mouth. 'Ilie brackets of the appliance arc thereby placed in an optimum position in relation to the patient's teeth.
Tliosc skilled in the art will appreciate that the invention described herein is susceptible to variation and modifications other than those specifically described. For example the east, orthodontic bracket and configurable bracket pad may be made of any suitable material, . The configurable bracket pad may be shaped by casting, moulding or by a grinding process. All such variations and modifications are to be considered within the scope of the present invention, the nature of which is to be determined from the foregoing description.
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|Citing Patent||Filing date||Publication date||Applicant||Title|
|WO2015025255A3 *||15 Aug 2014||28 May 2015||Universidad Nacional De Colombia||Orthodontic tool for the placement, positioning and attaching of brackets on the vestibular surface of the tooth|
|17 Nov 2005||AL||Designated countries for regional patents|
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