Transfer device including groove extending along the gum and related manufacturing method

Abstract

The present invention provides a method for making a transfer device, the method comprising providing a physical solid model having a shape corresponding to the positive shape of a patient's dental arch and the positive shape of one or more appliance analogs, the one or more appliance analogs comprising a ramp extending from the analog in a generally gingival direction. A transfer tray can be formed on the physical solid model, wherein the transfer tray represents a negative replica of at least a portion of the solid model. One or more receiving portions and associated grooves are correspondingly formed in the tray, each receiving portion approximating at least a portion of the shape of the appliance analog and each groove approximating at least a portion of the shape of the ramp. An appliance associated with the appliance analog is placed in a receiving portion of the one or more receiving portions, and the appliance can be bonded to the tooth surface of the patient's dental arch.

Description

Background Art

[0001] Orthodontic appliances are commonly used in orthodontic treatment to move one or more teeth from an initial position (sometimes referred to as misalignment or malocclusion) to a desired position in a patient's dentition. For example, the patient's teeth may be moved so that the labial sides of the teeth are aligned with each other to achieve or maximize an aesthetically pleasing appearance of the entire dentition. In addition, in some cases, one or more teeth may be moved to correct the malocclusion. In conventional orthodontic brackets, the movement of teeth is typically achieved by a pre-biased archwire, which is attached to the teeth via brackets and applies force to the teeth toward the desired position over a longer period of time. The ends of the orthodontic archwires are typically connected to a small appliance called a buccal tube, which in turn is secured to the patient's molars. In many examples, a set of brackets, buccal tubes, and archwires are provided for each of the upper and lower dental arches.

[0002] In many types of orthodontic techniques, the precise placement of the appliances on the teeth is an important factor in helping to ensure that the teeth are moved to their intended final position. For example, one common type of orthodontic treatment technique is known as "straight wire" technology, where the archwire is positioned in a horizontal plane at the end of treatment. For example, if the brackets are attached to the teeth too close to the biting surface or outer cusps of the teeth, an orthodontist using straight wire technology may find that the teeth are over-intruded in their final position. On the other hand, if the brackets are attached to the teeth closer to the gums than is appropriate, the final position of the teeth may be more prominent than desired.

[0003] So-called treatment planning systems are used to determine the desired positions of the teeth in a computer simulation prior to any actual treatment. For example, such planning systems help to avoid collisions between teeth and brackets for tooth positions other than the initial position, and further allow brackets and archwires to be designed and arranged to match a variety of clinical situations, such as the position of the teeth in the initial position, in the desired position, and in between. Such treatment planning is widely used, in particular, for lingual brackets. Lingual brackets often have a custom design that is individually used for each tooth and patient, because, in addition to the labial surfaces of the teeth, the lingual surfaces vary greatly in shape relative to each other, so that a "one size fits all" bracket shape cannot usually be used. Some treatment planning systems also allow the design of such custom brackets that precisely match the tooth surfaces and the patient's desired clinical situation. Therefore, the custom brackets usually have to be placed precisely on the teeth at the positions predetermined during treatment planning.

[0004] Brackets can be placed on teeth by both direct bonding techniques and indirect bonding techniques. Generally speaking, indirect bonding techniques involve the use of a transfer device (e.g., a fixture, a dental tray, or a bonding template) whose shape matches the configuration of at least a portion of the patient's dental arch. A set of appliances (such as brackets) are releasably connected to the device at certain predetermined locations. An adhesive is applied to the base of each appliance and the device is then placed on the patient's teeth to ensure contact between the appliance base and the corresponding tooth surface until the adhesive hardens. Next, the device is removed from the teeth and from the appliances so that all appliances previously connected to the device are now bonded to the corresponding teeth at their intended predetermined locations.

[0005] International Publication No. WO2014 / 093084 (Blees et al.) describes a method for making a transfer tray from an integrated physical entity model. The integrated physical entity model represents a shape consisting of the positive shape of the patient's dental arch and the positive shape of a set of bracket analogs. The shape of the bracket analogs may substantially correspond to the shape of the desired orthodontic bracket, but may include less significant or fewer undercuts, grooves, and recesses than the corresponding bracket body. The shape of the dental arch and the set of analogs may cooperate to form a continuous piece, which may allow the creation of a transfer tray in which the bracket may be removably placed and positioned without significantly damaging the transfer tray. In addition, the transfer tray prepared by using the integrated physical entity model may allow for precise positioning of the bracket while allowing the bracket to be removed with relatively little force. Summary of the invention

[0006] Forming the transfer bracket on an analog or approximation of the selected bracket shape contrasts the method of WO2014 / 093084 with many indirect bonding systems which are typically formed directly onto a selected orthodontic bracket or an exact approximation thereof. However, a difficulty with the physical model used in this process is that the bracket analog must often be adjusted to remove features with large overhangs (e.g., hooks and ligature wings) which are difficult to create via additive manufacturing techniques or require supports. The use of supports requires more material and time to remove during the manufacturing process and carries the risk of damage to the appliance analog which would result in a defective transfer device.

[0007] The inventors of the present disclosure have discovered that retaining ramps and other structures can be coupled to an appliance analog and extruded along the surface of a dental model. This approach tends to improve manufacturability, appliance loading, and appliance removal. Virtual merging of the dental model with the analog and ramps allows for the creation of a physical model without external support. Forming a transfer device on such a physical model also creates grooves that provide clearance for forceps when loading the appliance into the transfer device.

[0008] In one aspect, the present disclosure provides an orthodontic transfer device for placing an orthodontic brace on a dental arch, the device comprising: a main body comprising an inner surface that substantially conforms to the contour of at least one tooth of the dental arch, an appliance receiving portion, and a groove that is fluidically connected to the receiving portion and extends from the receiving portion in a gingival direction, wherein the depth of the groove near the receiving portion is greater than the depth of the groove at the gingival edge of the tray body.

[0009] On the other hand, the present disclosure provides a method for making an orthodontic transfer device including a body, the method comprising providing a three-dimensional virtual model of at least a portion of a dental arch, the dental arch comprising a plurality of virtual teeth, gums, and a mold body extending from the gums. The method further comprises: providing a virtual appliance analogue comprising a base and a body, the appliance analogue optionally comprising a retaining ramp precursor extending from the gingival region of the appliance body; and placing the appliance analogue on the labial surface or the lingual surface of one of the plurality of virtual teeth. Then, the retaining ramp precursor is extruded from the appliance analogue to at least one region adjacent to the gums. Once the extrusion step of the desired number of ramps is completed, a physical model of the combined virtual dental arch and appliance analogue can be manufactured, and the transfer device is on the physical model.

[0010] The transfer device can be formed by arranging an elastic sheet on the physical model so as to cover at least a portion of the tooth side of the physical model with the sheet. Next, a plastic sheet can be arranged on the physical model, wherein the elastic sheet is arranged between the plastic sheet and the physical model. The plastic sheet is deformed on the physical model so that it at least surrounds the tooth side of the physical model and so that it surrounds the elastic sheet between the plastic sheet and the physical model. Subsequently, the elastic sheet can be replaced with a hardenable material and hardened. Other materials and methods can also be used to form the device (e.g., a dental tray).

[0011] When providing a physical entity model, the method of the present disclosure may include the following steps: providing a virtual dental arch that replicates at least a portion of a patient's dental arch; and providing a set of virtual orthodontic brackets for the virtual dental arch. Accordingly, a set of virtual analogs is provided (e.g., created), each analog being associated with a virtual bracket in the set of virtual brackets and approximating or representing the shape of the associated virtual bracket. The shape of at least one of these analogs is typically different from the shape of the associated bracket, but not necessarily. The analog is placed at a desired position on the tooth surface, and a virtual entity model is realized, and then the virtual dental arch and the set of virtual analogs are merged. Then, a physical entity model can be manufactured based on the virtual entity model.

[0012] On the other hand, the present disclosure provides an orthodontic transfer device for placing an orthodontic brace on a dental arch, the device comprising: a main body, the main body comprising an inner surface that substantially conforms to the contour of at least one tooth of the dental arch, an appliance receiving portion, and a groove that is fluidically connected to the receiving portion and extends from the receiving portion in a gingival direction, the groove connecting the gingival edge of the main body with the receiving portion.

[0013] For the purposes of this specification, the term "virtual" refers to a three-dimensional computer representation of an object, preferably based on a mathematical representation of a three-dimensional shape in data form and processable by a computer. Such virtual objects in data form, including their visualization (e.g., wireframes or digital renderings) are well known in the field of computer-aided design (CAD).

[0014] For the purposes of this specification, the term "a set" means "a plurality".

[0015] As used herein, "hardenable" describes a material or composition that can be cured (e.g., polymerized or crosslinked) or at least partially solidified, for example, by removing a solvent (e.g., by evaporation and / or heating), by heating to initiate polymerization and / or crosslinking, by irradiation to initiate polymerization and / or crosslinking, and / or by mixing one or more components to initiate polymerization and / or crosslinking.

[0016] As used herein, "hardened" refers to a material or composition that has been cured (eg, polymerized or cross-linked) or solidified.

[0017] As used herein, as a modifier to a characteristic or property, unless otherwise specifically defined, the term "substantially" means that the characteristic or property will be readily recognizable by a person of ordinary skill, without requiring absolute precision or a perfect match (e.g., within + / -20% for a quantifiable characteristic). Unless otherwise specifically defined, the term "substantially" means a high degree of approximation (e.g., within + / -10% for a quantifiable characteristic), but again does not require absolute precision or a perfect match. Terms such as identical, equal, uniform, constant, strict, etc. should be understood to be within a common tolerance, or within a measurement error applicable to a particular situation, rather than requiring absolute precision or a perfect match.

[0018] "Mesial" refers to the direction toward the center of the curve of the patient's dental arch.

[0019] The "distal aspect" refers to the direction away from the center of the patient's dental arch curve.

[0020] The "occlusal plane" refers to the direction toward the outer tips of the patient's teeth.

[0021] "Gingival aspect" refers to the direction toward the patient's gums or gums.

[0022] "Facial" refers to the direction toward the patient's cheek or lips.

[0023] "Lingual" refers to the direction toward the patient's tongue.

[0024] In several places throughout the application, guidance is provided through lists of examples, which examples can be used in various combinations. In each case, the recited list serves only as a representative group and should not be interpreted as an exhaustive list. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a facial view of a physical mock-up having a set of appliance analogs according to an embodiment of the present disclosure;

[0026] Figure 2 for Figure 1 Occlusal view of the physical solid model;

[0027] Figure 3A is an enlarged partial perspective view of a tooth including an appliance analog and a ramp;

[0028] Figure 3B is an enlarged partial perspective view of another tooth including an appliance analog and a ramp;

[0029] Figure 4 A workflow for creating a virtual entity model according to an embodiment of the present disclosure;

[0030] Figure 5 is a facial view of a virtual physical model including an appliance analog placed on a tooth surface according to an embodiment of the present disclosure;

[0031] Fig. 6A is a perspective view of an appliance analog including a ramp precursor according to an embodiment of the present disclosure;

[0032] Figure 6B is a perspective view of an appliance analog including a ramp precursor according to another embodiment of the present disclosure;

[0033] Figure 7 is a face view of a virtual solid model including an extrusion ramp according to an embodiment of the present disclosure;

[0034] Figure 8 is a face view of a virtual solid model including an extrusion ramp according to other embodiments of the present disclosure;

[0035] Fig. 9 is a photograph of a transfer tray formed from a physical mock-up of the present disclosure;

[0036] Fig.10 for Fig. 9 a photograph of a cross section of a transfer tray, magnified to illustrate certain features;

[0037] Fig.11 is a schematic cross-sectional view of a transfer tray formed from a physical mock-up of the present disclosure;

[0038] Fig.12 A bracket having a bracket disposed in a receiving portion according to an embodiment of the present disclosure Fig. 9 A schematic cross-sectional view of a transfer device;

[0039] Fig.13 is a perspective view of an appliance analog on teeth of a virtual physical model of a patient's dentition according to an embodiment of the present disclosure;

[0040] Fig.14 for Fig. 9 A cross-section of the appliance and a perspective view along the extrusion path of the FACC; and

[0041] Fig.15 According to the embodiment of the present disclosure, Fig.13 A perspective view of an extrusion ramp with an appliance positioned along the gingiva and roughly following the outer contours of the virtual dentition and supporting body.

[0042] The layers in the depicted embodiments are for illustrative purposes only and are not intended to limit the thickness (relative or otherwise) or position of any component.

[0043] Although the above-mentioned drawings show several embodiments of the present disclosure, as indicated in the specification, other embodiments are also conceivable. In all cases, the present disclosure introduces the present invention in an exemplary and non-restrictive manner. It should be understood that a large number of other modifications and embodiments can be designed by those skilled in the art, which all fall within the scope of the present invention and conform to the essence of the principles of the present invention. DETAILED DESCRIPTION

[0044] Figure 1 to Figure 2A physical solid model 10 is shown, which represents the shape of a patient's dental arch 12 including a plurality of teeth 13 and gums 14, a set of appliance analogs 20 (for clarity, not every analog or tooth shown in the figure is represented by a reference line), and a ramp 30 extending from the analog 20 in a generally gingival direction. The exemplary solid model 10 shown in the drawings is a patient's lower dental arch, but it should be understood that the method of the present disclosure is equally applicable to the patient's upper dental arch. The solid model includes a support body (i.e., a mold body) 15 that extends below the gums 14 to provide stability, thereby improving ease of use in solid model creation and subsequent transfer device manufacturing. The solid model 10 also includes a midline groove 60 on one or both of the lingual and labial surfaces of the support body 15, which can be used to assist in the placement of a transfer device derived from the physical solid model 10.

[0045] The analog 20 represents or approximates an orthodontic appliance (typically, but not exclusively, an orthodontic bracket) as they are used in conjunction with an archwire to move a patient's teeth 13 from a malocclusion to a desired position. In the physical mock-up 10, the patient's teeth 13 are represented as having a malocclusion at the beginning of treatment or at a new treatment stage. Alternatively (although not shown), the physical mock-up may include only a portion of the dental arch (e.g., a dental arch quadrant or a single tooth) where a transfer device will be used to bond the appliance to only a portion of the patient's dental arch.

[0046] The physical model 10 can be used to physically shape a transfer device (not shown in these figures) for bonding the appliance at a predetermined position on the patient's teeth. The transfer device forms a negative replica of at least a portion of the physical model 10. For example, such a transfer device can be obtained by taking an impression from the physical model 10, by overmolding the physical model 10, or by another technique in which a positive physical model 10 is used to preferably directly shape a negative replica. The physical model 10 is preferably configured to provide a predetermined bite edge, which on the one hand allows the orthodontic appliance to be held or fixed in the transfer device, but on the other hand facilitates the removal of the transfer device from the physical model 10 or the patient's teeth without damaging the transfer device or debonding the appliance from the patient's teeth.

[0047] Orthodontic brackets typically include a defined undercut of a certain size and shape that may hinder or obstruct the non-destructive removal of the transfer device, and therefore in the physical model 10, the appliance is represented by an analog 20, which may not form an exact replica of the appliance to be bonded, but only approximates the shape of the appliance to control the undercut to a desired level. However, it should be noted that the appliance may be represented by an analog that forms an exact replica of the appliance (at least in areas that are not connected to or integrated with the ramp 30), while a bracket that forms an undesirable undercut may be represented by an analog that has an approximate shape of such a bracket. Therefore, the transfer device replicated from the physical model preferably obtains a shape with a level of undercut, thereby allowing the bracket to be retained and removed non-destructively from the patient's teeth.

[0048] The appliance analog 20 includes an appliance body 22, a base 23 adjacent to the tooth surface, and an archwire slot 24 extending generally mesial-distal across the body 22. The archwire slot 24 in the appliance analog 20 does not represent the typical facial-lingual depth of an actual archwire slot on a given appliance, but rather reflects a reduced depth to manage the bite edge. The appliance body also includes protrusions 26 positioned on the occlusal and gingival sides of the archwire slot 24, each protrusion representing the facial surface of a ligature wing. Other bracket features not depicted (such as hooks, self-locking mechanisms such as clips or gates, etc.) may also be at least partially represented in the analog 20.

[0049] The ramps 30 extend from the body 22 of the appliance analog in a direction toward the gingiva 15. Each ramp 30 has a height "H" measured from the outer face 31 to the tooth surface 14 and a mesial-distal width "W". The height "H" is generally shorter than the buccal-labial height of the analog (including the base 21 and the body 22), i.e., the area close to the gingival margin area 27 of the analog 20. In some embodiments, the height "H" may increase or remain constant over a portion of the ramp length. However, in a currently preferred embodiment, the height "H" tapers over at least a portion of the ramp length, resulting in the ramp being higher than the gingiva 15 or the supporting body 16 near the bracket.

[0050] The mesial-distal width "W" of the ramp is generally commensurate with the mesial-distal width of the simulated appliance body 22, including any support structures or locking mechanisms (e.g., clips) on the mesial and distal ends of the archwire slot. In other embodiments, the mesial-distal width "W" of the ramp may be smaller or larger than the mesial-distal width of the appliance body 22. Although not depicted, the width "W" may also increase or decrease in size along the length of the ramp 30. In a currently preferred embodiment, the width "W" is no greater than the mesial-distal width of the appliance, as this tends to prevent the bracket from sliding out of its corresponding receiving portion in the transfer device and can provide visual feedback during the process of loading the appliance in the transfer device.

[0051] Figure 1 , Figure 2 and FIG. 3A to FIG. 3B The outer surface 31 and the side surfaces 32, 33 of the ramp 30 depicted in the figure are each substantially planar, so that the ramp 30 has a generally rectangular shape in a cross-section taken along a plane parallel to the archwire slot and / or perpendicular to the vertical axis 18. In other embodiments, the ramp may have any suitable cross-sectional shape or combination of shapes (e.g., trapezoidal, dome-shaped, etc.). For example, the outer surface 31 may be circular with planar side surfaces 32, 33 to facilitate removal of a subsequently formed transfer device. Each ramp 30 on the physical model 10 may each have the same or different cross-sectional shapes. In other embodiments, certain groups of ramps 30 may share the same cross-sectional shape with each other, and the cross-sectional shapes of groups in different quadrants or positions on the dentition 12 are different.

[0052] At least a portion of each ramp 30 extends in a gingival direction substantially parallel to a vertical axis 18 of the physical solid model 10. The vertical axis 18 is perpendicular to the occlusal plane of the dental arch 12, which can be determined using techniques known in the art and described further below. For a y-axis Y oriented on the tooth surface with the archwire slot substantially perpendicular to the occlusal plane or the like, otherwise generally parallel to the vertical axis ( Figure 3A ) of the orthodontic device analog, almost the entire ramp extends parallel to the vertical axis 18. If the orthodontic device analog is oriented at an inclined angle relative to the vertical axis 18 ( Figure 3B ), the ramp 30 may include a first ramp section 35 extending from the analog 20 in a direction perpendicular to the archwire slot and / or parallel to the y-axis Y of the analog. The first ramp section 35 transitions to a distal second ramp section 37 extending parallel to the vertical axis 18. The transition may be as shown in FIG. Figure 3BIn the depicted embodiment, the first section 35 is angled, arcuate along a single radius of curvature, or includes compound curvatures. In a currently preferred embodiment, the first section 35 extends a sufficient distance (e.g., 1 mm to 2 mm) from the analog body 22 to avoid inadvertently removing features on the analog 20 or causing difficulties in loading the resulting transfer device.

[0053] Each ramp 30 is generally integral with the outer surface of the physical solid model 10 so that there is no gap between the side edges 32, 33 and the teeth 13, gums 14 and support body 15. Figure 7 In other implementations depicted in , ramp 30 extends at least partially in a plane that is offset from the outer surface of physical mock-up 10. While such implementations may still be used to create viable transfer devices in accordance with the present disclosure, the resulting physical mock-up is typically more difficult to manufacture, requires physical removal of material from the mock-up to ensure proper transfer device fit, and may be more susceptible to damage.

[0054] The physical solid model 10 can be manufactured by additive manufacturing, and thus the dental arch 12, the support body 15, the analog 20 and the ramp 30 can all be formed as a single piece in the physical solid model 10. In such a case, the physical solid model 10 can be obtained without assembling or attaching the analog 20 or the ramp to the dental arch 12. Therefore, the position of the analog 20 relative to the dental arch 12 can be determined by computer assistance, and manual assembly tolerances can be avoided. Examples of suitable additive manufacturing processes include: solid free-form manufacturing such as 3D printing processes, stereolithography methods, fused deposition modeling, layered solid manufacturing, laser engineering net shaping, selective laser sintering, shape deposition manufacturing, selective laser melting, and solid grinding solidification.

[0055] Designing physical models

[0056] The fabrication of the physical entity model is usually based on a virtual entity model prepared in a computer system. Such a virtual entity model preferably corresponds to a mathematical representation of a three-dimensional shape that can be processed by a computer (e.g., by a CAD (computer-aided design) system). In addition, the virtual entity model is preferably provided in the form of computer data that can be used to control an additive manufacturing machine for fabricating a physical entity model defined by the virtual entity model. The virtual entity model can be designed or generated by superimposing or merging a virtual dental arch of the patient with a set of virtual analogs, as further described below.

[0057] Generally speaking, and if Figure 4As depicted in , the process 100 for designing a physical model begins with obtaining a virtual model of the patient's dental arch (step 110). The virtual dental arch model can be modified to create a solid virtual mold body (step 120). An appliance analog (typically a virtual bracket analog) is obtained (step 130) and placed at a treatment-related location on the teeth (step 140). At this stage, the appliance analog may include a ramp precursor structure, or the ramp precursor may be added after the analog is placed on the teeth. The ramp precursor is extruded along the vertical axis of the model in the direction of the gingival edge of the virtual physical model body (step 150). Optionally, the extrusion can be performed at a draft angle relative to the body. The analog, ramp, and virtual dental arch are then combined to form a complete virtual physical model (step 160). Individual aspects of the process will be discussed in further detail below.

[0058] Figure 5 An incomplete virtual solid model 200 is shown. The virtual solid model 200 combines the shape of the virtual analog 220 with the shape of the ramp precursor 230 and the virtual dental arch 212. The virtual analog 220, the ramp precursor 230, and the virtual dental arch 212 may be obtained from discrete independent virtual parts, or the dental arch 212 may be provided with computer assistance (e.g., by additional design or modification of the dental arch) and the virtual analog 220 may be added to the dental arch 212. Those skilled in the art will be able to use other techniques known in the art of computer-aided design to provide the virtual solid model 200 and combine the shapes of the virtual analog and the virtual dental arch. At various stages, the process may include interaction with a physician responsible for treating the patient. The physician interaction may be implemented using a client process programmed to receive tooth positions and models, and path information from a server computer or process in which other steps of the process are implemented. In some or all embodiments, Figure 5 The treatment plan may be presented in a computer-readable storage medium, such as a clinician's computing device and / or a manufacturer's computer, or both. The computer-readable storage medium stores computer-executable instructions that, when executed, configure a processor to perform the virtual model preparation and treatment planning techniques described below.

[0059] As an initial step in creating a virtual model of the patient's dental arch, a mold or scan of the patient's teeth (and underlying oral tissue) needs to be obtained. This generally involves creating a representation of the patient's teeth and gums, and may involve taking a wax bite, using impression materials, casting, direct contact scanning, x-ray imaging, tomography, ultrasound imaging, and other techniques for obtaining positional and structural information about the teeth, jaws, gums, and other orthodontically relevant tissues. A digital data set can be derived from this data, which represents the current arrangement of the patient's teeth and other tissues. The virtual model of the dentition can then be reconstructed based on the digital data.

[0060] A currently preferred technique for acquiring at least a portion of the initial arrangement (or any subsequent arrangement) is digital scanning. A virtual dental model representing the patient's dental structure may be captured using digital intraoral scanning or by digitally scanning an impression or other physical dental model. Scanning devices that allow the virtual dental arch to be provided in the form of digital data are available, for example, under the trade name Lava Scan. TM Scan ST and Lava TM Chairside oral scanner COS (Lava TM Chairside OralScanner COS) are both available from 3M Deutschland GmbH. Alternatively, other intraoral scanners or intraoral contact probes may be used, such as the True Definition Scanner available from Midmark Corporation. TM Scanners or TRIOS scanners available from 3Shape A / S. As another option, the digital data file can be obtained by scanning an impression of the patient's teeth. As yet another option, the digital data can be obtained by scanning a physical model of the patient's teeth. The model for scanning can be made by pouring a casting material (such as plaster of Paris or epoxy resin) into the impression of the patient's teeth and curing the casting material. The model can be scanned using any suitable scanning technology (such as X-ray, laser, computed tomography (CT) and magnetic resonance imaging).

[0061] Digital data can be "cleaned" by deleting any data points that are obviously erroneous. For example, files in STL format representing tooth surfaces can be repaired by STL processing software to delete erroneous data points, and these files contain data points that are significantly beyond the normal expected geometric relationship of adjacent data points. In addition, the STL processing software can add missing tooth data points to create realistic, smooth curved tooth shapes. Alternatively, or in addition, data cleaning can be performed on the data file before converting the data to an STL file. As an additional option, data of hidden features of the patient (such as the patient's tooth roots and mandibular structure) can also be obtained. For example, CT scanning technology can be used to obtain data representing the patient's entire tooth structure (including the roots). The data obtained by CT scanning can then be "stitched together" with other data obtained by scanning the patient's crowns using another scanning technology to provide a more comprehensive virtual representation.

[0062] The tooth list can be segmented to produce one or more discrete, movable 3D tooth object models representing individual teeth. The tooth model can also be separated from the gums into separate objects. Segmentation allows the user to characterize and manipulate the tooth arrangement as a set of separate objects. Advantageously, a computer can derive diagnostic information from these models, such as arch length, bite position, space spacing between adjacent teeth, and American Board of Orthodontics (ABO) objective scores.

[0063] A tooth coordinate system defined by coordinate axes can be defined for each discrete tooth surface in a virtual dental arch. The coordinate system may include a mesial-distal axis, a buccal-lingual axis, and an occlusal-gingival axis for each tooth, wherein each axis is calculated to be perpendicular to the other two axes. The coordinate system can be defined using calculated or selected landmarks. Alternatively, a coordinate system can be created by defining a point on a virtual tooth, receiving axis input data defining a first axis and a second axis associated with the virtual tooth, calculating a basic normal vector of a portion of the tooth surface around the point, and calculating a tooth coordinate system based on the axis input and the calculated vector. U.S. Patent No. 9,622,835 (Raby et al.) illustrates such a method and other example methods for creating a tooth coordinate system. The tooth coordinate system allows various modifications to one or more virtual teeth associated with the coordinate system. Aspects that can be adjusted or modified for each tooth include: torque, tip, primary rotation, mesial-distal movement (with or without interproximal repositioning (IPR)), occlusal-gingival translation, and buccal-lingual translation. Each of these aspects involves movement in one of the six degrees of freedom defined by the coordinate axes of the respective tooth surface.Such modifications also include positioning and / or attaching the virtual analog to the tooth.

[0064] One or both of the occlusal plane and the midsagittal plane of the dentition can be specified for the virtual model. The occlusal plane is an imaginary surface through which the teeth occlude, generally approximated by a plane. The midsagittal plane is an imaginary plane that passes longitudinally through the middle of the dental arch, dividing it into left and right halves. The initial approximation of the occlusal plane can be based on the shape or coordinate system of some or all tooth surfaces of a single dental arch belonging to the dentition 212. For example, the occlusal plane can be defined by identifying three points of the plane that tangentially contacts the superimposed on the dentition 212. For a given dental arch, these three points typically include at least one contact point from the left molar, one contact point from the right molar, and one contact point from the central or lateral teeth. In another embodiment, the occlusal plane is defined as the best fit plane to the point representing the origin of the tooth coordinate system, as previously defined. In fact, the plane represents the average of these origins, which are generally located at the incisor edge of the tooth, the tip of a single bite head, or the tip of the buccal side bite head. The occlusal plane can also be used to calculate and define the vertical axis of the model. The vertical axis lies in a plane perpendicular to the occlusal plane and can be used to measure the orientation of the analog on the tooth and control the orientation of the ramp 230 .

[0065] Similarly, the mid-sagittal plane may be derived based on the shape of the arch according to a coordinate system of the tooth surfaces of the dentition 212. The occlusal plane and the mid-sagittal plane may be manually adjusted to a position and / or orientation relative to the dentition surface as desired.

[0066] The area beneath the teeth and / or gums can be extruded into a planar surface to create a virtual support body 216. Typically, the extrusion is performed along a path generally perpendicular to the occlusal plane to a common plane spaced from about 2 to about 30 mm from the occlusal plane or the apex of the gums on the model, as desired, prior to creating the support body. Creation of the support body can be done before or after the virtual analog is placed on the dental arch, but is preferably done before creating the complete ramp.

[0067] Optionally, and once the initial data set has been processed and before the appliances are placed on the virtual dental arch, the desired positions of the teeth in the patient's dental arch may be determined. The desired final positions of the teeth may be received, for example, from a physician in the form of a descriptive prescription, may be calculated using an orthodontic prescription, or may be computationally inferred from the clinical prescription. By specifying the desired final positions of the teeth and digital representations of the teeth themselves, the final position and surface geometry of each tooth may be specified to form a complete model of the teeth at the desired end of treatment or stage of treatment. The result of this step is a set of digital data structures that represent the desired and / or orthodontically correct repositioning of the model teeth relative to assumed stable tissue. Further details regarding software and processes that can be used to derive final positions are disclosed in U.S. Patents Nos. 6,739,870 (Lai et al.), 8,194,067, 7,291,011, 7,354,268, 7,869,983, and 7,726,968 (Raby et al.). In some implementations, the desired final position of the teeth can be determined by the placement and / or orientation of the appliances, as described below.

[0068] Next, the method of creating a physical model proceeds to the step of obtaining a virtual appliance and positioning the virtual appliance relative to the virtual dental arch. Although discussed on the basis that the virtual appliance is a virtual bracket, those skilled in the art will appreciate that other virtual appliances suitable for bonding to tooth surfaces (e.g., attachments, molar tubes, buttons, splints, sheaths, etc.) may also be used to create analogs for coupling to a virtual dental arch.

[0069] There are a variety of treatment planning systems that allow for computer-assisted design and / or placement of virtual appliances relative to a virtual dental arch. Such systems are described, for example, in U.S. Pat. Nos. 7,210,929 (Raby et al.), 7,811,087 (Wiechmann et al.), and 7,993,133 (Cinader et al.). Virtual brackets may be at least partially designed and / or retrieved from a database. Each bracket or the like may be automatically and / or manually positioned relative to a virtual tooth in a virtual dental arch. Examples of systems for automatically placing and / or adjusting virtual appliances are described in U.S. Pat. Nos. 7,210,929 (Raby et al.), 7,940,258 (Raby et al.), and 8,517,727 (Raby et al.).

[0070] The desired position of the bracket / analog on the model can be determined in any of a variety of ways. For example, a user at an appliance manufacturer's facility can use modeling software to place an analog / appliance on a model of a patient's dental arch based on standards or guidelines from an orthodontic treatment philosophy. These appliance placement standards or guidelines may be specific to each tooth in the model, for example, the position of the archwire slot relative to the clinical crown of each tooth may be marked. The user can also place the bracket / analog according to specific instructions provided by different treatment professionals. Each bracket and each tooth can be manipulated as a separate object within the virtual environment and fixed in the environment The position of each bracket relative to the coordinate system associated with the tooth corresponding to the bracket. The virtual bracket can be connected to the virtual archwire, and the final position of the tooth can be calculated based on the position of the bracket and the selected archwire. Assuming that the final position is approved, the virtual analog can be placed in a position corresponding to the virtual bracket. As an alternative to moving the appliance, the user can alternatively define the desired position of the teeth as described above, and the computer can include programming instructions to determine the appropriate position to place the appliance so as to move the teeth to those desired positions. Examples of conducting virtual orthodontic treatment in this manner are disclosed in issued US Patent Nos. 6,739,869 (Kopelman et al.) and 7,354,268 (Raby et al.).

[0071] If the user or other professional is not completely satisfied with the final predicted positions of the teeth, a new final position of the virtual teeth can be calculated and displayed based on the modified positions of the virtual appliances or virtual teeth. These steps can be repeated as many times as necessary until all parties are satisfied. Data representing the selected positions of the appliances can be recorded for further processing, as well as identification data of each appliance (such as brand name and manufacturer part number), tooth identification data (such as tooth type and position in the mouth), and patient data (such as name and date of birth or patient identification number).

[0072] In an exemplary embodiment, a virtual analog is obtained based on (e.g., by modification of) a virtual bracket. In an exemplary embodiment, the virtual bracket is a labial bracket, which is typically standardized by regulation and available "off the shelf." However, those skilled in the art will recognize that the methods and systems of the present invention may also be used in conjunction with lingual and labial brackets, including brackets that can be customized for each tooth of each patient, or a combination of customized brackets and standard brackets. In one embodiment, a virtual bracket is selected from a library of pre-existing bracket configurations; such bracket configurations may feature a standard or semi-custom bonding pad that is merged / combined with the bracket body. For example, such a fully constructed appliance may be stored and accessed as a CAD or STL file. The appliance data may be scanned using the scanning techniques described above, or may be generated directly using 3D data from a published appliance configuration file or other manufacturing specification.

[0073] An exemplary possibility of providing a custom pad for a virtual bracket is disclosed in US Pat. No. 7,811,087 (Wiechmann et al.). The bracket design may be performed on a computer storing a three-dimensional virtual dental arch of the patient. The shape of the patient's dental arch (including the shape of the teeth and their positions relative to each other) may be provided in the form of a computer-processable representation (e.g., a digital data file). The tooth-facing pad geometry (i.e., the bonding surface) may be derived directly from the tooth geometry represented in the virtual dental arch, so that the pad obtains a three-dimensional surface that substantially accurately matches the corresponding tooth surface. In this regard, the term "substantially accurately" means that the surfaces are identical, except for the eventual presence of tolerance deviations that may be caused by making the pad. This allows for relatively precise placement of the bracket on the tooth and helps maximize the bond strength.

[0074] Another part of the orthodontic appliance (the bracket body), which contains a slot for receiving an archwire and other features that allow the wire to be fixed into the slot (e.g., hooks, ligature wings, grooves, etc.), is available on the computer as a predefined virtual model, for example in the form of a bracket body library. In order to provide a set of virtual brackets for a virtual dental arch, certain predetermined virtual bodies can be selected. The virtual bodies are typically aligned with their slots relative to each other, for example so that a generally U-shaped virtual archwire can run through the slots of all brackets. Once the slot positions of the bracket bodies are determined, the bracket bodies and corresponding bracket pads can be combined, for example virtually merged to form a set of virtual brackets. Common CAD programs have the ability to connect existing shapes to each other (e.g., Boolean operations). Optionally, the design of the virtual bracket or bracket part can be adjusted as needed to accommodate good articulation, hygienic requirements or other aspects.

[0075] The virtual bracket is used to generate a group of analogs based on it. Each analog in the group of analogs is associated with a virtual bracket in the group of virtual brackets, and in some cases represents its modification. In one embodiment, the modification step includes increasing the three-dimensional volume represented by the virtual brace by selectively modifying only a portion of the brace. For example, the modification step may include flattening or reducing the indentation present in the shape of the brace. The modification step may further include at least partially filling the space between the parts of the bracket shape, or adding a virtual structure to the shape of the brace. The bite edge that may otherwise hinder the placement of the bracket in the dental tray or ultimately prevent the transfer dental tray from being removed can be minimized or removed. In addition, the modification step may include optionally reducing the three-dimensional volume by selectively modifying another part of the bracket. For example, the modification step may include rounding the edge to address the wear of the physical bracket during the surface treatment step (e.g., during deburring or polishing). In addition, the modification step may include maintaining or substantially maintaining at least a portion of the original virtual bracket shape. The shape of each virtual analog may substantially correspond at least partially to the shape of a virtual bracket in the group of virtual brackets. Those skilled in the art will recognize various possibilities for modifying the shape, for example, by changing existing shapes, adding or removing shapes, virtually copying, cutting, extending, reducing, or other suitable techniques. Those skilled in the art will further be able to create a set of analogs in any suitable manner (e.g., through functions available on a CAD system) to provide a set of analogs in which the shape of at least one analog is different from the shape of the associated appliance.

[0076] The shape of the analog is adapted to facilitate removal of the transfer device based on the shape of the analog relative to the shape of the bracket. As mentioned above, the shape of one or more of these virtual analogs may correspond substantially exactly to the shape of the virtual bracket, but in most cases the shape of the virtual analog and the shape of the virtual bracket may differ at least in the area including the undercut.

[0077] The appliance analogs may be stored for presentation in an accessible library or generated after retrieval based on the intended position of the appliance on the dental arch.

[0078] The creation of the virtual analog may further include adding a ramp precursor to the virtual analog body or an otherwise unmodified virtual bracket body (e.g., a bracket that has not undergone any other shape adjustments). Fig. 6A and Figure 6B The bracket body 220 is depicted as coupled to the analog 220, at least partially filling the archwire slot undercut) and extends a relatively short distance (e.g., 1 mm to 2 mm) beyond the bracket body 220 along the major axis 235 toward the gingiva 215. The major axis 235 is generally occlusal-gingival and is oriented perpendicular to the mesial-distal axis of the archwire slot 224.

[0079] Fig. 6A and Figure 6B The ramp precursor 230 fills at least a portion of the available space between the gingival ligature wings 228 on the body 221 and the analog base 223, and extends the entire mesial-distal width of the analog body 221. The height "H" of the precursor 230 adjacent the analog body 221 is less than the overall height of the analog 220 measured from the tooth-facing surface of the base 223 to the facial surface of the body 221, thereby allowing a portion of the ligature wings 228 to protrude above the outer surface 231 of the ramp precursor. The protruding feature allows for better alignment of the receiving portion formed from the model with the facial features of the corresponding bracket, as well as indicating the correct orientation of the bracket to the loading transfer device.

[0080] Fig. 6A The ramp precursor 230 includes a planar outer surface 231 extending in a plane generally parallel to the bottom wall 226 of the archwire slot 224 and a plane tangent to the center of the base 223, wherein the base 223 is designed to contact the tooth surface. For some bracket specifications (not shown), the bottom wall of the slot will be inclined or substantially perpendicular to the base tangent plane (i.e., a vertical slot), and the precursor will generally extend parallel to a plane tangent to the center of the base rather than the bottom wall. Figure 6B The inclined ramp precursor 230 extends outwardly from the analog body 220 in an inclined manner relative to the analog base 223 and the bottom wall 226. When used in a corresponding physical entity model, Figure 6B The ramp precursor 230 tends to provide a larger gap between the transfer device and the tooth surface.

[0081] The virtual ramp precursor 230 can be a solid body ( Fig. 6A ) or as a hollow opening profile ( Figure 6B ) exists. The use of an opening profile may allow for enhanced identification of the extrusion surface as the ramp precursor extends toward the gingival edge of the support body 216, as further described below.

[0082] Back to Figure 5, the virtual dental arch 212 is depicted on the labial tooth surface 213 with the final determined virtual analog 220 position. The ramp precursor 230 is located at a generally gingival position relative to the analog body 220 and the archwire slot 224. Once the virtual analog 220 is satisfactorily placed on the dental arch, the ramp precursor 230 can be extruded along the vertical axis 218 in a generally gingival direction to the gingival edge 217 of the support body 216. Extruding the ramp precursor along the vertical axis prevents interference between adjacent ramps, thereby making the physical solid model easier to manufacture without substantial further modification of the virtual solid model. For the ramp precursor 230 that is oriented generally parallel to the vertical axis 218 after the placement step, the extrusion occurs in a direction parallel to the major axis 235 of the existing ramp precursor 230. If the major axis 235 of the ramp precursor 230 is oriented at an oblique angle relative to the vertical axis 218, the ramp precursor 230 transitions to a distal second ramp section 237 extruded parallel to the vertical axis 218 (see Figure 8 ). The transition can be angled, arcuate along a single radius of curvature, or include compound curvatures.

[0083] In other embodiments, the ramp precursor may be extruded along the long axis of a given virtual tooth, which may or may not be aligned with the vertical axis of the model. Alternatively, one edge of the ramp may be extruded along the long axis and the other edge along the vertical axis. Such a ramp may taper or widen in width as it approaches the gingival margin of the supporting body and may be suitable for certain bracket placements that are tilted at an angle relative to the occlusal plane.

[0084] Extrusion of the ramp precursor 230 toward the gingival edge 217 of the support body 216 creates a blocking ramp 240, such as Figure 7 and Figure 8 Extrusion may occur primarily in a plane defined by the outer surface 231 of the ramp precursor, as shown in FIG. Figure 7 Depicted. Depending on the orientation of the teeth in the patient's dental arch, some of the resulting extruded ramps may be offset from the support body 216 toward the face, potentially leaving gaps between sections of the ramp and the model when manufactured as a physical solid model. Manufacturing a physical version of such a ramp, particularly by additive manufacturing, can be difficult because the ramp requires additional material to create and support relative to the rest of the dentition model. In addition, the geometry of such a ramp can make it difficult to remove a transfer device formed on a physical model and use it for subsequent appliance placement. These issues can be alleviated by removing ramp material from the virtual solid model or the physical model, but doing so can increase the complexity of the process.

[0085] In the currently preferred embodiment, and as Figure 8As shown, the ramp 240 is extruded from the ramp precursor at a draft angle relative to the support body 216, so that the ramp height gradually decreases as it reaches the gingival margin 217. In an exemplary embodiment, the draft angle is about 10 degrees toward the support body 216. In other embodiments, characterized by different orientations of the patient's dentition, the draft angle can be significantly larger or smaller. Alternatively, a portion of the ramp can actually be removed.

[0086] In other embodiments, the ramp can be extruded so that the outer surface shares or approximates the contour of the virtual dentition. Such extrusion can occur from a ramp precursor or directly from a virtual bracket or bracket analog. Figures 13 to 15 In one embodiment shown, a bracket cross section 430 can be extruded along a clinical coronal axis (FACC), which is generally defined as the curve formed by the intersection of the mid-sagittal plane and the facial surface of the tooth. A suitable extrusion sweep path 450 follows the FACC and the model contour. The bracket cross section 430 can be taken along a mesial-distal plane tangent to the center of the bracket base 423 in contact with the tooth surface 413. Fig.14 As best shown, the bracket cross section 430 is generally rectangular and at least approximates the outer shape of the virtual bracket 420 or a bracket analog. Alternatively, the bracket cross section can be approximated by creating a generally rectangular offset shell having the same facial-lingual dimensions and mesial-distal dimensions as the bracket body 422. Another way to generate a starting area for the extrusion path can include projecting a gingivally disposed rectangle of the bracket onto the bonding surface 414 of the virtual tooth 413 (having the same width as the bracket and a height determined by the distance between the model base and the bracket), selecting a triangle on the tooth 413 within the projected area, and extruding the triangle perpendicular to the tooth 413 / model 412 surface 413 a distance equal to the facial-lingual dimension of the bracket.

[0087] The cross section 430 or other extrusion path origin can then be swept along the sweep path 450 to the bottom edge 417 of the virtual dentition model 410. Fig.15 As shown, this extrusion creates a ramp 440 having an undulating outer surface 431 having a profile that substantially matches the surface of a corresponding area of ​​the virtual dentition model. The facial-lingual height 442 of the ramp 440 varies over its length, but is generally smaller near the gingiva 415. In other embodiments (not shown), the height of the undulating ramp can be gradually reduced as the bottom edge is approached, for example by removing portions of the ramp at a predetermined draft angle or modifying the sweep path to a specific inclination as the bottom edge is approached.

[0088] A virtual entity model can be provided by combining a virtual dental arch and the set of virtual analogs, for example by computer-assisted merging or superposition. The virtual entity model, preferably in the form of a computer-processable three-dimensional data file, can be transmitted to an additive manufacturing machine, which manufactures a physical entity model based on the virtual entity model. Suitable additive manufacturing processes include: entity free-form manufacturing such as 3D printing processes, stereolithography methods, fused deposition molding, layered entity manufacturing, laser engineering net forming, selective laser sintering, shape deposition manufacturing, selective laser melting, and entity grinding solidification. The automated or semi-automated manufacturing of the physical entity model may additionally or alternatively include injection molding, lost wax casting, 5-axis milling, laser cutting and other manufacturing techniques. Alternatively, although not currently preferred, the components of the virtual entity model can be transmitted to an additive manufacturing machine and created separately, and the technician is responsible for placing and connecting the physical analogs to the physical dental arch. This approach may rely on guides or other devices created on the physical dental arch to facilitate analog placement, such as those described in U.S. Pat. Nos. 7,762,815 (Cinader et al.) and 8,235,717 (Kuperman). The analog may be secured in place during formation of the placement device, for example, by a temporary adhesive or by a friction fit with a guide such as described in U.S. Pat. No. 7,762,815. Specifically, a physical model may be created using a ramp used as a placement guide in the absence of a manufactured analog, wherein the physical bracket is aligned with one or more surfaces of the ramp.

[0089] The physical mockup may be made of a photocurable material, but in other examples may be made of a plastic material (e.g., melted from plastic fibers), metal, plaster, cement, or other chemically hardenable material. Fabrication may further include post-processing to remove uncured resin and remove support structures, or to rig various components.

[0090] Create a transfer device

[0091] Once the physical model is generated to a satisfactory degree, a transfer device can be created on the physical model. This can include sending instructions to a pressure forming or thermoforming machine to pressure form or thermoform one or more material sheets on the physical model to form a negative replica or sleeve. The sheet can be, for example, a deformable plastic sheet (e.g., an elastic thermoplastic). The sheet of material can be heated to a temperature at which the sheet becomes flexible. Pressure can be applied to the sheet simultaneously to form the sheet around the physical model. Once the sheet cools, it will have a shape that conforms to the physical model. The internal shape of the plastic sleeve basically conforms to the patient's current dental arch. Before the plastic sleeve is formed, a release agent can be applied to the physical model to facilitate the removal of the mold from the plastic sleeve later. The sleeve can be trimmed by laser or mechanical milling technology to remove excess or unnecessary material.

[0092] An exemplary method of making a dental tray includes using a variety of sheet materials described in U.S. Patent No. 10,368,961 (Paehl et al.). The method includes placing an elastic sheet on top of the occlusal side of the tooth represented by the physical entity model, wherein a plastic sheet is arranged on top of the elastic sheet. The elastic sheet and the plastic sheet are deformed in a direction toward the physical entity model. This can be achieved by generating a vacuum under the elastic sheet and the plastic sheet or generating pressure above the elastic sheet and the plastic sheet. The plastic sheet can be heated at least before and / or during the deformation. The plastic sheet is usually allowed to solidify by cooling so that it has sufficient rigidity for easy handling.

[0093] The elastic sheet can be made of a material selected from a dental impression material or other molding material, preferably having a Shore hardness of about 20 Shore A after hardening, and can have a thickness in the range of about 2 to about 5 mm. The elastic sheet preferably has a size (or area) suitable for surrounding at least a portion of the labial side, the occlusal side, and the lingual side of the tooth represented in the physical entity model. In addition, the size of the elastic sheet can be set to surround the entire physical entity model, multiple physical entity models, or parts thereof. The size of the elastic sheet 34 can be set to at least cover the footprint of one or more physical entity models in a plane roughly parallel to the occlusal side of the teeth in the physical model.

[0094] The plastic sheet is usually plastic, such as thermoplastic and deformable. The plastic sheet 35 can be purchased from Scheu Dental, Germany. The plastic sheet may be made of polyethylene terephthalate-ethylene glycol copolyester or Essix ACE available from Dentsply Sirona and may have a thickness ranging from about 0.75 mm to about 3.0 mm. Other suitable plastically deformable materials include polycarbonates such as Makrolon brand materials available from Bayer or Lexan brand materials available from General Electric. The size (or area) of the plastic sheet may correspond to the size of the elastic sheet, but will typically have larger dimensions.

[0095] In another example (not shown), a space suit coating may be used instead of an elastic sheet. Such a space suit coating may be obtained by applying a hardenable liquid or paste material onto a physical mockup and allowing the material to solidify. This may be performed by dip coating or by manual application using a dispensing syringe or brush. In the solidified state, the coating material is preferably elastic or brittle so that it can be removed from the physical mockup at a later stage, or may be soluble. As described above, the plastic sheet may be deformed over the coated mockup.

[0096] The plastic sheet, after deformation, may have a generally groove-shaped indentation or cavity that approximates the three-dimensional, scaled-up shape of the tooth (including analogs and ramps) represented in the physical mock-up.

[0097] In one embodiment, the transfer device replicates the negative shape of only a portion of the physical solid model, such as the shape of only one analog / ramp and the shape of at least a portion of the teeth in the dental arch. For example, a partial transfer device may allow for rebonding or replacement of a bracket in a patient's mouth. A generally transparent, hardenable material is then received within the cavity of the plastic sheet. Exemplary hardenable materials include: Alloy containing silicon carbide (purchased from Heinrich Schnarr GmbH, Germany); Odontosil TM , addition vulcanized silicone, purchased from Dreve Dentamid GmbH, Germany; and Memosil 2 brand vinyl polysiloxane material, purchased from Heraeus Kulzer Inc. In some specific implementations, the physical model can be matched with a deformed plastic sheet so that the hardenable material is enclosed between the physical model and the sheet. The amount of the hardenable material is preferably selected so that during the physical model and the sheet are matched, the hardenable material flows around the teeth and the like represented in the physical model (usually embedded in the relevant parts of the teeth and the like). For example, by using an autoclave or a pressure chamber, the matched physical model, the hardenable material and the sheet can be exposed to a vacuum or pressure to minimize the gap or bubbles between the teeth and the hardenable material. The hardenable material can then be hardened, or the hardenable material can be cured. The hardened flowable material is preferably elastic and has a Shore hardness between about 50 Shore A and 70 Shore A, preferably about 60 Shore A. The hardened flowable material and the deformed plastic sheet cooperate to form the transfer tray.

[0098] Alternatively, the physical mock-up model may be mated with a plastic sheet and dipped in a hardenable material that is distributed between the outer surface of the physical mock-up model and the inner surface of the cavity. The hardenable material is hardened to provide a positioning layer for the appliance.

[0099] In the presently preferred case, the positioning layer is adapted so that it can position and retain the bracket, and further so that it can be deformed to receive the bracket therein and remove the bracket therefrom. Thus, the positioning layer can be made of a relatively elastic and soft material (when solidified). When deployed in combination, the plastic sheet preferably provides the required mechanical rigidity and stability for the dental tray, and the positioning layer preferably provides a series of receiving portions for the transfer dental tray, in which the bracket can be accurately and removably retained. The shape of the positioning layer generally corresponds to the shape of the elastic sheet described above, but is typically made of a different material.

[0100] Optionally, the transfer tray can be created with an occlusal stop member, as described in U.S. Pat. No. 7,845,938 (Cinader et al.). The occlusal stop member typically includes a flat top surface and a bottom surface, having a shape such as a recess that matches the shape of the occlusal tip of the patient's dental arch. In certain embodiments, the occlusal stop member has one or more recesses that correspond to only some of the teeth in the dental arch, but an occlusal stop member having one or more recesses corresponding to each tooth of the dental arch can also be constructed. Other variations can also be used. For example, the occlusal stop member may extend along only a portion of the dental arch rather than along the entire dental arch. Multiple stop members can be provided, which may be spaced apart from each other and optionally connected. The occlusal stop member can be chemically or mechanically bonded to the plastic sheet and / or the hardenable material.

[0101] It should be understood that the transfer tray may be formed from only one or more layers of deformable plastic sheet material, without an accompanying elastic sheet or positioning layer. In such specific implementations, the plastic sheet material may be placed directly adjacent to the occlusal surface of the physical entity model, without the spacing provided by the elastic sheet material. Thus, the plastic sheet material, when deformed, directly surrounds the teeth and bracket analogs of the physical entity model, directly creating a bracket receiving portion that is used to removably retain the bracket for subsequent bonding. In such streamlined transfer tray embodiments, the physical entity model may be coated with a release agent to facilitate removal of the transfer tray from the entity model. According to typical methods for creating a transfer tray, the resulting tray represents a negative replica of at least a portion of the physical entity model.

[0102] As another alternative, the virtual transfer tray can be directly derived from the virtual physical model using the method described in U.S. Pat. No. 9,763,750 (Kim et al.). In one example of this method, the derivation can be performed by defining a guide line that extends across at least a portion of the dental arch and is spaced apart from the dental arch and the mounted analog. For example, the guide line follows a curved path that is roughly parallel to the facial surface of the virtual analog and is generally located in the occlusal plane. In a computer-assisted embodiment, the guide line is defined by outlining a line segment that connects the facial edges of the analog as viewed from the occlusal direction, offsetting the line segment outwardly toward the facial direction by a certain distance, and then applying a smoothing operation to the line segment. If necessary, the certain distance can be used to define the desired tray thickness. The method can continue by defining a series of fitting arcs, each fitting arc extending on the lingual surface, occlusal surface, and facial surface of the virtual dental arch model, and intersecting each guide line in a roughly perpendicular relationship, so that each fitting arc passes through the virtual model and the virtual analog without contact.

[0103] The outer surface of the virtual transfer tray shell can be formed by fitting the surface to the dental arch of the group of fitting. In some embodiments, the outer surface is an end-opening shell that completely covers the occlusal side, lingual side and facial side of the virtual entity model including the model and the analog. Optionally, a surface smoothing operation is subsequently performed on the outer surface. The remaining part of the virtual tray body is then derived using the outer surface. The solid virtual tray body can be formed by defining a composite surface, which includes an outer surface and a flat surface extending across the cavity formed by the outer surface. When virtually aligned with the virtual entity model, the virtual tray body surrounds both teeth and the analog. The physical model (including the analog) can then be virtually subtracted from the virtual transfer tray body to produce a virtual tray precursor. The virtual tray precursor will include a tray body that generally has a configuration similar to a shell, and also includes one or more receiving portions formed by a negative virtual impression of the analog. The virtual tray precursor, preferably in the form of a computer-processable three-dimensional data file, can be transferred to an additive manufacturing machine, which manufactures a physical transfer tray based on the virtual tray precursor according to the techniques discussed above.

[0104] A physical tray made directly from a virtual tray precursor may include a placement layer and a positioning layer. Alternatively, as described above, a mold approximating a deformed plastic sheet may be additionally made and coupled with a hardenable material to form a positioning layer.

[0105] In cases where the analog includes a modified shape relative to the corresponding appliance, placing the actual physical bracket in the receiving portion 320 can create one or more gaps between the body of the appliance and the surface of the receiving portion. In addition, imperfections or tolerable deviations introduced during bracket manufacturing can cause additional gaps to appear between the body of the appliance and the wall of the receiving portion. During placement of the bracket on the tooth surface, excess adhesive from the bracket base can flow into or otherwise fill these gaps. Adhesives often exhibit an affinity for the bracket surface and are difficult to remove once engaged, thereby adversely affecting the function of the bracket as described above.

[0106] When the bracket is bonded to the tooth, a filling material may be introduced into the tray receiving portion to protect the void 39 from excess adhesive. In the presently preferred case, the filler is a constant volume material; because once the filler is cured or hardened, there is no significant loss of volume. Particularly useful constant volume materials include flowable, hardenable materials such as Odontosil for creating a positioning layer. TM Suitable constant volume materials also include wax and other dental impression materials. In other embodiments, the filling material may be an expandable foam that is introduced in a smaller volume and then expands to fill one or more voids. Materials for expandable foams include polyethylene, polyurethane, silicone, or synthetic rubbers, such as ethylene-propylene diene or block copolymers such as those based on styrene. More exemplary details on the use of filling materials in the methods of the present disclosure can be found in U.S. Pat. No. 10,368,961 (Blees et al.).

[0107] Regardless of the method of creating the physical transfer device, the dimensions of the component layers may be tailored to match only a portion of a patient's dental arch, or to make the tray fit conveniently within the patient's mouth.

[0108] like Figures 9 to 12 As shown, the transfer device 300 (here a U-shaped tray) is formed to substantially match the teeth of the physical solid model and includes a series of receiving portions (represented by receiving portions 320) that substantially correspond to the outer surfaces of the analog and grooves (represented by grooves 330) that substantially correspond to the outer surfaces of the associated ramps. As depicted, the tray 300 includes an outer layer 305 and an inner positioning layer 306. The inner wall segments 308 of the inner layer 306 will generally have a contour that matches the contour of the patient's individual teeth, and an overall configuration that matches the orientation of each tooth relative to other teeth in the same dental arch. When placed on the dental arch, the inner wall segments 308 of the inner layer 306 will contact the labial, occlusal and lingual surfaces of the teeth, but other constructions may omit the surfaces that do not include the receiving portions 320.

[0109] Typically, the dental tray will include a receiving portion in the positioning layer 306 corresponding to each appliance analog on the physical and / or virtual mockup used in the process of creating the transfer device, and a groove corresponding to each ramp associated with the appliance analog. The groove 330 extends from the generally gingival area 322 of the receiving portion 320 to an opening 334 at or near the gingival edge 316 of the dental tray 310.

[0110] Figures 9 to 12 The sides of the facial wall 331 and groove 330 depicted in the figure are each substantially planar, so that the groove has a generally rectangular shape in a cross-section taken along a plane parallel to the mesial-distal axis of the receiving portion 320. In other embodiments, the groove may have any suitable cross-sectional shape or combination of shapes (e.g., trapezoidal, dome-shaped, etc.). For example, the facial wall 331 may be circular with planar side surfaces 332, 333 to facilitate removal of a subsequently formed transfer device. Each groove 330 in the transfer device may each have the same or different cross-sectional shapes. In other embodiments, certain groups of grooves 330 may include the same cross-sectional shapes as one another and different cross-sectional shapes from groups located in different quadrants or locations on the transfer device 300.

[0111] Each groove 330 in the plurality of grooves has a depth "D" (mesio-distal width) measured from the facial wall 331 to the tooth surface 14 when placed on the dental arch, and a length "L" measured from the groove opening 334 to the gingival most apex on the receiving portion 320, which is typically but not exclusively a concave portion corresponding to the ligature wing or hook. The depth is generally less than the depth of the receiving portion along a similar reference direction. In certain embodiments, the depth may be inclined or maintained constant over a portion of the groove length "L", so that the depth at the opening 334 may be deeper than the depth near the receiving portion. However, in a currently preferred embodiment, the depth tapers over at least a portion of the groove length, resulting in the groove 330 being shallower near the opening 334 at the gingival edge 316 of the transfer device 300 than the area of ​​the groove 330 near the receiving portion 320. Although not depicted, the width "W" may also increase or decrease in size along the length of the groove 330.

[0112] To utilize the transfer device, a bracket (represented by bracket 400) is placed in an associated receiving portion ( Fig.12 ). A thin layer of release agent can be applied to the transfer device and allowed to dry. Suitable release agents include silicone fluids, PVA, sprays, and wax emulsions. The use of a release agent allows the bracket to be easily removed from the receiving portion of the device.

[0113] The placement of the brackets in the receiving portion can be done manually, bracket by bracket, or by picking up a set of brackets previously placed on a physical model of the patient's teeth (because an empty transfer tray (without brackets) can be matched to a physical model of the patient's teeth including brackets) and separating the transfer tray from the patient's tooth model. In the latter step, the brackets are preferably retained in the transfer tray and released from the model. This can be achieved by a relatively light temporary bonding between the brackets and the model (e.g., by a temporary or weak adhesive).

[0114] An adhesive may be applied to the bonding surfaces of the brackets (and other appliances in the tray), and the transfer device may be placed on the teeth in the patient's mouth, where the adhesive is hardened or allowed to harden to establish a bond between the brackets in the tray and the patient's teeth. Once the bond is established, the plastic sheet or other outer layer may be removed, leaving the positioning layer in place on the patient's teeth. The positioning layer may be peeled off the patient's teeth, and the brackets bonded to the teeth. Thus, the force with which the brackets bond to the patient's teeth, and thereby the risk of damaging or affecting the bond during removal of the transfer tray, is minimized.

[0115] The use of transparent materials for the component layers can facilitate confirmation of the correct placement of brackets and / or other appliances on the teeth.

[0116] In addition, the transfer device can be used to bond only a single appliance to a patient's tooth. For example, a portion of the transfer device described above can be used to bond a single appliance to a single tooth after bonding other appliances (such as where access to the tooth is initially blocked by other teeth). As another example, a portion of the transfer device described above can be used to re-bond one or more appliances that have been inadvertently detached from a tooth, or to bond a new appliance to a tooth to replace the original appliance.

[0117] The various techniques of the present disclosure may be implemented in a variety of computer devices, such as servers (including cloud), laptop computers, desktop computers, notebook computers, tablet computers, handheld computers, smart phones, etc. Any component, module, or unit is described to emphasize the functional aspects and does not necessarily need to be implemented by different hardware units. The techniques described herein may also be implemented in hardware, software, firmware, or any combination thereof. Any features described as modules, units, or components may be implemented together in an integrated logic device or may be implemented independently as discrete but mutually cooperating logic devices. In some cases, various features may be implemented as integrated circuit devices, such as integrated circuit chips or chipsets.

[0118] If implemented in software, the technology may be implemented at least in part by a non-transitory computer-readable medium including the following instructions, which, when executed in a processor, performs one or more of the methods described above. The computer-readable medium may include a tangible computer-readable storage medium and may form a part of a computer program product, which may include packaging materials. The computer-readable storage medium may include a random access memory (RAM) such as a synchronous dynamic random access memory (SDRAM), a read-only memory (ROM), a non-volatile random access memory (NVRAM), an electrically erasable programmable read-only memory (EEPROM), a flash (FLASH) memory, a magnetic or optical data storage medium, etc. The computer-readable storage medium may also include a non-volatile storage device such as a hard disk, a magnetic tape, a compact disk (CD), a digital versatile disk (DVD), a Blu-ray disc, a holographic data storage medium, or other non-volatile storage devices. The term "processor" as used herein may refer to any one of the aforementioned structures or any other structure suitable for implementing the technology described herein. In addition, in some aspects, the functions described herein may be provided in a dedicated software module or hardware module configured to perform the technology disclosed herein. Even if implemented in software, the techniques may use hardware such as a processor for executing the software, and memory for storing the software. In any such case, the computer described herein may define a specific machine capable of performing the specific functions described herein. In addition, the techniques may be fully implemented in one or more circuits or logic elements that may also be considered a processor.

[0119] The entire disclosure of the patents, patent documents and publications cited herein are incorporated by reference in their entirety, as if each file were cited separately. Many other changes, modifications and additions are also possible without departing from the essence of the present invention. Therefore, the present invention should not be considered to be limited to the above-mentioned specific embodiments, but only limited by the fair scope of the following claims and their equivalents.

Claims

1. An orthodontic transfer device for placing an orthodontic appliance on a dental arch, the orthodontic transfer device comprising: A body comprising an inner surface conforming to the contour of at least one tooth of the dental arch, an appliance receiving portion, and a groove in fluid communication with the receiving portion and extending from the receiving portion in a gingival direction, the groove connecting the gingival edge of the body to the receiving portion, wherein the groove comprises a facial wall and opposing side walls, and wherein the facial wall is spaced apart from the inner surface of the body in a buccal-labial direction.

2. An orthodontic transfer device according to claim 1, wherein at least one appliance receiving portion includes one or more recessed areas corresponding to positive features on the body of the orthodontic appliance, and wherein the features include at least one of a ligature wing, a hook, and an archwire slot.

3. An orthodontic transfer device according to claim 1 or 2, wherein at least one receiving portion has a mesial-distal width, and wherein the width of the groove is no greater than the mesial-distal width of the receiving portion.

4. An orthodontic transfer device according to any one of claims 1 to 3, wherein the device is a curved tray designed to be placed on a plurality of teeth of the dental arch.

5. The orthodontic transfer device of claim 4, wherein the tray comprises a plurality of appliance receiving portions, and wherein each receiving portion is in fluid communication with a groove extending in a gingival direction to an edge of the tray body.

6. The orthodontic transfer device of claim 5, further comprising an orthodontic appliance engaged with each of the receiving portions.

7. An orthodontic transfer device according to claim 6, wherein the brace comprises a body and a base, and wherein the width of the groove is no greater than the mesial-distal width of the body of the orthodontic brace.

8. An orthodontic transfer device according to any one of claims 1 to 7, wherein the depth of the groove gradually decreases as it approaches the edge of the body, so that the depth of the groove near the receiving portion is greater than the depth of the groove at the gingival edge of the body.

9. The orthodontic transfer device according to any one of claims 1 to 8, wherein the groove has a rectangular or arcuate cross-sectional shape.

10. The orthodontic transfer device of claim 1, wherein a longitudinal axis of the groove is oriented at an acute angle relative to a vertical axis of the body.

11. An orthodontic transfer device according to claim 10, wherein the groove includes a first groove portion and a second groove portion, the first groove portion being closer to the receiving portion and having a longitudinal axis oriented at an acute angle relative to the vertical axis, and the second groove portion being closer to the gingival edge of the body and having a longitudinal axis oriented parallel to the vertical axis.

12. A method of making an orthodontic transfer device comprising a body, the method comprising: providing a three-dimensional virtual model of at least a portion of a dental arch, the dental arch comprising a plurality of virtual teeth, gingiva, and a mold body extending from the gingiva; providing a virtual appliance analog including a base and a body, the appliance analog including a retaining ramp extending from a gingival region of the appliance body; placing the appliance analog on the labial surface or the lingual surface of one of the plurality of virtual teeth, extruding the retaining ramp from the appliance analog to at least one area adjacent to the gingiva; creating a physical model of the combined virtual dental arch and appliance analog; and The transfer device is formed on the physical model.

13. The method of claim 12, wherein forming the transfer device on the physical model comprises thermoforming a sheet of material.

14. The method of any one of claims 12 to 13, wherein providing the appliance analog comprises selecting the appliance analog from a library of appliance analogs, and wherein each appliance analog in the library of appliance analogs comprises a retaining ramp having a same geometric structure.

15. The method of any one of claims 12 to 14, wherein extruding the ramp comprises the steps of extruding the ramp in a first direction and extruding a second portion of the ramp in a second direction, the second portion extending at an oblique angle relative to the first portion.

16. The method of claim 15, wherein extruding the ramp comprises decreasing the height of the ramp as the gingiva is approached.

17. The method of any one of claims 12 to 16, wherein providing a virtual appliance analogue comprising a base and a body further comprises: Provide a set of virtual orthodontic appliances; and providing a set of virtual analogs, each analog being associated with a virtual appliance in the set of virtual appliances, wherein each of the virtual analogs approximates or represents a shape of the associated virtual appliance, wherein at least one of the analogs has a shape that is different from a shape of the associated appliance.

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