Patent Publication Number: US-2023157792-A1

Title: An indirect bonding tray for bonding orthodontic appliances and methods of making and using the same

Description:
BACKGROUND 
     Orthodontic appliances such as brackets are used in orthodontic treatments for moving one or more teeth from an initial position (sometimes referred to as malposition or malocclusion) to a desired position in a patient&#39;s dentition. For example, by using an orthodontic treatment the patient&#39;s tooth may be moved such that their labial sides are aligned with each other to achieve or maximize an aesthetically pleasant appearance of the overall dentition. Further in some cases, one or more teeth may be moved to correct a malocclusion. The movement of teeth is typically achieved by a pre-biased elastic arch wire, which is attached via brackets to the teeth, and which applies a force to the teeth toward the desired position over a longer time period. The ends of orthodontic arch wires are often connected to small appliances known as buccal tubes that are, in turn, secured to the patient&#39;s molar teeth. In many instances, a set of brackets, buccal tubes and an arch wire is provided for each of the upper and lower dental arches of the patient. 
     In many types of orthodontic techniques, the precise position of the orthodontic appliances on the teeth is an important factor for helping to ensure that the teeth move to their intended final positions. For example, one common type of orthodontic treatment technique is known as the “straight-wire” technique, where the arch wire lies in a horizontal plane at the conclusion of treatment. If, for example, a bracket is attached to the tooth at a location that is too close to the occlusal or outer tip of the tooth, the orthodontist using a straight-wire technique will likely find that the tooth in its final position is unduly intruded. On the other hand, if the bracket is attached to the tooth at a location closer to the gingiva than is appropriate, it is likely that the final position of the tooth will be more extruded than desired. 
     Certain treatment planning systems have been used to determine the desired position of the teeth in a computer simulation in advance of any actual treatment. Such a planning system helps for example for avoiding collisions between the teeth and brackets in tooth positions outside the initial position, and further allows for the brackets and the arch wire to be designed and arranged to match with a variety of clinical situations, for example with the position of the teeth in the initial position, in the desired position, and positions between. For lingual brackets, such treatment planning is widely used. Lingual brackets often have a customized design individually for every tooth and patient because, other than the labial surfaces of a tooth, the lingual surfaces greatly vary in shape relative to each other so that a “one size fits all” bracket shape typically cannot be used. Some treatment planning systems also allow for designing such customized brackets which precisely match a tooth surface and the required clinical situations of a patient. Accordingly, customized brackets typically have to be precisely placed at positions on the teeth which are predetermined during the treatment planning For facilitating a precise placement of the brackets on a patient&#39;s teeth and for the orthodontist&#39;s reference, the brackets are often provided prepositioned on a plaster model replicating the patient&#39;s teeth. One example of a treatment planning software is disclosed in PCT Publication WO 2001/80761 “Interactive Orthodontic Care System Based on Intra-oral Scanning of Teeth.” As disclosed, the treatment planning software virtually superimposes brackets on teeth to generate a three-dimensional model comprising the three-dimensional tooth objects plus the virtual brackets at their intended locations. This three-dimensional model is supplied to a stereolithography (SLA) instrument for additive manufacturing a plastic model of the teeth with the brackets superimposed thereon. A thermoplastic foil is placed above the SLA model and the model and foil are placed within a pressure chamber. The chamber is pressurized so that the foil envelops the dentition and the brackets. The foil thus obtains small indentations where the brackets can be located. Other examples of treatment planning software are disclosed in the following U.S. Pat. Nos. 7,940,258; 7,869,983; 7,291,011; 7,354,268; 7,993,133; 8,517,727 
     A plaster model on which the brackets are placed is sometimes used in orthodontics to make a so-called “transfer tray” for facilitating the placement of the bracket on a patient&#39;s teeth. A transfer tray typically is adapted to hold a complete set of brackets at the predetermined position and allow the brackets to be placed and bonded on the teeth all at once, in one step, by a process referred to as “indirect bonding.” 
     In general, indirect bonding techniques involved the use of a transfer tray having a shape that matches the configuration of at least part of a patient&#39;s dental arch. A set of orthodontic appliances such as brackets or attachments are releasably connected to the tray at certain, predetermined locations. Adhesive is applied to the base of each appliance, and the tray is then placed over the patient&#39;s teeth until the adhesive hardens. Next, the tray is detached from the teeth as well as from the appliances, with the result that all the appliances previously connected to the tray are now bonded to the respective teeth at their intended, predetermined locations. One example of a method of making an indirect bonding transfer tray for orthodontic appliances is disclosed in published European Patent No. 2931166B1 Application No. 1 2196 586, “Method of Making a Mockup Including Analogs Approximating Orthodontic Brackets.” Another example of a method of making a transfer tray for orthodontic appliances is disclosed in U.S. Pat. No. 9,763,750 “Rapid Prototyped Transfer Tray for Orthodontic Appliances.” Others example of use of indirect bonding trays are disclosed in published U.S. Patent Application Publication No. 2010/0092904 A1, “Device for Positioning at Least One Orthodontic Element,” U.S. Patent No. 5,9711754A “Indirect Bonding Method and Adhesive for Orthodontic Treatment,” and U.S. Patent Application Publication No. 2008/0233528, “Indirect Bonding Trays for Orthodontic Treatment and Methods for Making the Same.” One example of a dental template for direct bonding of orthodontic appliances is disclosed in Provisional U.S. Patent Application Filing No. 62/940,290, “Dental Template for Direct Bonding Orthodontic Appliances” 
     Although certain advances have been made in methods of predetermining locations of orthodontic appliances on a patient&#39;s teeth and tools for placement thereof, additional advancements are desired by orthodontists and their patients. 
     SUMMARY 
     This disclosure relates to an indirect bonding tray. In one example, the disclosure is directed to a bonding tray comprising: a mold body for a patient-specific, customized fit with a plurality of teeth in the patient&#39;s dental arch, the mold body having an exterior surface and an interior surface opposite the exterior surface; one or more guide aperture configured to permit the placement of an orthodontic appliance on a surface of a tooth at a predetermined location aligned with the guide aperture, when the mold body is registered on the dental arch; and one or more guides extending from the exterior surface, wherein each guide is aligned with one of the guide aperture; one or more appliance holders, wherein each appliance holder is in slidable engagement with one of the guides. 
     In one aspect of this embodiment, the mold body includes a patient-specific, customized fit with both the labial and lingual surfaces of a plurality of teeth. In another aspect of this embodiment, the guide is configured to permit the placement of a base of the orthodontic appliance in a direction perpendicular to the labial surface of the tooth aligned with the guide aperture. In another aspect of this embodiment, the apertures include a substantially enclosed perimeter. In yet another aspect of this embodiment, the tray further includes an orthodontic appliance positioned within each appliance holder. In an aspect of this aspect, the holder and orthodontic appliance together are in a slidable engagement with the guide between a first position and a second position, wherein in the first position, the holder and orthodontic appliance are positioned away from the tooth, and in the second position, the base of the orthodontic appliance is in contact with the surface of the tooth. And, in a further aspect, the orthodontic appliance includes a layer of adhesive on its base. 
     In another aspect of this embodiment, the indirect bonding tray comprises a custom-engineered compliant mechanism where a portion of the mold body is pivotable relative to a portion of the mold body. In an aspect of this aspect, the custom-engineered compliant mechanism is a hinge, a pivot, a score line, a weakened portion, an engineered line of weakness, a line of concentrated stress, a frangible portion, a perforation, a bendable element, a thinner portion, a portion with lower modulus of strength, or a predetermined slot, void or gap, wherein the compliant mechanism is located at a predefined location or locations on the patient-specific, customized bonding tray. In another aspect of this aspect, the custom-engineered complaint mechanism is breakable at a predefined location to aid in separating portions of the facial mold body from the dental arch after one or more orthodontic appliances are bonded to the labial surface of the teeth. 
     In another aspect of this embodiment, the mold body comprises an elastomeric material. In another aspect of this embodiment, the mold body comprises a flexible silicone rubber. In yet another aspect of this embodiment, the mold body comprises a frangible material. 
     In another aspect of this embodiment, the interior surface of the mold body is configured to engage all teeth of the dental arch, and wherein the inner surface includes a plurality of contour portions, each portion matching the contour of a corresponding labial tooth surface. In another aspect of this embodiment the guide further comprises breakable positioning portions, and wherein the appliance holders are in slidable engagement with one of the guides between a first position and a second position, wherein in the first position the appliance holder is in contact with the breakable positioning portions. In another aspect of this embodiment, the mold body is manufactured by three-dimensional printing. In yet another aspect of this embodiment, the mold body comprises at least partially translucent materials. 
     In yet another aspect of this embodiment, each guide further comprises breakable positioning portions and each appliance holder includes slots for engaging with the breakable positioning portions. In another aspect of this embodiment, each appliance holder further comprises breakable positioning portions and each guide includes slots for engaging with the breakable positioning portions. In another aspect of this embodiment, the appliance holder and guide have a first friction fit, wherein in the first friction fit the appliance holder is located away from the intended tooth. In another aspect of this aspect, each appliance holder and guide have a second fit, wherein in the second fit the appliance contacts the intended tooth. 
     In another aspect of this embodiment, each guide further includes at least two surfaces configured to angle the appliance holder at a predetermined angle relative to the surface of the intended tooth. In one aspect of this aspect, each appliance holder includes at least two more surfaces configured to angle the appliance holder at a predetermined angle relative to the surface of the intended tooth. In another aspect of this embodiment, the indirect bonding tray further comprises a pressure plate to push all the appliance holders down their corresponding guides substantially simultaneously. In another aspect of this aspect, the pressure plate holds the orthodontic appliances in place next to the corresponding tooth surface until such orthodontic appliances are bonding to the teeth. In another aspect of this embodiment, the indirect bonding tray further includes an appliance holder tab. 
     In another aspect, the disclosure is directed to methods of using an indirect bonding tray. In one embodiment the method comprises: providing a mold body for a patient-specific, customized fit with a plurality of teeth in the patient&#39;s dental arch, the mold body having an exterior surface and an interior surface opposite the exterior surface and the mold body comprising one or more guides extending from the exterior surface, each guide including a guide aperture configured to permit the placement of an orthodontic appliance at a predetermined location on a surface of a tooth aligned with the guide aperture, when the mold body is registered on the dental arch; providing a plurality of appliance holders; providing a plurality of orthodontic appliances; placing one of the orthodontic appliances into each appliance holder; and slidably engaging each appliance holder with one of the guides. In another aspect of this embodiment, the method further comprises registering the mold on the patient&#39;s teeth. In another aspect of this aspect, the method further comprises bonding the orthodontic appliances to the teeth. In another aspect of this embodiment, the type of orthodontic appliance is preselected for each tooth and such appliance is placed in the orthodontic appliance holder for that tooth. 
     In another aspect, the disclosure is directed to a method of designing an indirect bonding tray. In one embodiment, the method comprises: receiving, by one or more processors, three-dimensional scan data of a tooth structure of a patient; designing, by the one or more processors, a custom indirect bonding tray for indirect bonding orthodontic appliances based on the three-dimensional scan data of the tooth structure of the patient, and the desired tooth structure of a plurality of teeth to receive an orthodontic appliance bonded to the patient, wherein the indirect bonding tray comprises: a mold body for a patient-specific, customized fit with a plurality of teeth in the patient&#39;s dental arch, the mold body having an exterior surface and an interior surface opposite the exterior surface; one or more guides extending from the exterior surface, the guide including a guide aperture configured to permit the placement of an orthodontic appliance on a surface of a tooth at a predetermined location aligned with the guide aperture, when the mold body is registered on the dental arch; and a plurality of appliance holders, wherein each appliance holder is in slidable engagement with one of the guides. In another aspect of this embodiment, the mold body is manufactured by three-dimensional printing. 
     In another aspect, the disclosure is directed to a method of bonding appliances to teeth. In one aspect of this embodiment, the method comprises: providing indirect bonding tray comprising: a mold body for a patient-specific, customized fit with a plurality of teeth in the patient&#39;s dental arch, the mold body having an exterior surface and an interior surface opposite the exterior surface; one or more guides extending from the exterior surface, the guide including a guide aperture configured to permit the placement of an orthodontic appliance on a surface of a tooth at a predetermined location aligned with the guide aperture, when the mold body is registered on the dental arch; and a plurality of appliance holders, wherein each appliance holder is in slidable engagement with one of the guides; positioning an orthodontic appliance within each appliance holder, wherein the orthodontic appliance includes a layer of adhesive on its base; placing the indirect bonding tray on the patient&#39;s dental arch; moving a plurality of the appliance holders to contact the layer of adhesive on the orthodontic appliances to the respective plurality of teeth through the guide apertures; bonding the orthodontic appliance to the teeth; and removing the indirect bonding tray from the patient&#39;s teeth. 
     In another aspect of this embodiment, the method further comprises: sliding each appliance holder from a first position to a second position, wherein in the first position the orthodontic appliance is away from the tooth and in the second position the orthodontic appliance is adjacent the tooth surface. In another aspect of this embodiment, the orthodontic appliance includes a layer of adhesive on its base. In another aspect of this aspect, the adhesive is applied to the base before the appliance is positioned within the holder. In another aspect of this embodiment, each guide further comprises breakable positioning portions and each appliance holder includes slots for engaging with the breakable positioning portions, wherein in the first position, the slots are engaged with the positioning portions, and further comprising breaking the breakable positioning portions when sliding the guides to the second position. In yet another aspect of this embodiment, the appliance holder and guide have a first friction fit, wherein in the first friction fit the appliance holder is located away from the intended tooth, and further comprising sliding the guides to a second fit, wherein in the second fit the appliance contacts the intended tooth. In another aspect of this embodiment, the method further comprises bonding the orthodontic appliances to the teeth. In another aspect of this embodiment, the type of orthodontic appliance is preselected for each tooth and such appliance is placed in the orthodontic appliance holder for that tooth. 
     In another aspect of this embodiment, the mold body further comprises a custom-engineered compliant mechanism where a portion of the mold body is pivotable relative to a portion of the mold body. In another aspect of this aspect, the custom-engineered compliant mechanism is a hinge, a pivot, a score line, a weakened portion, an engineered line of weakness, a line of concentrated stress, a frangible portion, a perforation, a bendable element, a thinner portion, a portion with lower modulus of strength, or a predetermined slot, void or gap, wherein the compliant mechanism is located at a predefined location or locations on the patient-specific, customized bonding tray. In another aspect of this aspect, the custom-engineered complaint mechanism is breakable at a predefined location to aid in separating portions of the facial mold body from the dental arch after one or more orthodontic appliances are bonded to the labial surface of the teeth. 
     In another aspect of this embodiment, the mold body comprises an elastomeric material. In another aspect of this embodiment, the mold body comprises a flexible silicone rubber. In yet another aspect of this embodiment, the mold body comprises a frangible material. 
     In another aspect, the disclosure is directed to a kit. In one embodiment of this kit, the kit comprises: an indirect bonding tray, the bonding tray comprising: a mold body for a patient-specific, customized fit with a plurality of teeth in the patient&#39;s dental arch, the mold body having an exterior surface and an interior surface opposite the exterior surface; one or more guides extending from the exterior surface, the guide including a guide aperture configured to permit the placement of an orthodontic appliance on a surface of a tooth at a predetermined location aligned with the guide aperture, when the mold body is registered on the dental arch; one or more orthodontic appliance holders, wherein each appliance holder is in slidable engagement with one of the guides. In another aspect of this embodiment, the kit further comprises a plurality of orthodontic appliances, wherein each appliance holder holds one orthodontic appliance. In another aspect of this aspect, the kit further comprises packaging for containing the tray and orthodontic appliances, wherein the packaging protects from light, curative loss, and contamination. In another aspect of this aspect, the plurality of orthodontic appliances each include a layer of adhesive and the packaging protects the adhesive from light. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a perspective view of an exemplary dental arch of a patient for use with an indirect bonding tray of the present invention for bonding orthodontic appliances to the teeth of the patient; 
         FIGS.  2 A  is a front perspective view of an exemplary embodiment of indirect bonding tray of the present invention; 
         FIGS.  2 B  is a rear perspective view of the indirect bonding tray of  FIG.  2 A ; 
         FIG.  3 A  is an exploded perspective view of one embodiment of an orthodontic appliance guide; 
         FIG.  3 B  is a perspective view of the orthodontic appliance guide of  FIG.  3 A ; 
         FIG.  4    is a perspective view of the indirect bonding tray of  FIGS.  2 A and  2 B  with the appliance holders of  FIG.  3    on the dental arch of  FIG.  1   ; 
         FIGS.  5 A and  5 B  are a cross sectional view of the indirect bonding tray of  FIG.  3    taking along lines A-A of  FIG.  4   ; 
         FIGS.  6 A and  6 B  are a perspective view of the dental arch of  FIG.  1    after orthodontic appliances have been bonded to the teeth; 
         FIG.  7    is a perspective view of another exemplary embodiment of the indirect bonding tray; 
         FIG.  8    is a perspective view of the tray of  FIG.  7   , where a portion of the tray is being removed from the patient&#39;s mouth; 
         FIG.  9    is a perceptive view of the tray of  FIG.  8   , where another portion of the tray is being removed from the patient&#39;s mouth; and 
         FIG.  10    is a schematic block diagram describing a workflow used to make an indirect bonding tray according to exemplary embodiments of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     The primary objective of orthodontics is to move a patient&#39;s teeth to a position where the teeth are esthetically pleasing. Orthodontic treatment may include standardized brackets and wires, such as those components in a “straight-wire” appliance system. Conventional orthodontic appliances such as brackets are positioned by hand by an orthodontist in defined positions and orientations according to standardized placement rules. The orthodontist may also visually gauge proper bracket positions and imagining treatment outcomes. After placement is determined, the brackets are then bonded by a small quantity of adhesive placed on the base of each bracket. The bracket may be bonded to the tooth using either a two-part chemical cure adhesive or a one-part light-cure adhesive. The uncured adhesive is sufficiently viscous and tacky to allow temporary adhesion and visual adjustment prior to final bonding. This method of bracket placement is known as “direct bonding.” To save time and ease of handling, some brackets are offered as precoated with adhesive or an adhesive system, such as for example APC™ Flash-Free Adhesive Coated Appliance System ,commercially available from 3M Company, St. Paul, Minn., which include an adhesive system of uncured adhesive integrated into a web of micron-sized polypropylene fibers arrayed in a nonwoven material format on the bracket bases when they come from the factory. Once the orthodontic appliances are bonded on the teeth, the combination of the arch wire and appliances adjusted over time move the teeth towards their intended final position. 
     A skilled orthodontist may become very good at visually gauging proper bracket positions and imagining treatment outcomes for patients. However, it can take many years to acquire this skill, and even then, manual wire bends and bracket repositioning may be needed later in treatment to correct minor placement errors and achieve better results. 
     The present invention provides indirect bonding trays for indirectly bonding orthodontic appliances to a patient&#39;s moth. These dental templates are formed using virtual treatment planning software often used in the indirect bonding process to provide accurate bracket placement, but include the advantage of indirect bonding the appliances normally (orthogonally) to the teeth surface, which provides good bond reliability. One possible disadvantage of prior indirect bonding methods is that the orthodontic appliance slides over the facial or lingual surface of the tooth in an occluso-gingival direction during installation, thus smearing or wiping adhesive off the bracket base before coming to rest in its target position on the tooth. This may result in a poor bond between the orthodontic appliance and the tooth, requiring rebonding or replacements, ineffective treatment, or unintentionally consumed appliances. Another disadvantage of indirect bonding is that it requires the delicate additional step of preloading the orthodontic appliances into the transfer tray in such a way that they are releasably connected to the tray at certain, predetermined locations. 
     The indirect bonding tray of the present invention does not have the disadvantages of the prior indirect bonding tray and placement procedure. The indirect bonding trays of the present invention provide more accurate placement of the orthodontic appliances, including more accurate measurement and analysis in comparison to direct bonding by hand. In addition, the indirect bonding trays and use thereof provides reduced doctor/patient time in the chair and better treatment outcomes. In fact, the orthodontist may be able to delegate the procedure for bonding the orthodontic appliances to another sufficiently qualified staff member because the planning of the position of each appliance is removed from the chairside procedure. Also, the indirect bonding trays may be shipped preloaded with the orthodontic appliances or brackets already mounted therein, which is an additional time saver. The orthodontic appliances may include a layer of adhesive, which cuts down on chair time for the patient and orthodontist. 
     The indirect bonding trays of the present invention allow for placement and bonding of the orthodontic appliances individually, allowing for greater control over adhesive delivery because the orthodontic appliances are bonded one at a time, instead of all at once. For example, the indirect bonding trays provide greater control over the finer aspects of orthodontic placement, such as controlling of the potential excess of filled adhesive (i.e., flash) from around the base&#39;s perimeter and forming a smooth film of adhesive between the base and the tooth. The specially designed guides in the trays are designed to deliver the orthodontic appliance at precisely the correct location and at the correct angle relative to the patient&#39;s tooth. 
     Other embodiments of the indirect bonding trays of the present invention allow for placement and bonding of a plurality of orthodontic appliances at the same time, which saves time for the patient to be in the chair. 
     With the indirect bonding trays of the present invention if a bracket is lost or damaged by the patient, it can be easily re-bonded using the original dental tray with a new bracket. Also, the tray, guides, and orthodontic brackets may all be shipped assembled in one package directly to the dentist, or the tray maybe shipped in one package and the guides with the orthodontic brackets placed in them maybe shipped in another package. The indirect bonding tray  10  could be included in a kit for the orthodontist for a specific patient. The kit would include the guides all preloaded with orthodontic appliances  60  each having an adhesive already applied to its base. The packaging could protect its components, such as the adhesive, from light, curative loss, or contamination. 
     In addition, the indirect bonding trays of the present invention may be digitally designed and printed using additive manufacturing to provide a patient specific customized dental template. 
       FIG.  1    illustrates an exemplary physical or virtual model of a dental arch  1  of a patient, which is useful for illustrating for use with a dental template of the present invention for indirect bonding orthodontic appliances to the teeth of the patient. The dental arch  1  includes teeth  2 , including facial surfaces  4  of the teeth, and gums  3 , including gingival tissue. 
       FIGS.  2 A and  2 B  illustrate an exemplary indirect bonding tray  10  of the present invention, which is used for indirect bonding orthodontic appliances to a patient&#39;s teeth. The indirect bonding tray  10  is specially designed to register and fit onto a specific patient&#39;s dental arch. As such, each tray  10  is made to have a patient-specific, customized fit with one particular patient. The indirect bonding tray  10  includes a mold body  12  having an exterior surface  14  and an interior surface  16  opposite the exterior surface  14 . The mold body  12  is designed to register or engage with at least a portion of the labial and lingual surfaces the individual patient&#39;s teeth, respectively. The mold body  12  may include labial, lingual, gingival and occlusal regions. The labial region  34  and lingual regions  36  are designed to register or engage with at least a portion of the gingival and occlusal surfaces the individual patient&#39;s teeth, respectively. Likewise, the gingival region  42  and occlusal regions  38  are designed to register or engage with at least a portion of the gingival and occlusal surfaces the individual patient&#39;s teeth, respectively. The indirect bonding tray  10  is designed to include these regions, depending on the final desired orthodontic appliance placement on the individual patient&#39;s teeth. 
     Each tray  10  is custom designed to fit a certain patient (“patient specific”), and thus has a customized fit with a plurality of teeth  2  in the patient&#39;s dental arch. For example, for embodiments of mold body  12  that contact the facial surfaces  4  and/or lingual surfaces of the teeth  2 , the inner surfaces  16  are contoured to match the corresponding facial tooth surfaces  4  and/or lingual surfaces of the individual patient. For embodiments that include mold body  12  that contact the gingiva of the patient, the gingiva region  42  include interior or inner surfaces  16  contoured to match a portion of the corresponding gingiva of that individual patient. 
     For mold body  12  embodiments that contact the molars of the teeth  2 , the interior surface or inner surfaces  16  are contoured to match the corresponding molar surfaces of the individual patient. For instance, the molars might fit into certain molar regions  40 , as illustrated. For one full dental arch, the mold body  12  may include a first molar portion  40  and a second molar portion opposite the first molar portion, such that the tray  10  engages all of the teeth in the patient&#39;s dental arch. Alternatively, the mold body  12  could include only one molar portion  40  or no molar portions  40 . That being said, the molar portions  40 , may serve as anchors for the indirect bonding tray  10  on the patient&#39;s teeth. In another embodiment, the mold body  12  could include a molar portion on any of first, second and third molars. The molar portion may or may not include an guide aperture  20 . Ideally, the indirect bonding tray  10  is designed to have a comfortable snap fit with the patient&#39;s teeth, by engaging with the naturally occurring undercuts on or between the teeth. 
     The dental template  10  may be designed to engage with all the teeth  2  in the patient&#39;s mouth, or only select plurality of teeth, depending on which teeth are to bear an orthodontic appliance  60 . For each tooth  2  that will receive an orthodontic appliance  60 , there is a corresponding guide aperture  20  shaped to guide an appliance holder  44  to a specific location on the adjacent tooth  2  to bond the appliance  60  at such position, when the mold body  12  is registered on an individual patient&#39;s dental arch. The apertures  20  have a substantially enclosed perimeter or an entirely enclosed perimeter. 
       FIGS.  2 A and  2 B  illustrate an indirect bonding tray  10  having one type of exemplary guide aperture  20  extending from the exterior surface  14 . However, various shapes of apertures are envisioned, so long as it helps guide the placement of where to bond the appliances  60  on the teeth  2  at a predetermined location with the use of the orthodontic appliance holder  44 . In fact, a certain shape of guide aperture could be used for certain teeth, to avoid mix ups like placing a cuspid orthodontic appliance on a bicuspid, for example. Although the Figures illustrate the use of only two guide apertures  20  and orthodontic appliance holders  44 , it is expected that the indirect bonding tray  10  could be designed to include any number of guide apertures and corresponding appliance holders  44 , and that the majority of the teeth  2  in the patient&#39;s arch  1  would receive orthodontic appliances through use of such tray  10 . Thus, the Figures should not be deemed as somehow limited. 
     The guide apertures  20  are designed to closely conform to the entire perimeter of the bracket base and holder  44 , and may possibly include a small tolerance for variation in the dimension of the bracket  60 , bracket base  62 , holder  44  and/or tray  10 , or to allow the formation of the adhesive fillet surrounding the base where it mates with the intended tooth. Each orthodontic appliance holder  44  is designed to slidably engage with one of the guides  18 , and to deliver an orthodontic appliance or bracket  60  to the predetermined location on a particular tooth of the patient. Each guide aperture  20 , guide  18 , and appliance holder  44  is aligned with a predetermined location for each tooth to receive an orthodontic appliance  60  bonded thereto. 
     As illustrated, the guide apertures  20  include a substantially enclosed perimeter, although this is not essential. The guide  18  include at least one surface or edge configured to engage a surface or edge feature of the corresponding orthodontic appliance holder  44  (illustrated in more detail in  FIGS.  3  and  4   ). The appliance holder  44  is designed guide the position and orientation of the bracket or orthodontic appliance  60  on the tooth surface, according to the digital treatment plan. Specifically, the appliance holder  44  is designed to place the base  62  of the orthodontic appliance  60  in a direction generally perpendicular to the labial surface of the tooth aligned with the guide aperture  20 , as illustrated in  FIG.  5   . Although, the appliance holder  44  may also be designed to place the base at a slight tilt to the generally perpendicular position relative to the labial surface, which assists in creating some custom torques or rotations of the tooth during treatment. 
     One exemplary example of a suitable orthodontic guide  18  for engaging with a guide aperture  20 . The appliance holder  44  and positioning portion  45  are illustrated spaced apart in  FIG.  3 A .  FIG.  3 B  illustrates the orthodontic appliance holder  44  inserted into positioning portion  45  to form the orthodontic guide  18 . An orthodontic appliance  60  (not illustrated) will be housed inside the holder  44 . 
     The guide  18  is illustrated as including two portions, an orthodontic appliance holder  44  and a positioning portion  45 . However, the guide may be in any configuration, so long as it connects with the guide aperture  20  and directs the orthodontic appliance  60  to the predetermined location on the patient&#39;s tooth. In the embodiment illustrated, the orthodontic appliance holder  44  includes a well  50  for receiving the orthodontic appliance  60 . The orthodontic appliance holder  44  is designed for receiving an appropriate orthodontic appliance  60  intended for that particular tooth in the well  50 . For example, a specific well  50  could be designed to only receive a particular sized and shaped base  62  of a particular orthodontic appliance  60  intended for that well  50 . In addition, the holder  44  may be designed such that the orthodontic appliance  60  is oriented in the proper direction, so that its base  62  is facing the tooth&#39;s surface, while positioned within the holder  44 . The holder  44  also has stop  48  for engaging with a breakable portion  22  in the positioning portion  45 . 
     In the illustrated embodiment in  FIGS.  2   a   , the positioning portion  45  of the guide  18  is designed to guide the orthodontic appliance  60  through the guide aperture  20  for bonding to the tooth. In this embodiment, the positioning portion  45  has a first wall  24 , a second wall  26 , a third wall  28 , and a fourth wall  30 . The first wall  24  is opposite the third wall  28 , and the second wall  26  is opposite the fourth wall  30 . The positioning portion  45  also has external walls  32 . External wall  32   a  is opposite first wall  24 . External wall  32   b  is opposite second wall  26 . External wall  32   c  is opposite third wall  28 . External wall  32   d  is opposite fourth wall  30 . 
     From assembly, while in transit from the supplier to the orthodontist, and up to just prior to bonding the orthodontic appliance  60  the specific patient, the orthodontic appliance  60  maintains its position within the orthodontic appliance holder  44 . Any configuration may be used for holding the appliance  60  within the holder  44 . As illustrated, the orthodontic appliance holder  44  may include a slot  46  with a stop  48  that engages with breakable portion  22  located within the positioning portion  45 . The slot  46  and breakable portion  22  are configured to fit together in slidable engagement into a position using the stop  48  such that the base of the orthodontic appliance  60  is not in contact with the bottom of the positioning portion, in other words, spaced apart from the intended tooth, when the tray  10  is on the patient&#39;s dental arch  1 . 
     As another embodiment, the appliance holder  44  and positioning portion  45  could be designed to frictionally fit together. In this embodiment, the holder  44  and portion  45  could have a first frictional fit and a second frictional fit. In the first friction fit, the appliance holder  44  is located away from the intended tooth. In the second frictional fit, the appliance  60  contacts the intended tooth. An orthodontist could move the appliance holder  44  from the first frictional fit to the second frictional fit by depressing the holder  44  into the portion  45  of the guide  18 . 
     The base  62  of the orthodontic appliance  60  ideally will include a layer of adhesive before the orthodontic appliance  60  is inserted into the well  50  of the holder  44 , and then shipped to the orthodontist. However, if not, when the orthodontist is ready to position the tray  10  onto the patient it was specifically designed for, the orthodontist will apply adhesive to all the bases  62  of the orthodontic appliances  60 . The adhesive may be applied either while the holder  44  and positioning portion  45  are engaged with each other with the appliance  60  therein. Or, the adhesive may be easily applied while the holder  44  carrying the appliance  60  is separated from the positioning portion  45 , and then the holder  44  and portion  45  may be then combined. The portion  45  of the guide  18  may be integrally formed as a part of the tray  10 , so that it is positioned over the intended guide aperture  20 , as illustrated in  FIG.  2 A . 
     Instead of the stop  48  and slot  46  configuration, in another example, the well  50  may be sized and shaped so that the base of the orthodontic appliance  60  is pressure fitted into the base of the well  50 . For example, the appliance  60  could be held in the well  50  by a friction fit between the stop  48  and the arch wire slot of the appliance  60 . As another example, the well  50  could contain an elastomeric-shaped in the negative of the appliance face opposite its base  62 . As yet another example, certain surface roughness within the well  50  could be used to assist holding the appliance  60 , along with certain low friction surface treatments to create an easier release if the release of the appliance  60  becomes difficult from the positioning portion  45 . 
     As another example, the base of the well  50  may include pressure sensitive adhesive or a gel adhesive that could advantageously be washed away with water after curing of the adhesive on the base of the orthodontic appliance. . 
     As yet other examples, a soft wax could hold the appliance  60  in the appliance holder  44 . A loose-knit non-woven fabric or loop structure could be used to grip the appliance  60  in position within the holder  44 . 
       FIG.  4    illustrates the indirect bonding tray  10  in registration with the patient&#39;s dental arch  1 . Each orthodontic appliance holder  44  is inserted into a corresponding portioning portion  45  to form guides  18 , with each holder  44  an orthodontic appliance  60  therein. Although not illustrated, it is intended that the indirect bonding tray  10  would include a plurality of guides  18  and guide aperture  20 , where each tooth would receive a guide  18  and corresponding orthodontic appliance  60 . 
     All the Figures illustrate an indirect boding tray  10  having guides  18  for guiding the orthodontist in placing and bonding the appliances  60  on the labial surface of the patient&#39;s teeth aligned with each corresponding guide aperture  20 . However, the indirect bonding tray  10  of the present invention may also provide a mold body  12  designed to assist in placing and bonding the appliances  60  on the lingual surface of the patient&#39;s teeth aligned with each corresponding guide aperture  20  and appliance guides  18 . 
     As mentioned above, although not illustrated, it is intended that the indirect bonding tray  10  would include a plurality of guides  18  and guide aperture  20 , where each tooth would receive a guide  18  and corresponding orthodontic appliance  60 .  FIG.  6 B  illustrates the patient&#39;s dental arch after such a tray  10  has been used to bond a plurality of orthodontic appliances  60  to the majority of the patient&#39;s teeth. 
     The ideal locations for each orthodontic appliance  60  on a tooth are predetermined by the design process described in more detail below. During the use of a tray  10  for indirect bonding, an adhesive or adhesive system may be applied to the base  62  of each appliance  60  by the orthodontist or a staff member. However, the indirect bonding tray  10  is especially useful for pre-coated orthodontic appliances  60 . Suitable available orthodontic appliances are commercially available from 3M Company based in St. Paul. 3M Company provides ceramic orthodontic brackets commercially as 3M™ Clarity™ brackets, metal brackets commercially as Victory Series™ brackets, Unitek™ brackets, and SmartClip™ self-ligating brackets. In addition, suitable commercially available pre-coated orthodontic appliances or brackets are available from 3M Company based in St. Paul, Minn. as APC™ brackets, APC™ PLUS brackets, and APC™ Flash-Free brackets. 
     Regardless if a coat of adhesive is applied to the bracket base or if pre-coated appliances are used, each orthodontic appliance  60  is then placed through the guide aperture by pressing down on holder  44 , which in turns causes the stop  48  to break the positioning portions  22 , and thus to move the appliance  60  to then contact the adhesive layer on the base of the appliance  60  onto the patient&#39;s tooth. The appliance  60  will remain in place until the adhesive hardens. These steps are illustrated in  FIGS.  5 A and  5 B . The orthodontist controls and selects the movement of each holder  44  within the portion  45  of the guide  18 . 
     Although not illustrated, an orthodontist may use a single plunger to push each holder  44  into its accompanying positioning portion  45 , or a pressure plate which is designed to push multiple holders  44  within their portions  45 . The plunger or plate may frictionally fit or mate with the holder  44  so it locks with acceptable pressure on the appliance holder  44  to firmly push the appliance holder within the positioning portion to correctly position each orthodontic appliance  60  on its intended tooth. 
     The indirect bonding tray  10  allows the orthodontic appliance  60  to be applied at a direction generally perpendicular to the surface of the tooth  2 , and in turn, helps minimize the potential to smear, or otherwise interference with, adhesives applied to the teeth during bonding. In a particular embodiment, the guide  18  is configured to permit the placement of the base  62  of the orthodontic appliance  60  in a direction perpendicular to the labial surface of the tooth aligned with the guide aperture  20 . Specifically, the orthodontic appliance holder  44  of the guide  18  may include at least two surfaces configured to angle the appliance holder  44  at a predetermined angle relative to the surface of the intended tooth. Thus, such surfaces of the holder  44  would engage with the surfaces of the orthodontic appliance  60  to deliver the appliance  60  at the predetermined angle. 
     Smearing of adhesive may be encountered in prior art orthodontic appliance bonding, for example, when using a two-component (or A/B type) chemical cure adhesive where one adhesive component is applied to the appliance and the other component is applied to the tooth. Additionally, with prior indirect bonding trays more adhesive smearing can potentially occur on the tooth side when the resultant physical transfer tray slides onto the patient&#39;s teeth from the occlusal direction towards the gingival direction. It is generally desirable to reduce the degree of adhesive smearing, since smearing can deplete the amount of adhesive at the bonding site and thereby decrease bond reliability. Smearing can also leave an unwanted film of adhesive on portions of the teeth that are not being bonded. After removal of the indirect bonding tray  10 , the adhesive used to bond each appliance  60  to the tooth is typically retained on the base of each appliance  60 , and each appliance  60  is firmly bonded in its intended location. 
     After the orthodontic appliances  60  have been firmly bonded to their intended locations on the teeth  2 , the indirect bonding tray  10  may be removed from the patient&#39;s dental arch.  FIG.  6 A  illustrates the patient&#39;s teeth with the exemplary orthodontic appliances  60  bonded to two teeth.  FIG.  6 B  illustrates the patient&#39;s teeth after use of an indirect bonding tray  10  having a plurality of guides  18  and guide aperture  20 , where each tooth would receive a guide  18  and corresponding orthodontic appliance  60 . The patient&#39;s dental arch in  FIG.  6 B  shows a plurality of orthodontic appliances  60  bonded to the majority of the patient&#39;s teeth. 
     One way to remove the indirect bonding tray  10  after the orthodontic appliances  60  are bonded is if the tray is made of thin silicone, the trays may be flexible enough to stretch and be removed easily from the patient&#39;s teeth. Another way is to include a “rip cord” along the silicone trays, similar to those ripcords on a pack of gum, which allows a tear in the tray along the occlusal-incisal surfaces. 
     Another way to remove the indirect bonding tray  10  after the orthodontic appliances  60  are bonded, is to first remove each appliance holder  44  from their individual positioning portions  45 . Such removal could be facilitated by use of holder tab on the end of the appliance holder (not illustrated). Next, all the positioning portions  45  could be removed from the tray  10 . This allows for the apertures  20  to be visible to the user, and such apertures  20  could be sized large enough around the bonded appliances  60  to allow the tray (or portions of the tray discussed below) to be removed from the patient&#39;s teeth. 
       FIGS.  7 ,  8  and  9    are convenient for illustrating exemplary steps for removing the indirect bonding tray  10  from the patient&#39;s mouth, after the orthodontic appliances  60  are bonded to the teeth. To facilitate easy removal from the patient&#39;s dental arch  1 , the indirect bonding tray  10  of the present invention also includes one or more custom engineered compliant mechanisms  70  designed into the mold body  12  at predefined locations. The compliant mechanisms  70  allow certain portions of the mold body  12  to pivot relative to each other around a planned radius. By pivoting the different portions of the mold body  12 , this allows a user or orthodontist to easily remove the mold body  12  from the patient&#39;s dental arch, after one or more orthodontic appliances  60  are bonded to the surface of the teeth. During the process of removal, a portion of the mold body  12  is rotated or bent away from the teeth of the patient, while another portion may stay registered on the teeth of the patient. This creates desired locations of space between the portions of the indirect bonding tray  10  and the patient&#39;s dental arch to allow at least certain portions of the tray  10  to be removed successively, or for the entire indirect bonding tray  10  to be removed in one piece, without impacting the location or orientation of the orthodontic appliance  60  on a corresponding tooth surface. 
     An engineered complaint mechanism  70  is different than a naturally occurring compliant mechanism, for instance in that it includes two aspects: (1) an engineered design and directional functionality of the mechanism and (2) an engineered location of the mechanism in the indirect bonding tray  10 . Both are developed strategically into the tray to facilitate flex for easy and non-disruptive removal of the tray from the patient&#39;s arch, usually after one or more orthodontic appliances are bonded to the surface of the teeth. The engineered complaint mechanisms are customized by placing them at predefined locations of a patient-specific, customized dental template. In contrast, a naturally occurring compliant mechanism  70  may exist by virtue of a thermoforming process or natural topography of the dentition in a commercially available aligner. 
     Suitable examples of custom-engineered compliant mechanism  70  include a hinge, a pivot, a score line, a weakened portion, an engineered line of weakness, a line of concentrated stress, a frangible portion, a perforation, a bendable element, a thinner portion, a portion with lower modulus of elasticity, or a predetermined slot, void, or gap. The compliant mechanism having one or more areas of weakness are engineered to concentrate stress and facilitate controlled bending, preferably with greater deflection resulting from lower applied forces. Another example of custom-engineered complaint mechanism  70  is breakable at a predefined location to aid in separating portions of the mold body  12  from the dental arch of the patient, after one or more orthodontic appliances are bonded to the labial surface of the teeth. For example, the mold body  12  could be made of a frangible material. In such case, the compliant mechanism itself becomes frangible and facilitates controlled breakage along engineered lines of weakness. 
     In using the custom-engineered complaint mechanisms, selected portions of the indirect bonding tray  10  may be removed successively, as illustrated in  FIGS.  8  and  9   , or almost the entire dental template may be removed in substantially one piece. Also, the selected portions may be pivoted or flexed to bend away from the teeth and then the mold body  12  may be removed from the patient&#39;s mouth in substantially one piece. 
     As part of the design process, described in more detail below, custom-engineered compliant mechanisms  70  are located at certain predetermined locations, and often will include designed pivot axes. The Figures illustrate certain exemplary compliant mechanisms and accompanying pivot axes. The mold body  12  illustrated includes compliant mechanisms  70   a - 70   c  designed into certain predetermined locations. Compliant mechanisms  70   a - 70   c  are all in the form of slots or slits, but could be any of the other types described above. The complaint mechanisms  70   a - 70   c  divide the mold body  12  into four different portions, which may be removed sequentially from the patient&#39;s mouth. The five portions are labeled first portion  72 , second portion  74 , third portion  76 , and fourth portion  78 . 
     The compliant mechanisms  70   a - 70   c  each include a pivot axis (not shown) that is generally orientated in an occluso-gingival direction. After the mold body  12  is registered on the dental arch  1 , and after the orthodontic appliances  60  are bonded to the teeth through the guide apertures  20 , the first portion  72  of the tray  10  may be pivoted along the axis of the complaint mechanism  70   a , as illustrated in  FIG.  8   . In the embodiments shown, such as the one with elongated slits or perforations proximal the bracket apertures, the gingival portion of the appliance may need to pivot 45 degrees or more and stay in this position for the dental template  10  to clear the orthodontic brackets  60 . The orthodontist may then break away first portion  72  from the second portion  74  remaining on the patient&#39;s teeth, or simply disengage the first portion from the dental arch. 
     Next, the gingival region  42  of the mold body  12  of the second portion  74  may be pivoted relative to the occlusal region  38  of the mold body  12  along the pivot axes of compliant mechanisms  70   a - 70   b . As illustrated in  FIG.  9   , the gingival region  42  between compliant mechanism  70   a  and complaint mechanism  70   b  is pivoted away from the dental arch  1 , thus exposing the gingival side of the orthodontic appliances. This motion assists in removing both the labial portion  36  and lingual mold portion  34 , of the tray  10  from the patient&#39;s dental arch. 
     In another embodiment (not shown), the compliant mechanism could include a pivot axis that is generally mesial-distal, and the mold body includes a mesial region and a distal region. In this embodiment, the mesial region is pivotable relative to a portion of the distal region at the custom-engineered compliant mechanism. The dental template may include one or more hinges at predeterminate locations proximate the guide apertures, allowing a portion of the mold body to be pivotable about at least one of the hinges. 
     Next, the orthodontist may remove the third portion  76  of the tray  10  by pivoting the gingival region  42  relative to the occlusal region  38  of the mold body  12  along the compliant mechanisms  70   b  and  70   c . Again, this motion assists in removing both the labial portion  36  and lingual mold portion  34  of the dental template  10  from the patient&#39;s dental arch but does not disturb the orthodontic appliances  60  bonded thereto. 
     Lastly, the orthodontist may pivot the fourth portion  78  (of the dental template  10  along the axis of the complaint mechanism  70   c , similar to how the first portion  72  was pivoted in  FIG.  8   . The portion  78  will then break away from the tray  10  remaining on the patient&#39;s teeth. This assists in removing the remaining labial and lingual mold bodies  36 ,  34  of the tray  10  from the patient&#39;s dental arch. Any of the portions  72 - 78  may be removed in any order determined by the orthodontist. 
     After the dental template is removed from the teeth, the orthodontic appliances  60  are now bonded to respective teeth at their intended, predetermined locations, as illustrated in  FIG.  6 A . The indirect bonding tray  10  provides a way to efficiently indirect bond orthodontic appliances  60  to a patient&#39;s mouth in optimized locations. 
     Although  FIG.  6 B  illustrates orthodontic appliances  60  bonded to all teeth, it is possible that the orthodontist may omit certain posterior teeth from treatment. In such cases, the indirect bonding tray  10  would be designed to include the teeth intended for treatment and would use other teeth for anchorage, for example the molars or bicuspids. 
     Indirect bonding tray  10  of the present invention are preferably made from elastomeric materials. For example, the mold body  12  of the tray  10  could be made of a flexible silicone rubber, a low-modulus polyurethane or silicone RTV. With these materials, the tray including guide apertures  20  could deform to a high percentage elongation to assist in clearing the orthodontic appliances  60  without exerting enough tensile or shear forces to de-bond the brackets. The guide apertures  20  may also be deformable to aid in the removal of the indirect bonding tray  10 . 
     In some embodiments, indirect bonding tray  10  of the present invention are made from an elastic polymeric material that generally conforms to a patient&#39;s teeth, and may be transparent, translucent, or opaque. In some embodiments, the tray  10  is a clear or substantially transparent polymeric material that may include, for example, one or more of amorphous thermoplastic polymers, semi-crystalline thermoplastic polymers and transparent thermoplastic polymers chosen from polycarbonate, thermoplastic polyurethane, acrylic, polysulfone, polyprolylene, polypropylene/ethylene copolymer, cyclic olefin polymer/copolymer, poly-4-methyl-1-pentene or polyester/polycarbonate copolymer, styrenic polymeric materials, polyamide, polymethylpentene, polyetheretherketone and combinations thereof. In another embodiment, the tray  10  may be chosen from clear or substantially transparent semi-crystalline thermoplastic, crystalline thermoplastics and composites, such as polyamide, polyethylene terephthalate. polybutylene terephthalate, polyester/polycarbonate copolymer, polyolefin, cyclic olefin polymer, styrenic copolymer, polyetherimide, polyetheretherketone, polyethersulfone, polytrimethylene terephthalate, and mixtures and combinations thereof. In some embodiments, the tray  10  is a polymeric material chosen from polyethylene terephthalate, polyethylene terephthalate glycol, poly cyclohexylenedimethylene terephthalate glycol, and mixtures and combinations thereof. One example of a commercially available material suitable as the elastic polymeric material, which is not intended to be limiting, is DURAN 3413, a clear sheet of polyethylene terephthalate, glycol modified (PETg), available from Scheu Dental Tech of Iserlohn, Germany. Another example of suitable material is ethylene vinyl acetate. 
     If the indirect bonding tray  10  is made of a material having high modulus and low elongation, such as three-dimensional printed methacrylate resin, then the template is frangible and will break at the compliant mechanisms  70 , such as a score line, a weakened portion, or an engineered line of weakness. If the tray  10  is made of a material having a relatively lower modulus and higher elongation, such as thermoformed PETG, then the template will bend at the compliant mechanisms  70 , but remain intact with the remaining of the template while allowing the portion to be removed from the patient&#39;s mouth. To form certain complaint mechanisms  70   a - c , excess material could be trimmed away after thermoforming, such as with a five-axis CNC mill, a LASER cutter or a water knife. The guide apertures  20  could be cut similarly. 
     The indirect bonding tray  10  may be manufactured by a three-dimensional (3D) printing process (e.g. additive manufacturing), such as stereolithography (SLA). Alternatively, a suitable method of manufacture is thermoforming the dental indirect bonding tray, followed by computer numerical control (CNC) trimming, or robotic trimming, of excess material, or to cut apertures, slots, perforations, or the like. 
       FIG.  10    is a schematic block diagram describing a workflow used to make an indirect bonding tray for indirect bonding orthodontic appliances on a patient&#39;s teeth according to exemplary embodiments of the present invention. The first block, designated by the numeral  100 , represents the step of providing a virtual model of a patient&#39;s dental structure, as illustrated in  FIG.  1   . This virtual model of the patient&#39;s dental structure can be obtained using digital data provided using a hand-held intra-oral scanner such as the intra-oral scanner commercially available from 3M Company (St. Paul) as 3M™ True Definition Scanner. Alternatively, other intra-oral scanners or intra-oral contact probes may be used. As another option, the digital data may be obtained by scanning an impression or other negative replica of the patient&#39;s dental structure. As still another option, the virtual model representing the patient&#39;s dental structure may be obtained by scanning a positive replica of such dental structure or by using a contact probe on the positive replica. The positive replica used for scanning may be made by pouring a casting material (such as plaster of Paris or epoxy resin) into an impression of the patient&#39;s teeth and allowing the casting material to cure. If scanning is used, any suitable scanning technique may then be used to obtain the virtual arch model representing the patient&#39;s dental structure, including X-ray scanning, laser scanning, computed tomography (CT), magnetic resonance imaging, or blue light scanning, such as GOM ATOS 3D scanner. 
     Additional steps may be used to further refine the digital data before rendering the virtual arch model of the patient&#39;s dental structure. For example, the digital data representing the virtual model may be additionally filtered or processed by removing erroneous data points. For example, STL (stereolithography) data files representing a tooth surface that include a data point significantly outside the normal expected geometrical relationship of adjacent data points could be fixed by STL-handling software to remove the erroneous data points. In addition, tooth data points that are missing could be added by software that manipulates STL files to create realistic, smoothly curved tooth shapes. In some embodiments, data processing is carried out before conversion of the data to an STL file. 
     The workflow then proceeds to block  102 , where one or more virtual orthodontic appliances are placed at desired locations on the teeth of arch model to form a composite model. For one embodiment of the present invention, the orthodontic appliances are represented by labial brackets. In an alternative embodiment, the orthodontic appliances are represented by lingual brackets. In yet another embodiment, the orthodontic appliances are represented by attachments for improving the engagement of Clear Tray Aligners (CTAs). Regardless, the orthodontic appliances including their overall shape and corresponding bases for attachment to the teeth are directly provided in the form of an STL file, or other digital image, by the appliance manufacturer. One suitable appliance manufacturer is 3M Company based in St. Paul. 3M Company provides ceramic orthodontic brackets commercially as 3M™ Clarity™ brackets, metal brackets commercially as Victory Series™ brackets, Unitek™ brackets, and SmartClip™ self-ligating brackets, and brackets having uncured adhesive on the bracket bases commercially available as APC™ II brackets, APC™ PLUS brackets, and APC™ Flash-Free brackets. Alternatively, the digital images representing the orthodontic appliances may be provided by scanning the physical appliance, or appliances, themselves. Preferably, the orthodontic appliances are exact virtual replicas of the physical appliances to be bonded to the teeth of the patient. 
     The desired locations for the virtual orthodontic appliances on the teeth of the virtual dental arch model of the patient can be determined in any of a number of ways. In one example, the treating professional manually selects and places the virtual orthodontic appliances directly on the model using the local computer. In some embodiments, the modeling software treats each appliance and each tooth as a separate object within the 3D environment and fixes the position of each orthodontic appliance within the 3D space relative to a coordinate system associated with the tooth of the corresponding appliance. The modeling software can then, for example, virtually connect the virtual orthodontic appliances to a virtual arch wire selected by the practitioner and compute the final positions of the teeth based on the positions of the orthodontic appliances and the selected arch wire. The modeling software can then display the virtual teeth in their final occlusion for review by the treating professional. 
     If the treating professional is not entirely satisfied with the final predicted positions of the teeth, the treating professional may use the modeling software to manipulate one or more of the virtual orthodontic appliances relative to the virtual teeth. Based on these adjustments, the modeling software can again virtually connect the virtual orthodontic appliances to the virtual arch wire, for example, to simulate the movement of teeth to new final positions. The new final positions of the teeth, determined by the positions of corresponding virtual appliances, are then computed and displayed for review. These steps can be repeated as many times as desired until the treating professional is satisfied with the final positions of the teeth as represented by the modeling software. As an alternative to moving appliances, the treating professional may instead use the modeling software to define the desired positions of teeth, and have the modeling software determine the suitable locations to place the virtual orthodontic appliances in order to move the teeth to those desired positions. Examples of virtual orthodontic treatment are disclosed in issued U.S. Pat. No. 6,739,869 (Kopelman et al.), U.S. Pat. No. 7,354,268 (Raby et al.) and U.S. Pat. No. 7,993,133 (Cinader, Jr. et al.), all of which are hereby incorporated. 
     As another option, the step in block  102  may be carried out by a technician at a location remote from the treating professional&#39;s office. For example, a technician at the orthodontic appliance manufacturer&#39;s facility may use the modeling software to place orthodontic appliances on the arch model based on standards or guidelines from an orthodontic treatment philosophy, such as for example that of Drs. MacLaughlin, Bennett, and Trevisi. These standards or guidelines for appliance placement may be specific to each tooth in model, and call out the position of the arch wire slot (an occlusal-gingival height, for example) with respect to the clinical crown of each tooth. The technician may also place orthodontic appliances in accordance with particular instructions provided by the treating professional. Once the technician is satisfied with the orthodontic appliance positions and the resulting finished positions of the teeth, the model, together with the data representing the positions of orthodontic appliances, are transmitted to the treating professional for review. The treating professional can then either approve the technician&#39;s appliance placement positions or reposition the orthodontic appliances as desired. 
     As yet another option, the local computer can automatically suggest locations of orthodontic appliances on the teeth to the treating professional. Again, these proposed orthodontic appliance locations are optionally based upon an orthodontic treatment philosophy or other known standards or guidelines in the art. Examples of automatically placing virtual brackets on teeth are described in issued U.S. Pat. No. 7,210,929 (Raby et al.), U.S. Pat. No. 8,517,727 (Raby et al.) and U.S. Pat. No. 7,940,258 (Stark et al.), all of which are hereby incorporated by reference. As before, the treating professional has the opportunity to review the computer-proposed locations of orthodontic appliances and can either approve the placement positions or reposition the orthodontic appliances as desired. 
     Next, block  104  illustrates the derivation of a mold body that a patient-specific, customized fit with a plurality of teeth in the patient&#39;s dental arch and the desired locations for the selected orthodontic appliances when bonded to the teeth. In this embodiment, the derivation proceeds by defining a guidance line that extends across at least a portion of the arch. The guidance line follows a curved path that is generally parallel to the facial surfaces of the teeth and generally lies in an occlusal plane. However, one or more guidance lines may also be defined which traverse the occlusal or lingual surfaces of the arch. In one computer-assisted embodiment, the guidance lines are defined by tracing a line segment that connects the facial-most edges of teeth as viewed from the occlusal direction, offsetting the line segment outwardly towards the facial direction by a certain distance and then applying a smoothing operation to the line segment. The process in block  104  continues by defining a series of fitted arcs, each of which extends over the lingual, occlusal, and facial surfaces of the virtual model of the teeth in the dental arch and intersects each guidance line in a generally perpendicular relationship such that each fitted arc passes over without contacting the model. In this example, each fitted arc is generally semi-circular in shape and begins at a location lingual relative to the teeth and terminates at a location facial to the teeth. 
     The outer surface of the model represents the exterior surface of the mold body and may be formed by fitting a surface to the set of fitted arcs. In some embodiments, the outer surface is an open-ended shell that completely covers the occlusal, lingual, and facial sides of the assembly that includes the model, desired locations for the appliances intended to be later bonded through the guide apertures, and desired custom-engineered compliant mechanisms, as discussed above, which will aid in the removal of the mold body from the dental arch. Optionally, a surface smoothing operation is subsequently executed on the outer surface. Then, a virtual mold body is derived using the outer surface. When virtually aligned with the virtual arch model, the mold body surrounds both the teeth, provides optimized locations for the orthodontic appliances to be later mounted through guide apertures, and provides locations and shapes of the custom-engineered complaint mechanism to be used later in removal of the mold body from the dental arch, after the orthodontic appliances are bonded to the surface of the teeth. 
     Next, there is a virtual subtraction of the specific patient&#39;s dental structure model to produce a virtual mold body precursor. The mold body precursor includes the mold body, which now has a shell-like configuration and further includes locations for the guide apertures formed by the bases of the negative virtual imprints of the selected orthodontic appliances and locations for the custom-engineered appliances and further includes the positioning portions and orthodontic appliance holders 
     In block  106 , a finished virtual indirect bonding tray is produced by molding and trimming a mold body to create a gingival edge, guide apertures shaped to allow placement of the intended orthodontic appliances on the surfaces of the selected teeth, orthodontic positioning portions and appliance holders, and optional custom-engineered compliant mechanisms that will aid in removal of the mold body from the dental arch, after one or more of the orthodontic appliances are bonded to the surface of the teeth. 
     It is noted that the above steps in blocks  102 - 106  represent just one possible sequence of steps used to produce the finished virtual indirect bonding tray. Further steps or substitutions of the above steps may be used to accomplish the same result. Moreover, the steps described need not be executed in the exact order shown above. 
     Block  108  shows the fabrication of a physical mold body from the virtual mold using additive manufacturing techniques. As used herein, “additive manufacturing” is a process that takes virtual designs from Computer Aided Design (CAD) or other modeling software, transforms them into a series of thin, virtual, horizontal cross-sections and then re-constructs each cross-section in physical space, one after the next until the model is finished. For example, an additive manufacturing machine may read in data from a CAD drawing and lay down successive layers of liquid, powder, or sheet material, in order to build up the physical model. By automatically aligning and fusing together a series of cross-sections, the virtual model and physical model can correspond almost identically. Advantageously, the layer-by-layer aspect of rapid prototyping allows the creation of nearly any shape or geometric feature. As an added benefit, rapid prototyping also provides flexibility to fabricate articles that include two or more interpenetrating components with substantially different material properties. 
     Particular examples of “additive manufacturing” techniques include, but are not limited to, three-dimensional (3D) printing, selective area laser deposition or Selective Laser Sintering (SLS), electrophoretic deposition, robocasting, Fused Deposition Modeling (FDM), Laminated Object Manufacturing (LOM), stereolithography (SLA) and photostereolithography. Issued U.S. Pat. Nos. 5,340,656, 5,490,882, 5,204,055, 5,518,680, 5,490,962, 5,387,380, 5,700,289, 5,518,680, and 4,672,032 describe examples of suitable additive manufacturing techniques (also known historically and in certain applications as “rapid prototyping” techniques). Particularly suitable additive manufacturing machines include the VIPER brand SLA system from 3D Systems (Rock Hill, S.C.), EDEN brand 500V printer from Objet Geometries Ltd. (Rehovot, ISRAEL), and ProMaker MovingLight 3D technology DLP printer from Prodways (Les Mureaux, France). 
     Once fabricated, the resulting physical mold body will be the finished indirect bonding tray  10  of the present invention, including all designed-in guide apertures  20 , guides  18  including both holders  44  and positioning portions  45 , and one or more of the custom-engineered compliant mechanisms for a specific patient. The indirect bonding tray  10  may then be used by the orthodontist to direct bond the selected orthodontic appliances onto the patient&#39;s teeth, as discussed in detail above. 
     Alternatively, the workflow could include first the step of additive manufacturing the physical mold body in block  108  followed thereafter by trimming the resulting physical mold body to include the prior designed guide apertures and compliant mechanisms as represented by block  110 . One example of a suitable trimming tool is a Roland DWX-50 5-Axis Dental Milling Machine, available from Roland DGA Corporation (Irvine, Calif.). 
     The complete disclosures of the patents, patent documents, and publications cited herein are incorporated by reference in their entirety as if each were individually incorporated. A number of other variations, modifications and additions are also possible without departing from the spirit of the invention. Accordingly, the invention should not be deemed limited to the specific embodiments described above, but instead only by a fair scope of the claims that follow and their equivalents.