Patent Description:
<CIT> describes a method for stereolithographically making an object by alternating the order in which similar sets of vectors are exposed over two or more layers.

<CIT> describes orthodontic devices produced by direct fabrication techniques.

One promising application of additive manufacturing is the manufacturing of oral appliances and components. However, some aspects of additive manufacturing have made this approach less than ideally suited for at least some oral appliances. For example, directly fabricated polymers may have less than ideal strength and can warp in at least some instances.

Generally, when directly fabricating photopolymers, the amount of light energy delivered to the initial layers can be substantially greater than the amount of light energy used to fabricate the rest of the part. The amount of light energy is related to the amount of polymer cross linking in the directly fabricated photopolymer. The light energy may be increased for the first layers to increase adhesion between the photopolymer and a fabricate platform. If the initial layers, also referred to as the 'burn in' layers, do not provide adequate adhesion, the part may not the fabricated successfully. The light energy can also be increased for the initial layers to compensate for inaccuracies in the initial levelling process, in which the application platform is less than ideally aligned with the optical beam components used to fabricate the layers. The light energy may reduce for the remaining layers, which can be directly fabricated with similar amounts of light energy.

Changing the amount of light energy among the layers can cause warpage of the part in at least some instances. Delivering different amounts of light energy to different layers typically results in different amounts of crosslinking in the layers. The photopolymers can shrink when cured, and the amount of shrinkage can be related to the amount of crosslinking. Varying amounts of crosslinking and curing may produce different levels of shrinkage within a part. The differing amounts of shrinkage can lead to the development of internal stresses within the part that may manifest as warpage or curling.

This effect can be further enhanced with directly fabricated parts in which the lateral dimensions of the part along the build platform area are large compared to the thickness of the part along the fabrication direction. Additionally, structures that are located away from the build platform may experience movement as the base structure warps. To decrease these effects, parts can be suspended away from the build platform and held there by thin pillars that join the part to the platform. However, such pillars may take additional time to fabricate and may be removed in a subsequent manufacturing step, increasing the time and complexity of the manufacturing process.

In light of the above, there is a need for improved methods and apparatus for deposition manufacturing and for parts that can be manufactured with decreased warpage. Ideally, such methods, apparatus and parts will overcome at least some of the aforementioned limitations of the prior approaches.

The methods and apparatus disclosed herein allow manufacturing of oral appliances such as dental devices with fewer steps and decreased deformation such as warpage. The methods and apparatus allow directly fabricating oral devices that reduce warpage when directly fabricated directly to a build platform. In some embodiments, an oral appliance comprises an elongate structure with a surface directly fabricated on a platform of a additive manufacturing machine, such as a 3D printer, in which the oral appliance comprises one or more structures to decrease deformation and decrease manufacturing steps, such as the removal of standoffs.

A better understanding of the features, advantages and principles of the present disclosure will be obtained by reference to the following detailed description that sets forth illustrative embodiments, and the accompanying drawings of which:.

The following detailed description and provides a better understanding of the features and advantages of the inventions described in the present disclosure in accordance with the embodiments disclosed herein. Although the detailed description includes many specific embodiments, these are provided by way of example only and should not be construed as limiting the scope of the inventions disclosed herein. The methods, apparatus and dental appliances disclosed herein are well suited for combination with many dental appliances and applications, such as an aligner for aligning a plurality of teeth, a retainer, a palatal expander, a bracket for placing attachments on a plurality of teeth, an attachment for coupling to teeth, a nightguard, a functional appliance, and a directly fabricated aligner thermoforming mold. The presently disclosed methods, apparatus and appliances are well suited for direct fabrication with deposition manufacturing, sometimes referred to as additive manufacturing or 3D printing, fused deposition modeling, stereo lithography (SLA), digital light projector (DLP) printing, continuous DLP, inkjet spray, and metal printing. Also, the presently disclosed methods and apparatus are well suited for the additive manufacturing of different materials onto a single appliance, such as inkjet printing with a plurality of different materials to fabricate an appliance comprising a plurality of different materials.

In some embodiments, the orthodontic appliances herein (or portions thereof) can be produced using direct fabrication, such as additive manufacturing techniques (also referred to herein as "3D printing"). Additive manufacturing techniques can be categorized as follows: (<NUM>) vat photopolymerization (e.g., stereolithography), in which an object is constructed layer by layer from a vat of liquid photopolymer resin; (<NUM>) material jetting, in which material is jetted onto a build platform using either a continuous or drop on demand (DOD) approach; (<NUM>) binder jetting, in which alternating layers of a build material (e.g., a powder-based material) and a binding material (e.g., a liquid binder) are deposited by a print head; (<NUM>) fused deposition modeling (FDM), in which material is drawn though a nozzle, heated, and deposited layer by layer; (<NUM>) powder bed fusion, including but not limited to direct metal laser sintering (DMLS), electron beam melting (EBM), selective heat sintering (SHS), selective laser melting (SLM), and selective laser sintering (SLS); (<NUM>) sheet lamination, including but not limited to laminated object manufacturing (LOM) and ultrasonic additive manufacturing (UAM); and (<NUM>) directed energy deposition, including but not limited to laser engineering net shaping, directed light fabrication, direct metal deposition, and 3D laser cladding. For example, stereolithography can be used to directly fabricate one or more of the appliances herein. In some embodiments, stereolithography involves selective polymerization of a photosensitive resin (e.g., a photopolymer) according to a desired cross-sectional shape using light (e.g., ultraviolet light). The object geometry can be built up in a layer-by-layer fashion by sequentially polymerizing a plurality of object cross-sections. As another example, the appliances herein can be directly fabricated using selective laser sintering. In some embodiments, selective laser sintering involves using a laser beam to selectively melt and fuse a layer of powdered material according to a desired cross-sectional shape in order to build up the object geometry. As yet another example, the appliances herein can be directly fabricated by fused deposition modeling. In some embodiments, fused deposition modeling involves melting and selectively depositing a thin filament of thermoplastic polymer in a layer-by-layer manner in order to form an object. In yet another example, material jetting can be used to directly fabricate the appliances herein. In some embodiments, material jetting involves jetting or extruding one or more materials onto a build surface in order to form successive layers of the object geometry.

In some embodiments, the direct fabrication methods provided herein build up the object geometry in a layer-by-layer fashion, with successive layers being formed in discrete build steps. Alternatively or in combination, direct fabrication methods that allow for continuous build-up of an object geometry can be used, referred to herein as "continuous direct fabrication. " Various types of continuous direct fabrication methods can be used. As an example, in some embodiments, the appliances herein are fabricated using "continuous liquid interphase printing," in which an object is continuously built up from a reservoir of photopolymerizable resin by forming a gradient of partially cured resin between the building surface of the object and a polymerization-inhibited "dead zone. " In some embodiments, a semi-permeable membrane is used to control transport of a photopolymerization inhibitor (e.g., oxygen) into the dead zone in order to form the polymerization gradient. Continuous liquid interphase printing can achieve fabrication speeds about <NUM> times to about <NUM> times faster than other direct fabrication methods, and speeds about <NUM> times faster can be achieved with the incorporation of cooling systems. Continuous liquid interphase printing is described in <CIT>, <CIT>, and <CIT>.

As another example, a continuous direct fabrication method can achieve continuous build-up of an object geometry by continuous movement of the build platform (e.g., along the vertical or Z-direction) during the irradiation phase, such that the hardening depth of the irradiated photopolymer is controlled by the movement speed. Accordingly, continuous polymerization of material on the build surface can be achieved. Such methods are described in <CIT>.

In another example, a continuous direct fabrication method can involve extruding a composite material composed of a curable liquid material surrounding a solid strand. The composite material can be extruded along a continuous three-dimensional path in order to form the object. Such methods are described in <CIT>.

In yet another example, a continuous direct fabrication method utilizes a "heliolithography" approach in which the liquid photopolymer is cured with focused radiation while the build platform is continuously rotated and raised. Accordingly, the object geometry can be continuously built up along a spiral build path. Such methods are described in <CIT>.

The direct fabrication approaches provided herein are compatible with a wide variety of materials, including but not limited to one or more of the following: polymer matrix reinforced with ceramic or metallic polymers, a polyester, a co-polyester, a polycarbonate, a thermoplastic polyurethane, a polypropylene, a polyethylene, a polypropylene and polyethylene copolymer, an acrylic, a cyclic block copolymer, a polyetheretherketone, a polyamide, a polyethylene terephthalate, a polybutylene terephthalate, a polyetherimide, a polyethersulfone, a polytrimethylene terephthalate, a styrenic block copolymer (SBC), a silicone rubber, an elastomeric alloy, a thermoplastic elastomer (TPE), a thermoplastic vulcanizate (TPV) elastomer, a polyurethane elastomer, a block copolymer elastomer, a polyolefin blend elastomer, a thermoplastic co-polyester elastomer, a thermoplastic polyamide elastomer, or combinations thereof. The materials used for direct fabrication can be provided in an uncured form (e.g., as a liquid, resin, powder, etc.) and can be cured (e.g., by photopolymerization, light curing, gas curing, laser curing, crosslinking, etc.) in order to form an orthodontic appliance or a portion thereof. The properties of the material before curing may differ from the properties of the material after curing. Once cured, the materials herein can exhibit sufficient strength, stiffness, durability, biocompatibility, etc. for use in an orthodontic appliance. The post-curing properties of the materials used can be selected according to the desired properties for the corresponding portions of the appliance.

In some embodiments, relatively rigid portions of the orthodontic appliance can be formed via direct fabrication using one or more of the following materials: a polyester, a co-polyester, a polycarbonate, a thermoplastic polyurethane, a polypropylene, a polyethylene, a polypropylene and polyethylene copolymer, an acrylic, a cyclic block copolymer, a polyetheretherketone, a polyamide, a polyethylene terephthalate, a polybutylene terephthalate, a polyetherimide, a polyethersulfone, and/or a polytrimethylene terephthalate.

In some embodiments, relatively elastic portions of the orthodontic appliance can be formed via direct fabrication using one or more of the following materials: a styrenic block copolymer (SBC), a silicone rubber, an elastomeric alloy, a thermoplastic elastomer (TPE), a thermoplastic vulcanizate (TPV) elastomer, a polyurethane elastomer, a block copolymer elastomer, a polyolefin blend elastomer, a thermoplastic co-polyester elastomer, and/or a thermoplastic polyamide elastomer.

Optionally, the direct fabrication methods described herein allow for fabrication of an appliance including multiple materials, referred to herein as "multi-material direct fabrication. " In some embodiments, a multi-material direct fabrication method involves concurrently forming an object from multiple materials in a single manufacturing step using the same fabrication machine and method. For instance, a multi-tip extrusion apparatus can be used to selectively dispense multiple types of materials (e.g., resins, liquids, solids, or combinations thereof) from distinct material supply sources in order to fabricate an object from a plurality of different materials. Such methods are described in <CIT>. Alternatively or in combination, a multi-material direct fabrication method can involve forming an object from multiple materials in a plurality of sequential manufacturing steps. For instance, a first portion of the object can be formed from a first material in accordance with any of the direct fabrication methods herein, then a second portion of the object can be formed from a second material in accordance with methods herein, and so on, until the entirety of the object has been formed. The relative arrangement of the first and second portions can be varied as desired, e.g., the first portion can be partially or wholly encapsulated by the second portion of the object. The sequential manufacturing steps can be performed using the same fabrication machine or different fabrication machines, and can be performed using the same fabrication method or different fabrication methods. For example, a sequential multi-manufacturing procedure can involve forming a first portion of the object using stereolithography and a second portion of the object using fused deposition modeling.

Direct fabrication can provide various advantages compared to other manufacturing approaches. For instance, in contrast to indirect fabrication, direct fabrication permits production of an orthodontic appliance without utilizing any molds or templates for shaping the appliance, thus reducing the number of manufacturing steps involved and improving the resolution and accuracy of the final appliance geometry. Additionally, direct fabrication permits precise control over the three-dimensional geometry of the appliance, such as the appliance thickness. Complex structures and/or auxiliary components can be formed integrally as a single piece with the appliance shell in a single manufacturing step, rather than being added to the shell in a separate manufacturing step. In some embodiments, direct fabrication is used to produce appliance geometries that would be difficult to create using alternative manufacturing techniques, such as appliances with very small or fine features, complex geometric shapes, undercuts, interproximal structures, shells with variable thicknesses, and/or internal structures (e.g., for improving strength with reduced weight and material usage). For example, in some embodiments, the direct fabrication approaches herein permit fabrication of an orthodontic appliance with feature sizes of less than or equal to about <NUM>, or within a range from about <NUM> to about <NUM>, or within a range from about <NUM> to about <NUM>.

The direct fabrication techniques described herein can be used to produce appliances with substantially isotropic material properties, e.g., substantially the same or similar strengths along all directions. In some embodiments, the direct fabrication approaches herein permit production of an orthodontic appliance with a strength that varies by no more than about <NUM>%, about <NUM>%, about <NUM>%, about <NUM>%, about <NUM>%, about <NUM>%, or about <NUM>% along all directions. Additionally, the direct fabrication approaches herein can be used to produce orthodontic appliances at a faster speed compared to other manufacturing techniques. In some embodiments, the direct fabrication approaches herein allow for production of an orthodontic appliance in a time interval less than or equal to about <NUM> hour, about <NUM> minutes, about <NUM> minutes, about <NUM> minutes, about <NUM> minutes, about <NUM> minutes, about <NUM> minutes, about <NUM> minutes, about <NUM> minutes, about <NUM> minutes, about <NUM> minutes, or about <NUM> seconds. Such manufacturing speeds allow for rapid "chair-side" production of customized appliances, e.g., during a routine appointment or checkup.

In some embodiments, the direct fabrication methods described herein implement process controls for various machine parameters of a direct fabrication system or device in order to ensure that the resultant appliances are fabricated with a high degree of precision. Such precision can be beneficial for ensuring accurate delivery of a desired force system to the teeth in order to effectively elicit tooth movements. Process controls can be implemented to account for process variability arising from multiple sources, such as the material properties, machine parameters, environmental variables, and/or post-processing parameters.

Material properties may vary depending on the properties of raw materials, purity of raw materials, and/or process variables during mixing of the raw materials. In many embodiments, resins or other materials for direct fabrication should be manufactured with tight process control to ensure little variability in photo-characteristics, material properties (e.g., viscosity, surface tension), physical properties (e.g., modulus, strength, elongation) and/or thermal properties (e.g., glass transition temperature, heat deflection temperature). Process control for a material manufacturing process can be achieved with screening of raw materials for physical properties and/or control of temperature, humidity, and/or other process parameters during the mixing process. By implementing process controls for the material manufacturing procedure, reduced variability of process parameters and more uniform material properties for each batch of material can be achieved. Residual variability in material properties can be compensated with process control on the machine, as discussed further herein.

Machine parameters can include curing parameters. For digital light processing (DLP)-based curing systems, curing parameters can include power, curing time, and/or grayscale of the full image. For laser-based curing systems, curing parameters can include power, speed, beam size, beam shape and/or power distribution of the beam. For printing systems, curing parameters can include material drop size, viscosity, and/or curing power. These machine parameters can be monitored and adjusted on a regular basis (e.g., some parameters at every <NUM>-x layers and some parameters after each build) as part of the process control on the fabrication machine. Process control can be achieved by including a sensor on the machine that measures power and other beam parameters every layer or every few seconds and automatically adjusts them with a feedback loop. For DLP machines, gray scale can be measured and calibrated before, during, and/or at the end of each build, and/or at predetermined time intervals (e.g., every nth build, once per hour, once per day, once per week, etc.), depending on the stability of the system. In addition, material properties and/or photo-characteristics can be provided to the fabrication machine, and a machine process control module can use these parameters to adjust machine parameters (e.g., power, time, gray scale, etc.) to compensate for variability in material properties. By implementing process controls for the fabrication machine, reduced variability in appliance accuracy and residual stress can be achieved.

In many embodiments, environmental variables (e.g., temperature, humidity, Sunlight or exposure to other energy/curing source) are maintained in a tight range to reduce variable in appliance thickness and/or other properties. Optionally, machine parameters can be adjusted to compensate for environmental variables.

In many embodiments, post-processing of appliances includes cleaning, post-curing, and/or support removal processes. Relevant post-processing parameters can include purity of cleaning agent, cleaning pressure and/or temperature, cleaning time, post-curing energy and/or time, and/or consistency of support removal process. These parameters can be measured and adjusted as part of a process control scheme. In addition, appliance physical properties can be varied by modifying the post-processing parameters. Adjusting post-processing machine parameters can provide another way to compensate for variability in material properties and/or machine properties.

Although specific reference is made to oral components, such as orthodontic devices and molds for orthodontic devices, the methods and apparatus disclosed herein will find application many fields such implantable devices, cardiology, orthopedics, and generally product design within the healthcare industry. It may also be useful in other industries such as aviation, automotive, in particular for component fabrication etc..

<FIG> illustrates an exemplary dental device <NUM> for positioning an attachment <NUM> on a patient's tooth <NUM>. One or more the components of the device <NUM> can be directly fabricated to inhibit warpage as described herein, and the device <NUM> may comprise at least one component directly fabricated with at least one layer to inhibit warpage as described herein. The dental device <NUM> may comprise a body <NUM>, an attachment <NUM> and one or more supports <NUM>. The dental device <NUM> can be sized and shaped to be positioned on a plurality of a patient's teeth present in an upper or lower jaw. The body <NUM> may include many suitable structures for placement on one or more of the patient's teeth, such as a thin shell polymeric appliance comprising a plurality of teeth receiving cavities sized and shaped to receive the patient's teeth. The dental device <NUM> may couple to the attachment <NUM> by one or more supports <NUM>, and the body <NUM> may comprise an opening so as to expose at least a portion of tooth <NUM> during placement of the attachment <NUM>. In some embodiments, the dental device <NUM> and the attachment <NUM> may be formed as a single component. For example, the dental device <NUM> and the attachment <NUM> may be directly fabricated at the same time using additive manufacturing as described herein. In other embodiments, some components of the dental device <NUM> are manufactured separately and coupled together prior to placement on the patient's teeth. For example, a freestanding attachment <NUM> can be coupled to the supports <NUM> using conventional joining techniques such as plastic welding or adhesives prior to placing the dental device <NUM> on the patient's tooth. The attachment <NUM> coupled to the body <NUM> prior to placement on the patient's teeth can allow the attachment to be accurately positioned on the patient's tooth. Once the attachment <NUM> has been appropriately positioned on the patient's tooth, the attachment <NUM> can be adhered to the tooth. The attachment <NUM> can be used to apply beneficial forces to the tooth with polymeric shell dental appliances. For example, the attachment can be used with the Invisalign® treatment commercially available from Align Technology.

The described devices and methods are applicable to the direct fabrication of the dental device <NUM> with the attachment <NUM> as a single component, direct fabrication of the dental device <NUM> with the attachment <NUM> as a separate component, or to the direct fabrication of the attachment <NUM>.

<FIG> illustrates the attachment <NUM> secured to a patient's tooth <NUM>. The attachment <NUM> may be used as an anchor in orthodontic procedures and may enhance the performance of an orthodontic device in the movement of teeth. In some examples, the attachment <NUM> may be bonded to the tooth by an adhesive. A surface of the attachment <NUM> may comprise a smooth surface to bond to the tooth, or have a texture to enhance the bonding between the tooth and the attachment <NUM>. The surface bonded to the tooth may have an attachment surface that is complementary to a surface of the tooth to which it is being bonded.

<FIG> shows an exemplary dental device <NUM> placed a patient's teeth. One or more the components of the device <NUM> can be directly fabricated to inhibit warpage, as described herein, and the device <NUM> may comprise at least one component fabricated with at least one layer to inhibit warpage, as described herein. The device <NUM> may comprise a surface <NUM>, which has been directly fabricated on, for example, a stereolithographic <NUM>-D printer. The surface <NUM> can be located on a side of the dental device opposite a tooth engaging surface of the device. The surface <NUM> may be located occlusal of the teeth. During fabrication, the surface <NUM> may be fabricated on a build platform, sometimes referred to a fabrication platform. In some embodiments, the surface <NUM> may comprise one or more burn in layers, as described herein. The at least one layer to inhibit warpage may comprise structures located in the burn in layer or other layers of the device, e.g. stress relieving structures, or structures located on different layers away from surface <NUM>, as described herein.

The dental device <NUM> comprises a body <NUM>, a plurality of attachments <NUM>, a plurality of supports <NUM> that couple the attachments <NUM> to the body <NUM>, a plurality of registration structures <NUM>, and a plurality of support structures <NUM> that couple the registration structures <NUM> to the body <NUM>. The body <NUM> may comprise one or more elongate structures <NUM>. The body <NUM> may comprise a single U-shaped component comprising one or more elongate structures <NUM>, or it may comprise a plurality of elongate structures <NUM> that may be joined together. The locations of each of the plurality of attachments on each of the teeth may be determined by a treatment professional with planning software, and the device <NUM> directly fabricated in accordance with the positions determined with the treatment planning software.

In use, the body <NUM> may provide a reference structure for positioning the attachments <NUM> relative to a patient's teeth while the registration structures <NUM> may secure and position the body <NUM> relative to the patient's teeth. While the registration structures can be placed on the patient's teeth in many ways, in some embodiments the registration structures are located on the body <NUM> for placement at mesial locations on the patient's teeth. The dental device <NUM> may be positioned in a patient's mouth with the registration structures <NUM> contacting the patient's teeth to orient the attachments <NUM> in a predetermined location. With the attachments <NUM> in the correct location, the attachment <NUM> may be bonded to the tooth. Once the attachments <NUM> are bonded to the tooth, the supports <NUM> may be removed from the attachments <NUM> freeing the dental device <NUM> from the patient's teeth. The dental device <NUM> may then be removed from the patient's mouth leaving the attachments <NUM> bonded to the patient's teeth in the desired locations, for example the predetermined locations.

In some embodiments, the elongate body <NUM> comprises one or more structures to decrease deformation, as described herein, to place the attachments <NUM> at the appropriate positions on the patient's teeth. For example, the one or more elongate structures <NUM> of body <NUM> may comprise the one or more structures to decrease deformation, as described herein, to place attachments <NUM> at the appropriate locations on the patient's teeth. While the one or more structures to decrease deformation can be configured in many ways, in some embodiments, the surface <NUM> comprises a plurality of stress relieving structures, such as a plurality of platforms. Alternatively or in combination, the elongate structures <NUM> may comprise a layer to inhibit warpage of the surface <NUM>, such as an opposing layer with a similar amount cross-lining and light exposure as the burn in layer of surface <NUM>.

<FIG> and <FIG> show an exemplary dental device <NUM> in connection with a <NUM>-D digital model <NUM> of a patient's teeth and <FIG> shows a portion of the dental device <NUM> in a free standing configuration. The <NUM>-D digital model <NUM> can be used as a basis to generate instructions to directly fabricate one or more components of the dental device <NUM>, and in some embodiments the entire dental device <NUM>. One or more the components of the device <NUM> can be directly fabricated to inhibit warpage, as described herein, and the device <NUM> may comprise at least one component directly fabricated with at least one layer to inhibit warpage, as described herein. The device <NUM> may comprise a surface <NUM>, which has been directly fabricated on an additive manufacturing device, such as <NUM>-D printer. These structures to decrease warpage can be identified on the <NUM>-D model prior to directly fabricating the dental device <NUM>. The surface <NUM> can be located on a surface or in directly fabricated layers of the device opposite a tooth engaging side of the device or between the tooth engaging side of the device and a tooth engaging side or surface of the device, and surface <NUM> can be identified on model <NUM>. The surface <NUM> may comprise one or more burn in layers, as described herein, and the model <NUM> configured accordingly. The at least one layer to inhibit warpage may comprises structures located in the burn in layer, e.g. stress relieving structures, or structures located on different layers away from surface <NUM>, as described herein. Each of these structures can be identified on the <NUM>-D model prior to directly fabricating the dental device <NUM>. For examples, the one or more elongate structures <NUM> can be configured for directly fabricating with structures to inhibit warpage, as described herein.

The dental device <NUM> comprises a body <NUM>, a plurality of attachments <NUM>, a plurality of supports <NUM> coupling the attachments <NUM> to the body <NUM>, registration structures <NUM>, and support structures <NUM> coupling the registration structures <NUM> to the body <NUM>.

<FIG> shows a vestibular view of the model <NUM> of the patient's teeth and the dental device <NUM>. As shown in <FIG>, the dental device <NUM> is sized and shaped to complement a patient's teeth. The body <NUM> may include recesses <NUM> that receive an occlusal surface of at least one tooth. The recesses <NUM> may be shaped to complement the occlusal surface of a patient's tooth. The plurality of supports <NUM> may couple to the body <NUM> and extend around an attachment <NUM>. A plurality of extensions <NUM> may extend from the support <NUM> to the attachment <NUM>. The extensions <NUM> may have a weaker structure than the supports <NUM> such that the extensions <NUM> are breakable at a coupling point with the attachment <NUM>. In use, after the attachment <NUM> is bonded to the tooth the extensions <NUM> may be broken at the coupling point and the dental device <NUM> may be removed from the patient's mouth, leaving the attachments <NUM> in place, and bonded to the patient's teeth.

<FIG> shows a lingual view of a patient's teeth and shows the registration structures <NUM> interacting with the patient's teeth. Each registration structure <NUM> is coupled to the body <NUM> by a support structure <NUM>. The registration structure <NUM> and the recesses <NUM> may secure the dental device <NUM> within a patient's mouth to position the attachments <NUM> at a predetermined position.

<FIG> shows a dental device <NUM> after directly fabricating the device <NUM>. The dental device <NUM> may be formed of a single structure or may be formed by a plurality of structures that are coupled together. For instance, each portion of the body <NUM> having a recess <NUM> for receiving a tooth may be formed separately from the remaining portions such that elements of the body <NUM> are joined by tooth receiving portions. The spacing between the attachments <NUM> and the registration structures <NUM> may be equal to the width of a patient's teeth at a particular location, or in some examples, the spacing may be slightly less that the width of a patients tooth such that an elastic deformation of the supports <NUM> or the support structures <NUM> is used to fit the dental device <NUM> over the patient's teeth. The resulting inward bias may help to position and hold the dental device <NUM> on the patient's teeth.

<FIG> shows a cross section of an example dental device <NUM> showing an example directly fabricated resin layers <NUM>. The dental device <NUM> is shown as having a body <NUM> and a structure <NUM> extending away from the body <NUM>. For example, structure <NUM> may comprise one or more of a support <NUM>, a support structure <NUM> or one or more elongate structures <NUM>. Although a single structure <NUM> is shown, a dental device may comprise a plurality of structures <NUM> extending from the body <NUM>, for example. In some embodiments, a dental device may not have a support structure. In some embodiments, the dental device <NUM> may be an orthodontic aligner and the layers <NUM> may be layers forming the orthodontic aligner, including the sidewalls of one or more tooth receiving cavities.

The dental device <NUM> comprises a plurality of successively directly fabricated layers <NUM>. A first layer <NUM> is directly fabricated directly on a build platform <NUM> and each successive layer is directly fabricated to each previous layer. If the build platform <NUM> is referenced as an X-Y plane with the Z axis extending away from the build platform <NUM>, then the cross section of <FIG> is shown along a plane perpendicular to the build platform <NUM> and parallel to the Z axis and shows each successive layer building in the Z direction. Thus, each layer increases the dimension of the dental device in the Z direction as each directly fabricated resin layer is formed.

In the example of <FIG>, the first layer <NUM> may comprise surface <NUM> of the dental device. In an orthodontic aligner, the first layer <NUM> may be a occlusal or incisal surface of an orthodontic aligner, and the device can be fabricated by directly fabricating each layer of resin with a similar amount of cross linking, so as to decrease deformation. In some embodiments, the amount of cross-linking may be controlled by adjusting the amount of light energy used to cure the resin. In some examples, the amount of light energy is selected to be just above the amount of light energy to adhere the first layer <NUM> to the build platform <NUM>. The dose may be delivered at a rate of <NUM> W/cm^<NUM>. In some embodiments, about refers to amounts between <NUM>% and <NUM>% of the amount of light energy to adhere the first layer to the build platform. In some embodiment, the amount may be between <NUM>% and <NUM>% of the amount, for example, so as to decrease deformation. In some embodiments, the layers may be cured with an energy dose sufficient to cure the resin to its green strength. In some embodiments, the layers may be cured with a dose of between <NUM>% and <NUM>% or between <NUM>% and <NUM>% of the green strength dose. In some embodiments, the layers may be cured with a dose less than the green strength dose. In some embodiments, the first layer may be cured with a dose sufficient to adhere the layer to the build platform and subsequent layers may be cured with a dose to cure the resin to its green strength. In some embodiments, subsequent layers may be cured to less than their green strength, such as at least <NUM>% less dose or <NUM>% less dose.

<FIG> shows a cross section of an example dental device <NUM> showing example layers for inhibiting warping of one or more components of the device, such as the body <NUM>. In this example, the first layer <NUM> is directly fabricated using an amount of light energy selected to be above a minimum amount for adhering the first layer <NUM> to the build platform <NUM>. Subsequent layers are cured with an amount of light sufficient to adhere the layer to the first layer <NUM> but maintain a consistent amount of light as layers are added. For example, the first layer <NUM> may be cured with a light dose sufficient to adhere the first layer to the build platform provided at a rate of. <NUM> W/cm^<NUM> and subsequent layers may be cured with a dose less than the dose of the first layer at a rate of. <NUM> W/cm^<NUM>. In some examples, each subsequent layer may have an amount of light, or dose that is less than <NUM>% of the amount of light used to cure the first layer. In some examples, each subsequent layer may have a light amount that is between <NUM>% and <NUM>% of a median light amount for the subsequent layers. This approach can be combined with approaches to inhibit deformation, as described herein.

<FIG> shows a cross section of an example dental device <NUM> showing example layers for inhibiting warping of the body <NUM>. In the example of <FIG>, a first layer <NUM> is cured using an amount of light energy, a dose, sufficient to adhere the first layer <NUM> to the build platform <NUM>. Another layer <NUM> can be directly fabricated similarly to first layer <NUM> so as to offset effects of stress of first layer <NUM>. After first layer <NUM> is cured, a plurality of subsequent layers <NUM> is cured using an amount of light energy less than the amount used to cure the first layer <NUM>. The layer <NUM> can be directly fabricated with an amount of light similar to layer <NUM>. The layer <NUM> may comprise an outer layer <NUM> of the body <NUM> opposite the first layer <NUM>. The layer <NUM> can be cured using an amount of light energy similar to the amount of the first layer <NUM>. In some examples, the layers between the first layer <NUM> and the outer layer <NUM> may be fabricated with an amount of light energy that is less than <NUM>% of the amount of light energy used to directly fabricate the first layer <NUM> and the outer layer <NUM>, for example. Although layer <NUM> is shown as an outer layer, layer <NUM> may comprise an inner layer located a sufficient distance from layer <NUM> to decrease deformation. In some embodiments, layer <NUM> may be an intermediate layer between the first layer and a final layer.

In some examples, each of the layers between the first layer <NUM> and the outer layer <NUM> may be fabricated using a similar amount of light energy. In other examples, the amount of light energy for the layers may be varied, but with a symmetrical relationship about a midline <NUM> of the body <NUM>. For example, after the first layer <NUM>, each subsequent layer may be cured using an amount of light energy lower than the previous amount up to the middle layer or midline <NUM>, between the first layer <NUM> and layer <NUM>. Each subsequent layer would be cured with an amount of light energy that is similar to the opposite layer relative to the middle layer or midline <NUM>. For example, if a first layer <NUM> were cured with a first dose amount, the second layer may be cured with a light energy of <NUM>% lower dose than the first dose. A third, mid layer may be cured with a light energy of <NUM>% lower dose than the first dose, a fourth layer opposite the second layer relative to the middle layer or midline <NUM> may be cured with an amount of <NUM>% lower dose than the first dose, and the outer layer <NUM>, which is opposite the first layer <NUM> relative to the midline <NUM> may be cured with an amount of light energy of the first dose. In some embodiments, each layer from the first layer to the midline may be cured with a dose that is stepwise reduced by <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>% or <NUM>% of the first dose and each layer from the midline to the outer layer may be cured with a dose that is stepwise increased by <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>% or <NUM>% of the first dose.

While this example lists only five layers, one of ordinary skill in the art will recognize that the symmetric pattern may be applied to any number of layers. In some embodiments, each successive layer between the first layer and the midline or middle layer is cured with successively lower amounts of energy and every successive layer between the midline or middle layer and the outer layer is cured with greater amounts of energy. In some embodiments, each subsequent layer between the first layer and the midline or middle layer is cured with <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>% or <NUM>% less than each previous layer. In some embodiments, each layer between the midline or middle layer and the outer layer is cured with <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>% or <NUM>% less than each subsequent layer.

<FIG> illustrates an example of a layer <NUM> of a body <NUM> having a pattern for inhibiting warpage. The layer <NUM> is viewed perpendicular to the build platform <NUM> and may represent a view of a single layer. In some embodiments, the layer <NUM> is shown as a curing mask for a layer. In some examples, a single layer may be fabricated using the pattern shown, or in other examples, the pattern may be repeated for multiple layers to form a platform. The layer <NUM> includes first areas <NUM> of resin cured using a light amount or first dose suitable for adhesion to the build platform <NUM> or a previous layer and second areas <NUM> of resin cured with a second dose or lower light amount or left uncured. In some embodiments, the mask depicts areas <NUM> where light energy is provided to cure the layer and areas <NUM> where less or no light energy is provided to cure the layer. The first areas <NUM> may comprise surface <NUM> of the dental device <NUM>. In some examples, in place of resin cured with a low light amount, the resin may be uncured such that no resin remains in the second areas when the part is removed from the build platform <NUM>. The pattern of <FIG> alternates the first areas <NUM> and the second areas <NUM> in a checkerboard pattern. The pattern may cover the entire surface of the body contacting the build platform <NUM>, or in some examples, the pattern may cover a limited area. These areas can be located on the first layer, for example. In some embodies, each layer formed of the object may be formed using a checkerboard, or alternating mask, such as that shown in <FIG>, for the internal structure of the object. In some embodiments, the infill percentage of between first areas <NUM> and second areas <NUM> may be <NUM>%, wherein the overall area of first areas and second areas is equal. In some embodiments, the infill percentage may be <NUM>%, wherein the first areas represent <NUM>% of the cross-sectional area of the layer, while second areas <NUM>, may represent <NUM>% of the cross-sectional area of the layer. In some embodiments, first areas may represent an amount equal to or greater than <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, or <NUM>% of the area of the layer while second areas represent an amount equal to or greater than <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, or <NUM>% of the area of the layer. In embodiments, wherein the first areas of a layer are at or greater than <NUM>%, the layer is continuous, in that the greater cured areas are connected across the layer, while in layers wherein the checkerboard pattern of a layer includes first areas with less than <NUM>%, then the first layers may not connect across the layer and the layer is discontinuous.

In some embodiments, a layer may include a third area cured at a third dose. The third area, similar to that of the first and second layers, may include an area equal to or greater than <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, or <NUM>% of the layer.

<FIG> illustrates an example layer or cure mask <NUM> of a body <NUM> having a pattern suitable for inhibiting warpage of a dental device <NUM>. The pattern of <FIG> includes first areas <NUM> of resin cured with a high light amount, such as a dose sufficient for the resin to achieve green strength or handling strength, and second areas <NUM> of resin having a low light amount or no light amount. The pattern of <FIG> is a tiled pattern, in which the first areas <NUM> of resin do not contact one another and are separated by the second areas <NUM> of resin having low or no curing. These areas <NUM> may comprise areas of the burn in layer, and may comprise areas of surface <NUM> of device <NUM>. Areas <NUM> may represent an amount equal to or greater than <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, or <NUM>% infill in a layer. Layer or mask <NUM> in <FIG> is discontinuous in all directions. In some embodiments, the layer or mask <NUM> may be used for any of the layers of a directly fabricated device.

In some embodiments, a similar pattern shown in mask <NUM> may be used to form the internal portion of each layer of a deice. In such embodiments, areas <NUM> of the layers form internal columns extending in the Z direction in the internal structure of a device, such as the sidewalls of an orthodontic aligner.

<FIG> illustrates an example layer or cure mask <NUM> of a body <NUM> having a pattern suitable for inhibiting warpage of a dental device <NUM>. The pattern of <FIG> comprises stripes of first areas <NUM> of resin cured with a high light amount, such as a dose sufficient for the resin to achieve green strength or handling strength, and stripes of second areas <NUM> of resin having a low light amount or no light amount. The pattern of <FIG> is a striped pattern. In some examples, the stripes of first areas <NUM> may run perpendicular to the longest dimension of the body <NUM> adhered to the build platform <NUM>. For example, if the body has a length greater than a width, then the stripes <NUM> may run the width of the body. These areas <NUM> may comprise areas of the burn in layer, and may comprise areas of surface <NUM> of device <NUM>. Areas <NUM> may represent an amount equal to or greater than <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, or <NUM>% infill in a layer. In some embodiments, the layer or mask <NUM> may be used for any of the layers of a directly fabricated device.

In some embodiments, a similar pattern shown in mask <NUM> may be used to form the internal portion of each layer of a deice. In such embodiments, areas <NUM> of the layers form internal wall extending in the Z direction in the internal structure of a device, such as the sidewalls of an orthodontic aligner. The walls may be said to be continuous along the length of the wall in the internal structure of the device, but discontinuous in directions between walls.

<FIG> illustrates an example cross section of a dental device. The dental device of <FIG> includes tapered platforms <NUM> that the reduce the amount of resin contacting the build platform <NUM>. The tapered platform structures <NUM> may be arranged in any of the patterns described in reference to <FIG>. The tapered platform structures <NUM> may extend through a plurality of layers. A plurality of grooves may extend between the plurality of platform structures <NUM>. In some examples, the layers may be cured using the previously described techniques to decrease deformation, e.g. warpage. These areas <NUM> may comprise areas of the burn in layer, and may comprise areas of surface <NUM> of device <NUM>. These areas <NUM> may comprise areas of the burn in layer, and may comprise areas of surface <NUM> of device <NUM>. With reference to <FIG>, in orthodontic aligner <NUM> is depicted. The orthodontic aligner <NUM> may include a plurality of tooth receiving cavity <NUM>. The orthodontic aligner <NUM> may be fabricated using additive manufacturing techniques such as those described herein. The additive manufacturing techniques described herein for reducing warpage and stress the fabricated part are well suited for devices having a low aspect ratio wherein the height along a build direction <NUM> such as the Z axis is greater than the cross-sectional size <NUM> of the device in an X - Y plane parallel to the build plate. The aspect ratio may be less than <NUM> (the height being one-fourth of the cross-sectional size), less than <NUM>, less than <NUM>, less than <NUM>, or less than <NUM>. The cross-sectional size may be a greatest distance between locations of the device within an X - Y plane.

<FIG> depicts a cross-section of the orthodontic aligner <NUM> of <FIG> taken along A-A of a tooth receiving cavity <NUM>. The tooth receiving cavity <NUM> includes a buccal sidewall <NUM> a lingual sidewall <NUM> and an occlusal wall <NUM>. Each sidewall includes an outward facing surface <NUM> and an inward facing surface <NUM>. The cross-section depicted in <FIG> shows how the internal structure or infill may be formed or cured such that the material reaches is green strength. In particular, the tooth receiving cavity structure is formed using one or more of the masks discussed above. For example, the mask <NUM> depicted in <FIG>. The first areas <NUM> of each layer form columns <NUM> of green strength material within the structure of the aligner <NUM> while the second areas <NUM> form portions of uncured or less cured resin between the columns <NUM>. In some embodiments, the columns may intersect the outer surfaces of the structure, such as the outward facing surface <NUM> and the inward facing surface <NUM>. In some embodiments, one or more of the infill columns <NUM> may begin at a first end on an external surface of the aligner and end at a second end on an external surface of the aligner. In some embodiments, the orthodontic aligner <NUM> is formed such that the lessor uncured volumes of resin corresponding to second areas <NUM> are held within the aligner between its external surfaces. After formation an curing of the external surfaces <NUM>, <NUM> and the first areas <NUM> of the aligner to a green strength, the aligner may be subjected to a secondary curing process wherein the uncured material or resin corresponding to the areas <NUM> are cured along with the first areas <NUM> to an ultimate or final strength.

<FIG> shows a cross section of the aligner along line B-B of <FIG>. The cross-section of the aligner <NUM> shows a single layer of the aligner in Annex light plane parallel to the plane of a build platform on which the aligner <NUM> is formed. The infill pattern <NUM> may be similar to the mask <NUM> shown in <FIG>. The cured or green strength portions of the aligner are represented by first areas <NUM> and perimeters <NUM> and <NUM> that represent the outer or external surfaces of the aligner. In some embodiments, first areas <NUM> may be intersected by the perimeters <NUM>, <NUM>. For example, first area <NUM> is intersected by perimeters <NUM> such that the first area <NUM> and the perimeters <NUM> are continuous with each other.

<FIG> shows a method <NUM> for fabricating devices described herein. At block <NUM> a three-dimensional model of the device, such as an orthodontic device, is sliced into a plurality of layers. Slicing process divides the three-dimensional model into a plurality of two-dimensional layers each representing a portion of the height of the device represented by the three-dimensional model. For example, if a layer height is <NUM> then each layer would represent a <NUM> thick portion of the device.

At block <NUM> a first mask for a first of the plurality of layers is determined. A mask may be a two-dimensional, planar, representation of the cross-section of the device at a particular layer height. For a first layer of a model divided into <NUM> layer heights, a first layer may represent the cross-sectional structure of the device at a height between zero and <NUM>. A first mask may include a projected image of an external perimeter and an infill for a first curing operation for first areas of the first layer. At block <NUM>, a light energy dose and radiation strength may be determined for curing first areas of the device within the first layer. The light energy dose may be sufficient to cure a resin to its green strength and adhere the resin to the build plate. For subsequent layers the light energy dose may be sufficient to cure the resin to its green strength and adhere the resin to the previously cured layer.

At block <NUM> a second mask for the first layer of the plurality of layers be determined. The second mask may include a projected image of an infill for a second curing operation for second areas of the first layer. In some embodiments, a second mask may include the perimeters, the first areas, and the second areas. At block <NUM>, a light energy dose and radiation strength may be determined for curing second areas of the device within the first layer. The light energy dose may be less than sufficient to cure a resin to its green strength. In some embodiments, the curing dose provided during exposure of the first mask may be insufficient for the material to reach its green strength, however the first areas may be cured to their green strength upon receiving a second dose according to the second mask that includes a mask of the first areas, the second areas, and the perimeters.

After completion of step <NUM> the process may repeat the steps <NUM> and <NUM> for each of the layers of the plurality of layers of the three-dimensional model.

At block <NUM> instructions performing the plurality of layers may be output. Outputting the instructions may include storing the instructions or sending them to a fabrication machine, such as an additive manufacturing machine.

At block <NUM> a first layer of the plurality of layers of a device is cured using the first mask for the first dose. At block <NUM> the first layer of the plurality of layers of the device is cured using the second mask at the second dose. Blocks <NUM> and <NUM> may be repeated for each of the plurality of layers of the device.

At block <NUM> a postprocessing or secondary curing process may occur. For example, after the formation of each of the layers the device in blocks <NUM> and <NUM>, the device may be subject to a secondary curing process by which the resin in the device including both the green strength rather than resin and the less than green strength resin are cured to their final or ultimate strength.

With reference to <FIG> shows an example schematic of an additive manufacturing device <NUM>, such as 3D printer. The additive manufacturing device <NUM> comprises a print head <NUM>, such as a projector, and a build platform <NUM>. The additive manufacturing device <NUM> comprises a processor <NUM>, which includes a central processing unit (CPU) <NUM> and memory <NUM>. The processor <NUM> can be configured with instructions to directly fabricate the appliance, as described herein. The instructions may comprise instructions to directly fabricate each of the plurality of layers along a direction of deposition in order to form the precursor appliance, as described herein. During the direct fabrication process the print head <NUM> prints each of the plurality of layers and the separation distance between the print head <NUM> and the build platform <NUM> increases. In some embodiments the printhead may be a projector the projected light according to the masks discussed herein.

Although <FIG> shows the additive manufacturing device <NUM> in a vertical orientation with a print head <NUM> located above a build platform <NUM>, other types of additive manufacturing devices are suitable for use with the disclosed embodiments. For example, the print head <NUM> can be located beneath the build platform <NUM>. In general, the direct fabrication process forms a single planar layer at a time that is approximately parallel to the build platform <NUM>. After forming a layer, the print head <NUM> may move away from the build platform <NUM> and a new layer is formed. Alternatively or in combination, the build platform <NUM> may move away from the print head <NUM>. Each successive layer is built on the previous layer, for example on top of or beneath the previous layer. Although the additive manufacturing device <NUM><NUM> is shown in a vertical orientation, other orientations can be used to one or more of the components as described herein, for example horizontal or oblique orientations.

<FIG> shows a schematic of a method <NUM> for manufacturing a dental device. At step <NUM>, direct fabrication configuration is selected to directly fabricate a plurality of layers of resin to form a body having a lower substantially planar surface and an upper surface. In some examples, at step <NUM>, a plurality of layers are directly fabricated with each of the plurality of layers cured to have a similar amount of polymer cross-linking. In some examples, at step <NUM>, a plurality of layers our directly fabricated with a first layer of the substantially planar surface and a second layer spaced from the first layer, in which each of the first layer and the second layer has an amount of polymer cross-linking greater than an amount of polymer cross-linking of a plurality of inner layers between the first layer and the second layer. In some examples, at step <NUM>, a plurality of layers are directly fabricated with an increased dimension of the body in the direction of potential warping, so as to decrease deformation, e.g. in the Z direction as described herein. In some examples, at step <NUM>, a plurality of layers are directly fabricated with the lower surface comprising a pattern of platforms defined with a plurality of grooves in the substantially planar surface.

Although <FIG> shows a method of manufacturing a dental device, in accordance with some embodiments, a person of ordinary skill in the art will recognize many adaptations and variations. For example, the steps can be performed in a different order, some of the steps repeated and some of the steps removed.

As detailed above, the computing devices and systems described and/or illustrated herein broadly represent any type or form of computing device or system capable of executing computer-readable instructions, such as those contained within the modules described herein. In their most basic configuration, these computing device(s) may each comprise at least one memory device and at least one physical processor.

The term "memory" or "memory device," as used herein, generally represents any type or form of volatile or non-volatile storage device or medium capable of storing data and/or computer-readable instructions. In one example, a memory device may store, load, and/or maintain one or more of the modules described herein. Examples of memory devices comprise, without limitation, Random Access Memory (RAM), Read Only Memory (ROM), flash memory, Hard Disk Drives (HDDs), Solid-State Drives (SSDs), optical disk drives, caches, variations or combinations of one or more of the same, or any other suitable storage memory.

In addition, the term "processor" or "physical processor," as used herein, generally refers to any type or form of hardware-implemented processing unit capable of interpreting and/or executing computer-readable instructions. In one example, a physical processor may access and/or modify one or more modules stored in the above-described memory device. Examples of physical processors comprise, without limitation, microprocessors, microcontrollers, Central Processing Units (CPUs), Field-Programmable Gate Arrays (FPGAs) that implement softcore processors, Application-Specific Integrated Circuits (ASICs), portions of one or more of the same, variations or combinations of one or more of the same, or any other suitable physical processor.

Although illustrated as separate elements, the method steps described and/or illustrated herein may represent portions of a single application. In addition, in some embodiments one or more of these steps may represent or correspond to one or more software applications or programs that, when executed by a computing device, may cause the computing device to perform one or more tasks, such as the method step.

In addition, one or more of the devices described herein may transform data, physical devices, and/or representations of physical devices from one form to another. For example, one or more of the devices recited herein may receive image data of a sample to be transformed, transform the image data, output a result of the transformation to determine a 3D process, use the result of the transformation to perform the 3D process, and store the result of the transformation to produce an output image of the sample. Additionally or alternatively, one or more of the modules recited herein may transform a processor, volatile memory, non-volatile memory, and/or any other portion of a physical computing device from one form of computing device to another form of computing device by executing on the computing device, storing data on the computing device, and/or otherwise interacting with the computing device.

The term "computer-readable medium," as used herein, generally refers to any form of device, carrier, or medium capable of storing or carrying computer-readable instructions. Examples of computer-readable media comprise, without limitation, transmission-type media, such as carrier waves, and non-transitory-type media, such as magnetic-storage media (e.g., hard disk drives, tape drives, and floppy disks), optical-storage media (e.g., Compact Disks (CDs), Digital Video Disks (DVDs), and BLU-RAY disks), electronic-storage media (e.g., solid-state drives and flash media), and other distribution systems.

A person of ordinary skill in the art will recognize that any process or method disclosed herein can be modified in many ways. The process parameters and sequence of the steps described and/or illustrated herein are given by way of example only and can be varied as desired.

The various exemplary methods described and/or illustrated herein may also omit one or more of the steps described or illustrated herein or comprise additional steps in addition to those disclosed. Further, a step of any method as disclosed herein can be combined with any one or more steps of any other method as disclosed herein.

Unless otherwise noted, the terms "connected to" and "coupled to" (and their derivatives), as used in the specification and claims, are to be construed as permitting both direct and indirect (i.e., via other elements or components) connection. In addition, the terms "a" or "an," as used in the specification and claims, are to be construed as meaning "at least one of. " Finally, for ease of use, the terms "including" and "having" (and their derivatives), as used in the specification and claims, are interchangeable with and shall have the same meaning as the word "comprising.

The processor as disclosed herein can be configured with instructions to perform any one or more steps of any method as disclosed herein.

As used herein, the term "or" is used inclusively to refer items in the alternative and in combination.

As used herein, characters such as numerals refer to like elements.

Claim 1:
A method (<NUM>) of manufacturing an oral device (<NUM>), comprising:
directly fabricating a plurality of layers of photopolymer resin to form a body (<NUM>) comprising a lower substantially planar surface and an upper surface; and
wherein the lower, planar surface is fabricated directly to a build platform and wherein at least a first one of the plurality of layers is cured with a first dose to a first strength and at least a second one of the plurality of layers is cured with a second dose to a second strength to inhibit warpage of the body, wherein a first layer at the planar surface and a second layer at the upper surface are directly fabricated with a greater amount of polymer cross-linking than an amount of polymer cross-linking of an inner plurality of layers between the first layer and the second layer, wherein the amount of cross-linking is controlled by the amount of light energy used to cure the layers.