Patent Application
20240138957
The subject matter of the present disclosure relates generally to the field of orthodontic devices. More particularly, the present disclosure relates to user removable orthodontic devices.
An objective of orthodontics is to move a patient's teeth to positions where function and/or aesthetics are optimized. Traditionally, appliances such as braces are applied to a patient's teeth by a treating practitioner and the set of braces exerts continual force on the teeth and gradually urges them toward their intended positions. Over time and with a series of clinical visits and reactive adjustments to the braces by the practitioner, the appliances to move the teeth toward their final destination.
More recently, alternatives to conventional orthodontic treatment with traditional affixed appliances (e.g., braces) have become available. For example, systems including a series of molded plastic aligners have become commercially available from Align Technology, Inc., San Jose, Calif, under the trade name Invisalign® System. The Invisalign® System is described in numerous patents and patent applications assigned to Align Technology, Inc. including, for example in U.S. Pat. Nos. 6,450,807, and 5,975,893.
The Invisalign® System typically includes designing and fabricating multiple aligners to be worn by the patient before the aligners are administered to the patient and used to reposition the teeth (e.g., at the outset of treatment). Often, designing and planning a customized treatment for a patient makes use of computer-based 3-dimensional planning/design tools. The design of the aligners relies on computer modeling of the patient's teeth in a series of planned successive tooth arrangements, and the individual aligners are designed to be worn over the teeth, such that each aligner exerts force on the teeth and elastically repositions the teeth to each of the planned tooth arrangements.
Arguably, such aligners are less noticeable than traditional braces because typically aligners are constructed from a transparent material, however, many believe that aligners are easily noticeable due to the glossy sheen of the transparent material. Like traditional braces, aligners are required to be worn nearly constantly (20-22 hours a day), with breaks allowed for eating and cleaning teeth. Only small breaks are allowed because aligners do not have enough flexibility to account for teeth drifting out of alignment, which is based on physical and material characteristics of the aligner. Increasing the working tolerance to account for higher drift requires increasing the working elasticity of an aligner, i.e., the amount an aligner can stretch to mount to teeth without causing permanent deformation, but a highly elastic aligner typically will not provide enough force to move teeth required for orthodontic treatment.
Additionally, it is not uncommon for a treatment case to veer “off-track”. By “off-track” it is meant that the prescribed aligner no longer fits the patient dentition. This phenomenon can arise due to a number of reasons the most common being the patient failing to wear the device as prescribed. When a treatment case goes “off-track”, the typical course of action is to restart the treatment from the beginning. This, of course, is inconvenient and undesirable for the lost time and cost.
Issues like these contribute to failed results or require restart of treatments because patients fail to wear the aligners according to prescribed requirements. A novel aligner that overcomes the above-mentioned challenges is therefore desirable.
Embodiments of the invention relate to orthodontic appliances, systems, and methods of use as summarized in the following paragraphs. Some embodiments relate to orthodontic appliances that maximize working elasticity.
Some embodiments relate to an orthodontic appliance that includes a set of stacked shells shaped to receive teeth. The shells are bonded to one another along a perimeter portion of the shells, and define a chamber (optionally liquid-tight) between the shells for accommodating motion and flex of the shell to contact the teeth. The shells may be bonded together mechanically and optionally chemically. In embodiments, the shells are made of different types of materials, and optionally transparent. In a preferred embodiment, the outer shell exposed to the mouth has a higher flexural modulus than the first shell to contact the teeth. Without intending to being bound to theory, the shell with less flex tends to maintain an overall force on the appliance to move the teeth even if the first shell is deformed to accommodate a wider range of teeth positions and/or correct teeth positions that have veered off-track.
Some embodiments relate to an orthodontic appliance that can have shells shaped to receive teeth. The shells can be stacked and substantially non-affixed to one another.
Some embodiments relate to an orthodontic appliance that can have shells shaped to receive teeth. The shells can be stacked and varyingly affixed to one another.
Some embodiments relate to an orthodontic appliance that can have a plurality of shells shaped to receive teeth being mechanically engaged and provide stiffness for applying force to reposition teeth and substantially non-affixed to maximize working elasticity.
Some embodiments relate to an orthodontic appliance that can have a stack of mechanically engaged shells. The stack of mechanically engaged shells can have a stiffness substantially equivalent to a single shell of the same thickness as the stack. The stack of mechanically engaged shells can have the ability to at least partially mechanically disengage to increase working elasticity.
Some embodiments relate to an orthodontic appliance that can have a first shell having cavities shaped to receive teeth. The orthodontic appliance can include a second shell than can be shaped to receive the first shell. The second shell can be stacked over the first shell. Surfaces between the first shell are second shell can be mechanically engaged but significantly non-affixed to each other.
In some embodiments, the second shell and first shell can be affixed to one another at discrete attachment locations of the first and second shells
In some embodiments, the first shell can have a bottom first surface for directly engaging the teeth and a top first surface opposite the bottom first surface. The second shell can have a bottom second surface for mechanically engaging the top first surface of the first shell and a top second surface opposite the bottom second surface. The top first surface and the bottom second surface are not significantly affixed to each other.
In some embodiments, the discrete attachment locations of fixation comprise less than 1-80% of the combined surface areas of the top first surface and the bottom second surface.
In some embodiments, the first shell has a first edge between top first and bottom first surfaces, and the second shell has a second edge between top second and bottom second surfaces, wherein the discrete attachment locations are located about the first and second edges.
In some embodiments, the shells can be made of the same material.
In some embodiments, a relatively highly elastic shell can be provided between said shells.
In some embodiments, the shells can include a first shell that can have cavities shaped to receive teeth, and at least one additional shell that can be shaped to receive the first shell, wherein the at least one additional shell can be stacked over the first shell.
In some embodiments, the first shell and at least one additional shell can be affixed to one another at discrete attachment locations of the first and at least one additional shell.
In some embodiments, the first shell can have a bottom first surface for directly engaging the teeth and a top first surface opposite the bottom first surface. The at least one additional shell can have a bottom second surface for mechanically engaging the top first surface of the first shell and a top second surface opposite the bottom second surface. The top first surface and the bottom second surface can be arranged to not be significantly affixed to each other.
In some embodiments, the first shell can have a first edge between top first and bottom first surfaces, and the at least one additional shell can have a second edge between top second and bottom second surfaces. The discrete attachment locations can be located about the first and second edges.
In some embodiments, the first shell can have a bottom first surface for directly engaging the teeth and a top first surface opposite the bottom first surface and a first edge defined therebetween. The at least one additional shell can have a bottom second surface for mechanically engaging the top first surface of the first shell and a top second surface opposite the bottom second surface and a second edge defined therebetween. Some or all of the first edge and the second edge can be arranged to not contact one another.
In some embodiments, the at least one additional shell can be a second shell, and the shells can include a third shell.
In some embodiments, the shells can only consist of the first, second, and third shells.
In some embodiments, the second edge can be affixed to the top or bottom first surface.
In some embodiments, the first edge can be affixed to the bottom or top second surface.
In some embodiments, the first edge and the second edge can be separated by 0.2-2.0 mm.
In some embodiments, the at least one additional shell can be a second shell, and the shells can include a third shell having a bottom second surface for mechanically engaging the top second surface of the second shell and a top third surface opposite the bottom third surface and a third edge defined therebetween. Some or all of the first edge, second edge, and third edge can be arranged to not contact one another.
In some embodiments, the first edge, second edge, and third edge are separated by 0.2-3.0 mm.
In some embodiments, all of the shells can be constructed from a same type of material.
In some embodiments, varyingly affixed can mean having attachment locations that can be less than 1-80% of the combined surface areas of the shells.
In some embodiments, varyingly affixed can mean having attachment locations that can be less than 1-60% of the combined surface areas of the shells.
In some embodiments, varyingly affixed can mean having attachment locations that can be less than 1-40% of the combined surface areas of the shells.
In some embodiments, varyingly affixed can mean having attachment locations that can be less than 1-20% of the combined surface areas of the shells.
Some embodiments relate to a system for repositioning teeth from an initial tooth arrangement to a final tooth arrangement. The system can include a plurality of orthodontic appliances shaped to receive and reposition teeth. The plurality orthodontic appliances can include at least one aspect of the orthodontic appliances described herein.
Some embodiments relate to a method for repositioning teeth from an initial tooth arrangement to a final tooth arrangement. The method can include steps of incrementally using the system.
In some embodiments, the at least one orthodontic appliance of the system can be used less than 12 hours a day.
In some embodiments, an orthodontic appliance can include more than 2 shells, and in preferred embodiments, it can include 3-5 shells.
In some embodiments, at least one shell has at least one hole located or arranged in the shell for specific purposes and functionality. The hole(s) may be arranged in the shell(s) to, for example, control physical properties or to allow air to pass therethrough for a specific purpose such as to enhance inter-shell bonding.
Additionally, in embodiments, the shell or shells could have roughened or otherwise altered surfaces such as texture, pits, grooves and/or folds. During the manufacturing process, material from the first shell may flow into the holes (or other features present in the surface) in the opposing second shell. When the material from the first shell occupies the space in the second shell, the combined structure exhibits different and unique physical properties compared to the properties of the individual shells.
In embodiments, one region of the shell has more or less material deposited into the holes than another region.
In embodiments, one region of the shell has a different type of material deposited into the holes than another region.
In embodiments, the holes are round. In other embodiments, the holes are oblong, square, or otherwise-shaped. The holes can take a wide variety of different shapes and sizes.
Additionally, the holes present on a shell may vary along the shell or by region along the shell.
In embodiments, the first shell features an adherence region that includes larger holes than other regions to allow the adherence region to receive more material of the second shell during manufacturing.
In some embodiments, the space between the shells carries an active ingredient. In embodiments, the space between the shells carries an ingredient formulation for controlled release of the active ingredient. In embodiments, a thick gel may contain an active ingredient that is slowly released over time.
In embodiments, a method of making an orthodontic appliance comprising stacking a second shell on top of a first shell, sealing the first shell to the second shell along a first perimeter interface thereby defining an open space or chamber between the first shell and the second shell.
In embodiments, the sealing may be performed chemically, mechanically or thermally.
In embodiments, the method of making comprises trimming the shells, and optionally, trimming the shells about 1 mm from the CEJ.
In embodiments, the steps of sealing and trimming are performed using a hot tip or laser tool, and optionally, the steps of sealing and trimming are performed simultaneously using the hot tip or laser tool.
In embodiments, the method further comprises minimizing or prohibiting the first shell from bonding to the second shell within the perimeter. The central region may be blocked or masked, for example, during the sealing process.
In embodiments, the chamber comprises at least one tack-free contact point between the first shell and the second shell within the defined chamber, each contact point permitting movement (e.g., lateral and vertical) between the first shell and the second shell.
In embodiments, the chamber can further comprise at least one predetermined fixation point between the first shell and the second shell within the defined chamber, each fixation point prohibiting movement between the first shell and the second shell. The chamber may thus feature a combination of fixation points and/or tack-free contact points separated from one another by gaps, serving to permit acceptable motion between the assembled shells during use.
For a better understanding of at least certain embodiments, reference will be made to the following Detailed Description, which is to be read in conjunction with the accompanying drawings.
The figures depict various embodiments of the present invention for purposes of illustration only, wherein the figures use like reference numerals to identify like elements. One skilled in the art will readily recognize from the following discussion that alternative embodiments of the structures and methods illustrated in the figures may be employed without departing from the principles of the invention described herein.
Embodiments are disclosed that relate to orthodontic appliances constructed from multiple shells for the purpose of maximizing working elasticity. By “working elasticity” is it meant the capability of an orthodontic appliance to elastically deform to attach to an initial location of the teeth. This flexibility can allow an orthodontic appliance to obtain a greater range of initial tooth arranging (i.e., flexing) positions that differ from the appliance's target tooth arranging (i.e., resting) position. Possible benefits include greater break time (e.g., 8-12 hours) between required wear periods and greater latitude for patient non-adherence to required wear-times, and hence increased efficacy.
Before the present invention is described in greater detail, it is to be understood that this invention is not limited to particular embodiments described, as such can, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present invention will be limited only by the appended claims.
Where a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limit of that range and any other stated or intervening value in that stated range, is encompassed within the invention. The upper and lower limits of these smaller ranges can independently be included in the smaller ranges and are also encompassed within the invention, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the invention.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present invention, representative illustrative methods and materials are now described.
It is noted that, as used herein and in the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise. It is further noted that the claims may be drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for use of such exclusive terminology as “solely,” “only” and the like in connection with the recitation of claim elements or use of a “negative” limitation.
As will be apparent to those of skill in the art upon reading this disclosure, each of the individual embodiments described and illustrated herein has discrete components and features which can be readily separated from or combined with the features of any of the other several embodiments without departing from the scope or spirit of the present invention. Any recited method can be carried out in the order of events recited or in any other order that is logically possible.
All existing subject matter mentioned herein (e.g., publications, patents, patent applications and hardware) is incorporated by reference herein in its entirety except insofar as the subject matter may conflict with that of the present invention (in which case what is present herein shall prevail). U.S. application Ser. No. 17/871,903, filed Jul. 23, 2022, and entitled “ELASTIC ORTHODONTIC APPLIANCES, SYSTEMS, AND METHODS FOR USE”; and US Publication No. 20210153979, filed Jan. 13, 2021, and entitled “ELASTIC ORTHODONTIC APPLIANCES, SYSTEMS, AND METHODS FOR USE”, are incorporated herein by reference in their entirety for all purposes.
In some embodiments, only certain teeth received by an appliance will be repositioned by the appliance while other teeth can provide a base or anchor region for holding the appliance in place as it applies force against the tooth or teeth targeted for repositioning. In some cases, many or most, and even all, of the teeth will be repositioned at some point during treatment. Teeth that are moved can also serve as a base or anchor for holding the appliance as it is worn by the patient. Typically, no wires or other means will be provided for holding an appliance in place over the teeth. In some cases, however, it may be desirable or necessary to provide individual anchors on teeth with corresponding receptacles or apertures in the appliance so that the appliance can apply a selected force on the tooth. Basic methods for determining an orthodontic treatment plan using a series of incremented appliances as well as instructions for molding orthodontic appliances, are described in U.S. Pat. Nos. 6,450,807, and 5,975,893, which are incorporated by reference herein, but only to an extent that those patents do not contradict the newer teachings disclosed herein.
An appliance can be designed and/or provided as part of a set of a plurality of appliances. In such an embodiment, each appliance may be configured so a tooth-receiving cavity has a geometry corresponding to an intermediate or final tooth arrangement intended for the appliance. The patient's teeth can be progressively repositioned from an initial tooth arrangement to a target tooth arrangement by placing a series of incremental position adjustment appliances over the patient's teeth. A target tooth arrangement can be a planned final tooth arrangement selected for the patient's teeth at the end of all planned orthodontic treatment. Alternatively, a target arrangement can be one of many intermediate arrangements for the patient's teeth during the course of orthodontic treatment. As such, it is understood that a target tooth arrangement can be any planned resulting arrangement for the patient's teeth that follows one or more incremental repositioning stages. Likewise, an initial tooth arrangement can be any initial arrangement for the patient's teeth that is followed by one or more incremental repositioning stages.
The orthodontic appliances can be generated all at the same stage or in sets or batches, e.g., at the beginning of a stage of the treatment, and the patient wears each appliance until the pressure of each appliance on the teeth can no longer be felt or has resulted in the maximum amount of expressed tooth movement for that given stage. A plurality of different appliances (e.g., set) can be designed and even fabricated prior to the patient wearing any appliance of the plurality. After wearing an appliance for an appropriate period of time, the patient replaces the current appliance with the next appliance in the series until no more appliances remain. The orthodontic appliances are generally not affixed to the teeth and the patient may place and replace the appliances at any time during the procedure (e.g., patient-removable appliances).
The final orthodontic appliance or several appliances in the series may have a geometry or geometries selected to overcorrect the tooth arrangement, i.e., have a geometry which would (if fully achieved) move individual teeth beyond the tooth arrangement which has been selected as the “final.” Such over-correction may be desirable in order to offset potential relapse after the repositioning method has been terminated, i.e., to permit movement of individual teeth back toward their pre-corrected positions. Over-correction may also be beneficial to speed the rate of correction, i.e., by having an appliance with a geometry that is positioned beyond a desired intermediate or final position, the individual teeth will be shifted toward the position at a greater rate. In such cases, the use of an appliance can be terminated before the teeth reach the positions defined by the appliance.
While the orthodontic appliance 10 is shown in an exploded view for the purpose of better understanding, the shells of the orthodontic appliance 10 are intended to be mechanically engaged with one another in a stack. “Mechanically engaged” is defined herein as the substantially non-affixed or varyingly affixed engagement between one or more shells to approximate the strength of a single shell appliance of approximately the same thickness as the stacked shells.
Mechanical engagement can be obtained by stacking the shells while having the lower-shell engaging surface of the second shell largely conforming to the upper surface of the first shell. In some embodiments, shells can be stacked loosely, i.e., without a compressive or an interference fit between shells or such that an upturned stack of shells self-disassembles, before being made substantially non-affixed or varyingly affixed. The shells are substantially non-affixed (or varyingly affixed) because a substantial amount of surface areas between the shells are not bonded or otherwise made inseparable through some process, with the remaining surfaces being affixed. In some embodiments, substantially non-affixed or varyingly affixed shells have less than 1-2%, 1-5%, 1-10%, 1-20%, 1-40%, 1-60%, or 1-80% of the combined contacting surfaces of the shells affixed. The area of non-fixation can be limited according to the needs of the appliance, hence, in some embodiments, a majority the surface areas of the appliance are affixed, while the remaining part is non-affixed because only the latter requires high working elasticity.
In some embodiments, the lack of substantial fixation between shells provides greater working elasticity to the orthodontic appliance 10 because the teeth-engaging shell can flex more due to being thinner while the outer shells are allowed to flex in multiple directions away from the teeth-engaging shell. In some embodiments, this can result in partial mechanical disengagement between some of the engaging surfaces of the shells, however the disengagement is not enough to significantly impair flexural modulus of the device required for aligning the teeth to the target position.
In some embodiments, shells of the orthodontic appliance 10 can be non-identical such that surface areas of one shell is greater or less than another shell. Accordingly, in some embodiments, edges, which are defined by the top and bottom surfaces of each shell, of such shells can be separated by gaps (e.g., 0.20-3.0 mm), as depicted by
Providing one or more of such gaps can be used to tune flexural modulus of the orthodontic appliance 10 and also result in less tongue irritation to the patient that can occur due to material thickness where edges are bonded at the same location. To alleviate irritation, gaps can be placed in areas that face inwards towards the mouth, resulting in stepped edges (e.g., edges 14a, 16a, 18a) facing the tongue, or the tooth-engaging shell can have a smaller surface area than shells stacked thereon, resulting in interior, tooth-facing steps and a single shell edge (e.g., edge 16a) that can contact the tongue. In some embodiments, the bottom-most, tooth-engaging shell, can have a greater or lesser total surface area than a second shell stacked thereon, which can result in at least a portion of the edge of the second shell being separated from the edge of the tooth-engaging shell. In some embodiments, only portions of the edges that face towards the mouth have such a gap, and in other embodiments, a uniform or non-uniform gap can exist between the entirety of edges. In some embodiments, the orthodontic appliance 10 can include shells, each having different surface areas.
The shells can have thicknesses ranging from 0.001-0.040 inches, and in embodiments, from 0.001-0.015 inches thick, and can be constructed from 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 or a combination thereof. In some embodiments, shells are coated with lubricous materials or provided with surface treatments to decrease friction between the shells. In some embodiments, interior portions of the shells are treated with hydrophobic coatings to prevent liquid intrusion into the shells. In some embodiments, shells of relatively more flexibility can be used in conjunction with stiffer shells. Flexible shells can be constructed from hydrogels, styrenic block copolymers (SBC), silicone rubbers, elastomeric alloys, thermoplastic elastomers (TPE), thermoplastic vulcanizate (TPV) elastomers, polyurethane elastomers, block copolymer elastomers, polyolefin blend elastomers, thermoplastic co-polyester elastomers, thermoplastic polyamide elastomers, or a combination thereof. Flexible shells may also provide the benefit of a gasket to prevent liquid intrusion between the shells.
After formation, shells can be affixed to one another according to the desired working elasticity required for the patient. Methods of fixation include chemical bonding, localized melting, fasteners, and/or localized physical deformation to key the shells together. Before or after fixation takes place, excess material from the sheet can be trimmed to form a final tooth positioning appliance that can be used for orthodontic treatment of a patient. The edges of the shells can be sealed with a flexible material such as silicone to prevent liquid intrusion.
One or a series of physical tooth models, such as the model described above, may be used in the generation of elastic repositioning appliances for orthodontic treatment. Similar to the process above, each of the appliances can be generated by thermoforming a multilayer polymeric material over a mold of a desired tooth arrangement to form a dental appliance. The tooth positioning appliance of the desired tooth arrangement generally conforms to a patient's teeth but is slightly out of alignment with the initial tooth configuration. Placement of the elastic positioner over the teeth applies controlled forces in specific locations to gradually move the teeth into the desired configuration. Repetition of this process with successive appliances comprising new configurations eventually moves the teeth through a series of intermediate configurations to a final desired configuration.
In embodiments, the appliances 100, 200, and 300 are assembled by mechanical attachment. Preferably, the first lower shell has a larger extended ledge (e.g., 130, 230, 330) and is mechanically roughened by e.g., a sander. Then, the second top shell is thermoformed onto the first shell. The roughened surface increases adhesion between the shells.
With reference to
It is also to be understood that although the spacing or chamber 530 between the shells 510, 520 is shown in
The appliance 600 may be formed by stacking two thin plastic sheets. The upper sheet and lower sheet may be made of the materials described herein such as, for example, polyurethane, polyamide, polycarbonate, or polyester. The unbonded stack of sheets is placed over the tooth model/mold 620. The dental model may be made by casting or more preferably, a 3D printed or SLA model. The plastic stack and model 620 are then sealed in a pressure chamber, where pressure and heat are applied to thermoform the plastic to the model. When the process is finished, the multi-layer plastic “negative” is removed from the 3D printed “positive” model. The multi-layer plastic “negative” is trimmed so excess plastic is removed and the edges are polished. The appliance 600 is complete once it has been cleaned and dried.
Optionally, a sacrificial layer (not shown) may be disposed between the sheets prior to the thermoforming step. The sacrificial layer serves to maintain an open space between the shells which, as described herein, provides elasticity to the appliance. Exemplary materials for the sacrificial layer include water or distilled water. The water vaporizes during the thermoforming step, leaving a small space between the upper and lower shells. As described herein, apertures or vents may be added to the sheets to allow the vapor to escape during the thermoforming step.
Notably, in the variation shown in
With reference to
It is also to be understood that although a trench is a suitable feature for facilitating bonding the sheets to one another during the thermoforming step, this structural interlocking feature may vary widely. For example, and with reference to
With reference to
It is to be understood that these interlocking features (e.g., 630, 680, 710, 712) may vary in shape. For example, and with reference to
Additionally, the thermoforming or interlocking features need not be directed inward. In embodiments, the features bow or protrude outward from the mold such as, for example, button or rib 722 which is shown protruding outward from the gum region of the model 720.
Additionally, the bevel, fold, trench, rib, trim path, etc. may be continuous or intermittent. Although a continuous bevel is preferable to provide more bonding surface area, and to prevent moisture from seeping into the space between the shells, embodiments of the invention provide for discrete tabs or intermittent structures to create mechanical interlocking. Examples of such intermittent features include buttons, tabs, holes, detents, indents, recesses, etc. These intermittent features may be arranged along or in the vicinity of the gingival margin region on the mold. Indeed, the invention is intended to include a wide variety of features to facilitate thermoforming the shells to one another except where limited by any appended claims.
Appliances as shown in
The lower shell (or shell to contact the teeth) was thermoformed over a dental model from a 0.015″ inch polymer sheet of Isoplast® 2530 ETPU, manufactured by Lubrizol Corporation, (Wickliffe, Ohio).
The molded sheet was trimmed and its perimeter or ledge was mechanically roughened by a rotary tool with sanding capability.
A second 0.015″ inch polymer sheet of Eastar® 6763 PETG, manufactured by Eastman Chemical Company, was then thermoformed onto the first shell where the edge of the second shell contacts the roughened ledge of the first shell. The roughened ledge serves to increase adhesion during thermoforming. The sheet(s) were then trimmed as shown in the figures. Each of the manufactured appliances included a chamber as described herein for mitigating lower shell displacement, allowing flexibility, and maintaining the desired flexural modulus or force on the tooth contacting portion of the appliance.
Appliance 400 as shown in
Thermoforming. A lower shell was thermoformed over a dental model from a 0.015″ inch polymer sheets of Isoplast® 2530 ETPU.
Dipping. The perimeter edge of the lower ETPU shell (shell to contact the teeth) was dipped in ethanol to form an adhesive or sticky area.
The lower shell was flipped upside down, and its convex portion was placed in a masking solution (e.g., distilled water) up to but not beyond the desired adhesion area to prohibit bonding across this convex area. The area of non-adhesion is controlled by the area dipped into the masking solution. The area of non-adhesion corresponds to the boundary of the sealed chamber (530) between the shells. In embodiments of the invention, the sealed chamber is created by masking or dipping a predetermined area of the 1st shell in a masking solution.
Thermoforming second shell. An upper shell of 0.015″ inch polymer sheet of Eastar® 6763 PETG was thermoformed over the ethanol-treated lower shell.
Trimming. The lower and upper shells were trimmed as shown until the edges were substantially flush.
Inventors observed the edge of the second shell chemically bonded to the edge of first shell. The shells formed a continuous (gapless) bond along the perimeter. The shells cooperated with one another as described above to provide the open chamber serving to mitigate off-track patient cases.
Mechanical Test Analysis
With reference to the table below and the plot shown in
The table shows the mean values of the flexural modulus are within 3% of one another. However, the data also shows that the range of the flexural moduli of the V4 appliance is tighter than that of V1. Particularly, the range of V4 is 123 MPa and the range of V1 is 304 MPa. The V4 aligner thus appears to be at least as good or better than the V1 aligner in the sense that the mean is within 3% and the range is tighter, and based on this data.
Benefits
The chemical-enhanced assembly method described in connection with V4 appears to have some benefits/advantages over the purely mechanical assembly method described in connection with V1 without adversely impacting the intrinsic properties of the aligner including, without limitation:
Greater interlayer adhesivity, strength and consistency in interlayer adhesion because the chemical bonding technique may be applied with better precision than the bonding technique based solely during mechanical engagement.
Fewer chamber leaks using the chemical bond, thus reducing the need to clean saliva trapped in the aligner chamber.
Greater likelihood the chamber is well defined and uninterrupted, gapless, and unbonded.
Greater anatomical fit range, i.e., can adapt to a wider range of teeth configuration and off-track cases.
Greater ability to accommodate a greater number of attachment locations.
Improved clinical effectiveness to move teeth to the prescribed position/alignment.
These and other benefits arise from the configurations and manufacturing techniques described herein.
A test appliance was formed in accordance with embodiments of the invention for comparison in functionality to a conventional dental appliance.
The test appliance(s) were prepared according to the following:
A 0.015″ inch polymer sheet of Isoplast® 2530 ETPU was arranged on top of a 0.015″ inch polymer sheet of Eastar® 6763 PETG to form an unbonded composite stack.
Thermoforming. The stack was then thermoformed over a dental model as shown in
Trimming. The edges, about 1 mm below the CEJ, of the appliance were trimmed, polished and cleaned.
A conventional orthodontic appliance 930 as shown in
Both the test and control appliances were tested using the same fixtures and test methodology. The testing conducted was used to determine teeth correction forces resulting from different aligner planning stage movements. Tooth forces were measured when the designated aligners were placed on the stereolithography (SLA) models (namely, the dental models) which had either one or three stages of correcting movement from the base line state.
The objective of the testing was to determine forces that a one (1) or three (3) stage aligner can impart on a tooth in a simulated clinical setting. The forces applied by the aligner were to cause motions as shown in
All testing was conducted in room temperature air.
The tooth used for force measurements was cut from the SLA model to be used with the appropriate aligners. Prior to cutting the tooth from the SLA model, one or more imprints (e.g., 910 shown in
With reference to
Multiple appliances were created, each one having a different activation for a particular tooth. Three (3) appliances were made for each activation point and we tested at eight (8) activation points including one activation point for zeroing the transducer. By activation it is meant the amount of tooth movement (namely, distance) per aligner stage.
Left/Right translation tests were conducted with the tooth in question attached to the load cell allowing tension and compression readout during the range of motion specified. For translation tests, the tooth was mounted such that the centerline of the applied load passed through the center of the portion of the tooth that was covered by the aligner to mitigate bending loads.
The results are shown in
A theoretical optimal activation curve 1110 shows a constant, relatively low, force of about 70 (gf) applied to the teeth for activation points ranging from 0 to 0.6 mm.
The test appliance 1120 evidences a gradual increase in force from 100 to 140 (gf) between activation points ranging from 0 to 0.6 mm.
The control appliance 1130 evidences a relatively steep increase in force from 250 to 1225 (gf) between activation ranging 0 to 0.6 mm.
The data suggests the test device has substantial benefit in maintaining a lower and even force to the teeth during aligner stages and treatment. (1) The clinically desired force (about 70-100 gf) to move teeth appears to continue, even after the tooth is translated. This acceptable force continues to the final destination or desired tooth target location (namely, at activation point 0.0 mm). (2) The maximum force applied by the test aligner to the tooth remains within the optimal clinical force ranges and does not exceed 200 gf. Excessive force causes root resorption and tooth movement. (3) The test aligner data evidences that overcorrection to assure a tooth reaches the prescribed location shall not cause pain or discomfort due to excessive force.
Without intending to be bound to theory, the space between the upper and lower shells allow one shell to flex and slide relative to the other, providing the above-described benefits.
We performed tests on our test aligner sheet and a conventional aligner sheet according to a modified ASTM-D790, in which we performed testing at a temperature of 37 degrees C. and 90-95% humidity.
The test sheet was made by stacking a polyurethane sheet on a polyester sheet, and adding a thin layer of silicone oil between the plastic sheets. Two ends of the sheets were heat sealed, creating a thin oil layer. The oil layer was added to prevent the sheets from contacting each other, and to mimic the chamber (e.g., space 530 of
For the control sheet, we used the Zendura™ FLX Aligner Materials described above.
Our results are shown in
As anticipated, the control sheet has a steep elastic region 1010 along the flexural stress/strain curve until it reaches its yield point, which is shown occurring at about 5% strain, at 1530 gram-force, after which inelastic deformation occurs.
This has the implication that an orthodontic appliance made from this material, after 5% strain, would no longer apply force to urge the tooth to the desired destination. Such an appliance would no longer be clinically effective and would need to be replaced. It is also apparent from the plot that excessive force is required to reach 5% strain. This level of force is outside the optimal range desired for orthodontic tooth movement.
Flexural stress/strain curve 1020 represents the data arising from the test sheets in accordance with embodiments of the invention and as described above. The test sheets' elastic region is initially step until the strain reaches about 5%, 100 gram-force, after which hyper-elasticity continues at a gradual rate until 20% strain, and ultimately until the yield point 1022, 25% strain, 200 gram-force.
This has the implication that up to 25% strain, and notably between 5% and 25% strain, (and more notably between 5% and 20%), an appliance made from the test sheets can still apply force to teeth that have been adjusted/moved. Such an appliance would continue to have a clinical benefit as long as it remains within the hyper-elastic region of the stress strain curve and up to 25%.
What is also notable is that the test sheets' curve 1020 has a much lower force than that shown in the control sheet curve 1010. For example, the force measured in the elastic region 1020 ranges from 0 to 200 gram-force and 150 gram-force is not reached until 20% strain. As stated herein, avoiding excessive force is desirable.
Without intending to be bound to theory, the anticipated space between the upper and lower shells allow one shell to flex and slide relative to the other, providing the above-described benefits. We submit these flexural stress/strain data evidence this phenomenon.
It is to be understood the invention may vary widely and is intended to include any one feature or combination of features described above except where the invention is explicitly limited in any appended claims.
For example, the roughening, trimming, and dipping may be performed in any order or sequence or combination except where such steps are exclusive to one another.
Additionally, in embodiments, with or without the mechanical interlock features described above, the trimming or cutting step is performed with a hot tip or laser tool.
Inventors have discovered the cutting with a hot tip or laser tool also has the capability of sealing. In embodiments, the edges of the stacked shells are trimmed and sealed simultaneously using the hot tip or laser tool. When a hot tip or laser tool is used to trim and seal the edges, polishing is optional or can be omitted. In a sense, the hot tip or laser trimming performs two, and optionally three steps in one. That is, trimming, sealing, and polishing are collectively performed by the hot tip or laser tool. An example of a suitable laser tool to trim, seal and polish the shells is the LAC—Laser Aligner Cutter, manufactured by Dental Axes LLC (West Palm Beach, Florida).
Additionally, in alternative embodiments, two sheets can be stacked together and thermoformed simultaneously using a mold versus a serial type of thermoforming process. Optionally, one or more vents are added to one or more of the sheets prior to thermoforming. The vents allow air to escape during the thermoforming step, creating a more continuous edge seal. In embodiments, the vents are arranged near the edge of the sheet. In embodiments, the vents are arranged 5-30 mm, and more preferably 10-20 mm from the perimeter of the sheet. The vent diameter may also vary. In embodiments, the diameter of vent ranges from 1-10 mm, more preferably 3-6 mm.
Additionally, in embodiments, the chamber spacing or space comprises a thin layer or liquid, gel, oil, or release agent.
In embodiments, the chamber spacing or height is controlled by application of a liquid or gel such as, for example, water. A method includes adjusting how much water is present in order to control the quantity of water vapor generated to control the chamber distance. For example, a thin layer of water may be applied between the shells, and when two thermoforming steps are desired, just prior to the second thermoforming step to keep the shells from sticking during the second thermoforming step. Preferably, the application of these agents is on top of the first shell.
Additionally, in embodiments, a method of assembly includes the application of a thin layer silicone, PTFE, a mold release agent, or dried non-ionic detergent. Additional categories of agents to prevent stick and control the chamber height distance include high boiling compounds such as mineral oil, silicone oil and natural oils such as corn, olive, and canola oil.
Additionally, in embodiments, the chamber or spacing between the shells varies, and in some embodiments, the inner surfaces of the shells touch one another at one or more locations throughout the chamber. At these so-called ‘contact points’ in the chamber, there is no separation distance between the shells. In such embodiments of the invention, the shells do not stick to one another in these regions. Thus, in embodiments, whether (or not) there is a space between the shells, the opposing shells are able to move and flex relative to one another in response to the forces imparted onto the shells arising from errant or off-track teeth and the inherent flex/stiffness programmed into the shells, described above.
Additionally, in embodiments, the space or chamber between the shells carries an active agent or ingredient. In embodiments, the space between the shells carries an ingredient formulation for controlled release of the active ingredient. For example, a thick gel may contain an active ingredient that is slowly released over time. Examples of orthodontic appliances for delivery of an active agent are described in copending provisional patent application no. 63/287,023, filed Dec. 7, 2021, entitled “ORTHODONTIC DEVICES FOR DELIVERY OF AN ACTIVE AGENT” incorporated herein by reference for all purposes.
Additionally, and although reference was made throughout the disclosure to a lower shell to contact the teeth corresponding generally to an orthodontic appliance for treating the teeth in the lower jaw, the invention is equally applicable and relevant to treating the teeth in the upper jaw in which case the upper-most shell would be the shell to contact the teeth, and the lower shell would be the shell exposed to the mouth. Indeed, embodiments of the invention are intended to cover orthodontic appliances to move and treat the teeth in the upper or lower jaws as the case may be.
Throughout the foregoing description, and for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the described techniques. It will be apparent, however, to one skilled in the art that these techniques can be practiced without some of these specific details. Although various embodiments that incorporate these teachings have been shown and described in detail, those skilled in the art could readily devise many other varied embodiments or mechanisms to incorporate these techniques. Also, embodiments can include various operations as set forth above, fewer operations, or more operations; or operations in an order. Accordingly, the scope and spirit of the invention should be judged in terms of the claims, which follow as well as the legal equivalents thereof.
This claims priority to provisional patent application No. 63/421,158, filed Oct. 31, 2022, and entitled BEVELED DENTAL MODELS AND ORTHODONTIC APPLIANCES MADE THEREFROM, the entirety of which is incorporated by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 63421158 | Oct 2022 | US |
