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Publication numberWO2014076188 A1
Publication typeApplication
Application numberPCT/EP2013/073843
Publication date22 May 2014
Filing date14 Nov 2013
Priority date15 Nov 2012
Publication numberPCT/2013/73843, PCT/EP/13/073843, PCT/EP/13/73843, PCT/EP/2013/073843, PCT/EP/2013/73843, PCT/EP13/073843, PCT/EP13/73843, PCT/EP13073843, PCT/EP1373843, PCT/EP2013/073843, PCT/EP2013/73843, PCT/EP2013073843, PCT/EP201373843, WO 2014/076188 A1, WO 2014076188 A1, WO 2014076188A1, WO-A1-2014076188, WO2014/076188A1, WO2014076188 A1, WO2014076188A1
InventorsYong-Min Jo
ApplicantYong-Min Jo
Export CitationBiBTeX, EndNote, RefMan
External Links: Patentscope, Espacenet
Improved method for manufacturing orthodontic appliances
WO 2014076188 A1
Abstract
A method for manufacturing orthodontic appliances is provided, wherein the orthodontic appliance is manufactured by means of vacuum molding or pressure molding of a sheet of thermoplastic polymer film, utilizing a positive tooth model that is impregnated with a composition comprising at least one oily component. In addition, orthodontic appliances obtainable from said method are provided.
Claims  (OCR text may contain errors)
A method for manufacturing dental appliances, the method comprising the steps of
- providing a positive tooth model,
- providing a sheet of a thermoplastic polymer film,
- subjecting the sheet of thermoplastic polymer film to vacuum molding or pressure molding utilizing the positive tooth model,
wherein
the positive tooth model is impregnated with a composition including at least one oily component before the sheet of thermoplastic polymer film is applied to the positive tooth model and subjected to molding.
The method according to claim 1 , wherein the positive tooth model in impregnated with the composition in that the composition is sprayed onto the positive tooth model, preferably from a distance of about 10 cm.
The method according to claim 1 or 2, wherein the at least one oily component is selected from the group consisting of Vaseline and essential oils.
The method according to any one of claims 1 to 3, wherein said at least one oily component is an essential mint oil, preferably selected from the group consisting of peppermint oil, spearmint oil, Japanese mint oil and poleimic oil.
The method according to any one of claims 1 to 4, wherein said
composition includes an aqueous component.
The method according to any one of claims 1 to 5, wherein said
composition includes a protic solvent or an aprotic solvent.
7. The method according to any one of claims 1 to 6, wherein said
composition includes one or more excipients, preferably selected from the group consisting of as surfactants, odorants, flavors, colorants, stabilizers, preservatives and the like.
8. The method according to any one of claims 1 to 7, wherein said
composition includes a propellant, preferably selected from the group consisting of propane, butane and pentane.
9. The method according to any one of claims 1 to 8, wherein the positive tooth model was manufactured by means of rapid prototyping, preferably by a method selected from the group consisting of three-dimensional powder bed ink jet head printing, fused deposition modeling, fused filament fabrication, melted and extrusion modeling, direct metal laser sintering, electron beam melting, selective heat sintering, laminated object
manufacturing, digital light processing, selective laser sintering and stereolitography.
10. The method according to any one of claims 1 to 9, wherein said
thermoplastic polymer film is transparent.
1 1 . The method according to any one of claims 1 to 10, wherein said sheet of thermoplastic polymer film further comprises an intermediate layer.
12. The method according to any one of claims 1 to 10, wherein the method further comprises the steps of providing a sheet of an intermediate film, and subjecting the sheet of the intermediate film to vacuum molding or pressure molding utilizing the positive tooth model before the sheet of thermoplastic polymer film is subjected to pressure molding or vacuum molding utilizing the assembly comprising the positive tooth model and the intermediate film molded thereon, wherein the positive tooth model is impregnated with the composition before the sheet of intermediate film is applied to the positive tooth model and subjected to molding.
13. The method according to claim 13, wherein the composition is sprayed onto the assembly comprising the positive tooth model and the intermediate film molded thereon before the sheet of thermoplastic polymer film is subjected to molding.
14. A dental appliance, obtainable by a method as defined in any one of claims 1 to 13.
15. The dental appliance according to claim 14, wherein said dental appliance is selected from the group consisting of aligners, retainer, trays.
16. Use of a composition including at least one oily component for
manufacturing of orthodontic appliances by means of subjecting a sheet of thermoplastic polymer film to vacuum molding or pressure molding utilizing a positive tooth model, wherein the composition is used to impregnate the positive tooth model prior to molding.
17. The use according to claim 16, wherein the composition is sprayed onto the positive tooth model, preferably from a distance of about 10 cm.
18. The use according to claim 16 or 17, wherein the at least one oily
component is selected from the group consisting of Vaseline and essential oils.
19. The use according to any one of claims 16 to 18, wherein said at least one oily component is an essential mint oil, preferably selected from the group consisting of peppermint oil, spearmint oil, Japanese mint oil and poleimic oil.
20. The use according to any one of claims 16 to 19, wherein the composition includes an aqueous component.
21 . The use according to any one of claims 16 to 20, wherein the composition includes a protic solvent or an aprotic solvent.
22. The use according to any one of claims 16 to 21 , wherein the composition includes one or more excipients, preferably selected from the group consisting of as surfactants, odorants, flavors, colorants, stabilizers, preservatives and the like.
23. The use according to any one of claims 16 to 22, wherein the composition includes a propellant, preferably selected from the group consisting of propane, butane and pentane.
Description  (OCR text may contain errors)

Improved method for manufacturing orthodontic appliances

The present invention concerns the field of orthodontic appliances. More specifically, the present invention is directed to the manufacturing of orthodontic appliances and to orthodontic appliances obtainable by said method.

Orthodontic appliances are used for repositioning teeth, for straightening teeth, or for keeping them in their position within the jaw. An orthodontic appliance comprises a polymeric shell having cavities shaped to receive and optionally reposition teeth from one arrangement to a successive arrangement. The polymeric shell will preferably, but not necessarily, fit over all teeth present in the upper or lower jaw. For repositioning or straightening teeth, a series of orthodontic appliances may be used to incrementally reposition individual teeth. Successive appliances are worn in a particular sequence, and a given appliance is replaced by a successive appliance when the teeth either approach or have reached the target end position for that stage of treatment.

With respect to the present invention, the terms "orthodontic appliance" and "dental appliance" are used synonymously, and comprise polymeric shells having cavities shaped to receive teeth. Orthodontic appliances for keeping teeth in a given position are commonly referred to as "retainer", whereas orthodontic appliances resiliently repositioning teeth are commonly referred to as "aligner". Usually, no wires or other means will be provided for holding the appliance in place over the teeth.

The orthodontic appliance is preferably formed from a sheet of a suitable thermoplastic polymer film. The term "thermoplastic" refers to thermosoftening plastics, i. e. polymers that become pliable or moldable above a specific

temperature, and return to a solid state upon cooling. Examples of suitable thermoplastic polymer films for forming dental appliances are available under the trade names BIOCRYL® "C", 1 .5, 2, or 3 mm thick sheets of PMMA, BIOCRYL® "M", or DURAN +, 0.5, 0.625, 0.75, 1 .0, 1 .5, or 2.0 mm thick sheets, from SCHEU- DENTAL GmbH, 58642 Iserlohn, Germany.

In manufacturing an orthodontic appliance, a positive model of the teeth, the upper jaw or the lower jaw, or a portion of the jaw including the teeth is prepared. Then the orthodontic appliance is formed from a sheet of the suitable thermoplastic polymer film by using a conventional vacuum molding machine or pressure molding machine. The molding machine forms an orthodontic appliance directly from the thermoplastic polymer film in that said sheet of thermoplastic polymer film is put onto the positive tooth model and molded in that the film is softened and in that vacuum or pressure is applied. After molding, the solidified polymeric sheet is removed from the molding machine in conjunction with the positive tooth model. The positive tooth model has to be removed from the mold including the

orthodontic appliance. The molded sheet of thermoplastic polymer comprises the shape of at least a part of the positive tooth model. The excess thermoplastic polymer material has to be trimmed so that only the dental appliance is obtained.

Today, positive tooth models are often generated by means of rapid prototyping. When using positive tooth models generated by means of rapid prototyping, in particular when utilizing the 3D powder bed technology, the positive tooth model has a somewhat rough surface, even if it is impregnated with a binder. Using such positive tooth models for pressure molding of orthodontic appliances, result in orthodontic appliances possessing a rough inner surface, i.e. the surface facing the teeth. Hence, the orthodontic appliance is no longer transparent as the thermoplastic polymer sheet was, but becomes translucent. Translucent orthodontic appliances are clearly visible when worn by a patient. However, the vast majority of patients prefer non-noticeable orthodontic appliances.

For improving the optical appearance of an orthodontic appliance a thin film may be placed between the positive tooth model and the sheet of thermoplastic polymer film when the orthodontic appliance is molded.

The inventor surprisingly found that the optical appearance of an orthodontic appliance that is manufactured by means of pressure molding can be improved if an slightly oily and slightly aqueous composition is sprayed onto the positive tooth model, in particular when the positive tooth model is a positive tooth model generated by means of rapid prototyping.

In a first aspect, the present invention provides a method for manufacturing an orthodontic appliance having an improved optical appearance.

In a second aspect, the present invention provides orthodontic appliances obtainable from the method according to the first aspect of the invention.

In a third aspect, the present invention provides the use of an oily and aqueous composition in manufacturing orthodontic appliances. The present invention will be described with respect to particular embodiments, but the invention is not limited thereto, but only to the claims. Where an indefinite or definite article is used when referring to a singular noun, e.g. "a", "an", "the", this includes a plural of that noun unless something else is specifically stated.

Furthermore, the terms first, second, third and the like in the description and in the claims are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein. Moreover, the terms top, bottom, over, under, beyond and the like in the description and in the claims are used for descriptive purposes and not necessarily for describing relative positions. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other orientations than described or illustrated herein. It is to be noticed that the terms "comprising" and "including", used in the present description and claims, should not be interpreted as being restricted to the means listed thereafter; it does not exclude other elements or steps. Thus, the scope of the expression "a device comprising means A and B" or "a device including means A and B" should not be limited to devices consisting only of components A and B. It means that with respect to the present invention, the only relevant components of the device are A and B.

According to the first aspect of the invention, a method for manufacturing an orthodontic appliance is provided, wherein the orthodontic appliance has an improved optical appearance. The method comprises the steps manufacturing the orthodontic appliance by means of vacuum molding or pressure molding. I.e. the method comprises providing a positive tooth model and a sheet of a thermoplastic polymer film, and subjecting the sheet of thermoplastic polymer film to vacuum molding or pressure molding utilizing the positive tooth model. In the method of the invention, the positive tooth model is impregnated with a composition including at least one oily component before the sheet of thermoplastic polymer film is applied to the positive tooth model and subjected to vacuum molding or pressure molding.

In an embodiment of the first aspect, the positive tooth model is impregnated with said composition in that said composition is sprayed onto the positive tooth model. Spraying the composition onto the tooth model preferably occurs prior to placing the thermoplastic polymer sheet onto said positive tooth model, and subjecting said thermoplastic polymer sheet to vacuum molding.

In an additional embodiment, the composition is sprayed onto the positive tooth model from a distance of about 10 cm. Spraying the composition onto the positive tooth model allows obtaining an even distribution of the composition on said positive tooth model, and also permits precise control of the amount of

composition that is applied to the positive tooth model.

In another and/or alternative embodiment, the at least one oily component of the composition is selected from the group consisting of Vaseline and essential oils. In a further embodiment the Vaseline is pharmaceutically acceptable Vaseline, i.e. highly pure white Vaseline which is free of any acids. In another further

embodiment, the essential oil is an essential oil extracted from a mint species. Hence, the essential oils can be selected from a mint species selected from the group consisting of peppermint (Mentha peperitae), spearmint (Mentha crispae), Japanese mint (Mentha arvensis) and pennyroyal (Mentha pulegium). Hence, the essential oil can be selected from the group consisting of peppermint oil (Oleum Menthae peperitae), spearmint oil (Oleum Menthae crispae), Japanese mint oil (Oleum menthae arvensis) and poleimin oil.

In an additional and/or alternative embodiment, the composition may comprise an aqueous component, i.e. water. Hence, the composition comprising an oily component may be present in form of an emulsion. In a further embodiment, said emulsion may be an oil-in water emulsion or a water-in-oil emulsion.

In an additional and/or alternative embodiment, the composition may comprise a solvent for the oily component. Said solvent may be a protic solvent such as - for example - ethanol or an aprotic solvent.

In another embodiment, the composition comprises one or more pharmaceutically acceptable excipients such as surfactants, odorants, flavors, colorants, stabilizers, preservatives and the like.

In another and/or alternative embodiment, the composition is provided in combination with a propellant, for example propane, butane or pentane. Thereby the composition can be provided as a spray composition for being applied onto the positive tooth model.

In another and/or additional embodiment of the method, said positive tooth model is a positive tooth model that was manufactured by rapid prototyping, i.e. by a technique for quickly fabricating a scale model of a physical part or assembly using three-dimensional computer aided design data.

In a further embodiment, the positive tooth model is one that was manufactured by a method selected from the group consisting of three-dimensional powder bed ink jet head printing, fused deposition modeling, fused filament fabrication, melted and extrusion modeling, direct metal laser sintering, electron beam melting, selective heat sintering, laminated object manufacturing, digital light processing, selective laser sintering and stereolitography. From the perspective of accuracy, ease of manufacturing and the like, three-dimensional powder bed ink jet head printing is advantageous. Positive tooth models obtained by rapid prototyping possess a somehow rough surface. Hence, utilizing such positive tooth models for manufacturing an orthodontic appliance by means of vacuum molding or pressure molding will result in orthodontic appliances having a rough inner surface, i.e. the surface of the orthodontic appliance which will face the teeth. Said roughness of the inner surface leads to orthodontic appliances being rather translucent than transparent if a transparent thermoplastic polymer film is used for manufacturing said

orthodontic appliance. A translucent orthodontic appliance is easily noticeable when worn by a patient, and this is hardly appreciated by said patient. In addition, orthodontic appliances having a rough inner surface are more difficult to clean and to keep aseptic.

Hence, in another and/or alternative embodiment, the sheet of thermoplastic polymer film is transparent.

In another and/or alternative embodiment, the sheet of thermoplastic polymer film further comprises a thin intermediate layer that is going to face the positive tooth model upon vacuum molding and/or pressure molding. Thin intermediate films were used to improve the optical appearance of orthodontic appliances when manufactured by means of vacuum molding. However, the results are still unsatisfying from the patient's perspective. The method of the present invention significantly improves the optical appearance of the orthodontic appliance, i.e. the resulting orthodontic appliance it still transparent as the thermoplastic polymer film for its manufacturing is. This effect is also obtained if a thin intermediate film between the positive tooth model and the thermoplastic polymer film is used during vacuum molding or pressure molding of the orthodontic appliance. I does not matter whether the intermediate film is provides as a separate sheet or whether it is provided as being adhered to the sheet of thermoplastic polymer film.

In another and/or alternative embodiment, a separate thin intermediate film may be used in the method of manufacturing an orthodontic appliance. It is to be understood that the intermediate film consists of a thermoplastic polymer too. However, the intermediate film is thinner than the thermoplastic polymer film for providing the orthodontic appliance. That is, the intermediate film has a thickness of about 0.1 mm, whereas the thermoplastic polymer film for providing the orthodontic appliance has a thickness of at least about 0.5 mm and may even have a thickness of about 3.0 mm.

In this embodiment, the intermediate film is pressure molded or vacuum molded utilizing the positive tooth model, and remains applied to the positive tooth model when the thermoplastic polymer film is pressure molded utilizing the assembly of positive tooth model and molded intermediate film. In this embodiment, the positive tooth model is impregnated with the composition before the intermediate film is subjected to pressure molding or vacuum molding in that the composition is sprayed on the positive tooth model as described herein above. After molding of the intermediate film, said mold is not removed from the positive tooth model, but remains thereon and the composition is sprayed on the open face of the molded intermediate film before the sheet of thermoplastic polymer film is subjected to pressure molding or vacuum molding utilizing the assembly of positive tooth model and molded intermediate film thereon.

Beyond providing a better optical appearance of the orthodontic appliance resulting from this embodiment of the method according to the present invention, this embodiment provides the advantage that the mold of the thermoplastic polymer film can be removed from the assembly much easier. The intermediate film usually remains attached to the positive tooth model while the molded thermoplastic polymer film is released for excising the orthodontic appliance. The assembly comprising the positive tooth model and the intermediate film thereon can be used for further moldings.

Hence, the method of this embodiment may comprise the following steps:

- providing the positive tooth model,

- providing the sheet of intermediate film,

- providing the sheet of thermoplastic polymer film,

- spraying the composition onto the positive tooth model,

- subjecting the sheet of intermediate film to vacuum molding or pressure molding utilizing the positive tooth model, - optionally spraying the composition onto the assembly comprising the positive tooth model and the intermediate film molded thereon and remaining attached thereto,

- subjecting the sheet of thermoplastic polymer film to vacuum molding or pressure molding utilizing the assembly comprising the positive tooth model and the intermediate film molded thereon and remaining attached thereto,

- removing the molded thermoplastic polymer film from said assembly, and

- excising the orthodontic appliance from the molded thermoplastic polymer film.

According to the second aspect, the present invention provides orthodontic appliances that are obtainable by a method according to the first aspect of the invention, i.e. by vacuum molding or pressure molding, wherein a positive tooth model is impregnated with a composition comprising at least one oily component before the thermoplastic polymer sheet is applied and subjected to molding.

The orthodontic appliance that is obtained by the method according to the first aspect of the invention has a smoother inner surface compared to an orthodontic appliance that is manufactured by vacuum molding or pressure molding without impregnating the positive tooth model prior to the molding. In addition, an orthodontic appliance obtained by the method according to the first aspect of the invention is transparent provided that a transparent thermoplastic polymer film is used for its manufacturing, whereas an orthodontic appliance that is manufactured by vacuum molding or pressure molding without impregnating the positive tooth model prior to the molding becomes translucent upon its molding, despite utilizing a transparent thermoplastic polymer film for its manufacturing. The orthodontic appliance according to the present invention has a better patient's compliance as its use is less noticeable than using a translucent orthodontic appliance.

In an embodiment, the orthodontic appliance is selected from the group consisting of aligner, retainer and trays.

According to the third aspect, the present invention provides the use of a composition comprising at least one oily component for manufacturing an orthodontic appliance by means of subjecting a sheet to a thermoplastic polymer film to vacuum molding or pressure molding utilizing a positive tooth model.

In an embodiment of the use, the composition is sprayed onto the positive tooth model, preferably from a distance of about 10 cm.

In another and/or alternative embodiment of the use, the at least one oily component is selected from the group consisting of Vaseline and essential oils.

In another and/or alternative embodiment of the use, the at least one oily component is an essential mint oil, preferably selected from the group consisting of peppermint oil, spearmint oil, Japanese mint oil and poleimic oil.

In another and/or alternative embodiment of the use, the composition includes an aqueous component.

In another and/or alternative embodiment of the use, the composition includes a protic solvent or an aprotic solvent.

In another and/or alternative embodiment of the use, the composition includes one or more excipients, preferably selected from the group consisting of as surfactants, odorants, flavors, colorants, stabilizers, preservatives and the like.

In another and/or alternative embodiment of the use, the composition includes a propellant, preferably selected from the group consisting of propane, butane and pentane.

Example

A positive tooth model was generated by powder bed 3D inkjet head printing using a ZPrinter 650 (3D Systems, Rock Hill, SC) at highest possible resolution. The positive tooth model was impregnated by using Cetron® Spray (Scheu-Dental GmbH, Iserlohn, Germany) which comprises spearmint oil and n-butane as propellant which was sprayed onto the positive tooth model from a distance of about 10 cm. A sheet of a so called intermediate film having a thickness of 0.1 mm (ISOFOLAN®, Scheu-Dental GmbH, Iserlohn, Germany) was heated to 85°C and subjected to pressure molding at 5.3 bar for 25 seconds utilizing said positive tooth model and a BIOSTAR® vacuum molding machine (Scheu-Dental GmbH,

Iserlohn, Germany). Then a sheet of thermoplastic polymer film having a thickness of 0.75 mm (DURAN®, Scheu-Dental GmbH, Iserlohn, Germany) was heated to 85°C and subjected to pressure molding at 5.3 bar for 25 seconds utilizing the positive tooth model already provided with the molded intermediate film thereon using the BIOSTAR® vacuum molding machine (Scheu-Dental GmbH, Iserlohn, Germany).

The orthodontic appliance was excised from the resulting mold whereas the intermediate film remained attached to the positive tooth model. The orthodontic appliance exhibited a clear and transparent appearance, whereas an orthodontic appliance that was manufactured the same way, but without impregnation of the positive tooth model appeared translucent. In addition, it turned out that the impregnation led to an easier removal of the molded orthodontic appliance from the positive tooth model.

Patent Citations
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US5103838 *9 Feb 199014 Apr 1992Yousif Edward NDental night guard
US7802987 *18 Aug 200028 Sep 2010Align Technology, Inc.Methods and systems for lubricating dental appliances
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Classifications
International ClassificationA61C7/08, A61C13/34
Cooperative ClassificationA61C7/08, A61C13/34
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