Packaging system for pre-pasted orthodontic bracket

A packaged, pre-pasted orthodontic bracket includes a container having an open well therein and a top surface surrounding the well. A cover film with a central hole is disposed over the top opening of the well and secured to the top surface of the container with a layer of adhesive. An orthodontic bracket mounted in the central hole of the cover film has a base, a central portion extending from the base, at least two opposed tie wings extending from the central portion of the bracket, and a layer of light-curable adhesive disposed on the base of the bracket. The bracket is mounted in the central hole of the cover film such that the cover film contacts the central portion of the bracket and supports the bracket with the adhesive layer and base inside the well and the tie wings outside the well. Preferably, the bracket is supported such that the layer of light-curable adhesive is spaced from a bottom wall of the well, and the cover film and the container are opaque to light in the wavelength range used to cure the light-curable adhesive.

TECHNICAL FIELD

The invention relates to the packaging of orthodontic devices, in particular to a packaged, pre-pasted orthodontic bracket wherein the bracket is mounted in a well in a package and supported with a cover film such that the pre-pasted base of the bracket is suspended in the well.

BACKGROUND OF THE INVENTION

Modern orthodontic techniques include repositioning teeth that are misaligned, too close together or otherwise mis-positioned. In order to reposition the teeth, the teeth are connected to an arch wire that serves as a guide, urging the teeth into the desired position and orientation. In order to connect the teeth to the arch wire, small brackets with slots for receiving the arch wire are attached to the teeth. The ends of the arch wire are normally attached to the molars with another orthodontic appliance known as a buccal tube. In some cases, the bracket or tube is brazed or welded or brazed to a metal band placed around the patient's tooth. However, the preferred method of attaching brackets to a patient's teeth is by means of an adhesive. Bonding brackets to a patient's teeth is more comfortable for the patient, cosmetically more appealing and faster in practice than the use of metal bands.

Applying an appropriate amount of adhesive to the base of an orthodontic appliance such as a bracket or buccal tube can be a time consuming and tedious task for the orthodontist or his or her assistant. Too little adhesive may result in the bracket coming loose from the tooth after installation while an excessive amount of adhesive will be pushed out from between the bracket and tooth, requiring removal. Further, while two-part chemically curing adhesive systems are available for bonding orthodontic brackets to a patient's teeth, many practitioners prefer photo sensitive adhesives that are cured upon exposure to light in the visible spectrum for a relatively short period. Consequently, time is also a factor insofar as the adhesive applied to the bracket can only be exposed to visible light for a limited period before the bracket is positioned on the tooth.

In order to address these issues, pre-pasted orthodontic appliances were developed. Pre-pasted orthodontic appliances have an adhesive, normally a photo sensitive, light curing adhesive, applied to the base of the bracket before the bracket is packaged. Pre-pasted brackets reduce the amount of time required to install brackets on the patient's teeth by eliminating the need for the orthodontist to apply the adhesive to the bracket. Pre-pasted brackets also reduce the amount of wasted adhesive as the manufacturer can precisely control the amount and placement of the adhesive on the base of the bracket.

Packaging for brackets with a pre-applied light curing adhesive must protect the adhesive from exposure to light, as well as from contamination and evaporation. Further, if the adhesive adheres to the package, the adhesive coating may be disturbed when the bracket is removed from the package. Thus, in some cases, the pre-pasted portion of the orthodontic appliance is isolated from the package material with a release coating or layer. In addition, the package should present the bracket to the orthodontist in a fashion that facilitates quick and convenient removal of the bracket from the package.

SUMMARY OF THE INVENTION

A packaged, pre-pasted orthodontic bracket in accordance with the invention includes a container having an open well therein and a top surface surrounding the well. A cover film with a central hole is disposed over the top opening of the well and secured to the top surface of the container with a layer of adhesive. An orthodontic bracket mounted in the central hole of the cover film has a base, a central portion extending from the base, at least two opposed tie wings extending from the central portion of the bracket and a layer of light-curable adhesive disposed on the base of the bracket. The bracket is mounted in the central hole of the cover film such that the cover film contacts the central portion of the bracket and supports the bracket with the adhesive layer and base inside the well and the tie wings outside the well. Preferably, the bracket is supported such that the layer of light-curable adhesive is spaced from a bottom wall of the well, and the cover film and the container are opaque to light in the wavelength range used to cure the light-curable adhesive.

In one variation, a second layer of adhesive secures the cover film to the central portion of the bracket. In another aspect, the cover film has a radial slit therein extending from the central hole to an outer edge of the film, permitting the film to be wrapped around the central portion of the bracket. Thus, the film may be wrapped around the bracket such that the film extends more than 360 degrees about the central hole forming an overlapping end flap.

DETAILED DESCRIPTION

Referring toFIGS. 1 and 2, a pre-pasted orthodontic bracket and package assembly10of the invention includes a bracket12and a container16. Bracket12is supported part way inside a circular well14of container16. Well14has a cylindrical sidewall15and a flat bottom wall17. Container16may be vacuum formed from an appropriate plastic material such as polyethylene or an ethylene copolymer with a filler or dye that renders the substrate opaque to visible light. See commonly-assigned U.S. Patent Publication 20020195363, Dec. 26, 2002, the contents of which are incorporated by reference herein. Bracket12includes a pair of opposed tie wings18, a narrowed central portion20and a flat base24. A light curable adhesive paste layer22, typically curable with visible light in the 400-510 nm wavelength range, is adhered to the bottom surface of base24.

A circular skirt or cover film26formed from a thin flexible plastic film covers well14and supports bracket12in the well. Skirt26has a rectangular central opening28configured to receive bracket12, and is adhered to the upper surface of container16around the periphery of well14with an annular pressure sensitive adhesive layer30. In order to protect light-curable adhesive layer22, skirt26and container16are opaque to visible light, at minimum to wavelengths effective to cure the adhesive, in this example actinic radiation in the range of 400-510 nm. If an additional cover is used as described further below, then skirt26may be transparent.

Bracket12is positioned in opening28such that skirt26encircles central portion20of the bracket, preferably at a location below and spaced apart from tie wings18. Skirt26supports the bracket with tie wings18extending above container16and adhesive layer22suspended and spaced above bottom wall17of well14. Thus, adhesive layer22is prevented from contacting container16, avoiding the possibility that the light curable adhesive layer22will be disturbed by contact with the container.

Referring toFIG. 2, skirt26may be produced by cutting a piece of plastic film to form a circular shape with a central opening28. Skirt26is slit in a radial direction forming a slit39such that a first end34of skirt26may overlap a second end36of the skirt, forming a tab38. Since tab38is not in contact with pressure sensitive adhesive layer30, a practitioner may readily grasp tab38with a tweezers or similar tool to peel skirt26away from container16. Alternatively, the tab portion38may a separate piece that is applied to an otherwise circular blank used to make skirt26. Skirt26could also be formed as a pair of overlapping pieces of plastic that overlap one another on opposite sides of opening28, each half having a three-sided notch therein which form opening28when the two halves are superposed.

Inner edges of skirt26may engage central portion20around its periphery, causing a slight elastic deformation of skirt26and thereby holding bracket12in the position shown. For this purpose, central opening28has dimensions slightly smaller than central portion20at the location where skirt26engages central portion20. Alternatively, if central opening28is slightly larger and engages central portion20at its narrowest point, mechanical engagement can be used to hold bracket12. Given sufficient stiffness of skirt26, bracket12cannot move either into or out of well14when skirt26is in place.

Turning toFIGS. 3 and 4, in a further variation, a package assembly40utilizes a skirt42that slopes slightly upwardly from its outer perimeter to central opening28. The sloped configuration of skirt42results in easier application of the skirt to container16and gives the skirt the shape of a truncated cone. Preferably, the slope of skirt42from the outside perimeter of the skirt to the edge of opening28is in the range of from about 0.012 to 0.015 inches per inch, or from about 0.012 to 0.015 degrees. As used herein, the term “about” refers to nominal values within normal manufacturing tolerances.

Optionally a second layer32of pressure sensitive adhesive is positioned around the inner periphery of skirt42to adhere skirt42to the bracket. Second adhesive layer32aids in sealing well14to prevent deterioration of paste layer22. Preferably, layer32is formed on skirt42and is releaseably adhered to midportion20or bracket12, so that no adhesive residue if left behind when skirt42is removed.

Packages according to the invention are preferably placed inside a secondary container providing a gas-tight seal, such as a zip-loc bag. This is especially useful if no inner adhesive layer32is used. In addition, one or more caps or covers may be provided over the container16. As shown inFIG. 3, a flange60of a cylindrical plastic cover61is secured outside of skirt42by a third layer of pressure sensitive adhesive62, which may comprise a radial enlargement of adhesive layer30. A tab63is provided to aid in peeling off cover61at the time of use. Cover61may be made of a plastic opaque to visible light, in which case skirt42may be made of a transparent plastic film.

Turning toFIG. 5, a package50for multiple orthodontic brackets comprises a plurality of circular wells14formed in a plastic strip52. A plurality of brackets12are each supported in a well14by a skirt26as shown inFIG. 1. Package50is configured for six brackets12, but the package may be configured for a greater or lesser number of brackets, depending upon the particular application and specific type of brackets, and may have more than one row of brackets.

FIG. 6illustrates an embodiment similar to that ofFIG. 5wherein a single rectangular cover70similar in construction to cover61covers all of the brackets12until the time of use. A removal tab71is provided at one end of strip52, and a rectangular outer flange72of cover70is secured to the strip by a pressure sensitive adhesive in the same manner as cover61.

FIG. 7illustrates a series of individually packaged brackets12using covers61as inFIG. 3. Containers16are formed in a strip with perforations76between each container to permit the user to remove one bracket package at a time.

While certain embodiments of the invention have been illustrated for the purposes of this disclosure, numerous changes in the method and apparatus of the invention presented herein may be made by those skilled in the art, such changes being embodied within the scope and spirit of the present invention as defined in the appended claims.