Dentistry – Orthodontics
Reexamination Certificate
2001-05-29
2003-07-08
Shaver, Kevin (Department: 3732)
Dentistry
Orthodontics
C433S006000
Reexamination Certificate
active
06589050
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to fragranced orthodontic appliances and particularly flavored or fragranced orthodontic appliances having encapsulated fragranced oils encapsulated and distributed throughout the matrix of the polymeric appliance. Orthodontic appliances are employed in the practice of correction or prevention of irregularities of the teeth or structure of the oral cavity. These appliances are custom made to conform to the upper and lower palate of the mouth and typically consist of a hard acrylic resin in which wires or auxiliary devices can optionally be embedded. Some such appliances are Frankel, Bionator, Bite Splint, Retainer, Sagittal, and Bonded Palatal Expander, etc. These appliances are unlike other dental prosthesis in that they are custom made with what is commonly known in the art as “cold cure” acrylic.
“Cold cure” acrylic is made up of two components: a polymeric component and a monomeric component. To produce the desired acrylic material, the polymer is used as the powdered compound and the monomer is used as the liquid compound. These materials are prepared in a away that when mixed a free radical polymerization of the monomeric liquid occurs at room temperature which results in a solid homogeneous acrylic material. Typically, the polymer and monomer are comprised of an ester of acrylic or methacrylic acid with methyl methacrylate liquid and poly(methyl methacrylate) powder being, the orthodontic appliance industry standard material. Other esters such as ethyl methacrylate have been used but are not in wide spread use in methyl methacrylate.
Orthodontic appliances are commonly used as part of a regimented treatment program and habitual wearing of the appliance is required to achieve the desired result. Anyone who has had orthodontic treatment is aware of the discomfort associated with the wearing of an orthodontic appliance such as Retainer. They are bulky and often impeded clear speech. Exposed wires can also be an embarrassment, especially to younger people. As a result of these discomforts patient compliance in wearing these appliances is less than ideal.
In order to improve patient compliance with the use of these appliances the concept of flavoring or fragrancing the appliance has been applied. For example, U.S. Pat. No. 5,080,583 discloses the use of fragrancing or flavoring oil in the liquid monomeric component of the “cold cure” acrylic resin thereby achieving a flavored or fragranced appliance. U.S. Pat. No. 3,808,686 discloses the use of a scented surface coating applied as a solution onto the prepared acrylic device. These approaches have proven disadvantageous as they provide a relatively short-lived flavor or fragrance, i.e., typically 2 to 3 days in the case of U.S. Pat. No. 5,080,583 and, only minutes in the case of the surface coating. It can be speculated that simply increasing the quantity of flavor or fragrancing oil in the case of U.S. Pat. No. 5,080,583 could increase the duration of the flavor or fragrance. This has also proved disadvantageous because the inventor found that cold cure was inhibited. Thus there is a limit to the total quantity of flavor or fragrance that the appliance can contain. The prior art also discloses the inclusion of a flavor-releasing capsule in the acrylic base member designed to release flavor over long periods. However, this approach has also proved disadvantageous because the appliance is required to be of suitable thickness to accommodate the capsule and most appliances such as those listed are simply too thin.
SUMMARY OF THE INVENTION
Clearly there is a need to develop a technology for fragranced or flavored orthodontic appliances and a method of forming such appliances where the flavor or fragrance endures longer than 2 to 3 days, the preparation technique is the traditional “cold cure” process and it can be applied to most all orthodontic appliances. The terms fragranced oils or flavored oils are used interchangeably or separately depending upon their intended function. In the case of orthodontic appliances, both functions are useful or important. As will be understood, however, a fragranced oil such as spearmint also has a flavor. For ease of description herein, the term fragrance and fragranced oil will be used to include either or both functions regardless of whether the primary purpose of the additive is for flavoring or fragrance.
The above mentioned objectives are attained by the present invention which is directed to a fragranced orthodontic appliance which provides for a flavor and fragrance that endures significantly longer than 2 to 3 days.
The present invention is directed to a cold cure fragranced acrylic orthodontic appliance comprised of a hard cold cure base member that is prepared from a suitable powdered polymeric component and a liquid monomeric component, wherein both the liquid and the powdered component contain a selected fragrancing oil. Further, the suitable powdered polymeric component is comprised of one or more monomeric derivatives of acrylic or preferably methacrylic acid and a fragrancing oil. These materials are designed such that once the liquid monomeric component and the polymeric powdered component are combined under the appropriate conditions the material will “cold cure” and result in a homogeneous acrylic copolymer having a longer lasting fragrance.
The method of producing the fragranced orthodontic appliance of this invention utilizes suspension polymerization to encapsulate the fragrance in the powdered component thereby permitting inclusion of the fragrance in both the liquid and powder components of the appliance. The method of this invention thus includes forming a polymerized powder containing the desired fragrance by mixing a monomer or more preferably comonomers and a fragrance oil in a water suspension, heating and agitating the suspension to initiate suspension polymerization, separating and drying the polymerized polymer as small spheres or beads of the polymer containing the fragrance. The liquid component is formed by mixing the acrylic monomer or preferably methacrylate comonomers with a flavoring agent. Finally, the fragranced polymeric orthodontic appliance is formed by applying the polymeric powder component and liquid component to a mold of an orthodontic appliance and cold curing the orthodontic appliance under pressure by conventional means.
In the most preferred embodiments of the fragranced orthodontic appliance and method of this invention, the monomers are of derivatives of acrylic acid, more preferably derivatives of methacrylic acid, most preferably methyl methacrylic acid or ester. Thus, the method of this invention includes forming the polymeric powder component by mixing an acrylic monomer or more preferably a monomer of methacrylate, most preferably derivatives of methyl methacrylate acid and a fragrance oil in a water suspension forming a methacrylate or acrylic acid ester, then heating and agitating the suspension to initiate the polymerization and drying the acrylic or methacrylate polymer or copolymer to form a powder having the preferred fragrance encapsulated therein. The liquid component also preferably includes a monomer or comonomer selected from the group consisting of methacrylic or acrylic acid, more preferably methacrylic acid esters, most preferably including at least 30% by weight methyl methacrylate or more preferably at least 50% methyl methacrylate. The comonomer is preferably butyl methacrylate. The method of forming the liquid component thus includes mixing the monomer and comonomer preferably including methacrylic acid esters, most preferably including methyl methacrylate and a fragrance oil. The orthodontic appliance is then made by applying the polymeric fragranced powder and the liquid fragranced component to a mold of the orthodontic appliance and cold curing the orthodontic appliance as described.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention relates to the preparation of fragranced orthodontic appliances using what is known in the art as “cold cure” acry
Mackey Paul W.
Woods Tanya L.
Bumgarner Melba
Howard & Howard
Shaver Kevin
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