Dentistry – Orthodontics – Bracket
Reexamination Certificate
2000-07-19
2001-03-20
Lucchesi, Nicholas D. (Department: 3732)
Dentistry
Orthodontics
Bracket
C433S022000
Reexamination Certificate
active
06203317
ABSTRACT:
DESCRIPTION
This invention relates in general to an orthodontic elastomeric appliance having a slippery outer surface when wetted and a method of making the appliance, wherein the appliance is formed of elastomeric material and coated with a polymer film which when wetted becomes slippery, and more particularly to an orthodontic polyurethane ligature having a slippery outer surface when wetted, and a method of making the ligature including molding the ligature of polyurethane and coating the ligature with a hydrophillic polymer blend so that the ligature, when used in the mouth and wetted, will have a slippery surface to facilitate the movement of brackets on an archwire and decrease treatment time.
BACKGROUND OF THE INVENTION
Heretofore, it has been well known to form orthodontic appliances of elastomeric material and to mold orthodontic ligatures of elastic urethane, such as shown in U.S. Pat. No. 3,530,583. Similarly, U.S. Pat. Nos. 3,758,947 and 4,900,250 also disclose the molding of orthodontic elastomeric appliances.
It has also been known to coat elastomeric medical devices with a hydrophillic film as shown in U.S. Pat. Nos. 4,100,309 and 4,642,267 so that the medical appliances when wet have a low coefficient of friction and are hydrophillic.
Orthodontic treatment of patients nearly always involves the use of metal, ceramic or plastic brackets in combination with metal archwires. The brackets are provided with archwire slots and tie wings for receiving ligatures to retain the archwires on the brackets. Generally, these ligatures are made of elastomeric material, including polyurethane, as above mentioned. Polyurethane ligatures exhibit a high contact adhesiveness to metal archwires. This contact adhesiveness creates an opposing force and inhibits the movement of brackets along an archwire, thereby increasing treatment time. This problem created by the ligatures has been addressed in the design of self-ligating brackets and other specialty brackets. However, such specialty brackets produce other problems such as loss of rotational control and the inability to use ligatures for cosmetic purposes.
SUMMARY OF THE INVENTION
The present invention solves the problem of contact adhesiveness by coating elastomeric ligatures with a polymer that exhibits slipperiness as soon as it is contacted by water or saliva in the mouth. Thus, the coated elastomeric ligatures of the present invention are slippery when wet and therefore overcome the contact adhesiveness problem to allow ease of movement of brackets along an archwire, thereby decreasing treatment time.
The present invention accordingly is in an orthodontic elastomeric appliance such as of polyurethane or other urethane material that is elastomeric and which is coated so that it will be slippery on the outer surface when wetted in the mouth. Any suitable polymer coating that becomes slippery when hydrated may be applied to the elastomeric appliance, such as the coatings disclosed in the above mentioned U.S. Pat. Nos. 4,100,309 and 4,642,267.
It is therefore an object of the present invention to provide a new and improved orthodontic elastomeric appliance that is slippery when wetted to enhance the treatment time of a patient.
Another object of the present invention is to provide a polyurethane ligature coated with a hydrophillic polymer blend which renders the ligature slippery when wetted in the mouth of a patient to decrease the coefficient of friction between the metal archwire and the ligature.
In accordance with the present invention, the coating applicable to the elastomeric appliance may comprise a solution of methylene chloride, methyl ethyl ketone and polyvinylpyrrolidone in which the appliances may be dip-coated, and thereafter air-dried and oven-baked. It will be appreciated that the elastomeric appliance of the present invention will be generally referred to as a ligature although it may be a series of ligatures in chain form, as shown in the above referred to U.S. Pat. No. 4,900,250. Further, it will be appreciated that while it is preferable that the ligature herein referred to is molded such as by injection molding, it could be otherwise formed such as by stamping from a sheet of material.
Accordingly, the orthodontic polyurethane ligature of the invention with a polymer coating will substantially reduce the coefficient of friction between the ligature and the archwire to facilitate the movement of brackets along an archwire and decrease the overall treatment time.
REFERENCES:
patent: 3530583 (1970-09-01), Klein et al.
patent: 3758947 (1973-09-01), Kesling
patent: 4100309 (1978-07-01), Micklus et al.
patent: 4642267 (1987-02-01), Creasy et al.
patent: 4900250 (1990-02-01), Kesling et al.
patent: 5378146 (1995-01-01), Sterrett
patent: 5419913 (1995-05-01), Podell et al.
Lucchesi Nicholas D.
TP Orthodontics Inc.
Zickert Lloyd L.
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