Dentistry – Orthodontics – Bracket
Reexamination Certificate
2001-04-03
2002-11-19
Manahan, Todd E. (Department: 3732)
Dentistry
Orthodontics
Bracket
C206S309000, C401S129000
Reexamination Certificate
active
06482003
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to the delivery of dental adhesives and particularly to the delivery of dental adhesives in small or single dose quantities. The invention is more particularly applicable to the delivery of dental adhesives for the bonding of orthodontic appliances to teeth.
BACKGROUND OF THE INVENTION
Providing dental adhesives to dental practitioners in a form that they can be efficiently used and so that excess quantities are not exposed or wasted has been the subject of a number of efforts. Single dose delivery systems have been developed in which a dental adhesive or composite of a quantity that is no greater than that needed for a single application or as a single dose include, for example, the delivery system described in U.S. Pat. No. 5,860,806, hereby expressly incorporated herein by reference.
With the development of orthodontic brackets such as those described, for example in U.S. Pat. No. 4,068,379, the orthodontic brackets with bases for adhesive bonding to teeth have replaced tooth encircling bands as the primary appliances for connecting orthodontic archwires to teeth. With banded appliances, archwire supports mounted on bands encircle the teeth to hold the archwire supports in place on the teeth. Brackets, on the other hand, rely solely on an adhesive bond between the base or pad of the bracket and the surface of the crown of the tooth. Adequate bond strength between the teeth and the bracket bases has traditionally required the dentist or an assistant to dispense adhesive onto the bracket at chairside, using single or multiple part dental adhesives specifically developed for securing orthodontic appliances to teeth. Popular single part adhesives are cured by ultraviolet light, while multiple part adhesives cure chemically, following the mixing of the adhesive immediately preceding use. Multiple part or chemical cure adhesives are often capable of producing bonds that are stronger than with the light cured adhesives.
The application of adhesives to brackets at chairside is a time consuming activity for a dental or orthodontic practitioner. In preparing adhesive at chairside, the quantity of adhesive dispensed must be carefully controlled by the orthodontist or other office personnel. Cleanup is required, which must be done by the doctor, whose time is expensive. The handling of brackets during the application of adhesive can result in misorientation of the appliances or a mixup of appliances, which are usually each designed to fit a specific tooth.
One attempt to minimize the chairside handling of adhesives in the application of orthodontic appliances to teeth has been the introduction of orthodontic brackets with light cured adhesive pre-applied to the bracket bases. While these brackets with pre-applied adhesive are attractive to orthodontists for their promise of convenience and ease of installation on the teeth of the patient, such brackets have been associated with an increased failure rate of the bond between the bracket bases and the teeth.
One cause of failures of the bonds between the bracket and a tooth is due to the use of an adhesive beyond its actual shelf life. The shelf life of adhesive that has been pre-applied to brackets is optimistically claimed to be twenty-four months. In practice, environmental factors, such as heat, humidity, etc., during transit and storage of the brackets having the pre-applied adhesives, shorten the shelf life of the adhesive. Furthermore, orthodontic brackets with adhesives pre-applied seldom reach the offices of orthodontists immediately following manufacture, so that some portion of the shelf life of the adhesive is already spent by the time the brackets are received into inventory by the orthodontist. In addition, careful records and careful inventory control by the doctor is required to insure that all adhesively pre-coated brackets are used in a first-in first-out (FIFO) basis and before the adhesive becomes too old.
Orthodontic brackets are often stocked by orthodontists in sufficient quantities so that the doctor has available appliances of various types and sizes to use on any common occasion in the treatment of patients. Maintaining appliance inventories necessarily requires that certain appliances will be in inventory longer than others. Ordinarily, orthodontic brackets are made of metal or other materials that have shelf lives that exceed the technological lives of the appliance, that is, the appliance can usually be stored until it is used or becomes obsolete, which can be many years from the stocking of the appliance by the doctor. Orthodontic brackets have a cost of several dollars each to the doctor, for example, four U.S. dollars per bracket at the time of this patent application. The cost of the adhesive used to secure orthodontic brackets to teeth is substantially less than the cost of an ordinary bracket. A single dose of adhesive, that is, the amount of adhesive necessary to secure a single orthodontic bracket to a tooth, varies from a few cents when supplied separately to about a 75 cent/bracket price premium charged by an adhesively pre-coated bracket manufacturer. As a result, the pre-application by a bracket manufacturer of a few cents worth of adhesive to the base of a bracket has the undesirable effect of limiting the shelf life of a relatively expensive orthodontic appliance.
There are additional disadvantages to the adhesively pre-coated orthodontic appliances currently available to orthodontists. The packaging of such appliances, for example, is quite expensive to produce and is bulky. One hundred cases, for example, might occupy several cubic feet of space in a dentist's office, which is equal, for example, to that occupied by a small appliance or piece of furniture. Individual brackets having pre-applied adhesive are packaged in sealed packages which must be individually opened at chairside. Appliance delivery systems cannot readily accommodate these brackets or bracket packages, and separate systems for dispensing adhesive primer must be used. Only one part, light curable adhesives, can be pre-applied to brackets. Use of multiple part adhesives, which can be up to thirty percent stronger, is not practical for use on pre-coated brackets. Furthermore, when the amount of pre-applied adhesive appears to be incorrect in a particular situation, there is no easy way for the orthodontic practitioner to adjust the quantity of adhesive in the dentist's office.
Accordingly, there is a great need on the part of orthodontic practitioners for a system for easily and conveniently applying orthodontic appliances to teeth with adhesive that does not have all of the disadvantages of the pre-adhesively coated orthodontic brackets of the prior art.
SUMMARY OF THE INVENTION
A primary objective of the present invention is to provide a dental practitioner a convenient supply of dental adhesive that can be used with a maximum reliability and efficiency and minimum amount of waste and mess. A particular objective of the invention is to provide such a supply of adhesive to an orthodontic practitioner for use in bonding orthodontic brackets to teeth.
A further objective of the present invention is to provide an orthodontic practitioner the advantages that adhesively pre-coated brackets have over the chairside application of adhesive from bulk sources to orthodontic appliances and overcoming the disadvantages of the adhesively pre-coated brackets of the prior art.
According to principles of the present invention, single doses of dental adhesive are provided on substrates and enclosed over an area of the card with a removable cover. The doses of adhesive are provided by dispensing one or more metered amounts of adhesive, preferably in the form of a high viscosity liquid or a paste, onto an area of the substrate, preferably in the form of a disposable card, over which a protective cover is secured. The cover keeps the adhesive out of contact with objects during shipping and handling, and sufficiently prevents exposure of the adhesive to chemicals or light or whatever other med
Andreiko Craig A.
Dixon Daniel R.
Manahan Todd #E.
Ormco Corporation
Wood Herron & Evans L.L.P.
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