Dentistry – Orthodontics – Bracket
Reexamination Certificate
1999-10-08
2001-03-27
Lewis, Ralph A. (Department: 3732)
Dentistry
Orthodontics
Bracket
C433S008000
Reexamination Certificate
active
06206690
ABSTRACT:
TECHNICAL FIELD
The present invention relates to orthodontic appliances, such as brackets and buccal tubes for fixation to the teeth of a patient. More particularly, the invention relates to such appliances with non-parallel opposite surfaces adapted to be gripped by a tool during installation and/or removal procedures.
BACKGROUND OF THE INVENTION
Improperly positioned teeth may be forced into desired positions through the use of a flexible wire, referred to by orthodontists as an archwire, and a series of appliances affixed to respective upper and lower teeth. The appliances currently take the form of specialized brackets and buccal tubes formed from suitable metallic or ceramic or plastic material. The orthodontist typically adheres the appliances to the teeth with an adhesive, although other fixation methods are known as well. Each appliance includes a slot or a hole to receive and control the position of the archwire.
The design of orthodontic appliances involves the balancing of several considerations. The appliance must adequately retain and position the archwire and further allow for adjustments to the archwire. Preferably, appliances are compatible with other dental attachments with minimal complexity and are strong yet compact. The most common bracket design is the so-called tie-wing bracket. This bracket includes a slot for insertion of the archwire and a plurality of projections referred to as wings. After the archwire is set in the slot of the bracket, either a tie wire or an O-ring is affixed beneath the wings and over the archwire at each end of the archwire slot. The tie-wing bracket is a simple design and provides excellent control of the archwire. Brackets of this type typically have parallel upper and lower surfaces of adequate size to be easily gripped with conventional orthodontic pliers. However, some orthodontic appliances are generally tubular in shape or otherwise have nonparallel, opposite surfaces. These appliances include buccal tubes used on rear molars to anchor and hold the archwire ends in proper alignment.
In one prior buccal tube design, for example, one outer surface slopes downwardly from a position close to the base or tooth mounting surface and an opposite outer surface extends essentially perpendicular from the base. A small gripping ledge is contained on the body of the buccal tube and intersects the sloped surface. In addition to facilitating patient comfort, one of the main functions of the sloping surface is to deflect food particles which may become lodged between respective buccal tubes of the upper and lower teeth as the patient chews food, especially hard foods such as hard candy, etc. Unfortunately, the sloping surface also impedes the ability of the orthodontist to grasp the buccal tube with a pair of conventional pliers during installation or removal procedures. The small gripping ledge on the body of the buccal tube is not easily grasped at all times and the orthodontist may therefore experience “shoot-out” of the buccal tube from the tool as one of the gripping jaws of the tool slides down the sloping surface.
While it would be desirable to continue providing one or more sloping surface in many orthodontic appliances, it would also be desirable to provide a orthodontic appliance, such as a buccal tube or other orthodontic bracket or appliance, with better gripping ability despite the presence of opposite, nonparallel appliance surfaces.
SUMMARY OF THE INVENTION
The present invention is therefore directed to an orthodontic appliance having nonparallel opposite surfaces, such as upper and lower surfaces, but having at least one specialized portion that may be securely gripped with an orthodontic tool during installation. The appliance generally includes a body with a plurality of outer surfaces. One surface is a mounting surface or base which is affixed against a tooth, such as with an adhesive or in another suitable manner. The body also includes a passage, such as an open-ended hole or an open channel, for receiving an archwire. Two opposed outer surfaces are nonparallel in that at least one of the outer surfaces generally slopes toward the other. The slope may be angular and planar or may be rounded. Other nonparallel configurations may derive benefit from this invention as well. In accordance with the present invention, a gripping portion is located on the body such that it intersects one of the nonparallel outer surfaces, such as the sloping outer surface. This portion creates a gripping surface which, in conjunction with the opposite outer surface, is used to grasp the body with much greater stability than previous appliance configurations having nonparallel opposite surfaces.
In one particular example, the upper outer surface of a buccal tube, as used on a lower molar, begins generally at an upper edge and slopes downward. The slope of this surface aids in patient comfort and causes food particles to be deflected away from the tooth and the corresponding upper buccal tube. The gripping portion may comprise at least two alternative forms. First, a notch or recess may be formed into the sloping outer surface. Second, the gripping portion may take the form of a small shelf which projects slightly outward from the sloping outer surface. Each form of the gripping portion creates a generally parallel gripping surface relative to the opposite gripping surface which may or may not also be formed as a notch or shelf. Ideal gripping is achieved when the gripping surfaces are parallel. However, the gripping portion of one nonparallel surface may be only substantially parallel with an opposite gripping surface and still achieve the objective of this invention.
A method of using the appliance is also contemplated by the present invention. Generally, an orthodontic gripping tool having movable jaws is positioned with its jaws on opposite sides of the appliance. The jaws are then closed and thus become seated on the body of the appliance. Seating is accomplished on a first gripping surface portion of one nonparallel surface and the opposing gripping surface which may or may not be another gripping surface portion formed on an otherwise nonparallel surface relative to the first gripping surface portion. The compressive force exerted by the tool is increased to ensure the appliance is firmly held. Then, the appliance is directed into the patient's mouth and affixed to the patient's tooth. The gripping tool is then released from the appliance after the appliance has been fixed to the tooth. A similar method, which is essentially the reverse of the installation method, may be used during a removal procedure.
Other features, objects and advantages of the invention will become more readily apparent to those of ordinary skill in the art upon review of the following detailed description of the preferred embodiments, taken in conjunction with the accompanying drawings.
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patent: 4936773 (1990-06-01), Kawaguchi
patent: 5094614 (1992-03-01), Wildman
patent: 5439378 (1995-08-01), Damon
patent: 5707231 (1998-01-01), Watt et al.
patent: 6053729 (2000-04-01), Brehm et al.
Lewis Ralph A.
Ormco Corporation
Wood Herron & Evans L.L.P.
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