Dentistry – Orthodontics – Bracket
Reexamination Certificate
2000-05-24
2001-06-19
Lucchesi, Nicholas D. (Department: 3732)
Dentistry
Orthodontics
Bracket
C433S011000
Reexamination Certificate
active
06247923
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to self-locking or ligatureless orthodontic brackets.
BACKGROUND OF THE INVENTION
Orthodontic brackets may be used with arch wires to straighten irregular teeth. These brackets are attached to the teeth and engage a flexible arch wire that exerts pressure upon them to move the teeth. The most commonly used brackets are edgewise brackets as shown in
FIGS. 1
,
2
, and
3
.
FIG. 1
shows a Siamese twin bracket,
FIG. 2
shows a single bracket with rotation wings, and
FIG. 3
shows a modified edgewise bracket known as Tip-Edge bracket. Such brackets typically include an arch wire slot that extends horizontally across the face of the bracket for the reception of the arch wire. This slot can be angularly oriented to minimize bending of arch wires. A pair of wings extend vertically on either side of the arch wire slot from the bracket enabling ligature means to be tied to the bracket to retain the arch wire in the slot. Stainless steel ligature ties or elastomeric ligature rings are conventionally used as the ligature means.
Placement of these small wires or elastomeric ligature rings requires considerable time during initial installation of an arch wire. It is also normally necessary to remove and replace the ligatures each time an arch wire is changed.
Ligatures also tend to make proper oral hygiene more difficult as the wires can trap food particles, and the twisted ends of a ligature may be shifted during cleaning into a position where irritation of the patient's gums or cheek tissues occurs.
When repositioning teeth with brackets, it is often necessary to cause the teeth and the brackets to slide along the arch wire. Since the ligature ties are in firm contact with the arch wire, friction is generated between the brackets and the arch wire affecting the tooth movements adversely.
Many of these problems presented by ligatures are overcome by self-locking orthodontic brackets. So far numerous attempts have been made to develop such brackets.
U.S. Pat. No. 2,671,964 to Russel et al. that was issued on Mar. 16, 1954 shows a hollow bracket with a slidable cover within. This bracket does not have tie wings that are necessary for engaging elastomeric chains and continuous ligature ties. U.S. Pat. No. 3,131,474 to Johnson also shows a hollow bracket with a slidable cover recessed with in. Both these brackets are hollow and have to be manufactured from metal sheets whereas the contemporary brackets are solid.
U.S. Pat. No. 5,094,614 to Wildman issued on Mar. 10, 1992 discloses a slidable closure that engages the front of the arch wire. The closure is recessed from the front or anterior surface of the disclosed bracket.
U.S. Pat. Nos. 5,275,557; 5,429,500, & 5,466,151 to Damon show a slidable cover supported by sliding guides that engage the opposed side surfaces of tying lugs. A transverse flat spring is recessed within the fixed wall to selectively engage indented areas on the posterior surface of the cover and serve as detent.
Another slidable cover has been disclosed in U.S. Pat. No. 5,322,435 issued to Pletcher on Jun. 21, 1994. A resilient member is provided to retain the slide member of the bracket in either the open or closed position, while preventing excessive sliding movement that could disengage the slide member.
Various other locking means such as a slidable spring cover, a hinged locking cover, a rotary slidable cover, a bail type rotatable cover etc. have been disclosed in different U.S. Patents. “Activa” produced by A Company, “Speed” and “Edgelock” produced by Ormco Corporation, and others are typical examples of ligature-less brackets that are commercially available.
Of all these different locking means a sliding closure is particularly desirable because it can be easily manipulated and it reduce the time required for opening and closing of the arch wire slot during periodic adjustments of the arch wire. It also provides more precise control of the arch wire:. The other means are more complex, however, and therefore difficult and expensive to manufacture Also, they are not as compact as would be desired. Additionally, it is difficult to use auxiliary attachments with brackets without tie wings. Also, with brackets having detachable parts, there are chances of such parts getting separated accidentally and getting lost or swallowed by patients. Moreover, springs used as locking means are not strong enough to hold the arch wire into the slot.
OBJECTS AND ADVANTAGES
The object of the present invention is to provide a locking device for an orthodontic bracket that operates on the face of the bracket for opening and closing the arch wire slot. This is possible by means of the self-locking bracket and its different embodiments as described in this specification.
Accordingly, several objects and advantages of the present invention are:
1. to provide a self-locking or ligatureless orthodontic bracket that is easy to use,
2. to provide a self-locking or ligatureless orthodontic bracket that helps in reducing the time taken during insertion and removal of an arch wire,
3. to provide a self-locking or ligatureless orthodontic bracket that is easy to fabricate thereby making it less expensive,
4. to provide a self-locking or ligatureless orthodontic bracket that facilitates the use of auxiliary attachments by means of tie wings,
5. to provide a self-locking or ligatureless orthodontic bracket that considerably reduces the friction caused by the tying of ligature means to retain an arch wire into the arch wire slot, thereby facilitating tooth movements.
6. to provide a self-locking or ligatureless orthodontic bracket wherein the arch wire slot is closed automatically by a cover on releasing the pressure applied to the cover to open the slot.
SUMMARY OF THE INVENTION
This invention relates to a locking mechanism for securing an arch wire to an orthodontic bracket slot. This means is very easy to manufacture and easy to operate for closing and opening the arch wire slot. It eliminates the need for ligature wires and elastic ligatures, while keeping the tie wings intact for auxiliaries like power chains and continuous ligature ties.
The bracket of this invention has several novel aspects. In general, the bracket includes a bracket body attached to a base that is contoured to fit a tooth surface. The body of the bracket has an arch wire slot extending horizontally across the labial/buccal surface. In the preferred embodiment, at least one tie wig extends out vertically from the body. A retainer member having a transverse part and two perpendicular horizontal extensions at the end is attached to the sides of the tie wing. A slidable cover is retained and guided in the passageway created between the retainer member and the surface of the tie wing. The slidable cover can be moved vertically towards the tip of the tie wing to open the arch wire slot and it can be moved in the opposite direction to close the arch wire slot after the engagement of an arch wire into the slot. The cover fits closely in the passageway and is frictionally retained.
Various different embodiments of the bracket, the cover, and the retainer member are described which facilitate movements of the slidable cover and prevent inadvertent dislodgment of the cover from the bracket.
Although many different embodiments of the cover and the retainer member are disclosed in the specification, the cover works in the same manner in all the embodiments, i.e. by sliding over the face of the bracket. The difference lies only in the manner in which the slidable cover is retained on the face of the bracket and is guided to open and close the arch wire slot.
The objects and advantages of the present invention will become apparent from a consideration of the drawings and ensuing description.
REFERENCES:
patent: 2671964 (1954-03-01), Russel et al.
patent: 3131474 (1964-05-01), Johnson
patent: 3780437 (1973-12-01), Wildman
patent: 4023274 (1977-05-01), Wallshein
patent: 4268249 (1981-05-01), Forster
patent: 4492573 (1985-01-01), Hanson
patent: 4559012 (1985-12-01), Pletcher
patent:
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