Dentistry – Orthodontics – Bracket
Reexamination Certificate
1999-06-08
2001-07-10
Lewis, Ralph A. (Department: 3732)
Dentistry
Orthodontics
Bracket
Reexamination Certificate
active
06257883
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates in general to pre-engaging orthodontic brackets and in particular to a pre-engaging twin orthodontic bracket and to a plurality of orthodontic brackets forming a set of braces.
BACKGROUND OF THE INVENTION
According to established orthodontic techniques, it is well known that one is able to ligate an archwire to a bracket utilizing an elastic, elastomeric or metal ligature. In a twin edgewise orthodontic bracket, the elastic ligature is stretched around respective undercuts of gingival and occlusal tie wings so as to overlay the archwire at mesial and distal ends of the bracket.
The ligating procedure involves carefully stretching the elastic or elastomeric ligature (or wrapping and twisting a metal ligature) around the tie wings utilizing appropriate orthodontic instruments. It has been found that the time-consuming ligation procedure contributes to lengthy chair time. Furthermore, the elastic ligatures are known to lose their elasticity with time and are subject to degradation. Also, the elastic and metal ligatures have been known to trap food particles in areas of the bracket which are difficult for the patient to clean, and to increase the level of friction against the archwire. Finally, the use of sharp metal ligatures around the bracket can subject the clinician to unnecessary exposure to infectious bacteria, or viruses such as hepatitis B, or possibly the HIV virus particularly in blood.
In an effort to overcome these disadvantages of elastic ligatures, certain advances have been made in the area of pre-engaging orthodontic brackets. Each of U.S. Pat. Nos. 4,144,642; 4,248,588; 4,698,017; 3,772,787; 4,786,242; 4,559,012; 4,561,844; 4,655,708; 4,077,126; 4,419,078; 4,634,661; 4,197,642; and 4,712,999 illustrate one or more designs of pre-engaging brackets. These prior art devices overcome some of the disadvantages associated with elastic ligatures. For example, pre-engaging orthodontic brackets eliminate, or at least reduce, exposure of the clinician to sharp ligatures, thereby alleviating the problem of contracting harmful bacteria or viruses. In addition, pre-engaging orthodontic brackets permit continuous low deflection differential archwire contact separately for both round and rectangular archwires at at least two different levels of contact, which is not possible with degrading elastic, elastomeric or rigid, high deflection metal ligatures. However, most of the known prior art pre-engaging orthodontic brackets lack the reliability and the accessible ease of operability that most clinicians require. In addition, the majority of prior art pre-engaging orthodontic brackets are of a single design that have three or fewer tie wings.
It is therefore an object of the present invention to provide a novel twin pre-engaging orthodontic bracket which obviates or mitigates at least one of the above-identified disadvantages associated with prior art orthodontic brackets.
SUMMARY OF THE INVENTION
According to one aspect of the present invention there is provided a pre-engaging orthodontic bracket for attaching an archwire to a tooth comprising:
a body having a lingual surface for attachment to a tooth, a pair of laterally spaced gingival tie wings and a pair of laterally spaced occlusal tie wings, said gingival and occlusal tie wings projecting from a labial surface of said body, both said gingival tie wings and occlusal tie wings at opposed mesial and distal sides of said body being separated by an interwing region of said body;
an archwire slot extending mesiodistally across said body and between the gingival and occlusal tie wings at opposed mesial and distal sides of said body to accommodate an archwire, said archwire slot being interrupted by said interwing region;
a locking shutter moveable relative to said body between an open position in which placement and removal of said archwire in said archwire slot is facilitated and a closed position in which placement and removal of said archwire in said archwire slot is inhibited; and
biasing means carried by said locking shutter and engageable with an archwire in said archwire slot when said locking shutter is in said closed position, said biasing means resiliently urging said archwire into said archwire slot to provide a continuous corrective force thereon.
In one embodiment, the biasing means is in the form of a leaf spring secured to the locking shutter. The leaf spring can extend mesiodistally or occlusiogingivally. In another embodiment, the locking shutter is formed of resilient material and biases the archwire when the locking shutter is in the closed position thereby to constitute the biasing means.
According to another aspect of the present invention there is provided a pre-engaging orthodontic bracket for attaching an archwire to a tooth comprising:
a body having a lingual surface for attachment to a tooth, a pair of laterally spaced gingival tie wings and a pair of laterally spaced occlusal tie wings, said gingival and occlusal tie wings projecting from a labial surface of said body, both said gingival tie wings and occlusal tie wings at opposed mesial and distal sides of said body being separated by an interwing region of said body;
an archwire slot extending mesiodistally across said body and between the gingival and occlusal tie wings at opposed mesial and distal sides of said body to accommodate an archwire, said archwire slot being interrupted by said interwing region;
a locking shutter movable relative to said body between an open position in which placement and removal of said archwire in said archwire slot is facilitated and a closed position in which placement and removal of said archwire from said archwire slot is inhibited; and
biasing means engageable with an archwire in said archwire slot when said locking shutter is in said closed position to urge said archwire toward said locking shutter to provide a continuous corrective force thereon.
In one embodiment, the biasing means is in the form of a resilient spring member extending mesiodistally along the archwire slot and secured to the body. The spring member has at least one free end and can be dimensioned to engage an archwire either within the archwire slot or exterior to the archwire slot. In another embodiment, the resilient spring member extends occlusiodistally across the archwire slot in the interwing region and is secured to the body adjacent one end thereof.
In another embodiment, the biasing means is in the form of magnetized elements within the body adjacent the archwire slot to present a repelling magnetic force to the archwire to bias the archwire towards the locking shutter. In yet another embodiment, the biasing means is in the form of a pair of spring-loaded pistons accommodated by the body adjacent opposed mesial and distal ends of the archwire slot to urge the archwire towards the locking shutter.
According to still yet another aspect of the present invention there is provided a pre-engaging orthodontic bracket for attaching an archwire to a tooth comprising:
a body having a lingual surface for attachment to a tooth, a pair of laterally spaced gingival tie wings and a pair of laterally spaced occlusal tie wings, said gingival and occlusal tie wings projecting from a labial surface of said body, both said gingival tie wings and occlusal tie wings at opposed mesial and distal sides of said body being separated by an interwing region of said body;
an archwire slot extending mesiodistally across said body and between the gingival and occlusal tie wings at opposed mesial and distal sides of said body to accommodate an archwire, said archwire slot being interrupted by said interwing region; and
a locking shutter pivotal about at least one pivot pin between an open position in which placement and removal of said archwire in said archwire slot is facilitated and a closed position in which placement of said archwire in said archwire slot is inhibited.
In one embodiment, the orthodontic bracket includes one pivot pin extending between the tie wings of one of the two pairs and wherein the locking
Lewis Ralph A.
Michael Best & Friedrich L.L.P.
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