Dentistry – Orthodontics – Bracket
Reexamination Certificate
2001-04-12
2004-12-07
Wilson, John J (Department: 3732)
Dentistry
Orthodontics
Bracket
C433S018000, C433S173000
Reexamination Certificate
active
06827574
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to an orthodontic appliance, and more particularly to an orthodontic bone anchor that can provide tension usable as fixed pushing, pulling or stabilizing points by the orthodontist in treating the malalignment of the teeth of a patient without disturbing adjacent teeth.
2. Description of Related Art
In traditional tooth movement, orthodontic brackets are placed on the teeth, and the brackets are connected to one another using orthodontic archwires. The orthodontic archwire in conjunction with tension bands guides and provides tooth-moving forces to certain teeth, using other teeth as anchors. This traditional method of tooth movement however, has several potential shortcomings. For example, in some patients, the tooth or teeth to be used as an anchor may be missing. Furthermore, although a particular tooth may be serving as an anchor in resisting an orthodontic force, in reality the tension band on the teeth being moved also will exert a counter-force on this “anchor” tooth which may cause undesirable movement of the anchor tooth.
Therefore, in treating many orthodontic patients, it is desirable to move some teeth yet stabilize other teeth which otherwise would move due to the reactive forces created in the mouth. Traditionally, this tooth stabilization, or differential tooth movement, has been achieved by applying lower forces in the mouth or by utilizing several teeth as the anchor. However, when lower forces are applied, orthodontic treatment requires significantly more time, and when several teeth are used in combination as an anchor, the resulting tooth-moving response may be somewhat unpredictable.
All orthodontic forces adhere to Newton's “Law of Reciprocal Forces.” If a tension band force is applied to retract or pull back an object such as a tooth, there exists an “equal and opposite” force to move another tooth or object forward. The resistive force value of the teeth is known as anchorage. Orthodontists may offset these reciprocal tendencies by using an extraoral force known as a headgear to augment the resistive force value of the teeth and as a way of obtaining differential tooth movement. Patient compliance is often inadequate as many patients do not want to wear the headgear. Poor compliance compromises orthodontic therapy and often the final result. Orthodontic forces are usually continuous, acting 24 hours a day. Realistically, most patients will not wear headgear more than 10-12 hours/day. Therefore, the posterior anchorage is typically fortified only 40-50% of the time. All too often, inconsistent usage or overt noncompliance will reduce this effect even more.
Endosseous implants which are placed deeply into bone, are useful when physical space within the mouth is available such as through absence of a molar, however, their use is limited in full dentition where space is at a premium. Endosseous implants are also not suitable in juvenile or adolescents because they are inserted into a hole which is drilled into the alveolar (tooth bearing) portion of the jawbone. Insertion of an endosseous implant into these areas will harm unerupted teeth forming in these areas. Since the juvenile and adolescent patients are still growing, an endosseous implant will be engulfed with continuing vertical development of the alveolar bone and will progressively sink to a lower level thereby becoming inaccessible and difficult to remove.
Subperiostal bone anchors have been known and used in dentistry for many years and their value in orthodontics has been acknowledged since at least the mid 1980's (Turley, J. Dent. Res. 63A:334, 1984). These bone anchors can be attached to bone just about anywhere in the mouth with little, if any likelihood of destruction of bone or teeth. Block and Hoffman first patented (Block, Orthodontic Anchor U.S. Pat. No. 5,066,224; Hoffman, Subperiosteal Bone Anchor; U.S. Pat. No. 5,538,427) then later published (Am. J. Orthod. Dentofac. Orthop. 107:251,1995) an orthodontic anchorage system that did not penetrate the bone as endosteal implants do but merely rested on the surface of the bone.
One of the difficulties with some of the prior art is that the devices were rigid, thick and are not moldable to the unique bone morphology found at the surgical site or into a desired direction. Further, the bone-anchor interface surface was often times very complex, being shaped to allow and foster bone ingrowth. After the many weeks for the prior art to osseointegrate, a further surgical procedure is necessary to uncover a portion of the anchor and attach an extruding abutment.
It will therefore be understood that the prior devices are rigid, cannot be adapted to irregular bony contours at the time of surgery, are somewhat bulky and thus limit intraoral placement to locations where overlying soft tissue is relatively thick, such as in the palate, and require two separate surgical procedures. Additionally the attachment procedure connecting the device to teeth is complex and often requires additional laboratory steps.
In the last 10 years small bone plates in numerous configurations have come into high use in orthognathic and maxillofacial reconstructive surgery with such plates being deformable and contourable to fit to a variety of irregular bony surgical sites. Contourable bone plates of “Y”, “T”, “L” and “I” shape configurations, and of more complex geometrical shapes, are available in a variety of thicknesses and with a selection of degrees of malleability.
U.S. Pat. No. 5,853,291 to Vincenzo discloses a thin, subperiosteal bone anchor for use in conjunction with orthodontic appliances having a plurality of moldable, scalloped leaves and arms to facilitate bone overgrowth and an upwardly extending stem with a variety of attachment connection mechanisms. The entire base and leaves of the anchor are scalloped to foster osteointegration. A sphere or rectangular tube projects upward. This anchor, although small, thin and moldable to bone, is highly three dimensional with its orthodontic attachment rising up from its planar fixation against the bone, is structured with tapering, leaf-like projections to foster osteointegration, whereas the present invention is in substantially a planar configuration when in use, is designed to be temporary and without osteointegration, includes a tension band holder and wire guide integrally fixated thereon which are structured to receive and attach other orthodontic adjustment and attachment devices and requires less traumatic surgical procedures to remove, thus has less morbidity to the patient.
The plates readily usable in orthognathic and maxillo-facial surgery, as described above, are generally relatively small (about 20-40 mm. in their major dimension). These small, malleable bone plates, often made of a titanium alloy contain a plurality of holes situated over the surface through which standard bone screws and fasteners can pass to attach the plate to bone and through which archwire can be threaded when attaching the distal end of the plate stemarm to orthodontic appliances within the mouth of the patient. Although the small, moldable bone plates function as adequate anchors and do not osteointegrate, the stemarm portion with only holes for attachment to other orthodontic hardware in the patient's mouth provide limited directional torque and control thereby restricting treatment options, compromising outcome, and often prolonging treatment time. These miniature prior art bone plates can be obtained from a variety of suppliers, e.g. KLS Martin, L. P. of Jacksonville, Fla., see pages 7-9, 35-37, 48, 58-60, 74-77, 101, and 102 of their Surgical Instrument Catalog, 1st edition, for examples and from W. Lorenz of Jacksonville, Fla., see pages 4, 5, 7, 10, 12, 17, 19, 20, 29, and 30 of the 1988 Surgical Instrument Catalog for examples.
In the orthodontic field a need exists for a non-osteointegrating, bendable temporary bone anchor and tension band connector for resisting tension band forces of the tension band attached to a toot
Malin Haley & DiMaggio, P.A.
Wilson John J
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