Dentistry – Orthodontics – Bracket
Reexamination Certificate
2000-10-06
2002-04-09
O'Connor, Cary E. (Department: 3732)
Dentistry
Orthodontics
Bracket
Reexamination Certificate
active
06368105
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an orthodontic bracket, and more particularly to an orthodontic bracket having a shiftable locking member so as to open or close an arch wire slot in a bracket body as well as a tool for an orthodontic bracket.
2. Description of the Related Art
As is known, orthodontic treatment is effected by fixing small appliances called orthodontic brackets to a patient's teeth. Namely, the orthodontic brackets are most commonly used by being fixed to the patient's teeth in an appropriate manner so as to correct the misaligned teeth by applying an external force thereto through an arch wire extending between the fixed orthodontic brackets.
As to the structure of these orthodontic brackets, they are constructed of a body having small slots and are adhered directly on the labial or lingual sides of the teeth or welded to such as metal bands attached to the teeth by cementing or by some other method.
As the form of use of the orthodontic bracket constructed as described above, an elastic arch wire, which is curved so as to conform to a dental arch, is placed in a slot in the bracket, and the tooth can be shifted over time by the restoring force of the elastic arch wire so that the teeth become well aligned.
Namely, with the orthodontic bracket, a force can be applied to the tooth in a desired direction (in the direction in which the tooth is shifted, rotated, or tilted) by the three-dimensional inclination of the slot formed in the bracket body or by the desired bending of the arch wire.
The conventional orthodontic bracket has tie wings, and a ligature wire or an elastomeric ligature ring is hooked on the tie wings so as to positively hold the arch wire to prevent the arch wire from coming out of the slot in the bracket. The dentition that should be treated is of malocclusion, in which the arch wires are greatly deformed when engaged. Orthodontic treatment is done by transmitting the restoring force of the arch wires through brackets to the tooth roots. Generally, in an early period of the treatment, a thin soft round wire is used, and an operation is required to loosen the ligature wire after ligating it such that the round wire freely slides within the slot (on a nonfrictional basis). In addition, the frictional force cannot be eliminated with the elastomeric ligature ring.
As treatment progresses, a thicker wire, a square wire, and a more highly rigid wire come to be used. When the shifting treatment is nearly completed, they are held for a while to prevent relapsing. At this time, there are cases where the tooth is strongly fastened by a ligature wire so that it practically does not shift.
In the orthodontic treatment as described above, different arch wires of many varieties are used in succession during the course of the treatment. During patient visits to the clinic, it is necessary to remove the ligature wire and adjust the bend of the arch wire or replace it. This operation requires much chair time and imparts discomfort to the patients.
In addition, an end of the ligature wire which has been cut after ligation is accommodated so as to be bent and thrust into a groove under the tie wing. Such modes of attachment lead to problems of food residues tending to adhere. As a result, comparatively large number of measures had to be taken in order to maintain good hygienic conditions inside the teeth. In addition, there are cases where the ligature wire causes the trouble of imparting stimuli to the soft tissue of the patient's tongue or cheek as its bent end becomes exposed from below the tie wing. If this ligature wire is cut and reshifted, the patient may swallow the dislocated ligature wire, or the treatment may make no progress. Further, in recent years serious concern has been expressed over various infectious diseases which occur due to bleeding caused by the piercing of the doctor's fingers by the ligature wire.
The various problems due to the use of such a ligature wire can be overcome to some extent by using a lock-type orthodontic bracket. Namely, this lock-type orthodontic bracket has the structure which does not require the tie wire for ligation, and has a locking member incorporated in the bracket and capable of shifting for opening or closing the slot in the bracket. As the locking members, there are, for example, rotating-type and sliding-type locking members. Since the locking members are capable of shifting, the retention of the arch wire in the slot or disengagement of the arch wire from the slot can be effected very easily. In addition, the structure is free of a bent portion of the ligature wire and is therefore trim, it is easy to avoid such as the sticking of food and its residue.
As shown in
FIG. 13
, with the orthodontic bracket having the aforementioned sliding-type locking member, an arch wire
50
in an arch wire slot
85
provided in a bracket body
82
is locked in the slot by a tip portion of a locking member
120
mounted on the bracket body
82
. As for the tip portion of the locking member
120
, its shift in the loosening direction is restricted by a stop groove
86
continuing to the slot
85
, for example. Normally, the arch wire
50
in the slot
85
is located on the bottom side of the slot, as shown in FIG.
13
. However, when an unexpected large external force is applied to the arch wire
50
, the arch wire
50
can enter the stop groove
86
and become caught therein, as shown in FIG.
14
.
In such a state, the arch wire
50
fails to shift smoothly inside the slot, and a hindrance is caused to the orthodontic treatment. To avoid such a state, it is conceivable to decrease the width W of the stop groove
86
, but if that width W is decreased, the function of the locking member
120
(the function of pressing down the wires ranging from the narrow round wire to the full-size square wire within the range of the elasticity) declines, so that it is not desirable to do so.
In addition, there has been a problem in that when an unexpected large external force is applied to the arch wire
50
, a tip portion
121
of the locking member
120
becomes twisted as the arch wire
50
is twisted, thereby rendering the wire retention unstable. In the structure disclosed in U.S. Pat. No. 5,906,486, an arrangement is shown in which the position of the tip portion of the locking member is restricted in such a manner as to close both ends of the stop groove. In such a structure, however, since the arrangement is provided so as to close both ends of the stop groove, the width of the tip portion of the locking member must be inevitably made smaller than the length of the slot. Accordingly, there has been a drawback in that the tip portion of the locking member has insufficient rotation control since its length for holding the arch wire is short.
SUMMARY OF THE INVENTION
The invention has been made to overcome the above-described problems, and its object is to provide an orthodontic bracket having a locking member which makes it possible to avoid the situation of the arch wire becoming coming out the slot and entering the stop groove, and which makes the retention of the arch wire more reliable and excels in the operating efficiency. In the orthodontic brackets of rhomboid-type and torque-in-base type orthodontic brackets, the object is to provide an orthodontic bracket excelling in the handling efficiency. Another object of the invention is to provide a tool excelling in the efficiency in handling the locking member.
In accordance with the invention, there is provided an orthodontic bracket including a base secured to a tooth surface, a bracket body extending in a substantially perpendicular direction from the base, an arch wire slot which extends in a mesiodistal direction substantially in a center of the bracket body and is open in the front, and a locking member capable of opening or closing the arch wire slot, wherein the locking member is structured in a substantially U-shaped cross-sectional configuration, one side thereof being formed as a base side portion
Orikasa Masaaki
Voudouris John C.
Kenyon & Kenyon
O'Connor Cary E.
LandOfFree
Orthodontic bracket and its tool does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Orthodontic bracket and its tool, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Orthodontic bracket and its tool will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2908364