Claims:
I claim
1. An orthodontic bracket comprising a bracket body having base, gingival, labial, occlusal, distal and mesial surface portions and a mesial-distal extending arch wire slot opening to the labial surface portion; an embracing retainer member mounted on the bracket body, the retainer member having opposed front and back portions thereof in embracing sliding engagement respectively with the labial and base body surface portions, the retainer member having a part of its front portion shaped to extend over the labial surface portion when in a corresponding slot closed position on the body to close the slot opening at the labial surface portion for retention of an arch wire in the slot, the retainer member being movable with said embracing sliding engagement on the body between the said slot-closed position and a slot-open position in which the slot opening at the labial surface portion is open, and means for positively retaining the member in at least the slot-closed position.
2. A bracket as claimed in claim 1, and including means for positively retaining the member in the said slot open position.
3. A bracket as claimed in claim 1, wherein the retainer member is a generally U-shaped flat member conforming to the labial, occlusal and base surface portions, and with the arms of the U constituting the said front and back portions in embracing sliding engagement with the labial and base surface portions.
4. A bracket as claimed in claim 3, wherein the said positive retaining means for the retainer member comprise a part of the back base-conforming portion of the member displaced out of the general plane thereof and engageable with a cooperating part of the bracket body.
5. A bracket as claimed in claim 2, wherein the retainer member is a generally U-shaped flat member conforming to the labial, occlusal and base surface portions, and said positive retaining means comprise a part of the back base-conforming portion of the member displaced out of the general plane thereof and engageable with two spaced cooperating parts of the bracket body.
6. A bracket as claimed in claim 4, wherein the said positive retaining means comprise a mesial-distal extending ridge of the retainer member engageable with the retainer member in the slot closed position in a cooperating recess in the bracket body base surface portion.
7. A bracket as claimed in claim 5, wherein the said positive retaining means comprise a mesial-distal extending ridge of the retainer member engageable when the retainer member is in the slot open and slot closed positions in respective spaced co-operating recesses in the bracket body base surface portion.
8. A bracket as claimed in claim 3 in combination with a tooth band, and wherein the part of the retainer member conforming to the base surface portion is accommodated in a recess formed between the band and the said base surface portion.
9. A bracket as claimed in claim 1, wherein the bracket body comprises two separate connected bracket body portions spaced apart medially distally and each provided with its respective retainer member.
10. A bracket as claimed in claim 9, and comprising an occlusal-gingival-extending opening disposed between the said connected bracket body portions.
11. A bracket as claimed in claim 1, and comprising a labial-extending projection extending from the labial surface portion and having mesial-distal-extending arm portions, the projection constituting an anchorage for elastic bands and the like.
12. A bracket as claimed in claim 1, in combination with a cooperating tool having two jaw members movable toward and away from one another by manipulation of an operator, the bracket body having two cam surfaces extending from the respective distal-mesial surface portions to the occlusal surface portion for engagement by the tool jaw members moving toward each other, the said cam surfaces urging the jaw members into corresponding engagement with the retainer member for movement of the retainer member by the jaw members from slot-closed to slot-open position.
13. A bracket as claimed in claim 1, wherein the part of the bracket body between the said gingival surface portion and the arch wire slot is provided with a mesial-distal aperture extending parallel to the arch wire slot for the reception of additional structure.
14. An orthodontic bracket comprising a bracket body having base, gingival, labial, occlusal, distal and mesial surface portions and a mesial-distal extending arch wire slot opening to the labial surface portion, and an embracing retainer member mounted on the bracket body, the retainer member having opposed front and back portions thereof in embracing retaining engagement respectively with the labial and base body surface portions the retainer member conforming closely to the said labial, occlusal and base portions and having a part of its front portion shaped to extend over the labial surface portion when in a corresponding slot closed position on the body to close the slot opening at the labial surface portion for retention of an arch wire in the slot, the retainer member being movable with said embracing sliding engagement on the body between the said slot closed position and a slot open position in which the slot opening at the labial surface portion is open, the back portion of the retainer member conforming to the base portion having a part thereof displaced out of the general plane thereof and engageable with corresponding spaced parts of the bracket body for positively retaining the retainer member in the said slot-closed and slot-open positions.
Description:
FIELD OF THE INVENTION
The present invention is concerned with improvements in or relating to orthodontic brackets that are employed in procedures for applying corrective moving forces to teeth.
REVIEW OF THE PRIOR ART
Brackets are almost universally used in orthodontic procedures and usually are fastened to a tooth band that is in turn mounted around the tooth, although they may instead be secured directly to the teeth, e.g., by cementing thereto. The brackets are connected together in the mouth of the patient by a thin springy arch wire that applies the required forces thereto.
In the technique most commonly employed, known generally as the "edgewise" technique, each bracket is provided with a mesial-distal-extending labially opening slot which receives a cooperating arch wire of selected cross-section and springiness. Each bracket is fastened to the wire by a ligature, usually comprising a thinner softer tie wire, that must be tied by hand by the orthodontist in the patient's mouth subsequent to the mounting of the brackets on the teeth and the insertion of the arch wire in the slots. The tie wire retains the arch wire in the slot, while permitting the necessary movement of the bracket along the arch wire as the tooth moves in the gum under the forces applied thereto.
In another technique now employed, known as the "Begg light wire" technique a somewhat thinner arch wire is employed, received in a slot located as close as possible to the tooth band, and retained in the slot by a pin passing through a gingival-occlusal-extending slot in the bracket. These pins must also be inserted in the patient's mouth.
For ease of manipulation a long tie wire is used, the unwanted long ends being severed after tying to leave short ends that must be tucked carefully away to avoid damage to the patient's mouth, teeth and gums. Similarly, the ends of the above-mentioned pins are severed after installation and the remaining short end carefully tucked away.
Despite the disadvantages of the brackets used in both of these procedures they continue to be employed since they have proven by experience to be flexible and successful in operation, and able to withstand the high stresses and harsh environment to which they are subjected in the human mouth.
Reference is made to copending application Ser. No: 195,132 filed Nov. 3, 1971 disclosing and claiming a new orthodontic bracket comprising a bracket body having base, labial, gingival, occlusal, distal and mesial surface portions and a mesial-distal extending arch wire slot opening to the labial surface portion, and a spring retainer member mounted on the bracket body and having a portion thereof extending over the labial surface portion to close the corresponding side of the arch wire slot for retention of the wire therein, the labially extending portion being displaceable against the resilience of the member for insertion of a wire in the slot.
DEFINITION OF THE INVENTION
It is an object of the present invention to provide a new orthodontic bracket.
It is a more specific object to provide a new slotted orthodontic bracket not requiring the use of a separate ligature for the retention of an arch wire in the slot thereof.
In accordance with the present invention there is provided an orthodontic bracket comprising a bracket body having base, labial, gingival, occlusal, distal and mesial surface portions and a mesial-distal extending arch wire slot opening to the labial surface portion; a retainer member mounted on the bracket body the retainer member having two opposed portions thereof in embracing sliding engagement with corresponding body surface portions with a portion thereof shaped to extend over the labial surface portion to close the corresponding side of the arch wire slot for retention of the wire therein, the retainer member being movable with said embracing sliding engagement on the body between two positions in which the slot labial side opening is respectively open and closed; and means for positively retaining the member in at least the said slot closed position.
DESCRIPTION OF THE DRAWINGS
Orthodontic brackets that are particular preferred embodiments of the invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings wherein:
FIG. 1 is a general perspective view showing a single bracket fastened to a tooth band with the retainer member thereof in the slot-closed position and with an arch wire shown positioned in the slot thereof,
FIG. 2 is a side elevation of the embodiment of FIG. 1 showing in solid lines the arch wire in process of insertion in the bracket and in broken lines fully inserted in the bracket,
FIG. 3 is a plan view from above of the bracket of FIGS. 1 and 2,
FIG. 4 is a general perspective view of a bracket of the invention and showing the form of a tool employed in moving the retainer member from the closed to the open position, part only of the tool being shown because of the scale involved,
FIG. 5 is a front elevation of a double bracket of the invention, and
FIGS. 6 to 10 are perspective views of other embodiments of the invention, parts of the brackets being shown broken away wherever necessary for clarity of illustration.
Similar parts are given the same reference in all the figures of the drawings.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Each bracket comprises a body 10 provided with oppositely extending flanges 11 by which it is fastened to a tooth band 12 that is placed by the orthodontist around a tooth 13. At the present time the usual practice is for the body and its flanges to be formed integrally with one another by drilling and/or grinding from a piece of stainless steel, the flanges thereafter being welded to the band 12, which is also of stainless steel. Other suitable materials and manufacturing processes can of course be used. The invention is also applicable to brackets with which flanges and tooth bands are not required, the bracket being cemented directly to the tooth for the period of the procedure.
For convenience in description the exterior surface of the bracket body 10 is described as comprising a labial surface portion 14, occlusal and gingival surface portions 15 and 16 respectively, connected by the labial portion 14, and two spaced mesial-distal surface portions 17, also connected by the labial portion. A base surface portion 18 opposite to the labial portion 14 also joins the occlusal and gingival portions and the two mesial-distal portions. It will be understood that in some embodiments the body surface may be so smoothly contoured that the adjacent surface portions merge smoothly with one another with no specific demarcation junction between them.
Referring now especially to FIG. 1, the body is provided with a mesial-distal-extending slot 19 opening in the labial portion and receiving an arch wire 20. The arch wire is illustrated as being of rectangular cross-section dimensioned to just fit snugly within the slot 19 but, as is well known to those skilled in the art, wires of other dimensions and cross-sections may be employed, depending upon the forces that are required to be applied to the tooth to be moved. Means for retaining the arch wire in the slot, while permitting relative movements in the required directions between the bracket and arch wire, comprise a generally U-shaped member 21 of thin flat stainless steel shaped to embrace the body 10 and conform closely with the base, occlusal and labial surface portions thereof. One base-conforming arm 21a of the spring member is inserted in a passage formed between the tooth band and the walls of a groove provided in the base surface portion 18 and can slide freely in the passage but without substantial play. The retainer member is movable between two positions, illustrated in FIG. 2 by showing the member in solid and broken lines, and in which labial-conforming arm 21b of the member respectively closes and does not close the slot labial opening.
The member is positively retained in its slot-closed position by the engagement of a ridge 22, formed by pressing the corresponding part of the arm 21b out of the general plane thereof, in a corresponding recess 23 formed in the base portion of the bracket body. Preferably, the retainer member also is positively retained in the slot-open position by engagement of the same ridge 22 with another recess 24 in the body base portion. In the slot-closed position the free end of the arm 21b rests on a ledge 25 formed at the corresponding side of the slot, so that the assembled bracket presents a labial surface that is as smooth as possible, reducing the possibility of irritation of the patient's lips, cheeks, etc.
The retainer member is readily moved from closed to open position at any time by use of the pincer or tweezer-type tool 26 partly shown in FIG. 4, the operative ends 27 of the tool facing each other and co-operating with sloping cam faces 28 that extend from each mesial-distal surface 17 to the occlusal surface 15. Thus, movement of the two ends 27 toward one another while in contact with the cam faces 28 forces the retainer member from the closed to the open position.
Other forms of mechanical engagement to provide the required positive retention between the retainer member and the bracket body, such as dimples and corresponding recesses, will be apparent to those skilled in the art.
In use the tooth bands with attached brackets are placed on the teeth and one end of the arch wire is locked to and end-most bracket by suitable means. Any retainer members not in the open position are moved to that position, and the orthodontist then inserts the rectangular wire in the slots and presses on the retainer members to move them to their closed positions, as illustrated by broken lines in FIG. 2. The member is of adequate strength and rigidity to retain the wire in the slot, but permits free movement of the bracket along the wire and, with wire cross sections other than that illustrated, will allow various rotations of the bracket relative to the wire.
A double bracket with two mesial-distally spaced bracket parts is illustrated by FIG. 5. The depth added to the base-lingual dimension of the bracket by the thickness of the flat metal member is substantially less than that required to provide suitable slots for tie wire retention so that, in addition to the ease of mounting the arch wire, the brackets can be of smaller depth, giving greater comfort to the patient and with less possibility of contact between the brackets and the inside of the mouth. It is also found that the occlusal-gingival dimension can be substantially reduced, with corresponding less possibility of occlusal interference in use. It will be noted from FIGS. 1 and 2 that the slot 19 is located nearer to the gingival portion than the occlusal portion, since there is no need as with prior brackets using ligatures to locate it approximately midway between the two tie slots, resulting in the arch wire being less susceptible to breakage or distortion from occlusal stresses.
FIG. 5 also shows how advantage can be taken of the above-mentioned reduced base-labial requirement to provide instead a bracket with an intervening portion 29 thick enough to accommodate an occlusal-gingival-extending hole 30. As illustrated this hole is capable of receiving a corresponding wire 31 forming, for example, one end of a spring used by the orthodontist for applying corresponding forces to the bracket. It will also be seen that a combination bracket may be provided having the wire and pin apertures necessary for use in the above-described light wire technique, as is disclosed for example in U.S. Pat. Ser. No: 3,163,933, the disclosure of which is incorporated herein by reference.
FIG. 6 shows an embodiment in which the edges of the slot 19 at its junction with the surface portions 17 are smoothly curved to permit rotation of the bracket about the wire without the slot edges biting into the arch wire and producing excessive frictional forces between them and the wire.
In the embodiment of FIG. 7 the sloping cam faces 28 are curved in both of the base-labial and mesial-distal directions, while the body 10 is provided only with a recess 24, the ridge 22 engaging beneath the junction of the gingival and base surface portions 16 and 18 to retain the member in the slot-closed position.
The retaining means of the embodiment of FIGS. 8 and 9 are the same as those of the embodiment of FIG. 7; the labial-conforming arm 21b however extends over the full extent of the labial surface portion 14 when in the slot-closed position, the free edge of the arm being smoothly rounded in a curve that is continued by the bracket body. The body is in addition provided with a gingivally extending smoothly rounded projection 32 having oppositely mesial-distal-extending arms, the projection serving as an anchorage for elastic bands that are used between brackets in some techniques.
In the embodiment of FIG. 10 the gingivally extending portion of the bracket body between the gingival surface portion and the arch wire slot is made sufficiently deep to permit the provision therein of a mesial-distal extending elongated aperture 33 of cylindrical cross-section. The tubular aperture thus formed extends parallel to the arch wire slot. Such a bracket is located in the mouth of the patient so that the aperture 33 is disposed to receive and mount any additional corresponding structure necessary or desirable for the procedure in use. For example, such a bracket in the 6T6 position can mount a bumper, and/or a bracket can be provided at each side of the mouth to receive the ends of a headgear that is worn by the patient only at night. A double bracket is illustrated, since it will usually be desirable to make the tubular aperture 33 as long as possible, but single brackets may also be provided with this feature.
Although in all the embodiments described the retainer member 21 is illustrated as completely flat on both sides, in other embodiments it may not be flat and, for example, the portion of the inside face closing the slot 19 may be corrugated or dimpled for engagement with the arch wire for some special purpose. The member may also take the form of two or more wire or strip members disposed side by side and mounted to be operatively equivalent to the single flat member particularly described.
Another valuable advantage that can be provided with a bracket in accordance with the invention is that usually the retainer member 21 is sufficiently stiff to be regarded as rigid, but in some embodiments it may be sufficiently resilient to apply persistent force of its own to the arch wire to move the tooth, in addition to that provided by the arch wire. In a double bracket the spring effect of both retainer members can be used to add to that of the wire in moving the tooth forward, while if only one retainer member is stressed in this way it applies a torque to the tooth to rotate it.