Dentistry – Orthodontics – Bracket
Reexamination Certificate
1999-07-27
2001-06-05
Wilson, John J. (Department: 3732)
Dentistry
Orthodontics
Bracket
C433S023000
Reexamination Certificate
active
06241516
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates an improvement of an orthodontic device in the orthodontic treatment, specifically, to an orthodontic device, which is welded to a band, such as a buccal tube, a lingual sheath, a lingual tube and the like.
2. Description of the Related Art
For orthodontic treatment, brackets retaining an arch wire are fixed on the surfaces of the patient's teeth and the elastic recovery of the arch wire is applied to the teeth via the bracket. The bracket is used with a buccal tube which is fitted over the molars of the patient with the aid of a band and its principal purpose is to retain the ends of the arch wire. As shown in
FIGS. 3A and 3B
, the buccal tube has a broad weld flange
12
. A rectangular tube body
11
and a hook
13
are brazed to the top surface of the broad weld flange
12
. The tube body
11
has a through-hole
11
a
through which an end of the arch wire is detachably passed in a mesiodistal direction. The hook
13
is used to engage an elastic ring or a ligature wire.
With this construction, the buccal tube has the advantage that it can be readily welded in position to the band by virtue of the broad weld flange
12
. On the other hand, in order to make the buccal tube, separate components have to be assembled by brazing and this not only lowers the efficiency of construction but also causes the disadvantage that the materials of the respective components may be embrittled by the heat of brazing. Moreover, brazing the rectangular tube body
11
to the top surface of the weld flange
12
results in the addition of the thickness of the flange
12
to the thickness of the bottom of the rectangular tube body
11
which defines the IN and OUT or prominence over the tooth enamel. Consequently, this makes it impossible to adjust the value of IN/OUT H to 0.3 mm according to the orthodontist's requirement. In a typical case where the bottom of the rectangular tube body
11
has a thickness of 0.5 mm and the flange
12
has a thickness of 0.3 mm, the value of H is 0.8 mm.
Under the circumstances, a compact, integrally molded buccal tube of the type shown in
FIGS. 4A and 4B
has recently been proposed. Since this buccal tube is molded as an integral unit (one-piece unit), it has the major advantage of eliminating the cumbersome assembling operation. In addition, it has the advantage of providing great latitude in meeting the orthodontist's requirement for H=0.3 mm. On the other hand, the width of the weld flange
12
in an occluso-gingival direction is adapted to be the same as the width of the rectangular tube body
11
in the same direction and this presents a serious problem when the flange
12
is welded to the band.
FIG. 5
shows how the buccal tube is welded to the band
14
. A pair of electrodes
15
in a spot welding machine are used to fix the weld flange
12
to the buccal surface of the band
14
. Needless to say, great difficulty is encountered with the welding procedure if the weld flange
12
is narrow. Particularly, due to the pressure applied during electric heating, the weld flange
12
fuses to become disfigured, and as shown in
FIG. 6
, pressure marks
16
are formed as concave portions and dusts
17
flown due to welding accidentally clog the entrance (exit) of the through-hole
11
a
, potentially making it impossible for an end of the arch wire to be passed through the hole
11
a
in the rectangular tube body
11
.
A method that could solve the aforementioned problem with the buccal tube of an integral molding type (so-called as a one-piece type) is to increase the length of the weld flange
12
as much as possible in a mesiodistal direction. If the weld flange
12
is elongated in a mesiodistal direction, because this flange
12
curves toward the lingual side, it can be welded in positions far from the entrance and exit of the through-hole
11
a
in the rectangular tube body
11
, thus eliminating the possibility of the disfigured flange or pressure marks to clog the entrance and exit of the through-hole
11
a.
This method is effective in preventing the clogging of the entrance and exit of the through-hole
11
a
. However, if the weld flange
12
is unduly long, the buccal tube no longer conforms to the shape of the band
14
. Finally, the band
14
may be deformed upon welding and eventually fails to fit to the crowns of corresponding molars.
A second method that could be applied is to broaden the rectangular tube body
11
as well as the weld flange
12
in an occluso-gingival direction. Given the same size of the through-hole
11
a
, the rectangular tube body
11
that is broadened together with the weld flange
12
also allows for the weld flange
12
to be welded in such positions that do not interfere with the entrance or exit of the through-hole
11
a.
The second method is also free from the problem of blocking the entrance and exit of the through-hole
11
a
. However, if the rectangular tube body
11
is broadened together with the weld flange
12
, it may then have occlusive interference with antagonistic teeth on the occlusion side or it may contact the gingiva on the gingival side to cause its potential swelling. As a further problem, brushing is difficult to perform and this is not desirable to oral hygiene. In addition, the usual practice in the second method is to make the top side (buccal side) of the rectangular tube body
11
round enough to relieve the discomfort that may be felt by the patient after being equipped with the buccal tube. However, the mold to make the rectangular tube body
11
is of such a construction that the position in which the hook
13
is formed lowers in a direction toward the buccal side to increase the chance of the hook
13
of contacting or burying in the gingiva. Further, food debris remaining under the hook
13
is difficult to brush off, again causing a problem in oral hygiene.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an orthodontic device which, in the case of being welded to a band, is free from the possibility that the entrance and exit of the opening through which a principal wire is to be passed are blocked.
The present invention has been accomplished under these circumstances of the conventional orthodontic devices. According to a first aspect of the present invention, an orthodontic device comprises a main body having an opening formed to permit detachable passage of a principal wire and a flange to extend in a mesiodistal direction such that the device is fixed via said extension flange to a band to be fitted over a teeth, wherein the width of the extension flange in an occluso-gingival direction is greater than the width of said main body in the same direction.
According to a second aspect of the present invention which is a modification of the first aspect, the positions in which the extension flange is to be fixed to the band are away from the boundary of the opening through which a principal wire is to be passed and displaced toward both the occlusal and gingival side.
According to a third aspect of the present invention which is a modification of the first or second aspect, the width of the main body in an occluso-gingival direction is small enough to avoid not only the occlusive interference with antagonistic teeth on the occlusion side but also the contact with the gingiva on the gingival side.
According to a fourth aspect of the present invention which is a modification of any one of the first to third aspects, hook lies on a ridgeline on both the gingival and buccal sides of the main body and extends in a direction toward the gingival-buccal side so that neither the main body nor the extension flange is present under said hook in a direction toward the lingual side.
In the present invention according to the first aspect, the width of the extension flange in an occluso-gingival direction is greater than that of the main body in the same direction. Accordingly, it is easy to fix the device to a band. Further, the broad shape of the extension flange has th
Orikasa Masaaki
Watanabe Yasushi
Bumgarner Melba
Kenyon & Kenyon
Tomy Incorporated
Wilson John J.
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