Dentistry – Orthodontics – Bracket
Reexamination Certificate
1999-10-12
2001-07-24
Mancene, Gene (Department: 3732)
Dentistry
Orthodontics
Bracket
C433S010000, C433S020000
Reexamination Certificate
active
06264468
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an orthodontic appliance for use for orthodontics, in which an improper alignment of teeth is corrected, the appliance including a wire and brackets adapted to be affixed to a tooth so that the wire can be hooked thereon.
PRIOR ART
Almost every conventional orthodontic appliance including a wire and brackets for correcting an improper alignment of teeth is adapted to be attached to an external side, i.e., a “labial side” of a tooth. The reason for such attachment is because the brackets and wire are easily attached to the labial side of a tooth and because the wire is easily adjusted on the labial side, when needed, as the correction progresses. In a case where an orthodontic appliance is attached to the labial side of teeth, however, every time the patient opens his or her mouth, the metallic orthodontic appliance, which looks abnormal at a glance, can be seen by other people, and therefore wearing such an orthodontic appliance for a long treatment period of nearly two years gives the patient under treatment a considerable amount of mental anguish.
To solve this problem and relieve such anguish an orthodontic appliance has been developed in which wires and brackets are attached to the internal side, i.e., the “lingual side” of teeth, where they are difficult to see from the outside, and such an orthodontic appliance has been used by some orthodontists, in actual orthodontic practice, for a long time. Japanese Examined Patent Publication (Kokoku) No. 57-44967 and the specification of U.S. Pat. No. 4,337,037 describe examples of such conventional orthodontic appliances that are attached to the lingual side of teeth. Brackets constituting a main component of such an orthodontic appliance are attached to the lingual surface of teeth using a bonding method or the like, and a common wire, the other main constituent component of the appliance, is then hooked in slots formed in the brackets. Thereafter, the common wire is ligated to the slots of the respective brackets with separate thin wires or the like. In general, the conventional brackets and wire that are affixed to the lingual surface of teeth have configurations illustrated in
FIGS. 2 and 3
, and
FIGS. 4 and 5
, and most of the parts thereof are made of metal (alloy).
A bracket
10
used in a first example of a conventional orthodontic appliance comprises, as shown in
FIG. 2
, a plate-like pad
13
adapted to be bonded to a surface
12
of a tooth
11
on the lingual (internal) side thereof and a bracket main body
14
made integral with the pad
13
by brazing or the like in such a manner as to be erect from the lingual surface of the pad
13
. The bracket main body
14
has three finger-like portions, which permits a main slot
15
and a sub-slot to be formed in the bracket
10
, the main slot
15
opening perpendicularly downward (when affixed to the maxilla) or perpendicularly upward (when affixed to the mandible) in a state in which the bracket
10
is affixed to the lingual surface of a tooth and the sub-slot
16
opening horizontally towards the lingua (in the above bracket affixing situation), and a wire
17
which is constituted by a metallic wire of an alloy or the like and has, for instance, a square cross-section is inserted into either of the slots
15
,
16
. The wire
17
generates, from a bending force or tension as a restoring force resulting from its intrinsic elasticity, a corrective force or moment to be imparted to a tooth or teeth
11
which deviate from a proper dental arch or are improperly rotated and moves or rotates the respective improperly positioned teeth
11
to proper positions on the dental arch, over time.
Furthermore, slots
18
and
19
between upper and lower portions of the bracket main body
14
and the pad
13
are used such that for instance, a thin wire or rubber band is hooked therein so as to ligate the wire
17
inserted into the main slot
15
(or the sub-slot
16
) to the bracket
10
for fixation thereto. In addition, reference numerals
20
,
21
denote a position of a central point or center line of the wire
17
when the wire
17
is installed in either of the slots
15
,
16
.
FIG. 3
shows a second example of a conventional orthodontic appliance that is affixed to the lingual side of a tooth. A bracket
22
in the second example has a pad
13
similar to that used with the bracket
10
in the first example of the conventional appliance, as shown in
FIG. 2
, and formed in a bracket main body
23
, that is made integral therewith, is a main slot
24
which opens horizontally towards the lingua. In addition, as in the case shown in
FIG. 2
, upper and lower slots
18
and
19
are also formed between the bracket main body
23
and the pad
13
, and at least one of the two can be used such that a thin wire or the like is hooked therein so as to ligate thereto a wire
17
when the wire
17
is inserted into a predetermined position in the main slot
24
indicated by reference numeral
25
denoting a central point (line) of the wire.
FIG. 4
is a plan view of all the mandibular teeth when the conventional bracket
10
shown in
FIG. 2
is affixed to the lingual surface of the respective teeth
1
to
7
represented by the anterior teeth
11
. In a case where the teeth are in a normal alignment, as is clear from
FIG. 4
, the surfaces on the labial side (outside) of the respective teeth
1
to
7
are in alignment with one another along the row of teeth without large irregularities in the surfaces and since, in many cases, there can be contemplated a smooth envelope relative to the labial surfaces of the respective teeth, as has been done conventionally, in a case where an orthodontic appliance comprising a wire and brackets is affixed to the labial side of a tooth, it is possible to use as a wire a smoothly curved “straight” wire which is free of specific bent portions (points where there is a drastic change in direction). On the other hand, there are marked irregularities in the lingual surfaces of a row of teeth when viewed in a vertical direction, and therefore in general there can be contemplated no smooth envelope relative to the lingual surfaces of the respective teeth.
Even in a normal condition, anterior teeth such as a central incisor
1
, a lateral incisor
2
and a canine tooth
3
are inclined, slightly curved and pointed, and have a relatively elongated vertical section as is clear from a tooth
11
shown in
FIGS. 2 and 3
. Moreover, although they look like as if they are scooped out on the lingual side in the crown, as is clear from
FIG. 4
, they are even with one another on the lingual surfaces in terms of teeth alignment. It is common, however, that there is a relatively large difference in the level of the lingual surface between the canine tooth
3
of the anterior teeth and a first premolar
4
situated adjacent to the canine tooth
3
and having a crown of a substantially cylindrical configuration in conjunction with a change in cross-sectional configuration between the anterior teeth and the posterior teeth. In addition, although the first premolar
4
and a second premolar
5
are generally in alignment with each other on the lingual side surface and a first molar
6
and a second molar
7
are also generally in alignment with each other on the lingual side surface, as is shown in
FIG. 4
, there is a slight difference in the level of the lingual side surface between the second premolar
5
and the first molar
6
.
Consequently, a bracket
10
,
22
is bonded to the lingual surface of the respective teeth
1
to
7
at a position as close to the gingiva
26
as possible, and where a pad
13
can be bonded, and a common wire
17
is then hooked in a main slot
15
,
24
such that tips of the anterior teeth on the mandible do not come into contact with the bracket and wire, so mounted on the lingual surface of anterior teeth of the maxilla so as not to hinder occlusion between the maxilla and mandible. With this construction, even in a state in which the respective teeth
1
to
7
are all correcte
Bumgarner Melba
Mancene Gene
Merchant & Gould P.C.
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