Dentistry – Orthodontics – Means to transmit or apply force to tooth
Reexamination Certificate
1999-08-18
2001-04-17
Wilson, John J. (Department: 3732)
Dentistry
Orthodontics
Means to transmit or apply force to tooth
C433S007000, C433S017000
Reexamination Certificate
active
06217323
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a dental distractor and particularly to a dental distractor for correcting severe front teeth crowding and protrusion in orthodontic treatment.
2. Description of the Prior Art
Conventional orthodontic treatment for severe anterior teeth crowding or protrusion generally includes the following five steps:
1. Extracting the first premolars.
2. Initial teeth leveling by using orthodontic brackets and arch wires. Depending on the alignment of teeth, this step lasts about three to six months.
3. Retracting canine backward into the first premolar extraction space for anterior teeth. This step lasts about four to six months for children and seven to eight months for adults.
4. Retracting anterior teeth to level the protruding teeth. This step lasts about six months.
5. Fine adjustment of occlusion and tooth angulation. This step takes about three to six months.
Total orthodontic treatment time will take one and a half to two years. It is too long a time for most patients. It is not esthetic to wear braces for such a long period and it is very burdensome for the patients to maintain their oral hygiene as well. It also is very inconvenient and time-consuming for the patients to visit orthodontist's office over such a long period. Two major steps make the period of orthodontic treatment long. They are the step 3 (canine retraction) and step 4 (anterior retraction), which take a whole year in total.
FIGS. 1 and 2
show a conventional method for canine reaction after first premolar extraction with an elastic power chain. The first molar is engaged with a molar band
12
and a bracket
121
welded on the buccal surface thereof. The canine
3
is engaged with a canine band
32
and a bracket
321
welded on the buccal surface thereof. An elastic power chain
2
is engaged between the brackets
121
and
321
. The elastic power chain
2
is made of synthetic rubber formed in a chain manner including a plurality of loops
21
. The chain is cut to a length desired and has the two end loops engaging respectively with the brackets. Through the elastic force of the elastic power chain
2
, the canine
3
may be pulled gradually toward the first molar
2
and a space being left behind the canine. The rubber of the power chain
2
tends to lose elasticity after soaking in saliva for a period of time. It usually takes more than six months to retract a canine into a desirable position (i.e., moving the canine rearward for 4-5 mm). It takes too much time and prolongs the total treatment time.
FIG. 3
illustrates another conventional method for canine retraction disclosed in U.S. Pat. No. 5,873,715 which is disclosed by the same inventor of the present invention. The method illustrated in U.S. Pat. No. 5,873,715 uses a dental distractor
4
. The dental distractor
4
includes a distractor head
41
, a movable joint
42
and a screw
43
. There is a molar band
121
a
mounted on the first molar
1
. The molar band
12
a
has buccal sheaths
121
a
welded on buccal surface. The buccal sheaths
121
a
have two spaced cylindrical bores located therein. The canine
3
has a canine band
32
a
mounted thereon. On the buccal surface of the band
32
a,
there is a reversed U-shaped hook
321
a
fixed thereon.
Referring to
FIGS. 3 and 4
, the distractor head
41
includes an engaging end
411
which is substantially a C-shaped bar. The engaging end
411
has an upper bar
4114
which has two legs
41142
engageable with the cylindrical bores of the buccal sheaths
121
a.
The engaging end
411
further has a lower bar
4112
connecting with one end of a sliding bar
415
. A screw seat
413
is fixed on the sliding bar
415
and has a first screw bore
4132
engageable with a screw bar
432
.
Referring to
FIG. 5
, the movable joint
42
includes a connecting screw
421
with a slot
4212
and a cap
4213
. The cap
4213
is to secure the hook
321
a
in the connecting screw
421
. There is a second screw bore
423
in the movable joint
42
enagageable with a screw bar
432
of the screw
43
and a sliding bore
425
. The sliding bar
415
slidably runs through the sliding bore
425
. The screw
43
has a screw head
434
at one end thereof.
When a patient is undergoing rapid orthodontic treatment for correcting severe anterior crowding or protrusion, the canine
3
has to be moved backward with the distractor immediately after the first premolar extraction and before the new alveolar bone is generated. The molar band
12
a
is mounted on the first molar
1
and the canine band
32
a
is mounted on the canine
3
before the first premolar extraction. Immediately after the first premolar extraction, the distractor head
41
is mounted on the molar band
12
a
by engaging the legs
41142
into the buccal sheath
121
a.
The movable joint
42
is engaged with the canine band
32
a
by inserting the hook
321
a
into the slot
4212
. Then the screw seat
413
is engaged with the movable joint
42
by turning the screw head
434
. For each turn or a fractional turn, the screw head
434
will drive the movable joint
42
back a definite distance toward the screw seat
413
, thus achieve the object of moving the canine
3
rapidly. The distractor of this invention may be made of high strength alloy with stable property and bio-compatibility.
By following orthodontist's instructions, patients may turn the screw head
434
easily by using a simple tool without going to orthodontist's office. The force generating by the screw
43
and the movable joint
42
is more effective than the elastic power chain.
The following is the general procedures of using this method to perform rapid orthodontic tooth movement:
1. Putting on orthodontic brackets for initial alignment and leveling anterior teeth for one or two months.
2. Extracting first premolars and putting on dental distractors to move the canines within three weeks.
3. Retracting anterior teeth backward for about 4-5 months.
4. Fine adjusting the occlusion and tooth angulation.
Although the second method (i.e., U.S. Pat. No. 5,873,715) disclosed above may speed up orthodontic treatment, it has the problem of having too complicated and too bulky a structure. It is particularly annoying to put it in the month which is delicate and sensitive. It is prone to hurt mucous membranes and even causes oral ulcers.
SUMMARY OF THE INVENTION
It is an object of this invention to provide a dental distractor that overcomes the problem of long orthodontic treatment time resulting from the conventional method of using elastic power chain which loses elasticity after soaking in saliva and offers faster orthodontic treatment. The dental distractor has simpler structure and smaller size than the bulky and complicated conventional dental distractor for patients to use more conveniently and comfortably.
The dental distractor according to this invention is mainly for rapid orthodontic tooth movement after the first premolar extraction is done. It includes a molar band mounted on a molar, a canine band mounted on canine, a first joint means, a second joint means and a screw bar means. The molar band has a molar triple tube located on a buccal side and the canine band has a canine triple tube located on another buccal side thereof. The second joint means includes a second hook engageable with the molar triple tube and a second joint engageable with a screw bar of the screw bar means. The first joint has a first hook engageable with the canine triple tube and a first joint engageable with the screw bar. There is a screw nut fixedly engageable with one end of the screw bar. Turning the screw nut, the first joint means will be moved toward the second joint means and consequently moving the canine rearward toward the first molar.
REFERENCES:
patent: 618105 (1899-01-01), Knapp
patent: 678452 (1901-07-01), Angle
patent: 4424031 (1984-01-01), Dahan
patent: 5645423 (1997-07-01), Collins, Jr.
Dougherty & Troxell
Wilson John J.
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