U.S. patent application number 09/785961 was filed with the patent office on 2001-11-01 for orthodontic appliance for the forward displacement of the lower jaw.
Invention is credited to Binder, Friedrich.
Application Number | 20010036615 09/785961 |
Document ID | / |
Family ID | 7877982 |
Filed Date | 2001-11-01 |
United States Patent
Application |
20010036615 |
Kind Code |
A1 |
Binder, Friedrich |
November 1, 2001 |
Orthodontic appliance for the forward displacement of the lower
jaw
Abstract
In an orthodontic appliance, referred to as Herbst hinge, for
the forward displacement of the lower jaw of a patient, with a pair
of telescopes, each comprising a telescopic tube and a telescopic
slide rod, which are attachable at their free ends in each case via
a joint to the patient's upper jaw and lower jaw, respectively, for
increasing the freedom of movement of the lower jaw while at the
same time achieving the therapeutically desired forward push onto
the lower jaw, it is proposed that the telescopes in the telescoped
state be rigid, as known per se, but in the extended state be
flexible.
Inventors: |
Binder, Friedrich;
(Kieselbronn, DE) |
Correspondence
Address: |
LEYDIG VOIT & MAYER, LTD
TWO PRUDENTIAL PLAZA, SUITE 4900
180 NORTH STETSON AVENUE
CHICAGO
IL
60601-6780
US
|
Family ID: |
7877982 |
Appl. No.: |
09/785961 |
Filed: |
February 16, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09785961 |
Feb 16, 2001 |
|
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PCT/EP99/06071 |
Aug 19, 1999 |
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Current U.S.
Class: |
433/19 |
Current CPC
Class: |
A61C 7/36 20130101 |
Class at
Publication: |
433/19 |
International
Class: |
A61C 003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 19, 1998 |
DE |
198 37 555. 7 |
Claims
1. Orthodontic appliance for the forward displacement of the lower
jaw of a patient, with a pair of telescopes, each comprising a
telescopic tube and a telescopic slide rod, which are attachable at
their free ends in each case via a joint to the patient's upper jaw
and lower jaw, respectively, characterized in that the telescopes
(16) in the telescoped state are rigid, as known per se, but in the
extended state are flexible.
2. Appliance as defined in claim 1, characterized in that the
telescopic tubes (18) are of rigid design and the slide rods (20)
of elastically deformable design.
3. Appliance as defined in claim 2, characterized in that the slide
rods (20) are made of an elastic plastic material whose modulus of
elasticity lies in the range of from 500 N/mm.sup.2 to 2,500
N/mm.sup.2.
4. Appliance as defined in any one of claims 1 to 3, characterized
in that the slide rods (20) have a conical area (26) at their ends
held slidingly in the telescopic tubes (18).
5. Appliance as defined in claim 4, characterized in that the
conical area (26) of the slide rods (20) extends over at least one
fourth of the length of the telescoping section of the slide rods
(20).
6. Appliance as defined in claim 4 or 5, characterized in that the
angle of taper is selected in the range of from 2.degree. to
15.degree., preferably from 5.degree. to 10.degree..
7. Appliance as defined in any one of claims 1 to 6, characterized
in that the telescopic slide rods (20) are made of a plastic
material.
8. Appliance as defined in any of claims 1 to 7, characterized in
that the telescopic tubes (18) are made of a plastic material, in
particular, a transparent plastic material.
9. Appliance as defined in any one of claims 1 to 8, characterized
in that the joints are ball joints and comprise a ball head (24,
25) which is to be attached to a tooth of the patient, and arranged
at a free end of the telescopic tubes (18) and the telescopic slide
rods (20), respectively, a ball socket (22, 23) which is of
elastically resilient design, and into which the associated ball
head (24, 25) is snappable.
10. Appliance as defined in claim 9, characterized in that the ball
sockets (22, 23) are integrally formed with the telescopic tubes
(18) and the telescopic slide rods (20), respectively.
11. Appliance as defined in claim 9 or 10, characterized in that
the ball sockets (22, 23) have slots (30, 31) extending at right
angles to the circumferential line of their opening.
12. Appliance as defined in any one of claims 9 to 11,
characterized in that the telescopic tubes (18) have an opening
(28) which joins the cavity of the ball socket (22) to the interior
of the tubes (18).
Description
[0001] The invention relates to an orthodontic appliance for the
forward displacement of the lower jaw of a patient, which is
usually referred to as Herbst hinge.
[0002] Such appliances comprise a pair of telescopes, which each
consist of a metal telescopic tube and a metal slide rod guided
therein, and which are attached on both sides of the patient's jaw,
for example, via orthodontic bands, to the patient's upper and
lower jaws.
[0003] The appliance known in the literature as Herbst hinge can be
compared to an artificial joint between upper jaw and lower jaw (H.
Pancherz, Kleines Lehrbuch der Angle-Klasse II,1 unter besonderer
Berucksichtigung der Behandlung, Chapter 16, pages 225 to 251,
Quintessenz Verlags-GmbH, Berlin). When the jaw is closed the
telescopes are retracted or telescoped fully, and the Herbst hinge
can thus apply therapeutically desired forward pushing forces to
the lower jaw.
[0004] When the patient opens his jaw the slide rod travels a
certain distance out of the telescopic tube and thus allows the
patient limited space for his jaw movements. Owing to the rigidity
of the metallic telescopic tubes and slide rods, the Herbst hinge
is, however, relatively rigid and results in considerable
limitation of the freedom of movement of the lower jaw. If the
appliance is inappropriately fitted undesirably large forces can
also be exerted on the jaw or the appliance can be even be
destroyed as a result of this.
[0005] As a rule, the Herbst hinge is designed as a so-called
firmly attached fixture in order to permanently exert the necessary
forward pushing force on the lower jaw during the treatment.
However, it is not possible for the patient to briefly remove the
appliance to clean it for oral hygiene purposes.
[0006] Different solutions for attaching the telescopes to the
upper and lower jaws have been discussed in the literature. For
example, the textbook cited above describes the attachment by
screws to attachment parts affixed to the molars of upper and lower
jaws, as does U.S. Pat. No. 4,462,800. Another solution which works
with a pinning together is known from U.S. Pat. No. 5,183,388.
Attachment of the telescopic rods to the molars by ball pins and
securing rings is recommended in PCT/DK94-00183.
[0007] All these solutions have the disadvantage that the
attachment elements (e.g. screws, pins, securing rings) naturally
have to be very small, which makes it difficult even for
experienced staff to insert or remove the Herbst hinge, and in
individual cases these small parts, if handled clumsily, can be
swallowed by the patient.
[0008] The object of the invention is to further develop an
appliance of the kind described at the outset so that while the
therapeutically desired forward push on the lower jaw remains
ensured, a greater freedom of movement is imparted to the lower
jaw.
[0009] This object is accomplished in accordance with the invention
with the appliance described at the outset in that the telescopes
in the telescoped state are rigid, as known per se, but in the
extended state are flexible.
[0010] This constructional principle ensures that in the closed
state of the jaw (simultaneously the retracted or telescoped state
of the telescopes) the desired forward pushing forces can act, but
accord the lower jaw of the patient to be treated a considerably
increased freedom of movement when he opens his jaw (forward
pushing forces are not active here with the Herbst hinge).
[0011] A specific embodiment of this principle consists in that the
telescopic tubes are of rigid design, but the telescopic rods are
elastically deformable.
[0012] As an alternative thereto, in another embodiment the slide
rod can also be of rigid design, but the section guided in the
telescopic tube includes a conical area. Herein, as soon as the
slide rod is moved a certain length out of the telescopic tube, the
play between the telescopic tube and the slide rod increases, which
increases the freedom of movement of the lower jaw. If, in
addition, the slide rods are produced from an elastically
deformable material, a particularly good effect is achieved with
respect to increasing the freedom of movement of the lower jaw.
[0013] The conical area preferably extends over at least one fourth
of the length of the telescoping sections of the slide rods. Thus,
more freedom of movement is already created for the lower jaw at a
relatively early stage of opening the jaw.
[0014] An angle of taper of approximately 2.degree. is already
sufficient for a noticeable increase in the freedom of movement. As
a rule, a maximum angle of taper of approximately 15.degree. is
adequate to accord highly improved wearing comfort to the patient.
On the other hand, a limitation of the angle of taper to 15.degree.
eliminates the danger of the slide rod tilting in the telescopic
tube and exposes in the extended state of the telescope only a
small cross-sectional area of the mouth of the telescopic tube,
through which undesired materials such as, for example, bits of
food, etc., can penetrate into the telescope so that this limit is
also recommended from the point of view of oral hygiene.
[0015] In general, materials whose modulus of elasticity in tension
lies in the range of from 100 N/mm.sup.2 to 20,000 N/mm.sup.2 are
suitable for the manufacture of the inventive telescopes.
[0016] In accordance with the present invention, plastic is a
preferred material. It is not only easy to work to the required
shapes, but also offers aesthetic advantages over telescopes made
of metal. Both rigid and elastically deformable slide rods can be
made of plastic. Plastic is also suitable for the manufacture of
telescopic tubes. In the case of the latter, it is recommended, in
particular, to use transparent plastic, which not only allows
checking of the choice of the correct length of the slide rods,
but, in addition, also checking as to the cleanliness and the oral
hygienic state of the telescopes, in particular, the interior of
the telescopic tube. Preferred elastic plastic materials are those
of the polyolefins, EVAs and polyamides. These plastic materials
have a modulus of elasticity in tension in the range of
approximately 500 to 2,500 N/mm.sup.2 (German Industrial Standard
53457) and do not exhibit any breakage in the impact test (German
Industrial Standard 53453). Moreover, these plastic materials allow
an elastic deflection of the slide rods and/or telescopic tubes
without any noticeable deformation remaining after the
deflection.
[0017] Ball joints are also preferably used in the present
invention for attaching the telescopes to upper and lower jaws.
Here a ball head attached to the tooth serves for support on the
jaw, while a ball socket formed in each case at one end of slide
rod and telescopic tube engages over this ball head. The ball
socket is preferably of elastic resilient design so that it is
snappable onto the associated ball head.
[0018] The snapping of the ball socket onto the associated ball
head is facilitated by the choice of a sufficiently elastic plastic
material. However, limits are set here as the ball socket must be
inherently stable enough for it to transmit the correcting forces
unadulterated onto the ball head.
[0019] Alternatively, the ball socket can be provided with one or
several radially extending slots which extend as far as the mouth
opening of the socket. In this case, a stiffer plastic material can
then be used.
[0020] Finally, it is to be ensured that the holding forces between
ball head and ball socket are large enough for unintentional
detachment of the snap connection to be avoided.
[0021] Again the use of plastic for the fabrication of the slide
rods and the telescopic tubes, which, in this case, are integrally
formed with the ball sockets is favorable for this construction.
However, the use of metals which are generally recognized as safe
from the point of view of oral hygiene, such as, for example,
nickel-free steels or titanium, is recommended for the ball heads.
Not only do metallic ball heads better resist the forward pushing
forces which they are to transmit onto the lower jaw, but they are
also easier to attach with the necessary security, for example, by
means of metallic tooth bands, to the patient's teeth.
[0022] A continuous opening in the interior of the telescopic
tubes, which leads to the cavity of the ball socket, serves to
facilitate cleaning of the telescopes. Foreign matter which has
unintentionally penetrated into the telescopic tube can thus also
be easily flushed out by the patient himself, and the telescopes
can be kept in perfect condition as regards oral hygiene by the
patient himself. Here it is, of course, helpful for the telescopic
tubes, as already mentioned further above, to be made of
transparent plastic.
[0023] Provision is made in a preferred embodiment for the
telescopic tubes to have in their interior a stop for maximum
slide-in of the slide rods. When the telescope is retracted, which
results in transmission of the forward pushing forces, the
corresponding end of the slide rod is supported on the stop, and
the slide rod is thus prevented from being pushed in too far, which
could result in jamming of the free end of the slide rod. Moreover,
this also ensures that the therapeutically desired forward pushing
forces are maintained when the telescope is in the retracted or
telescoped state.
[0024] In addition, provision may be made for spacers forming the
stop to be inserted into the interior of the telescopic tube so as
to alter the forward pushing forces during the patient's treatment,
or to adapt the length of the telescope in the retracted or
telescoped state to the treatment success which has already
occurred. Alternatively, this can, of course, also be done by
adapting or exchanging slide rods of a different length.
[0025] As known per se, the transmission of forces can also take
place via a stop which is arranged at the end of the telescopic
slide rod adjacent to the ball socket. This stop is then supported
at the free end of the telescopic tube.
[0026] These and further advantages of the invention are the
subject matter of the subclaims and will be explained in further
detail hereinbelow with reference to the drawings, which
individually show:
1 FIGS. a schematic representation of the way in 1 a) and b) which
an orthodontic appliance according to the invention functions; a
section along cutting line 2-2 in the orthodontic appliance of FIG.
1 a) according to a first embodiment; a ball head for attachment of
the orthodontic appliance according to the invention to the tooth
of a patient; a sectional view of a second embodiment of the
orthodontic appliance according to the invention; a sectional view
of a third embodiment of the orthodontic appliance according to the
invention; and a sectional view of a fourth embodiment of an
orthodontic appliance according to the invention.
[0027] FIG. 1a) shows an inventive orthodontic appliance designated
by reference numeral 10 (referred to hereinafter as Herbst hinge),
which is attached at one end to an upper jaw 12 and at another end
to the lower jaw 14 of a patient. The Herbst hinge is attached in
pairs on both sides of the upper and lower jaws of the patient and
serves to forwardly displace the lower jaw of the patient.
[0028] The inventive Herbst hinge 10 comprises as main components a
telescope 16 with a telescopic tube 18 and a telescopic slide rod
20.
[0029] One end of the telescope 16 is joined to the upper jaw 12
and one end to the lower jaw 14.
[0030] For this purpose, the telescope 16 comprises at each end, in
one case in continuation of the telescopic tube 18, a ball socket
22, and, in the other case in continuation of the telescopic slide
rod 20, a ball socket 23, which can snap onto ball heads 24, 25,
each attached to a tooth of the upper jaw 12 and the lower jaw 14,
respectively.
[0031] The ball heads 24, 25 are usually welded onto so-called
orthodontic bands, and the bands are fitted onto the tooth intended
for the support. The orthodontic bands are not shown in FIGS. 1a)
and 1b).
[0032] When the patient's jaw is in the closed state (see FIG. 1a))
a forward pushing force for forward displacement of the patient's
lower jaw 14 is generated by the telescope 16 pushed together as
far as the stop, so that upper jaw and lower jaw are arranged in
the desired, ideal location relative to each other.
[0033] On opening the jaw (cf. FIG. 1b)), the telescope 16 is
extended, i.e., the telescopic rod 20 moves partially out of the
telescopic tube 18, and, of course, correction forces are no longer
active in this state.
[0034] The embodiment of the telescope 16, shown scaled-up in FIG.
2, comprises in accordance with the invention, at the end of the
telescopic slide rod 20 arranged telescopically in the telescopic
tube 18 a conically tapering section 26, which extends over more
than half the length of the part of the telescopic slide rod 20
received in the telescopic tube 18 in the retracted or telescoped
state. The angle of taper here is approximately 10.degree..
[0035] The telescopic tube 18 comprises at its end adjacent to the
ball socket 22 a bottom with an opening 28, which connects the
volume of the ball socket 22 with the interior of the telescopic
tube 18. It is thereby made possible to clean the interior of the
telescopic tube 18 in a simple way, and, in particular, to easily
flush out deposits which may develop in the interior of the
telescopic tube 18 in the course of use of the Herbst hinge.
[0036] The two ball sockets 22 and 23 comprise in the plane of the
longitudinal axis of the telescope 16 a slot 30, 31 running in a
radial direction and extending from a respective mouth opening 32,
33 of the sockets 22, 23 around approximately half of a
circumferential circle of the ball socket cross section.
[0037] These slots 30, 31 simplify the snapping of the ball sockets
onto the associated ball heads 24, 25.
[0038] Finally, FIG. 3 shows such a ball head 24, 25, by way of
example, which comprises a ball portion 34, which is held by way of
a neck 36 on a base 38. This base 38 serves for adherence or
welding to an orthodontic band 40, which is only outlined in FIG.
3.
[0039] As described above, the design of the slide rod 20 with the
conical area 26 allows, even when the patient's mouth opens
slightly and, as a result, the telescope 16 is extended, not only a
mesial movability of the lower jaw, but jaw movements in the
direction transverse thereto are also significantly facilitated.
The ball head/ball socket joints also contribute to this to a
certain extent.
[0040] If, in addition, the telescopic slide rod 20 is made of an
elastic material, there is a further reduction in the limitation of
the movability of the lower jaw, and there is an increase in the
wearing comfort for the patient. In the retracted state of the
telescope 16 (cf. FIGS. 1a) and 2), however, a sufficiently stiff
structure is obtained, as the telescopic tube 18 additionally
supports the slide rod 20 and substantially excludes elastic
deformations of the latter. In spite of the considerably increased
movability of the Herbst hinge in the extended state, when the jaw
is closed, i.e., when the telescope is pushed together, an exact
transmission of force onto the lower jaw, which is comparable with
the conventional Herbst hinges, is thereby achievable.
[0041] Owing to the simple snap mechanism, the patient himself can
remove the Herbst hinge to take care of his teeth and hygienically
treat the Herbst hinge as such, and he can also mount it again.
Moreover, the use of small parts, which even create handling
problems for experienced users, is dispensed with when mounting the
Herbst hinge.
[0042] This additionally results in shorter treatment times, also
when the dentist is carrying out a check-up.
[0043] It is particularly advantageous for the telescopic tube 18
to be made of transparent plastic as the correct choice for the
telescopic rod 20 can then be made very easily when the Herbst
hinge is in the assembled state. The manufacture of the telescopic
rod 20 from plastic has the additional advantage that prefabricated
lengths can be shortened relatively easily by the doctor in charge,
so that an optimal length of the slide rod 20 can be used for the
initially targeted treatment success without a plurality of slide
rods of different lengths having to be kept in stock.
[0044] An alternative procedure to this would be to use slide rods
of a constant length, but with progressive treatment success to
insert into the interior of the telescopic tube 18 further stops,
for example, in the form of rings, which successively shorten the
insertion length of the telescopic slide rod 20 into the tube 18
concomitantly with the treatment success.
[0045] Here, again, the transparent design of the telescopic tube
18 also is an aid, by means of which it is very easy to check
whether the fixing of the stop for the telescopic slide rod 20 has
been chosen correctly.
[0046] The manufacture from a plastic material has the further
advantage that the components can be manufactured much more
economically than corresponding metal components, and in the event
of wear or the like, these can also be exchanged without any great
expense in the course of the treatment. The wearing comfort is
significantly improved by the flexible design of the telescope 16,
and there is virtually no impairment in the perception of oral
hygiene by the patients since they themselves can remove the Herbst
hinge briefly for this purpose and can affix it again themselves.
This has, in particular, to do with the fact that additional
securing means are not necessary, and the Herbst hinges can simply
be snapped onto the ball heads which remain firmly mounted on the
teeth.
[0047] If excessively high forces are applied to the connection
points of the Herbst hinge with the upper and lower jaws, the
appliance can unclip itself so that here, too, damage to the Herbst
hinge or the teeth can be safely avoided.
[0048] If the Herbst hinge is made from a plastic material, an
economical production in an injection molding tool presents itself.
Moreover, the metal parts which are worn in the mouth are further
reduced to a significant extent by manufacturing the Herbst hinge
from plastic. The spatial conditions of the patients' upper and
lower jaws can be taken into account by necks 36 of the ball heads
24, 25 differing in length.
[0049] In FIG. 4 a second embodiment of the invention is shown, in
which a telescope 42 comprises a telescopic tube 44, which has at
one end a ball socket 46 protruding in a radial direction (in FIGS.
1 and 2 an embodiment is shown in which the ball socket adjoins the
telescopic tube in an axial direction). A telescopic slide rod 48
pushed fully into the telescopic tube 44 comprises at its free end
a conical area 50 which extends over approximately two-thirds of
the length of the slide rod and is adjoined by a cylindrical area
52 and (in this sequence) a ball socket 54. The ball socket 54 here
is arranged in axial continuation of the cylindrical area 52.
[0050] The ball socket 54 adjoins the cylindrical area 52, and the
latter is radially recessed (recess 56) in relation to the ball
socket 54. In the fully inserted state, the recess 56 abuts the
free end of the telescopic tube 44 and thereby forms a stop.
[0051] The end opposite the free end of the telescopic tube
comprises an opening 60 which exposes the interior of the
telescopic tube over the full cross section. This makes it possible
for the telescope to be cleaned with particularly great ease.
[0052] The ball sockets 46 and 54 can be designed in analogy with
the embodiments described in conjunction with FIGS. 1 and 2.
[0053] Differently from the second embodiment shown in FIG. 4, the
embodiment of an inventive telescope 62 shown in FIG. 5 comprises a
telescopic slide rod 64, which includes a conical area 66 which
extends almost over the entire length of the retracted telescopic
rod component. Furthermore, the ball socket 68 arranged on the
telescopic slide rod herein is arranged so as to protrude radially
from the slide rod and hence symmetrically in relation to the ball
socket 72 protruding form the telescopic tube 70. In this
embodiment, too, the end of the telescopic tube 70 adjacent to the
ball socket 72 is of open design so that any bits of food etc.
which may have penetrated into the telescope can be removed without
any trouble.
[0054] An embodiment of the inventive telescope, which is based on
the first embodiment described in conjunction with FIGS. 1 and 2,
is shown in FIG. 6. Herein, the telescope 74 comprises a telescopic
tube 76 and telescopic slide rod 78, which carry ball sockets 80,
82 adjoining oppositely arranged ends in an axial direction. The
telescopic tube interior is again connected by a continuous bore 84
to the cavity of the ball socket 80 to improve the possibility of
cleaning it.
[0055] Differently from the embodiment of FIGS. 1 and 2, the
telescopic slide rod 78 does not have any conical area, but has a
constant diameter essentially over its entire length. Here,
however, an elastic plastic material is used for the manufacture of
the telescopic rod 78, which allows a deflection of the telescopic
slide rod at the ball socket end from the axial direction A through
at least the diameter d. This dimension applies to the case where
the telescopic slide rod 78 is extended to a maximum permissible
extent.
[0056] In this embodiment, the improved wearing characteristic,
i.e., the increased movability of the lower jaw, is guaranteed
solely by the choice of material for the manufacture of the slide
rod 78. In the present case, a polypropylene material with a
modulus of elasticity in tension of approximately 1,500 N/mm.sup.2
was used. The slide rod 78 can be deflected as shown without any
deformations remaining after its return being observed.
[0057] This choice of material can, of course, be combined with the
conical design of the free end of the slide rod, as illustrated in
FIGS. 2, 4 and 5.
* * * * *