The present invention refers to a dental prosthesis stabilizer.

In particular, the present invention concerns a dental prosthesis stabilizer which is provided with two arms which are hinge-mounted to one another and with which an upper dental prosthesis and a lower dental prosthesis are coupled to each other, whereby a spring is provided at the hinge joint with which the upper prosthesis and the lower prosthesis are pushed away from each other.

Such dental prosthesis stabilizers are already known, for example from Belgian patent No. 1 ,006,478, whereby the springy hinge joint between the arms is situated at an invariable distance from the upper as well as the lower dental prosthesis and whereby the arms are hinge-mounted to the upper and the lower dental prosthesis by means of screws.

A disadvantage of these dental prosthesis stabilizers is that they cannot easily follow the natural movement of the jaws, as the hinge joint of the dental prosthesis stabilizer, around which the upper and lower dental prostheses hinge in relation to each other, is necessarily situated in the oral cavity, whereas the natural movement of the teeth follows the jaws which hinge in relation to a joint which is situated more in the back of the head.

This has for a result that prostheses, equipped with the above-mentioned dental prosthesis stabilizer, often come off the jaw.

Another disadvantage of such dental prosthesis stabilizers is that, if a part of the dental prosthesis stabilizer is worn or broken, such as for example when the spring breaks, the repair of such a dental prosthesis stabilizer causes a lot of inconveniences, as the dental prosthesis is usually given as a whole in the care of the dental technician during the repair period, since the dental prosthesis stabilizer cannot be disconnected from the dental prosthesis by an ordinary user.

A first improvement to the dental prosthesis stabilizers of the above-mentioned type is known from Belgian patent No. 09,900,277.

This improvement consists in making one of the arms of the dental prosthesis stabilizer telescopic, and in providing the other arm to a point of attachment in the form of a knob- shaped protrusion which can slide in a groove provided in the upper or lower prosthesis.

Thus is obtained much more freedom of movement for the above-mentioned hinge joint between the upper and lower dental prosthesis, so that it becomes easier to follow the natural movement.

Further, this improvement also makes sure that the dental prosthesis stabilizer can be easily disconnected from the dental prosthesis by an ordinary user, but only when the dental prosthesis is taken out of the mouth.

A major disadvantage of the latter form of known dental prosthesis stabilizers, however, is that they consist of a large number of parts, which entails a rather large risk of failure.

Another disadvantage related to the known dental prosthesis stabilizers is that the parts are exposed to a rather aggressive environment, especially to all sorts of fluids and food in the mouth, as a result of which the parts are very liable to wear.

Further, leavings often stay behind the parts of the known dental prosthesis stabilizers, with all the accompanying discomforts for a result. Further, it appears that some persons find it psychologically hard to wear any of the known dental prosthesis stabilizers, as they associate it with a horse bit because of the presence of visible metal parts of the dental prosthesis stabilizer.

WO 2007/016753 A1 describes a dental prosthesis stabilizer which is provided with two arms which are hinge-mounted to one another and with which an upper dental prosthesis and a lower dental prosthesis are coupled to each other, whereby a spring is provided at the hinge joint with which the upper prosthesis and the lower prosthesis are pushed away from each other. At least one of the arms is made telescopic and is formed of a bent far end of the above-mentioned spring, which can be axially moved in a bent guide, which guide is designed to be fixed on an upper dental prosthesis or a lower dental prosthesis or to be embedded therein. The spring used in products on the market is a torsion spring.

This spring causes noise and food retention; the live span is relatively short due to an overburdening of one point where the active part goes over into the passive part.

Further dental prosthesis stabilizers are known from DE 10 2008 029 086 B4, US 8,047,845 B2, US 2009/0317761 A1 , US 2012/ 0 003 607 A1 , US 2,876,540 A, US 3,362,072 A, US 1 ,467,079 A, US 4,773,859 A and WO 88/ 02 245 A1.

The present invention aims to remedy at least one of the above-mentioned and other disadvantages.

To this end, the present invention concerns a dental prosthesis stabilizer which is provided with two arms which are connected to each other by means of a hinge joint and with which an upper dental prosthesis and a lower dental prosthesis are coupled to each other, whereby, at the hinge joint, a spring is provided with which the upper prosthesis and the lower prosthesis are pushed away from each other, whereby the spring is an extension spring. Such spring is also known under the name of "pull spring" or "tension spring".

The dental prosthesis stabilizer according to the invention does not cause noise and avoids any food retention. The spring is more flexible and always puts itself in the ideal position and contributes the effect that dental prosthesis stabilizer is very user friendly.

To this end, the present invention also concerns a dental prosthesis stabilizer which is provided with two arms which are connected to each other by means of a hinge joint and with which an upper dental prosthesis and a lower dental prosthesis are coupled to each other, whereby, at the hinge joint, a spring is provided with which the upper prosthesis and the lower prosthesis are pushed away from each other, whereby the spring is made of titanium or an titanium alloy in particular Titanium 6-Aluminium 4- Vanadium (T16AI4V).

Thereby a more rigid dental prosthesis stabilizer is created which is better mouth and saliva resistant. The mouth acceptance by the patient and the life span of dental prosthesis stabilizer are considerably improved.

To this end, the present invention also concerns a dental prosthesis stabilizer which is provided with two arms which are connected to each other by means of a hinge joint and with which an upper dental prosthesis and a lower dental prosthesis are coupled to each other, whereby, at the hinge joint, a spring is provided with which the upper prosthesis and the lower prosthesis are pushed away from each other, whereby the spring covered by silicone.

Thereby a contact with saliva is avoided and the spring is better protected. The silicone in and around the spring supports the spring strength and even when the spring would break, it would stay in one piece. Also in this case the spring functions, but with less power of course.

According to a preferred embodiment of a dental prosthesis stabilizer according to the invention, both arms of the dental prosthesis stabilizer are made telescopic in the shape of a bent far end of the above-mentioned spring.

This embodiment provides even more freedom of movement to the hinge joint.

According to another preferred embodiment of a dental prosthesis stabilizer according to the invention, the bent far end of the spring which is designed for the lower dental prosthesis has a curvature radius which corresponds to the curvature radius of what is called the curve of Spee of the set of teeth of the person for whom the dental prosthesis is meant.

This curve of Spee is a curve which follows the shape of the profile of the set of teeth, as will be described more clearly hereafter. Additionally, the bent far end of the spring which is designed for the upper dental prosthesis and the accompanying guide preferably also have a curvature radius which is equal to the difference in distance between the hinge joint of the dental prosthesis stabilizer and the maxillary joint of the person for whom the dental prosthesis is meant.

An advantage of these embodiments of a dental prosthesis stabilizer is that the bent far ends of the spring, when the jaws open and close, thanks to the above-mentioned shapes of the bent far ends and the accompanying guides, can perfectly slide in the guides concerned without suffering any noticeable friction.

According to yet another preferred embodiment of a dental prosthesis stabilizer according to the invention, the hinge and the spring are enveloped by a capsule, which preferably is flexible.

This embodiment is advantageous in that the person wearing such a dental prosthesis stabilizer does not or hardly feel the presence of the dental prosthesis stabilizer in the oral cavity, in that the dental prosthesis stabilizer is additionally protected against negative chemical influences and in that no leavings can stay behind parts of the dental prosthesis stabilizer.

According to another preferred embodiment of a dental prosthesis stabilizer according to the invention, the spring (5) is made of steel, in particular high grade steel (stainless steel), and in particular steel nominated RVS316. The advantage of the use of this steel for springs of a dental prosthesis stabilizer is the durability and the strength that this steel provides. Furthermore this steel provides flexibility and elasticity. The dental prosthesis stabilizer according to this embodiment is very well mouth and saliva resistant, thereby also obtaining an excellent mouth acceptance by the patient.

In order to better explain the characteristics of the invention, the following description of a dental prosthesis stabilizer according to the invention is given as an example only, without being limitative in any way, with reference to the accompanying drawings, in which: Figure 1 schematically represents a dental prosthesis stabilizer according to a first embodiment of the invention;

Figure 2 represents a section according to line ll-ll in figure 1 to a larger scale; Figure 2 schematically represents the geometry of the dental prosthesis stabilizer from figure 1 with reference to a skull;

Figures 3 and 4 represent the dental prosthesis stabilizer according to figure 1 ,

applied to an upper and a lower dental prosthesis;

Figure 5 represents a perspective view of the extension spring used in the dental prosthesis stabilizer according to figure 1 ,

Figure 6 represents a perspective view of a silicone cover for the spring according to figure 5,

Figure 7 schematically represents a dental prosthesis stabilizer according to

a second embodiment of the invention;

Figure 8 a side view of the torsion spring used in the dental prosthesis stabilizer according to figure 7,

Figure 9 a plan view of the torsion spring according to figure 8,

Figure 10 a side view as in figure 8, with inserted plastic spool, and

Figure 11 a plan view of the spring according to figure 10. The dental prosthesis stabilizer 1 according to a first embodiment of the invention, represented in figures 1 and 2, mainly consists of two arms 2 and 3 which are connected to each other by means of a hinge joint 4, and whereby a spring 5, 51 , also shown in figure is provided at the hinge joint 4. According to this embodiment of the invention the spring 5 is an extension spring 51 , also called "pull spring" (or "tension spring"). According to one specific embodiment of the invention the spring 5, 51 is made of titanium or a titanium alloy, in particular Titanium 6-Aluminium 4-Vanadium (Ti6AI4V).

The arms 2 and 3 are made telescopic and are formed in particular of bent far ends 6 and 7 of the above-mentioned spring 51 , which can be axially moved in bent guides 8 and 9. These guides 8 and 9 are sealed at their respective free ends 10 and 11 , whereas they are open and provided with collars 14 and 15 respectively at the other far ends 12 and 13. Further, the hinge joint 4 and the spring 51 are enveloped by a flexible capsule 16, whereby this capsule is fixed to the guides 8 and 9 over the collars 14 and 15.

In the given example, the form of the guides and of the bent far ends of the spiral springs is circular and not chosen arbitrarily, as is illustrated by means of figure 2.

In this figure 2 is indicated a first circle A, which roughly follows the curve of Spee.

This means that the circle A with radius B touches the heads 26 of the set 28 of teeth 27 of the person concerned and goes through the maxillary joint 29. Further, the centre 30 of this circle A is situated more or less at the height of the forehead 31 , just above the eye sockets 32.

The hinge joint 33 of the dental prosthesis stabilizer 1 is preferably situated on this circle A at a distance B from the maxillary joint 29, whereby this distance B is preferably selected such that the hinge joint 33 is situated close to the last teeth 34 of the set of teeth 28.

Further, it is made sure that the bent far end 7 of the spiral spring 18, which is designed for a lower dental prosthesis, and the accompanying guide 11 have a curvature radius which corresponds to the curvature radius of the curve of Spee of the set of teeth 28 of the person for whom the dental prosthesis is meant, which in the given example corresponds to the radius B of the circle A.

According to the invention, the hinge joint 33 is first projected parallel to the connecting line C-C between the maxillary joint 29 and the centre 30 Of the circle A onto the line D- D' going through the centre 30 of the circle A and which is parallel to the connecting line E-E' between the hinge joint 33 and the maxillary joint 29. From the obtained projected joint 35 can then be drawn a circle F with radius B, going through the hinge joint 33.

This circle F determines the course of the bent far end 7 of the spiral spring 18 and the guide 9.

The far end 11 of the guide 9 is preferably situated at about a distance G from the hinge joint 33 which corresponds to the distance G between the maxillary joint 29 and the hinge joint 33.

Further, the bent far end 6 of the spiral spring 17, which is designed for an upper dental prosthesis, and the accompanying guide 8 are formed such that they mainly describe a circumference H which is formed of a circle H having the far end 11 of the guide 9 as a centre, and a radius G.

The far end 10 of the guide 8 is preferably situated on the vertical Ι-Γ through the far end 11 of the guide 9.

The use of a dental prosthesis stabilizer 1 according to the invention is simple and is illustrated by means of figures 3 and 4.

In these figures, two dental prosthesis stabilizers 1 , of which only one specimen is shown for the sake of simplicity, are provided on a dental prosthesis 36, which consists of an upper dental prosthesis 37 and a lower dental prosthesis 38, and whereby the dental prosthesis stabilizers 1 form the connection between the upper dental prosthesis 37 and the lower dental prosthesis 38.

This can be done by providing or boring holes in the respective parts 37 and 38 of the dental prosthesis 36 which make it possible to provide and fix the guides 8 and 9 in the parts 37 and 38 of the dental prosthesis 36, for example by means of gluing.

The flexible capsule 16 connects to the above-mentioned open far ends 12 and 13 of the guides 8 and 9, such that the mechanism as a whole consisting of the housing 19 with the spiral springs 17 and 18 therein is screened off the oral cavity.

Figures 3 and 4 represent the dental prosthesis 36 in the open and closed position respectively, whereby during the opening and closing of the dental prosthesis 36, the bent far ends 6 and 7 move to and fro in the guides 8 and 9.

Thanks to the bent shape of the guides 8 and 9, as described in detail above, practically no friction will occur during said movement. It is also clear that the spiral springs 17 and 18 exert a force with which the upper dental prosthesis 37 and the lower dental prosthesis 38 are pushed away from each other.

This force is only meant to prevent the parts 37 and 38 of the dental prosthesis 36 to become detached from the jaws, whereby this force is rather small of course, such that a person wearing a dental prosthesis 36, equipped with a dental prosthesis stabilizer 1 , is not bothered when putting his teeth on top of one another.

Further, it is clear that a dental prosthesis stabilizer 1 according to the invention offers the above-mentioned advantages by comparison with the known dental prosthesis stabilizers, namely that only very few components are required to compose the dental prosthesis stabilizer 1 , whereas no leavings can stay behind parts of the dental prosthesis stabilizer 1 thanks to the flexible capsule 16.

Further, the dimensions of a dental prosthesis stabilizer 1 according to the invention are preferably restricted and adjusted to the use in the oral cavity, whereby for example the hinge joint 4 is about the size of a tooth 27 at the most, so that the person wearing a dental prosthesis 36, provided with said dental prosthesis stabilizer 1 , is not bothered by its presence. A dental prosthesis stabilizer 1 may also have all sorts of other shapes than in the example shown. Thus, it is not excluded to realize the above-mentioned spring 5 as a single spring.

Nor must the flexible capsule 16 necessarily be a separate part, but it may for example be an integrated part of the guides 8 and 9.

Moreover, the bent far ends 6 and 7, as well as the guides 8 and 9 may have other shapes than the above-mentioned circular shapes in order to obtain for example even better friction characteristics as the bent far ends 6 and 7 move to and fro in the guides 8 and 9.

Figure 5 shows a spring 51 which is an extension spring having tow arms 2, 3 with round slices 39, 40. Preferably the spring is made of titanium or an titanium alloy, in particular Titanium 6-Aluminium 4-Vanadium (Ti6AI4V), however the extension spring can be made of other material(s). Titanium is relatively rigid and very mouth and saliva resistant. The spring according to the invention is very more flexible and durable spring compared to the spring in the prior art (made according to AISA 316 or DIN 1.4401) with a significant improvement in lifespan and mouth acceptance by the patient.

Each arm 2, 3 has a round slice 39, 40 at its end, however little hooks can also used instead of the round slices.

The spring 51 , made of titanium or an titanium alloy, in particular Titanium 6-Aluminium 4-Vanadium (Ti6AI4V) is produced in building up layers of about 3μ by laser using stereo-lithography. This production method makes it possible to make the spring 5 in one peace; whereby the active - middle - spring part has a wire diameter of about 0.5 mm, and the passive parts at the left and the right side of the active - middle - part have a wire diameter of about 1 mm.

Figure 6 shows a tube/silicone cover 41 for the spring 51.

The dental prosthesis stabilizer 1 according to a second embodiment of the invention, represented in figure 7 comprises a torsion spring 52 instead of a extension spring as represented in the figures 1 to 6. Such torsion spring 52 is known from US 2009/0917761 A1.

Figures 8 and 9 show the stabilizer 1 in a released, non integrated state. Said stabilizer consists of arms 521 and 522 on the outer ends of which an eyelet 529 is bent while the inner zones of the arms are connected with the coil spring forming the joint 526. In the design shown figures 10 and 1 show the same stabilizer as in in figure 8, only that here, the facing 5210, which is in the form of a plastic spool, is provided or place on the joint 526. The spool-type of facing 5210 has two mushroom-shaped flange parts 521 1 that are securely fastened or fastenable to each other by a foot part 5212 that centrally passes through and fills the joint 526. The flange parts 5211 are accordingly flush with both faces of the joint 6 and thereby prevent both impurities from entering the winding part of the joint 526 as well as direct contact with the movable spiral parts of the joint.

In a preferred embodiment the spring 52 is made of steel, in particular high grade steel (stainless steel), and in particular steel known under the term of RVS316.

Beside the different spring types (extension spring/torsion spring) the stabilizers according to the first and second embodiment may have the same structure comprising same components.

The present invention is by no means restricted to the embodiment given as an example and represented in the accompanying drawings; on the contrary, such an dental prosthesis stabilizer may have all sorts of shapes and dimensions while still remaining within the scope of the invention. Reference signs

I dental prosthesis stabilizer

2,3 arms

4 hinge joint

5 spring

51 , 52 extension spring, torsion spring

9 guide

I I far end of guide 9

14, 15 collar

16 capsule

17, 18 spiral spring

19 housing

20, 21 far end of intermediate plate

22 intermediate plate

23, 24 cover plate of housing 19

27 tooth

28 set of teeth

29 maxillary joint

30 centre of circle

33 hinge joint

36 dental prosthesis

37, 38 upper dental prosthesis, lower dental prosthesis

39, 40 round slice

41 silicone cover of spring 5, 51

A curve of Spee

B, G curvature radius

521 , 522 arms of spring 52

526 joint

529 eyelet

5210 facing

5211 flange parts

5212 foot part