WO1999017675A1

WO1999017675A1 - Zirconium oxide dental implant with internal thread

Info

Publication number: WO1999017675A1
Application number: PCT/FR1998/002094
Authority: WO
Inventors: Guy Peltier
Original assignee: Gourlaouen, Jeannine
Priority date: 1997-10-03
Filing date: 1998-09-30
Publication date: 1999-04-15
Also published as: DE19881695T1; DE19881695B4; FR2769207B1; FR2769207A1

Abstract

The invention concerns dental implants, more particularly a dental implant (1) comprising an external thread (2) and an internal thread (6). Said dental implant (1) is made of zirconium oxide. The invention also concerns a method for moulding said dental implant using metal inserts (7, 9).

Description

ZIRCONIUM OXIDE DENTAL IMPLANT WITH INTERNAL TAP

The present invention relates to dental implants. More particularly, it relates to dental implants having a central orifice necessary for the placement of a tapped abutment or a periodontal ring.

These implants are intended to be established in the human skeleton, preferably in the dental skeleton, and possibly in the animal skeleton. Unlike techniques using posts, which are placed in the natural root of the tooth, dental implants are established after extraction of the entire tooth. The bone tissue, once reformed, is then perforated for the placement of the dental implant. Most of the implants to be established in the bone tissue are made of the purest titanium possible. Titaniums T40, T50 and T60 are particularly used.

These titanium implants are often impacted in the bone. This means that they are fitted into a bone hole. The clearance between the implant and this bone drilling must be zero. Impacted implants can be covered with hydroxyapatite or porous titanium. Dental implants, and in particular those made of titanium, can also be screwed into the bone, which adds additional security as to the quality of the fixation of the dental implant.

For several years new implants have been tested. Some have been successfully adopted, including those based on zirconium oxide. These have the characteristic of being particularly robust, due to the hardness of the oxide material. zirconium itself. Implants based on zirconium oxide are therefore very appreciable because of their longevity.

The implants based on zirconium oxide which are currently available can sometimes have a conical axial central well. The shape of this well is polygonal, most often square or hexagonal. It is obtained by molding then sintering and it allows to receive the superstructures having a shape similar to that of the central well. These superstructures fit into the well and are then fixed with dental cement. However, despite this dental cement, and the robustness of the material based on zirconium oxide, the longevity of these implants is not yet optimal. One possibility for improving the quality of these implants would be to provide them with a tapped axial central hole. An adequate screw would then fix a false stump in the dental implant. The problem is that because of its extreme hardness, it is not possible to make this threaded axial central hole after the molding of the implant based on zirconium oxide.

This problem is solved according to the invention in that it presents a method of manufacturing dental implants based on zirconium oxide having a tapped axial central hole. This tapped hole is produced according to the invention at the time of molding of the dental implant, with a threaded insert which must reproduce the desired tapping in the implant. This screwed insert is removable and replaced or changed on its support, this support being a movable part of the mold. The internal thread is obtained by molding. Sintering is carried out by injection under high pressure into the mold of a paste based on zirconium oxide, followed by baking at high temperature. The tapped hole is used to receive various superstructures which are directly screwed into the implant based on zirconium oxide, or possibly maintained by suitable screws. These screws can eventually become antirotational thanks to the application of a resinous dental cement. Several solutions allowing the realization of the central threaded hole of the body of the dental implant will be proposed. The tapping is however always carried out at the time of molding the dental implant by high pressure injection of the material based on zirconium oxide. On the other hand, the dental implant in question is most often screwable. Consequently, the invention results in the manufacture of a dental implant having a better longevity than that of dental implants existing to date. We then speak, according to the invention, tap implant. This tapping allows to receive an adequate screw to fix a false abutment on the dental implant.

The invention therefore relates to a dental implant based on zirconium oxide provided with an external thread, characterized in that it comprises an internal thread produced by molding. The invention also provides a method of manufacturing such a dental implant.

The various aspects and advantages of the invention will appear more clearly in the following description with reference to the figures which are given for information only and in no way limit the invention. The figures show:

- Figure 1 shows, according to the invention, a dental implant and a tool for manufacturing this dental implant, making it possible in a first way to make a central axial hole tapped in the dental implant based on zirconium oxide; - Figure 2 illustrates a method for removing an insert used in the manufacture of the dental implant shown in Figure 1;

- Figure 3 shows a second method of manufacturing a dental implant having a threaded axial central hole;

- Figure 4 illustrates a method of extracting an insert used in the manufacture of a dental implant presented in Figure 3; - Figure 5 illustrates a method for extracting an insert used for the manufacture of a dental implant having a tapped axial central hole in case of difficulty with the methods illustrated in Figures 2 and 4. Figure 1 shows according to the invention a process for producing a dental implant 1 based on zirconium oxide, having a tapped central axial well. The dental implant 1 has an external thread 2. This external thread is triangular, symmetrical or asymmetrical and has vertices 2a and rounded recesses 2b. A buried end of this dental implant eventually ends in a hexagon 3. The upper end 4 of the dental implant 1 is cylindrical and smooth over a height which can vary from one to three millimeters. This upper end 4 constitutes the collar of the implant. This collar 4 has a polygonal, for example hexagonal bore 5 extended downwards from the dental implant 1 by an internal thread 6. This thread 6 is produced at the time of molding by a first removable insert 7, which will serve as a molding insert . The internal thread 6 also has its vertices and its rounded furrows. This generally ensures greater strength of the thread. According to FIG. 1, which is the representation of a preferred method for producing the dental implant in zirconium oxide, the first threaded insert 7 serves as a reproducer in the dental implant 1 at the time of molding. This first threaded insert 7 is provided at a lower end with a small cylindrical part 7d corresponding to the diameter of the core of the internal thread

6. Another end of the first threaded insert 7 comes out of the dental implant 1 and comprises, in the extension of the thread 6, a smooth cylindrical part 7a continued by a polygonal, preferably hexagonal, part 7b. This polygonal part is interrupted by a groove 7c in the form of a diabolo.

A mold for making the dental implant 1 with its external thread 2 comprises in particular a movable part 8 and a movable part 8f. In the movable part 8 a second insert 9, also called an auxiliary insert, is screwed in. centered way. The second insert 9 is provided with a hexagonal male part which fits exactly into the bore 5 of the implant 1. It has a smooth and hollow cylindrical bore 10a which makes it possible to receive the first insert 7. The second insert 9 serves as a guide for the first insert 7. It ensures the precision of the position of the internal thread of the dental implant. The first insert 7 is stuck in abutment in the second insert 9. The abutment occurs at a junction 7j between the thread 6 and the smooth cylindrical part 7a of the first insert 7 and of the hexagonal male part 5 of the second insert 9 The association of the mobile part 8, the first insert 7 and the second insert 9 constitutes a punch. This punch is affixed with centering on the fixed part 8f of the mold by means of a circular socket 8p. The second insert 9 ends at a polygonal upper end 10 buried in the movable part 8 of the mold. In the moving part 8 of the mold, there is a ball system 11 pushed by a spring 12. This spring 12 is held in abutment on the ball 11 by a hollow screw 13 in contact with one end of the spring 12. This mechanism consisting of the ball 11 of the spring 12 and the hollow screw 13 makes it possible to retain the insert 7 in the movable part 8 of the mold when a paste based on zirconium oxide is injected which will constitute the dental implant 1. It is by pressing on the groove 7c in the form of a diabolo that the ball 11 retains the insert 7 in the movable part 8.

When the implant 1 is molded, the mobile part 8 associated with the insert 9 moves back, leaving the insert 7 in place in the implant 1. When the mobile part 8 associated with the insert 9 recedes, the ball 11 rolls as it rises on the hexagonal end 7b of the insert 7. The second insert 9 being slid into the movable part 8 of the mold moves back with said movable part 8. The solution, comprising a ball 11 is preferred to maintain the insert 7 during the high pressure injection of the zirconium oxide paste. One could in fact maintain the insert 7 using a metal rod which would pass through the insert 7 through the movable part 8. But deterioration of the dental implant 1 is likely in case one forgets to remove this rod during removal of the movable part 8. The ball 11 does not require any special precautions when removing the movable part 8. The fixed part 8f of the mold is made up of two pieces which can separate along an axis d centered on the mold and thus reveal the dental implant 1.

Figure 2 illustrates a method for removing the insert 7 used for the manufacture of the threaded dental implant presented in FIG. 1. When the dental implant 1 still containing the insert 7 is removed from the mold, it is placed in a metal cage

17 of square shape and tightened in a vice in order to be deprived of the insert 7. This insert 7 is unscrewed by means of a hollow key 18 having a female polygonal shape 19, square or hexagonal, adapting to the shape male polygonal 7b, square or hexagonal, of

1 • insert 7. A knurled digital part 18a facilitates the unscrewing of the insert 7. Although not shown in FIG. 2, the buried end 3 in the form of a hexagon of the dental implant, mentioned during the description of Figure 1, allows to lock the implant when unscrewing. It also makes it possible to make the dental implant 1 anti-rotational when it is implanted in the bone.

FIG. 3 represents another method of manufacturing the dental implant 1. There are numerous parts presented there during the description of FIG. 1. Their function has not changed. This is the case of the dental implant 1, of its external thread 2, of its hexagonal termination 3 and of its collar 4. The collar 4 always has a hexagonal bore 5. In accordance with the method presented in FIG. 1, a first metal insert 7th machined or sintered with vertices and rounded fillet, serving as a reproducer for a tapping 2 of the dental implant 1, is used. A hexagonal well 7f with parallel sides extending from the end of the thread is arranged in the first insert 7e. This well receives a hexagonal end 9a of a second insert 9f screwed into the movable punch 8 of the mold. The two inserts 7e and 9f are thus fitted one into the other. The second insert 9f has a slightly conical hexagonal end 9b in order to keep it tight at the end of insertion. 1 insert 7th. Their horizontal position allows them to remain motionless with respect to each other. The second insert 9f is surmounted by a second hexagonal part 9c which serves as a reproducer in the dental implant 1. A third smooth cylindrical part 9d succeeds the hexagonal part 9c. It serves to center in the movable part 8 of the mold. Finally, a last threaded 9th screwed part blocks the second insert 9f in the movable part 8. Once the implant 1 is molded, the movable punch 8 of the mold moves back causing the insert 9f screwed into this punch 8, while giving up 1 ' insert 7e in the dental implant 1. The two parts of the mold opening, it remains to recover the dental implant 1 after extraction of the insert 7e.

As shown in Figure 4, this extraction can be done by a simple unscrewing. For this, use is made of a metal cage 17, square in this case. This metal cage 17 is clamped in a vice. After extraction of the movable part 8 from the mold, accompanied by the second insert 9 f, it suffices to insert the implant 1 in this cage and to orient the hexagonal end 3 of the dental implant in the hexagonal female housing of the cage 17. A digital key 14 is then used comprising a hexagonal end 16 penetrating the insert 7e. This digital key has a cylindrical diameter 15 which is centered in hexagon 5 of the dental implant 1. It is thus possible to unscrew the insert 7e. Figure 5 shows the possible remedy in case of difficulty to unscrew 1 insert 7e. One can pierce the insert 7 by means of a drill with a left propeller 20 of a drill 21 with a diameter slightly smaller than the core of the thread of the insert 7. It then remains to pass the control tap 22 for removing the little material remaining in the threads of the insert 7.

Other techniques can also be used to facilitate removal of the insert 7 or the insert 7e. One can, for example, spray the first insert 7 or 7 e using a substance which allows the dough not to stick to the metal surface of the insert before injecting the dough into the mold. zirconium oxide base. You can also immerse the dental implants for a few moments

1 molded and the first insert 7 or 7e in liquid nitrogen at about -250 ° C. The first insert 7 or 7e and the dental implant 1 being of a different nature, they will contract more or less slowly. The first metal insert 7 contracts much faster than the paste material based on zirconium oxide. Unscrewing the first insert 7 is therefore easier.

The present invention has been presented above in a preferred but nonlimiting embodiment.

It could indeed be accompanied by a small compensating ring, in order to raise the dental implant by the thickness of the gum. This compensating ring, called periodontal ring, could also be made of a material based on zirconium oxide and be tapped. Finally, this type of tapped implant based on zirconium oxide can find other applications than that of the dental field described above. This type of implant can indeed be screwed into any part of the human skeleton and thus participate in the installation of prostheses.

Claims

R E V E N D I C A T I O N S

1 - Dental implant (1) based on zirconium oxide, which can also be produced on the basis of aluminous or other ceramics, provided with an external thread (2) screwable into the bone tissues characterized in that it comprises a internal thread (6) produced by molding, which also finds its application in the medical field, in particular in bone surgery.

2. - dental implant (1) in zirconium oxide or ceramic according to claim 1 characterized in that the external thread (2) and the internal thread (6) have rounded tops and hollows.

3. - dental implant (1) in zirconium oxide or ceramic according to one of claims 1 to 2 characterized in that the upper end (4) of the dental implant (1) is smooth over a height of a few millimeters .

4. dental implant (1) in zirconium oxide according to one of claims 1 to 3 characterized in that the upper end (4) of the dental implant (1) has a hexagonal bore (5).

5. - Method for manufacturing a dental implant (1) in zirconium oxide or ceramic provided with an external thread (2) and an internal thread (6) characterized in that it comprises the following steps:

at. screwing with centering of a hollow auxiliary insert (9) in a movable part (8) of a mold of the dental implant (1), thus constituting a movable punch;

b. fitting of a molding insert (7) serving as an internal tapping reproducer embedded in the movable punch through the auxiliary insert (9);

vs. affixing with centering of the movable part (8) associated with the molding insert (7) on a mold determining the shape of the dental implant (1); d. sintering by injection under high pressure into the mold of a paste based on zirconium oxide and baking the paste based on zirconium oxide; e. removal of the movable punch leaving in place the molding insert (7); f. unscrewing the molding insert (7).

6 - Tool for manufacturing a zirconium oxide dental implant according to claim 4 characterized in that the movable punch comprises a ball (11) for retaining the molding insert (7) at the time of injection of the paste based on zirconium oxide.

7 - Tool for manufacturing a zirconium oxide dental implant according to claim 4 characterized in that an upper end of one auxiliary insert (9) and an upper part of the molding insert (7) entering the insert auxiliary (9) are polygonal.

8 - Tool for manufacturing a zirconium oxide dental implant according to claim 4 characterized in that the molding insert has a cylindrical lower end with a diameter equal to that of the core of the internal thread 6.