WO2006065213A1

WO2006065213A1 - Dental implant retaining screw and method for mounting an abutment on said implant

Info

Publication number: WO2006065213A1
Application number: PCT/SE2005/001915
Authority: WO
Inventors: Fadi El-Homsi; George Al Homsi
Original assignee: Fadi El-Homsi; George Al Homsi
Priority date: 2004-12-14
Filing date: 2005-12-14
Publication date: 2006-06-22
Also published as: SE0403025D0; SE0403025L; SE529995C2

Abstract

The present invention relates to a dental implant retaining screw comprising a left threaded screw portion (1) and a right threaded screw portion (2) , said screw portions (1, 2) defining a common axial direction (C-C) . The invention also relates to a method for mounting an abutment (8) on an implant (10) by means of a dental implant retaining screw. It is significant of the dental implant retaining scre of the present invention that the screw portions (1, 2) are mutually connected by means of a collar (3) having an extension perpendicular to the axial direction (C-C).

Description

Dental implant retaining screw and method for mounting an abutment on said implant.

Technical Field of the Invention

The present invention relates to a dental implant retaining screw comprising a left threaded screw portion and a right threaded screw portion, said screw portions defining a common axial direction. The invention also relates to a method for mounting an abutment on an implant by means of a dental implant retaining screw.

Prior Art

According to conventional technique one or two retaining screws are usually needed to fasten or to secure the abutment and the superstructure to its dental implant. The abutment is first anchored to the implant, and the superstructure is fastened with the retaining screw onto the implant abutment. To tighten or to loose the retaining screw with a screwdriver, a hole through the occlusal surface of the prosthesis must be available. This hole must be later filled with composite. Such a conventional technique is known from US Patent Application Publication No. US 2002/0123022 Al.

Another fastening procedure of the superstructure is cementing onto the abutment, however this technique allows no retrievability. This technique is aesthetic but complicated. From DE 101 01 907 Al is previously known a right and left threaded screw to be used for the mutual connection of implant pieces. The right and left screw interconnects two pieces of an implant. The screw is activated by a key that extends through a hole in one piece, said key engaging a recess in one end of the screw. When the screw is rotated the two pieces are brought to approach each other. However, the hole through one piece is a disadvantage since the hole must be filled with composite, see above.

Objects and Features of the Invention

It is a primary object of the present invention to provide a system of anchoring both abutments and superstructures in a simple and aesthetic way. It is a further object of the invention to allow repair, retrievability and checking of the system when needed. At least the primary object of the invention is fulfilled by means of a dental implant retaining screw that has been given the features of the independent appending claim. Preferred embodiments of the invention are defined in the dependent claims.

Brief Description of the Drawings Below embodiments of the invention will be described, reference being made to the accompanying drawings, where: Fig. 1 shows a perspective view of a dental implant retaining screw, the upper screw portion being left threaded and the lower screw portion being right threaded;

Fig. 2 shows a side view of the dental implant retaining screw according to Fig. 1, the lower screw portion being in the mounting phase in an implant and an abutment being in the mounting phase on the upper screw portion;

Fig. 3 shows a side view of the dental implant retaining screw according to Fig. 1 fully mounted in the implant, the abutment being fully mounted on the upper screw portion and carrying a superstructure (crown) ; Fig. 4 shows a side view of a torque spanner.

Fig. 5 shows a partly sectioned view of a superstructure

(bridge) that is mounted on two implants; Fig. 6 shows a side view of the dental implant retaining screw according to Fig. 1, said screw being equipped with an internally threaded washer that underlies the collar;

Fig. 7 shows a side view of an alternative embodiment of the dental implant retaining screw according to the present invention, the screw being equipped with a modified collar; and

Fig. 8 shows the dental implant retaining screw according to Fig. 7 mounted in a dental implant and carrying an abutment and a superstructure. Detailed Description of Preferred Embodiments

Referring to the drawings, like numbers indicate like parts throughout the views. As shown in Figs. 1, 2, 3, 6, 7 and 8 the present invention comprises a right threaded screw- hollow collar-left threaded screw unit.

The dental implant retaining screw shown in Fig. 1 comprises a left threaded screw portion 1 and a right threaded screw portion 2, said screw portions 1, 2 having a common, longitudinal centre axis C-C that defines the axial direction of the dental implant retaining screw according to the present invention. Intermediate the screw portions 1 and 2 the dental implant retaining screw comprises a collar 3, generally in the shape of a disc having a circular periphery. The collar 3 has a certain thickness in the axial direction of the dental implant retaining screw. The upper side of the collar 3 is denominated the reference numeral 5 and the lower side of the collar 3 is denominated the reference numeral 6. In the shown embodiment the peripheral surface of the collar 3 is provided with six holes 4 of 2 mm depth, said holes acting as a drive means, to allow the rotation of the dental implant retaining screw. To effect this rotation a specially designed torque spanner, see Fig. 4, is used.

The dental implant retaining screw and the abutment are preferably made from a material suitable for implant applications and the superstructure, such as gold, titanium, chromium cobalt or porcelain.

The torque spanner T, depicted in Fig. 4, comprises a shaft S and a pin P, the pin P being pivotally connected to the shaft S. In order to rotate the dental implant retaining screw the operator grips the shaft S and the pin P is inserted into a suitable hole 4. The rotation is the effected manually by the operator who displaces the pin P via the shaft S.

In Fig. 2 it is schematically shown how the dental implant retaining screw is mounted in an implant 10 that is fixed in a predrilled hole in the jawbone. The fixation may e.g. be effected by means of screwing or by means of press fit. In case the implant 10 is screwed into the jawbone the implant is equipped with an external thread. As can be seen from Fig. 2 the implant 10 comprises an implant platform 9 at its top. The right threaded screw portion 2 of the dental implant retaining screw is screwed into a first internally threaded hole 20 of the implant 10. The insertion of the right threaded screw portion 2 continues until only a first small distance 11 remains between the implant platform 9 and the collar 3. Then an abutment 8, with a second internally threaded hole 21, is screwed on the left threaded screw portion 1 until only a second small distance 11 remains between the abutment collar and the collar 3. If the pitch of the left threaded screw portion 1 and the pitch of the right threaded portion 2 are the same then the first small distance 11 and the second small distance 11 must have the same value and hence they are given the same reference numeral.

It is very important that the distance 11 between the implant platform 9 and the lower side 6 of the collar 3 of the dental implant retaining screw on one hand and the distance 11 between the upper side 5 of the collar 3 and the abutment 8 on the other hand have the same value. One preferred way to ensure the equality of the distances 11 is to use machining markings on the screw portions 1, 2 or a snap-on lock as reference points on the screw portions 1, 2 of the dental implant retaining screw. Now the final tightening of the dental implant retaining screw takes place, this being effected by rotating the collar 3 by using the torque spanner T. The right threaded screw portion 2 is then further inserted into the first internally threaded hole 20 and eventually the lower side of the collar 3 abuts the implant platform 9. Simultaneously the abutment 8 is prevented to rotate and hence the abutment 8 will be displaced axially relative to the left threaded screw portion 1 until the abutment 8 contacts the upper side 5 of the collar 3. Since the two distances 11 was equal before the final tightening the contact on the opposite sides of the collar will occur in principle at the same time. This is a key feature of the present invention, i.e. that there is a simultaneous contact on both sides of the collar 3. In this connection it should be pointed out that both screw portions 1, 2 must have the same pitch, i.e. a certain rotation of the collar 3 brings about the same axial displacement of the abutment 8 relative to the left threaded screw portion 1 and of the implant platform 9 relative to the right threaded portion 2.

When the tightening of the dental implant retaining screw is completed care should be taken that the dental implant retaining screw is not loosening from the implant 10. To this purpose the collar 3 of the dental implant retaining screw should be provided with a locking system. Such system could be achieved by joining the abutment 8, the collar 3 and the implant using different locking devices. In the shown embodiment the collar 3 is provided with a small first screw 15, see Fig. 3, mounted in an internally threaded small first hole 14, see Fig. 1, that is inclined 45° relative to the axial direction C-C of the dental implant retaining screw to prevent any rotation of the collar 3. When the small first screw 15 has been tightened the six holes 4 of the collar 3 will be filled with a composite. In Fig. 3 it is shown how a superstructure 7 is mounted on the abutment 8. Normally the superstructure 7 is fixed to the abutment by means of cementing, fusing or compressing. However, it is also feasible that there is a thread connection between the superstructure 7 and the abutment 8. To prevent the loosening of the superstructure 7 a small second screw 17, see Fig. 3, is screwed through an internally threaded small second hole 16, see Fig. 2, in the abutment 8 and the collar 3 of the dental implant retaining screw.

If it comes to a situation where the superstructure 7 is to be removed, the composite in the six holes 4 must first be removed by drilling, the small first screw 15 and the small second screw 17 must be unscrewed and the torque spanner T engaged with the holes 4 of the collar 3 for unscrewing the dental implant retaining screw. In Fig. 5 a superstructure 107 in the shape of a three unit bridge is shown, said bridge superstructure 107 being carried by two implants 10 that each is equipped with a dental implant retaining screw according to the present invention. Since the bridge superstructure 107 is carried by two implants 10 there is no risk that the bridge superstructure 107 tends to rotate relative to the implants 10. Therefore, no small first screw to prevent rotation is needed in the embodiment according to Fig. 5. In Fig. 6 a dental implant retaining screw is shown, said screw being equipped with an internally threaded washer 12 on the right threaded screw portion 2. In case where the implant platform 9 is deep subgingivally the washer 12 functions as a spacer to prevent the collar 3 from being positioned at a too low level.

The alternative embodiment of a dental implant retaining screw according to Fig. 7 differs from the embodiment according to Fig. 1 by the design of the collar 103. The collar 103 according to Fig. 7 is equipped with external facets 104, and more precisely the collar 103 is given a hexagonal shape. In order to effect rotation of such a collar 103 a conventional spanner could be used, said spanner engaging the facets 104.

In Fig. 8 the dental implant retaining screw according to Fig. 7 is mounted in an implant 10 and the dental implant retaining screw receives an abutment 108 with an external contour that is adapted to the external contour of the collar 103, i.e. the external contour of the abutment 108 is likewise hexagonal. A superstructure 7 is mounted on the abutment 108. The mounting is effected in principally the same way as the mounting shown in Fig. 3. As regards the locking of the collar 103 relative to the implant 10 laser welding or other methods may be used.

Feasible Modifications of the Invention

In the embodiments described above the upper screw portion 1 is a left threaded screw portion while the lower screw portion 2 is a right threaded screw portion. However, within the scope of the present invention it is feasible that these portions change places.

As an alternative to ensure the equality of the distances 11 spacers in the shape of open washers may be used, said washers having the same thickness. By the expression open washers should be understood washers that are not closed but having a gap in their circumference to make possible mounting and demounting. The washers are placed between the implant platform 9 and one side 6 of the collar 3, and between the other side 5 of the collar 3 and the abutment 8. When the two distances 11 are fixed, the washers are removed and the next step in the mounting procedure is effected. The material of the washers is preferably metal or hard plastic.

The right threaded screw portion 2 may be longer than the left threaded screw portion 1 or vice versa. In that case, either the implant 10 or the superstructure 7 must be screwed first, leaving a predetermined first distance 11 to the collar 3, said first distance 11 having the same value as the second distance 11 between the collar 3 and the abutment 8. The longer screw must be screwed first. The threads of the left threaded screw portion 1 and the right threaded screw portion 2 may have different shapes and diameters to fit the internally threaded implant 10 and the internally threaded abutment 8, and said threaded portions 1, 2 may be coated with gold. However, both screw portions 1, 2 should normally have the same pitch. In this connection it should be pointed out that theoretically screw portions having different pitch may be used. In such a case the first and second distances must not be the same. Instead each distance should be adapted to the pitch of the adherent screw portion. Within the scope of the present invention it is also possible that the collar has a lower cylindrical portion and an upper frusto-conical portion. Thereby, the upper side of the collar has a smaller or wider diameter than the lower side of the collar. By this design of the collar the implant and the abutment could have different diameters.

Claims

1. Dental implant retaining screw comprising a left threaded screw portion (1) and a right threaded screw portion (2) , said screw portions (1, 2) defining a common axial direction (C-C), c h a r a c t e r i s e d in that the screw portions (1, 2) are mutually connected by means of a collar (3; 103) having an extension perpendicular to the axial direction (C-C) .

2. Dental implant retaining screw according to claim 1, c h a r a c t e r i s e d in that the collar (3; 103) is equipped with means (4; 104) to facilitate the rotation of the collar (3/ 103) around the axial direction (C-C) .

3. Dental implant retaining screw according to claim 2, c h a r a c t e r i s e d in that the collar (3) is equipped with radial holes (4) .

4. Dental implant retaining screw according to claim 2, c h a r a c t e r i s e d in that the collar (103) is equipped with external facets (104) .

5. Dental implant retaining screw according to any of the previous claims, c h a r a c t e r i s e d in that the collar is partly frusto-conical.

6. Dental implant retaining screw according to any of the previous claims, c h a r a c t e r i s e d in that the collar

(3) is equipped with means (14, 15) to establish a locking relative to the implant (10) .

7. Method for mounting an abutment (8; 108) on an implant (10) by means of a dental implant retaining screw, said implant

(10) having a first internally threaded hole (20) , said abutment (8) having a second internally threaded hole (21), the dental implant retaining screw comprising a left threaded screw portion (1) and a right threaded screw portion (2), said screw portions (1, 2) defining a common axial direction (C-C) and being mutually connected by means of a collar (3; 103) having an extension perpendicular to the axial direction (C-C) , c h a r a c t e r i s e d in that one screw portion (2) is screwed into the implant (10) until a first small distance (11) remains between the implant (10) and the collar (3; 103), that the abutment (8; 108) is screwed on the other screw portion (1) until a second small distance (11) remains between the abutment (8; 108) and the collar (3; 103), that the dental implant retaining screw is rotated, while the abutment (8; 108) is prevented to rotate, until the collar (3; 103) is in contact with the implant (10) and the abutment (8; 108) .

8. Method according to claim 7, c h a r a c t e r i s e d in that said first and second small distances (11) are given the same value.

9. Method according to claim 7 or 8, c h a r a c t e r i s e d in that rotation of the dental implant retaining screw is effected via rotation of the collar (3; 103) .

10. Method according to any of the claims 7-9, c h a r a c t e r i s e d in that when the collar (3; 103) is in contact with both the implant (10) and the abutment (8; 108) the collar (3; 103) is fixed both relative to the abutment (8; 108) and to the implant (10) .