DE102005062431B3 - Tooth replacement part e.g. abutment, has recess for inserting screw head, and another recess having bearing surface that is arranged in coaxial manner in relation to central axis of recesses and has normal vector with directional component - Google Patents

Abstract

The part has a recess (4) for inserting a screw head (7) and another recess (5) for allowing passage of a shank (10). The recess (5) has a bearing surface (8) for the screw head, where the bearing surface is arranged in a coaxial manner in relation to a central axis (6) of the two recesses. The bearing surface has a normal vector with a directional component that is perpendicular to the central axis of the recess (5), where an acute angle is provided between the central axis and the bearing surface. An independent claim is also included for a system comprising a tooth replacement part.

Description

technical area

The The invention relates to a dental prosthesis part, which by means of a screw attachable to an implant comprising a first recess for insertion a screw head, a second recess for performing a Screw shank, wherein the second recess is opposite to the first recess has reduced diameter and continue comprising a coaxially arranged to a central axis of the recesses contact surface for the Screw head. The purpose of the invention is a tooth replacement part to be fixed with exact positioning by means of a screw on an implant, wherein the dental prosthesis part of the smallest possible Tensile load is suspended.

was standing of the technique

On An implant fixable dental prostheses are often made Ceramic materials, usually with metallic materials in order Combined with an implant. Ceramic materials have a low resistance to breakage, but have relative to the metallic materials such as titanium a very high hardness. Dental prostheses, In particular, abutments are therefore at the junction with the Implant with an inner part made of titanium or with a titanium core provided that absorb the load when screwing much better and into the implant.

adversely are by a complex production of the inner part of titanium resulting manufacturing and material costs.

Another Disadvantage is that a ceramic high strength can be selected must be in order to secure connection of the abutment with the implant to ensure. This will change the sanding and machining process of the abutment time-consuming.

Either WO 03/088868 A2 and WO 2004/080328 A1 describe tooth replacement parts which be fastened by means of a screw. The screws or screw heads point while contact surfaces on, which are formed at right angles with respect to the central axis. The respective contact surface of the Dental prosthesis is also perpendicular to the corresponding central axis aligned. Only the prior art described contact surfaces between the abutment and the implant are frusto-conical, wherein the corresponding angle between the contact surface thus formed and the central axis is an obtuse angle.

The The object of the invention is to form a dental prosthesis part in such a way and arrange that optimal connection to a dental implant taking advantage of the existing strength of the ceramic Material manufactured dental prosthesis is guaranteed.

presentation the invention

According to the invention a tooth replacement part, which by means of a screw on an implant is fastened, a first recess for insertion of a screw head and a second recess for passing a screw shank. The second recess has a reduced relative to the first recess Diameter up. The dental prosthesis part further comprises a coaxial arranged to a central axis of the recesses contact surface for the screw head, wherein the screw head facing contact surface with a normal vector a direction component perpendicular to the central axis of the second Recess and pointing away from this center axis pointing.

This ensures that the generated by the screw or the screw head contact force F on the contact surface of the dental prosthesis next to the directional component F _y in the direction of the central axis of the second excavation additionally has a directional component F _x in a direction perpendicular to the central axis and the central axis out. Thus, the clamping force acting on the tooth replacement part via the screw primarily generates pressure forces within the tooth replacement part, so that the occurrence of tensile stresses or cracks is prevented. The compressive strengths of ceramics are significantly higher than the tensile strengths, so that can be used by taking advantage of the direction of the invention of force introduction ceramics with lower strength. The tolerance range of the ceramic with respect to the acting screw force is thus increased.

The Inventive contact surface of the dental prosthesis as well as the corresponding contact surface the screw can be curved or as a special case also conical be designed.

Advantageously, the contact surface of the dental prosthesis part is rotationally symmetrical and the mantle curve of this contact surface is straight. The mantle curve is a sectional curve that generates the respective contact surface when rotating about the central axis. The contact surface with a straight mantle curve and a normal vector with a directional component to the central axis thus corresponds to a lateral surface of a truncated cone. The normal vector thus points in the same direction at every point of the contact surface. The directional component F _{x of} the contact force F is thus the same at every point of the contact surface. As a result, the contact force F acts evenly on the ge velvet contact surface and excessive pressure areas, which can lead to the formation of cracks in the dental prosthesis, are thus avoided.

Advantageous It is also this, that the first recess through a first inner wall of the dental prosthesis part is limited, wherein a transition surface between the first inner wall and the contact surface has a radius R1 and that the radius R1 between 0.1 mm and 0.3 mm, in particular 0.15 mm in size. Due to the inventive design the transition area Notches or cracking stresses within this highly loaded area of the dental prosthesis part avoided. Deviating from a radius corresponding Size are too other concave shapes, in particular elliptical shapes provided. In addition, in the area of the transition area first free space provided, the contact surface on the part of the invention limited and thus an additional attachment prevents the screw head in the transition area.

Further It is advantageous that the contact surface of the dental prosthesis with the center axis of the second recess an angle β between 50 ° and 89 °, in particular between 60 ° and 70 °, includes. Of the Angle β is an acute angle, so that generated compressive stresses according to the invention become. Depending on the ceramic used, the angles in the above Value range to choose so that the necessary screw force is introduced into the tooth replacement part becomes. In an embodiment of the contact surface with an arcuate envelope curve An effective angle can be assumed, in difference to the cone-shaped Forming the effectively resulting vector F of the system force describes.

advantageously, is the second recess through a second inner wall of the dental prosthesis limited, with a straight transition surface between the second inner wall and the contact surface is provided, the plan and is oriented at right angles to the central axis. The straight transition surface of the Tooth replacement part has, for example, against a sharp transition without a transitional surface Advantage that cracking stresses within the ceramic material avoided in the transition area become.

advantageously, is the second recess through a second inner wall of the dental prosthesis limited, with a curved transition surface between the second inner wall and the contact surface of the dental prosthesis provided is that has a radius. The curvature of the transition surfaces can also be another concave shape, for example, an elliptical shape have. A curved transition surface of the Dental prosthesis has the advantage that notches or cracking stresses prevented in the transition area become.

advantageously, is between the contact surface the screw and the screw shank provided a straight transition surface, which is aligned flat and at right angles to the central axis. This transition surface can also curved be and, for example, have a radius. The contact between the screw and the dental prosthesis exists only in the area of the two Contact surfaces. In different training of the transition surfaces of the dental prosthesis part and the screw prevents contact in the area of the transition surfaces. This is for example the case when the transition area of the Screw curved and the dental prosthesis part is made flat. This is in the Area of the transitional areas Free space provided, the contact surface on the part of the invention limited, so an extra Installation of the screw head in the transition area is prevented. While dressing The screw is exerted an investment force which leads to an elastic Deformation of the tooth replacement part and the screw leads, wherein the contact surface the screw slightly along the contact surface of the dental prosthesis part is moved. The two contact surfaces are under the effect of the contact force pressed together. In the absence of space in the area of the transition area it would be at the slight ones Displacement by tightening the screw to a point-like power transmission in the area of the transition area and thus to an excessive pressure range come. The intended clearance thus has the purpose of a uniform distribution the investment force over the entire contact area between the two contact surfaces provide and thus excessive pressure ranges, which lead to cracking can, to prevent.

Besides that is It is advantageous that a connection surface is provided, the against the implant can be applied, wherein the connection surface a Coating of gold or titanium and the coating between 1 μm and 20 μm thick is. The evaporation of the connection surface will damage the Implant through the harder Ceramic of the tooth replacement part prevented. In addition, the relatively offers soft coating compensates for existing manufacturing tolerances of implant and dental prosthesis.

It is advantageous that the connection surface is already provided in the blank stage of the dental prosthesis part and is designed as a reference surface which has a known relative position to the implant connection. An already prefabricated connection surface reduces the individual machining time as well as the accuracy requirement for the grinding machine. In addition to the prefabrication of the connection surface, it is also provided, the off For the screw and the contact surface for the screw, including the transitional surfaces, prefabricate already in the blank, so that it only has to be machined with respect to the contact surface for a tooth crown. For the grinding process, it is important that the position of the prefabricated dental prosthesis part can be determined in the grinding machine. For this purpose, the connection surface is designed as reference surfaces, which has a known relative position to the implant connection.

Advantageous is the dental prosthesis part of a pad having the core and a sheath formed, with the core of harder or stronger ceramic is formed than the coat. The high-strength Kern takes on the necessary clamping forces, the coat or the material of the shell much faster and easier to work is.

advantageously, is the core of zirconia and the sheath of feldspar ceramic or Leucite ceramics made. These are certified materials from dentistry and fulfill the requirements for the dental prosthesis part according to the invention.

Ultimately it is advantageous that the core and the mantle are connected, wherein the bonding agent is glue or glass solder. These connecting materials are also tested Materials from dentistry and are particularly advantageous Way to connect ceramics together.

Is solved the object by a system consisting of a tooth replacement part described above, wherein a screw is provided which has a screw head with a contact surface which is against the contact surface of the dental prosthesis part can be applied, wherein the contact surface of the Screw at least in the attached state corresponding to the contact surface of the Dental prosthesis part is formed.

For this It may be beneficial that the contact surface of the screw with the central axis an angle α between 91 ° and 130 °, in particular between 110 ° and 120 °, includes. The both angles α and β while additional angle to the total angle of 180 °.

Short description the drawings

The inventive method will be explained with reference to the drawing. Show it:

1 A schematic diagram in section with dental prosthesis and implant;

2 a sectional view according to 1 with a dental prosthesis consisting of a core and a sheath;

3a a sectional view of a dental prosthesis with convex contact surface;

3b a sectional view of a dental prosthesis with concave contact surface;

embodiment

An in 1 illustrated tooth replacement part 1 represents a so-called abutment on which a crown is placed. The ceramic abutment 1 is usually about a screw 2 with an implant in the jaw 3 connected. This is indicated by the abutment 1 a first and a second recess 4 . 5 on, which together with respect to the diameter two-stage through hole of the abutment 1 for the screw 2 form. The recesses 4 . 5 are substantially cylindrical and coaxial with a central axis 6 of the abutment 1 arranged.

For the purpose of installation of the screw 2 or her screw head 7 has both the abutment 1 as well as the screw 2 one with respect to the central axis 6 preferably conical bearing surface 8th respectively. 9 on. The contact surfaces 8th . 9 or the screw seat are designed such that the abutment 1 from the screw head 7 is taken from the outside, so that a particularly favorable pressure distribution within the loaded area of the abutment 1 arises, which is a rupturing of the abutment 1 by tightening or fastening the screw 2 prevented.

Both the contact surface 8th of the dental prosthesis or abutment 1 as well as the contact surface 9 the screw 2 close with the central axis 6 the same angle acute angle β or the obtuse supplementary angle angle α = 180 - β. The through the screw 2 or the screw head 7 Generated contact force F points according to 3a and 3b in addition to the directional component F _y in the direction of the central axis 6 In addition, a directional component F _x in a direction perpendicular to the central axis 6 and away from it.

The first recess 4 is through a cylindrical first inner wall 11 limited, to which the frustoconical contact surface 8th followed. In the transition area between the first inner wall 11 and the contact surface 8th is a transition surface designed as a radius R1 12 intended. The radius R1 is about 0.15 mm.

Next to it is in the area of the transition area 12 a free space 13 provided that the contact surface 8th . 9 limited to the part of the invention and thus an additional investment of the screw head 7 in the area of the transition area 12 prevented.

Between the contact surface 8th and one the second recess 5 limiting second inner wall 14 is also a rounded off transition area 15 with a radius R3, which may be about 0.15 mm, provided. For the purpose of limiting the contact surface 8th . 9 is a free space in this area 16 provided, the additional investment of the screw head 7 in the region of the transition surface 15 prevented.

Alternatively, this transition surface 15 according to the embodiment according to 2 also be designed plan, so that these the frustoconical contact surface 8th limited to the top. The transition area 15 is in this embodiment perpendicular to the central axis 6 aligned.

The screw head 7 the screw 2 is thus over its contact surface 9 against the contact surface 8th of the abutment 1 Anleg- or prestressed in the axial direction. For this purpose, a screw shaft engages 10 the screw 2 via a thread not shown in a thread on the blind hole 17 of the implant 3 ,

The abutment 1 has at its lower end face a connection surface 18 on, in the axial direction against a corresponding pad 19 of the implant 3 can be applied. The connection surface 18 also has a coating 20 made of gold or titanium.

The screw head 7 points between its contact surface 9 and his screw shaft 10 also a transitional area 21 with a radius R2. The radius R2 is about 0.15 mm.

According to the embodiment according to 2 is the abutment 1 from a core 5 and a coat 6 educated. The core 5 is formed of a high-strength material such as zirconia, whereas the mantle 6 is formed from a less solid, better machinable or grindable material such as feldspar ceramic or Leuzitkeramik. The core 5 and the coat 6 are connected via a glass solder or an adhesive. The area of the contact surface 8th including the transition area 12 with the radius R1 and the connection surface 18 with the coating 20 are part of the core 5 , so that the desired connection forces to the implant, not shown here 3 can be generated. The transition area 15 of the tooth replacement part 1 between the contact surface 8th and the second inner wall 14 as well as the transition area 21 between the contact surface 9 and the screw shaft 10 are flat and perpendicular to the central axis 6 educated.

The connection surface 18 has two diameter steps. The connection surface 18 has both in the region of the two diameter steps as well as in the area of the resulting end faces 32 to 34 the coating 20 on.

According to the embodiment 3a and 3b are the contact surfaces 8th of the abutment and the contact surfaces, not shown 9 the screw 2 formed with arcuate envelope curves. In 3a is a contact surface 8th of the abutment with a convex mantle curve and in 3b a contact surface 8th of the abutment with a concave mantle curve. This results in a force resulting from a plurality of vectors different angle, which can be described in summary using the effective contact force F. The contact force F also points next to the directional component F _y in the direction of the central axis 6 In addition, a directional component F _x in a direction perpendicular to the central axis 6 and towards this.

1

Dental prosthesis, abutment

2

screw

3

implant

4

first recess

5

second recess

6

central axis

7

screw head

8th

contact surface

9

contact surface

10

screw shaft

11

first inner wall

12

Transition surface, radius R1

13

first free space

14

second inner wall

15

Transition surface

16

second free space

17

blind

18

Connection surface on the tooth replacement part

19

Connection surface on the implant

20

coating

21

Transition surface, radius R2

30

core

31

coat

32 '

Forehead patch

33

Forehead patch

34

Forehead patch

B1

width

B2

width

D1

diameter

D2

diameter

R1

radius

R2

radius

F

Contact force, effectively

F _x

Force component in x-direction, perpendicular to the central axis 4

F _y

Force component in the Y direction, parallel to the central axis 4

α

angle

β

angle

Claims (18)

Tooth replacement part ( 1 ), which by means of a screw ( 2 ) on an implant ( 3 ) is fastened, comprising a first recess ( 4 ) for inserting a screw head ( 7 ), a second recess ( 5 ) for performing a screw shaft ( 10 ), wherein the second recess ( 5 ) one opposite the first recess ( 4 ) having a reduced diameter and further comprising a coaxial with a central axis ( 6 ) of the recesses ( 4 . 5 ) arranged contact surface ( 8th ) for the screw head ( 7 ), characterized in that the screw head ( 7 ) facing contact surface ( 8th ) a normal vector with a directional component perpendicular to the central axis ( 6 ) of the second recess ( 5 ) and from the central axis ( 6 ) pointing away, wherein the contact surface ( 8th ) of the tooth replacement part ( 1 ) with the central axis ( 6 ) of the second recess ( 5 ) includes an acute angle β. Tooth replacement part ( 1 ) according to claim 1, characterized in that the contact surface ( 8th ) of the tooth replacement part ( 1 ) rotationally symmetrical and that preferably the mantle curve of this contact surface is straight. Tooth replacement part ( 1 ) according to one of claims 1 or 2, characterized in that the first recess ( 4 ) through a first inner wall ( 11 ) of the tooth replacement part ( 1 ), wherein a transition surface ( 12 ) between the first inner wall ( 11 ) and the contact surface ( 8th ) has a radius R1. Tooth replacement part ( 1 ) according to one of claims 1 to 3, characterized in that the radius R1 between 0.1 mm and 0.3 mm, in particular 0.15 mm is large. Tooth replacement part ( 1 ) according to one of claims 1 to 4, characterized in that the contact surface ( 8th ) of the tooth replacement part ( 1 ) with the central axis ( 6 ) of the second recess ( 5 ) includes an angle β between 50 ° and 89 °, in particular between 60 ° and 70 °. Tooth replacement part ( 1 ) according to one of claims 1 to 5, characterized in that the second recess ( 5 ) by a second inner wall ( 14 ) of the tooth replacement part ( 1 ) is limited, with a straight transition surface ( 15 ) between the second inner wall ( 14 ) and the contact surface ( 8th ) is provided, the plan and at right angles to the central axis ( 6 ) is aligned. Tooth replacement part ( 1 ) according to one of claims 1 to 6, characterized in that the second recess ( 5 ) by a second inner wall ( 14 ) of the tooth replacement part ( 1 ), wherein a curved transition surface ( 15 ) between the second inner wall ( 14 ) and the contact surface ( 8th ) is provided, which has a radius R3. Tooth replacement part ( 1 ) according to one of claims 1 to 7, characterized in that between the contact surface ( 9 ) and the screw shaft ( 10 ) a straight transition surface ( 21 ) is provided, the plan and at right angles to the central axis ( 6 ) is aligned. Tooth replacement part ( 1 ) according to one of claims 1 to 8, characterized in that between the contact surface ( 9 ) and the screw shaft ( 10 ) a curved transition surface ( 21 ) is provided which has a radius R2. Tooth replacement part ( 1 ) according to one of claims 1 to 9, characterized in that a connection surface ( 18 ) is provided, which against the implant ( 3 ) can be applied, wherein the connection surface ( 18 ) a coating ( 20 ) made of gold or titanium. Tooth replacement part ( 1 ) according to one of claims 1 to 10, characterized in that the coating ( 20 ) is between 1 μm and 20 μm thick. Tooth replacement part ( 1 ) according to one of claims 1 to 11, characterized in that the connection surface ( 18 ) already in the blank stage of the tooth replacement part ( 1 ) is provided. Tooth replacement part ( 1 ) according to one of claims 1 to 12, characterized in that the connection surface ( 18 ) is designed as a reference surface, which has a known relative position to the implant connection. Tooth replacement part ( 1 ) according to one of claims 1 to 13, characterized in that the tooth replacement part ( 1 ) from a the pad ( 18 ) core ( 30 ) and a coat ( 31 ), the core ( 30 ) is formed of harder or stronger ceramic than the shell ( 31 ). Tooth replacement part ( 1 ) according to one of claims 1 to 14, characterized in that the core ( 30 ) of zirconium oxide and the sheath ( 31 ) is made of feldspar ceramic or leucite ceramics. Tooth replacement part ( 1 ) according to one of claims 1 to 15, characterized in that the core ( 30 ) and the coat ( 31 ), wherein the connecting means is glue or glass solder. System consisting of a tooth replacement part ( 1 ) according to one of the preceding claims, characterized in that a screw ( 2 ) is provided which a screw head ( 7 ) with a contact surface ( 9 ), which against the contact surface ( 8th ) of the tooth replacement part ( 1 ) can be applied, wherein the contact surface ( 9 ) of the screw ( 2 ) at least in the attached state corresponding to the contact surface ( 8th ) of the tooth replacement part ( 1 ) is trained. System according to claim 17, characterized in that the contact surface ( 9 ) of the screw ( 2 ) with the central axis ( 6 ) includes an angle α between 91 ° and 130 °, in particular between 110 ° and 120 °.