GB2252501A

GB2252501A - Root section for a dental implant

Info

Publication number: GB2252501A
Application number: GB9202366A
Authority: GB
Inventors: Philip Anthony Evans; Paul Harrison; John Fisher
Original assignee: Christopher John Watson
Current assignee: Christopher John Watson
Priority date: 1991-02-05
Filing date: 1992-02-04
Publication date: 1992-08-12
Anticipated expiration: 2012-02-04
Also published as: GB9202366D0; GB2252501B; GB9102429D0

Abstract

The root section comprises a proximal neck portion 18 having parallel-sided walls, an apex 28 of hemi-spherical or truncated conical form, and an intermediate portion 20 having a plurality of recesses 30 of predetermined form. The intermediate portion may be of tapered form and may include one or more anti-rotational slots. The root section may be composed of a bio compatible titanium based or fibre-reinforced polymer material and may have a thermally sprayed coating of hydroxy apatite. <IMAGE>

Description

DENTAL IMPLANTS This invention relates to dental implants and more particularly to root sections for dental implants.

The invention seeks to provide an improved form of root section for dental implants which will enhance the longer term stability of the implant by modifying the stress distribution within the alveolar bone structure, serving to maintain a healthy bone/implant interface, and which will simplify clinical procedures for the placement of implants.

According to the present invention there is provided a root section for dental implants comprising a proximal neck portion having parallel-sided walls, an apex of hemispherical or truncated conical form, and an intermediate portion having a plurality of recesses of predetermined form.

The intermediate portion will preferably be of tapered form, and may include one or more anti-rotational slots.

The root section will preferably be composed of a biocompatible titanium based or fibre reinforced polymer material, and the root section may be provided with a thermally sprayed coating of Hydroxy Apatite.

In order that the invention may be more readily understood, an embodiment thereof will now be described, by way of example, reference being made to the accompanying drawings, wherein: Figure 1 shows the component parts of a dental implant including a root section in accordance with the invention; Figure 2 is a longitudinal sectional elevation, to a larger scale, of the root section of Figure 1; Figure 3 is a plan view on Figure 2; and Figure 4 is an enlarged detail view of the encircled part of the root section shown in Figure 2.

Referring to the drawings, and firstly to Figure 1, the various component parts of a dental implant are referenced 2, 4, 6, 8, 10, 12, 14, and 16, where the component part 2 is the root section of the implant, and component parts 4 and 6 are protection members which are used temporarily and which are only in place relative to the root section 2 during the healing-in period to protect the internal bore of the root section 2. Component parts 8 and 10 represent the transmucosal components of a straight design and the component parts 12, 14, and 16 represent the transmucosal components of an angled design. The component parts 4 through 16 form no part of the inventive concept of the present invention and will therefore not be described in greater detail herein.

Referring now to Figures 2 and 3, which show the root section 2 of Figure 1 in greater detail, a proximal neck portion 18 of the root section is parallel-sided in order to reduce stress concentration in this area which is in contact with cortical bone. As will be seen, the root section 2 includes an intermediate portion 20 which is generally tapered, such taper resulting in the largest diameter at the proximal neck portion 18 so as to reduce stresses in this region. The proximal neck portion 18 has an external diameter D which is variable and which lies in the range 2mm to 6mm, and is cored as indicated by the reference numeral 22. The design or form of the core section is such that the transmucosal components 10 or 14 are fixed in position once located relative to the root section.The core may consist of an hexagonal portion 24 for location of the transmucosal components and a threaded portion 26 to secure said components or a bored hole to allow cementation of said components.

In order to promote uniform stress distribution and transfer of load in compression, the apex 28 of the root section 2 is of truncated conical form with an inclusion angle 8 of 1000 to 1500 and a flat w of length 0.5mm to 1.5mm. The diameter d at the base of the apex lies in the range 2.0mm to 3.0mm.

Instead of the apex 28 being of truncated conical form, it may be of hemi-spherical form having a radius of curvature lying in the range 0.5mm to 1.5mm.

The length Z of the root section 2 will lie in the range 8mm to 20mm, and located along the length of the root section, and between the proximal neck portion 18 and the apex 28, are a number of recesses 30. These recesses, which are provided for promotion of uniform stress distribution with transverse faces transmitting load in compression, will be variable in number, the number being dependent upon the length y of the root section 2. In a preferred embodiment of the invention, there will be two to fifteen such recesses.

One of the recesses 30 is shown in greater detail in Figure 4 and has the following characteristics: Angle W - 10 to 300 Angle X - 700 to 900 Angle Y - 0 to 600 Length a - O.2mm to 1.00mm Length Z - O.5mm to 5.00mm In order to prevent rotation following the healing-in period, the root section 2 incorporates an anti-rotational longitudinal slot 32 which will be machined into the recesses and which will have a depth lying in the range 0.lmm to 0.75mm. It will be appreciated that there may be more than one such anti-rotational slot.

All the component parts of the implant, including the root section 2, will be composed of a bio-compatible titanium based or fibre reinforced polymer material. A thermally sprayed coating of Hydroxy Apatite will be applied to root section 2; the properties of thermally sprayed Hydroxy Apatite are well documented, and serve to reduce the healing-in time period and also to promote a direct bond between the bone and the root section.

In the placement of dental implants utilising a root section in accordance with the invention, it is envisaged, due to the stepped tapered design, that the surgical placement kit will be relatively simple incorporating a water-irrigated pilot drill and a stepped tapered drill of appropriate dimensions. Staple gun introduction of the root section into an area where only the cortical bone has been removed may be a possibility in the case of a late implant. Of course, minimum preparation will be required in the case of immediate replacement following the extraction of a natural tooth. It is envisaged that clinical prognosis for implantation will consider the same indications currently identified.

The placement and use of root sections in accordance with the invention in dental implantation will be readily apparent to those skilled in the art, and therefore it is not thought necessary, within this specification, to describe their placement and use in greater detail.

Claims

CLAIMS:

1. A root section for a dental implant comprising a proximal neck portion having parallel-sided walls, an apex of hemi-spherical or truncated conical-form, and an intermediate portion having a plurality of recesses of predetermined form.

2. A root section in accordance with Claim 1, wherein said intermediate portion is of tapered form.

3. A root section in accordance with Claim 1 or Claim 2, wherein said root section is cored.

4. A root section in accordance with Claim 3, wherein the core comprises an hexagonal portion and a threaded portion, or a bore for cement.

5. A root section in accordance with any of Claims 1 to 4, wherein said truncated conical apex has an inclusion angle of 1000 to 1500, a flat of length 0.5mm to 1.5mm, and a base diameter lying in the range 2.0mm to 3.0mm.

6. A root section in accordance with any of Claims 1 to 4, wherein the hemi-spherical apex has a radius of curvature lying in the range 0.5mm to 1.5mm.

7. A root section in accordance with any of Claims 1 to 6, wherein the intermediate portion includes one or more anti-rotational slots.

8. A root section in accordance with any of the preceding Claims, wherein the root section is composed of a bio-compatible titanium based or fibre reinforced polymer material.

9. A root section in accordance with Claim 8, wherein the root section has a thermally sprayed coating of Hydroxy Apatite.

10. A root section for a dental implant substantially as herein described with reference to and as illustrated in the accompanying drawings.

11. A root section for a dental implant substantially as herein described.

12. A dental implant including a root section comprising a proximal neck portion having parallel-sided walls, an apex of hemi-spherical or truncated conical form, and an intermediate portion having a plurality of recesses of predetermined form.

13. A dental implant including a root section substantially as herein described with reference to and as illustrated in the accompanying drawings.

14. A dental implant including a root section substantially as herein described.