FR2788215A1 - Screw implant with anchoring thread for use in facial surgery or dentistry has thread divided into sections by notches in spiral line - Google Patents

Abstract

The screw implant consists of a head (12), a collar (14) and a threaded body (10) designed to be inserted at least partially into a bone and held in place by osteo-integration. The thread is divided into sections by a series of notches (32), the depth of each notch being no more than the height of the thread, and the combined length of all the notches between 20 and 50 per cent, and preferably 30 per cent, of the length of the thread. The number of notches is between one and eight and is preferably four for each turn of the thread, positioned so they are in a spiral line (H).

Description

The present invention relates to an implant with endosseous anchoring,

  of the type comprising a body of revolution intended to be received at least by

  tial in the bone and to be retained there by osseointegration, which body is

  provided, over part of its length, with a thread defined by a helical thread

  dal. It is known to use such implants in reconstructive surgery, in ENT

  and in dental implantology. In dentistry, we know implants intra-

  of this type adapted to receive a dental prosthesis. These implants have a length of between 7 and 20 mm. It is commonly 10 to 15 mm for a diameter usually 3.75 mm but up to 4, 5 or even 6 mm. The bone volume of the jaws allows placement

  implants of such lengths, which allows primary stabilization

  satisfying. In maxillofacial and ENT repair surgery, endosseous anchoring implants, of the extraoral type, have a maximum length of 3 to 5 mm, due to the thin thickness of the bone walls.

  in which they are located. Their restraint is therefore more delicate.

  The retention of the implant in the bone is obtained, on the one hand, by a sta-

  primary bility resulting from the mechanical maintenance operated by the threading and, on the other hand, by a secondary stability resulting from the osteointé-gration. The

  osseointegration phenomenon consists of a proliferation of bone cells

  thresholds in intimate contact with the implant surface without interposition of tissue

scar fibrous.

  In order to improve the retention of endosseous anchoring implants, it is known to seek to increase the contact surface between the implant and the

  bone cells by defining an adapted surface finish on the implant.

  In particular, some known implants have a pre-

  feeling a large number of micro-crevices, allowing an increase

  tation of the apparent surface of the implant. This particular surface condition is obtained, after suitable machining, by a chemical attack, known in dentistry, under the name of "etching" or by a mechanical treatment consisting of bombardment of the implant with microbeads of sand

or titanium oxide.

  These surface treatments, although they can significantly increase

  ficatively the bone-implant contact surface, may, despite cleaning, contaminate this surface due to the incrustation of material residues

  used for processing. In addition, this increase in the surface area

  annuity, especially in the case of a short implant, is not always

  sufficient to ensure satisfactory fixation of the implant in the bone.

  The object of the invention is to propose an implant with endosseous anchoring making it possible to ensure, after osseointegration, a reliable and lasting connection.

  between the implant and the bone in which it is implanted.

  To this end, the invention relates to an implant with endosseous anchoring, of the aforementioned type, characterized in that the thread comprises, over most of its length, successive notches delimiting disjoint sections of the thread.

  According to particular embodiments, the implant with anchoring in

  do-osseous comprises one or more of the following characteristics: - the depth of the notches is less than the height of the net and is advantageously substantially equal to the height of the net; - The ratio of the total length of the notches to the total length of the thread is between 20 and 50% and is advantageously substantially equal to 30%;

  - the net has between one and eight notches per turn and is advantageous-

four notches per turn;

  - the notches are distributed along at least one helix defined above -

  tubular body tour; - the winding direction of the or each propeller on which are

  distributed the notches and the winding direction of the helical thread are op-

  posed; - The notches are distributed along at least one generator of the body of revolution;

  - the sides of the sections of the net delimiting the notches are beveled-

  tees relative to the axis of the thread, according to the thickness of the thread; and

  - It has a peripheral flange extending the tubular body

  laire, which flange defines a bearing surface on the following bone wall

  in front of the entrance to the implantation site, and said flange is multiple

  nie of notches formed along the entire thickness of the collar and opening

  edge at its periphery, which notches are delimited by flanks whose front flank, considering the direction of screwing of the implant defined by the thread, is bevelled relative to the axis of the thread according to the thickness of the

  flange and defines, with the bearing surface, an acute angle.

  The invention will be better understood on reading the description which will

  follow, given only as an example and made with reference to the

  sins, in which: - Figure 1 is an elevational view of a bone anchored implant according to the invention; - Figure 2 is a top view of the implant of Figure 1; and

  - Figure 3 is a cross-sectional view of the screw taken

before line 111-111.

  The implant represented in FIGS. 1 to 3 is essentially intended for extra-oral implantations within the framework of maxillofacial surgery, restorative surgery or ENT. It has the general shape of a screw

of axis X-X.

  It comprises a body of revolution 10 intended to be received in the bone, at one end of which is formed a head 12 provided with a profile

  drive. The head 12 is separated from the body 10 by a perimeter collar

  spherical 14 defining a plane bearing surface 16 on the surface of the bone.

  The length of the body 10 measured along the axis X-X is between 3 and 5 mm.

  The implant is pierced axially with a tapped blind hole 18 extending

  axially and opening at the center of the head 12. This last pre-

  externally feels a hexagon drive 20.

  - The body 10 has, at its end opposite the head 12, an ex-

  frustoconical end 22 whose opening angle is obtuse. Over its length, the body 10 has, from the end 22, a second frustoconical section 24 followed by a threaded section 26, which is connected by a transition region

cylindrical 28 with collar 14.

  The frusto-conical section 24 is of progressively decreasing section

health towards the extremity of the body.

  The threaded section 26 has a thread of axis X-X defined by a thread

  helical 30 with preferably triangular and symmetrical profile.

  According to the invention, the net 30 comprises, over most of its length, successive notches 32 delimiting disjoint sections of the net. The notches 32 are identical and equidistant over the entire length of the net 30. The depth of the notches 32 is less than the height of the net 30,

  so that the notches 32 do not penetrate inside the cylinder core.

  body. Advantageously, the depth of the notches 32 is felt

  substantially equal to the height of the net 30.

  The length of the notches can vary from a fraction of a millimeter to

  several millimeters. Preferably, it is 2 mm.

  Advantageously, the net 30 has from 1 to 8 notches per revolution and

  preferably four notches per turn.

  Thus, the ratio of the total length of the notches 32 to the length

  total of the net 30 is between 20 and 50% and is preferably sensitive-

ment equal to 30%.

  The notches 32 are distributed along helices defined around the tubular body. One of the propellers is shown schematically by the dashed line H on the

figure 1.

  The propellers H on which the notches 32 are distributed have a winding direction preferentially opposite to the winding direction of the

helical thread 30.

  In addition, the flanks denoted 32A, 32B formed at the ends of the sections

  threads 30 are bevelled along the height of the screw relative to the axis X-X of the thread and extend along the direction of the propeller H defined by the

notches 32.

  As shown in FIG. 3, the intersection of the rear flank 32B of the notches, considering the direction F of screwing of the implant, with any plane transverse to the implant, extends radially to form if necessary

a self-tapping face.

  The flat bottom noted 32C of the notches has an irre-

  regular and coarse, while the surfaces of the net 30 have a state of

surface as smooth as possible.

  As a variant, the notches 32 are distributed along generatrices of the section 26 extending parallel to the axis X-X. The end 22, the second frustoconical section 24 and the first turns of the net 30 are cut by longitudinal notches 33 of section

  triangular facilitating the self-tapping of the bone by the implant itself. The children

  sizes 33 may however be missing.

  The flange 14, visible in Figure 2, has four notches 34 angularly distributed at its periphery. These notches extend over the entire thickness of the flange and open onto the periphery thereof. They

  have an axis offset angularly relative to the radius of the flange 14.

  In addition, the sides 34A, 34B bordering the notches are beveled relative to the axis X-X along the thickness of the flange. In particular, the front flank 34A, considering the direction F of screwing of the implant defined by the thread, delimits, with the bearing surface 16, an acute angle, thus defining a

  cutting edge 34C extending to the base of the corresponding flank 34A.

  It is understandable that with such an implant comprising frag-

  lying about the thread 30, when the implant is screwed into the recipient bone site, the friction between the surface of the thread and the previously tapped site is reduced compared to an unfragmented thread of the same profile, thus limiting

  thermal trauma resulting from screwing the implant.

  On the contrary, after bone healing, the bone cells form

  ment of the bony portions projecting into the notches 32, reducing

  the risks of unscrewing the implant.

  In addition, the notches 32 being distributed over propellers whose winding direction is opposite to that of the net 30, the bony columns in

  form of propellers which have developed through successive notches

  ves 32 have an inclination opposite to the resulting shear direction

unscrewing the implant.

  Finally, the notches 34, provided with the cutting edge 34C, maintained in contact with the bone surface, form corners and also oppose the unscrewing of the implant. In addition, it can be seen that the flange 14 is retained against a rotational movement by a bony outgrowth which develops by osseointegration through the notches 34 and covering at

  at least partially the base of the front flank 34A.

  For dental (intraoral) application, the principle of threading

  fragmented above is applied for screw-implants of all lengths.

  The only difference with the description above concerns the flange, ha-

  usually removed for implants larger than five millimeters.

  More generally, to improve the retention of implants with an endosseous anchoring, the notches formed in the net create on the surface of the implant macroscopic crevices which, once colonized by the

  bone cells, during osseointegration, give rise to so many small cla-

  bone vettes that there are crevices.

Claims (9)

  1.- Implant endosseous intra or extra-oral anchoring, of the type   carrying a body of revolution (10) intended to be received at least partially-   ment in the bone and to be retained there by osseointegration, which body (10) is provided, over part of its length, with a thread defined by a helical thread   (30), characterized in that the net (30) comprises, over most of its length   gueur, successive notches (32) delimiting disjoint sections of the net.   2.- Implant according to claim 1, characterized in that the depth-   the notch (32) is less than the height of the net (30) and is   suitably substantially equal to the height of the net (30).   3.- Implant according to claim 1 or 2, characterized in that the ratio of the total length of the notches (32) on the total length of the thread (30) is between 20 and 50% and is advantageously substantially equal to 30%.   4.- Implant according to any one of the preceding claims,   characterized in that the net (30) has between one and eight notches per   turn and advantageously four notches per turn.   5.- Implant according to any one of the preceding claims,   characterized in that the notches (32) are distributed along at least one   propeller (H) defined around the tubular body (10).   6.- Implant according to claim 5, characterized in that the winding direction of the or each propeller (H) on which are distributed the   notches (32) and the winding direction of the helical thread (30) are opposite.   7.- Implant according to any one of claims 1 to 4, character-   in that the notches (32) are distributed along at least one gener   ratrix of the body of revolution (10).   8.- Implant according to any one of the preceding claims,   characterized in that the sides (32A, 32B) of the sections of the net (30) delimit   mitant the notches (32) are beveled relative to the axis of the thread, before the thickness of the thread (30).   9.- Implant according to any one of the preceding claims,   characterized in that it comprises a peripheral flange (14) extending the tubular body (10), which flange (14) defines a bearing surface   (16) on the bone wall around the periphery of the entrance to the implantation site.   tion, and in that said flange (14) is provided with notches (34) formed along the entire thickness of the flange (14) and opening at its periphery, which notches (34) are delimited by flanks (34A, 34B) whose front flank (34A), considering the direction of screwing of the implant defined by the thread (30), is bevelled relative to the axis of the thread along the thickness   of the flange (14) and defines, with the bearing surface (16), an acute angle.