WO1993011717A1

WO1993011717A1 - Insert for endosseous implantation in odontology

Info

Publication number: WO1993011717A1
Application number: PCT/IT1992/000163
Authority: WO
Inventors: Renzo Zambello
Original assignee: Renzo Zambello
Priority date: 1991-12-16
Filing date: 1992-12-16
Publication date: 1993-06-24
Also published as: ITPS910019A1; AU3266093A; ITPS910019A0; IT1253519B

Abstract

An insert (1, 10), designed to be used in odontology, for endosseous implantation and subsequent anchorage of a prosthesis, performs a dynamic action, with a progressive compression of the osseous tissue on one side, to activate the osteoclasts, and the progressive depression on the other side, to activate the osteoblasts, so as to regenerate the osseous tissue in a more rapid and complete manner. In this way the waiting time before the application of the prosthesis is reduced and the anchorage more similar to the physiological one is obtained. The action of compression is obtained by means of expandable roots (3), adjustable by the implantation of the insert and during the successive check visits.

Description

INSERT FOR ENDOSSEOUS IMPLANTATION IN ODONTOLOGY.

TECHNICAL FIELD

The present invention concerns a particular insert, designed to be used in odotology.

More particularly the invention relater to an insert for endosseous implantation and for a successive anchorage of a dental prosthesis thereto.

BACKGROUND ART

To substitute missing teeth with permanent prostheses, in the past there have been used various types of implants, with screws, plates, nails, made of different materials.

The present prosthesis implants (implantations) are formed by two parts: a "foreign body", that is inserted completely in the bone, and a prosthesis, fixed to the foreign body.

At present, that "foreign body", no matter of its shape (flat, round, threaded or not, rough or smooth, with holes or without holes) externally appears as a single body that cannot be expanded. In fact, although it is constituted by several elements, in the part on contact with the bone, it takes a single fixed form, that cannot be changed.

What is inserted in the bone, remains always fixed, in the original position and with the original shape.

That body, of course biocompatible, is positioned by opening and dέcollement of the gingiva; a bigger or smaller strip of gingiva is moved according to the used method_*

In any case, with any type of "foreign body" inserted, with any insertion method being used and any therapy being applied after the operation, it is important that a sufficient bone recovery be awaited before the dental prosthesis is applied to the implantation, so that it well holds what has been embedded in it. The total time of bone recovery is about eighteen months, , but in the present state of knowledge _τ in order to be able to support the prothesis, a period of 6 months is sufficient, insofar as during such time the bone reaches an advanced phase of recovery. During this six-month time, some dentist covers the implantation by closing it under the strip of gingival mucosa (submerged implantation), others do not share such a solution that demands two operations on the gingiva. In any case the problem lies in avoiding as much as possible the danger of post-operation infection.

To have the implantation correctly working, without being rejected by the organism and without formation of granuloma by the foreign body, a situation called osseous integration between the foreign body and the bone must take place. When the recovery is completed, between the implantation and the bone there cannot be connective tissue (collagen fiber), but only a space C hat can vary between 200 and 400 Amstrongs) containing fundamental substance, based on proteoglycan. DISCLOSURE OF THE INVENTION

The object of the present invention is to obtain the best anchorage and therefore, an immediate stability of the insert, and to aid a rapid and complete regeneration of osseous tissue, thus reducing the waiting time before the permanent application of the prosthesis. The above object is obtained by an insert for endosseous implantation in odontology, that comprises an upper part, with a through threaded hole adapted for allowing the access for a tightening means and for subsequently applying a dental prosthesis thereto, and a lower part designed to be inserted in at least a recess located in the position where the insert must be placed.

The recess preferably has an annular shape so as to form a central osseous tissue protrusion therein; The lower part can be expanded by the operation of expanding means so as to push outwardly on the inside wall of the recess and to provoke a depression on the corresponding regions of the central protrusion. The subject insert performs a dynamic action, on one side with^'progressive tissue- compression such that it determines the activation of the osteoclasts, and on the other side with progressive depression, to activate the osteoblasts. This dynamic action is possible due to a particular insert used.

To understand the functioning of the proposed type of implantation and the relative performance, it is necessary to remind some characteristics of regeneration of the bone tissue exploited by the implan .

When forces are provided by e.g. elastic means or threads acting on the tooth are applied, after some months, the tooth will displace in the direction in which the force has acted.

The tooth presses (although with relatively modest intensity) the bone from the part on which the force acts, while from the other part a state of depression is created.

In the compressed part the osteoclasts, which are cells of bone reabsorption, are activated; in the other part (the depressed zone) the osteoblasts, i.e. the cells that reform the missing osseous tissue, are activated.

This biologic mechanism has been used in the new type of "dynamic" implantation that is now described. To this purpose the insert is furnished with expandable plates in form of roots, able to carry out the action of compression and depression of the osseous tissue.

The insert is set by the implantation and, if necessary, during the subsequent check visits. In this manner _r instead of waiting passively until the osseous tissue fills interstices, as in the single block implantation, the natural tendency of the bone, that is subjected to differentiated pressure in different regions, is stimulated. The bone actively reshapes itself following the direction of the pressure, producing osteoclasts in the side under the pressure and regenerating itself, due to the osteoblasts activation, in the opposit side.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is now described in a detailed way, with reference to the enclosed drawings, that illustrate, in the exemplifying way only, its possible embodiments.

The Figures 1 and 2 show two different perspective views of the insert, sectioned with a longitudinal intermediate plane. The Figure 3 shows a longitudinal section of the insert.

The Figures 4 and 5 show two different perspective views of the inside of the insert.

The Figures 6 and 7, show respectively a perspective sectioned view and a longitudinal section of a possible version of the insert.

BEST MODES OF CARRYING OUT THE INVENTION

The insert subject of the present invention, comprises two parts, namely an upper part 1 and a lower part 2, as indicated in the Figures.

The upper part 1 of the insert has a threaded through hole 2 , for subsequent application of the prosthesis thereto.

Reference numeral 3 indicates the roots of the insert that are constituted by the expandable plates, subdivided by slits 4.

The expansion of the roots is obtained, in the illustrated example, by screwing a dowel 9 in the threaded hole 5. The tip of the dowel, upon its rotation, provokes the expansion of the roots by pushing on the conical surface 6 inside the expandable plates.

To facilitate this expansion, the insert body can have a weakened section, e.g. with a smaller thickness, as shown in the figures, located in the middle part.

To procede with the implantation, at least one recess is made in the maxillary bone or in the mandible bone as it is needed; the recess has an annular shape, so that a a central osseous tissue protrusion remains formed therein.

After having positioned the insert in the recess, the expansion of the roots is obtained by screwing the dowel up to meet the resistance of the bone_.. The dowel can be actuated through the hole 2 made in the upper part, through which a tightening means, in form of a proper tool, is made to pass.

After the period of about twenty days, the patient will be examined and the position of the roots will be estimated radiologically. ^•

If it is found necessary, the roots can be expanded some more.

This procedure can be repeated more times, until the wanted position is reached and the sufficient recovery of the bone has occurred.

According to a second embodiment of the invention, shown in Figures 6 and 7, to expand the roots a mobile wedge shaped member 7 is slidingly located inside the section delimited by the said conical surface 6.

This member 7 can be moved upwards by means of a threaded rod 11 screwed in a threaded axial hole 8 made in the same member 7.

In both the embodiments of the implantation, the roots press (although with relatively modest intensity) the bone onto the internal surface of the recess while on the corresponding surface of the central protrusion a state of depression is created.

The biologic mechanism previously mentioned is thus started and the insert remains firmly fixed to the jawbone in very short time. For both the described embodiments, more than one recess can be made in the jawbone.

In this last case the plates 3, which form the roots, are further distant from each other while the slits are larger, so that each root is inserted in a respective recess.

Obviously, the constructive details, and the mechanism of the roots expansion in particular, could be different from those illustratively described, without getting out of the framework delimited by the present invention. INDUSTRIAL APPLICABILITY

With the described implantation, an immediate stability is obtained, due to the pression and depression exerted on the surfaces of the recess made in the jawbone and to the more effective anchorage thus obtained, distributed on more points, something like in the original tooth. Moreover, the resultant of the mechanical stresses that will act on the implant, will not discharge along only one axis, as in the monoblock implantation, but on more axes, and therefore the possible occluded damages (that mean a retraction first of the bone and then of the gingiva^', with substitution of the connectivum and consequent aesthetic damages, up to the loss of the function) will be limited.

Another important advantage results from the possibility of registering gradually and at more times the position of the roots, avoiding in this way the involvement of the mandibular nerve in particular, and maxillary sinus.

Also more rapid usability of the implant is achieved due to the stimulation of the bone regeneration, allowing for quicker prosthesis application.

Claims

1. Insert for endosseous implantation in odontology, comprising: an upper part (1) with a through threaded hole

(2) adapted for allowing the access for a tightening means and for subsequently applying a dental prosthesis thereto; a lower part (10) designed to be inserted in at least a recess located in the position where the insert must be placed, the said recess having preferably an annular shape so as to form a central osseous tissue protrusion therein; said insert being characterized in that said lower part (10) can be expanded by the operation of expanding means (5,6,7,8,9,11) so as to push outwardly on the inside wall of said recess and to provoke a depression on the corresponding regions of the said central protrusion.

2. Insert as in claim 1, characterized in that the said lower part (10) is subdivided by means of longitudinal slits (4) so as to form a plurality of plates (3) separated from each other and flexible outwardly under the action of the said expanding means (5,6,7,8,9,11).

3. Insert as in claim 2, characterized in that the said expanding means comprise: a threaded hole (5) made in said upper part, this threaded hole (5) being coaxial and adjacent to the said through hole (2); a conical surface (6) made coaxial and adjacent to the said threaded hole (5), said conical surface having the end with smaller diameter situated among the said expandable plates (3); a dowel (9) screwed into said threaded hole (5)_. so that it can be actuated through the said through hole (2) made in the said upper part (1), the said dowel (9) acting onto said conical surface (6) to progressively provoke the outward expansion of the said plates (3).

4. Insert as in claim 3, characterized in that a weakened section, adapted to make the expansion of said plates (3) easier, is formed between the said upper part (1) and the said lower part (10).

5. Insert as in claim 2, characterized in that the said expanding means include: a conical surface (6) made coaxial and adjacent to the said through hole (2), said conical surface having the end with larger diameter situated among the said expandable plates (3); a wedge shaped movable member (7), slidingly located inside the section delimited by the said conical surface (6), said wedge movable member (7) having a through axial threaded hole (8); a threaded rod (11) screwed into said axial threaded hole (8) made in said wedge movable member (7) and passing through the said through hole (2) made in the said upper part (1), the said threaded rod being adapted to provoke, upon its rotation, the upward movement of the said wedge movable member (7) and, cosequently the outward expansion of the said plates (3) .