WO1987007826A1

WO1987007826A1 - Replacement tooth root

Info

Publication number: WO1987007826A1
Application number: PCT/FR1987/000231
Authority: WO
Inventors: Serge Camprasse; Georges Camprasse
Original assignee: Serge Camprasse; Georges Camprasse
Priority date: 1986-06-23
Filing date: 1987-06-18
Publication date: 1987-12-30
Also published as: FR2600246B1; FR2600246A1; JPS63501959A; BR8707382A; DK90588D0; EP0271548A1; DK90588A

Abstract

Device intended to replace immediately or with a delay any natural tooth root as well as any loss of alveolo-radicular substance. It is embodied by a pivot made of calcium carbonate (aragonite-calcite) which is very hard, presents a very low porosity, has a slightly cylindroconical diameter and a variable length and has a well (2) drilled in its center of which the external face presents throughout its height a helical protuberance (1) forming a Z-shaped structure. Its upper extremity presents a shoulder (3) throughout its perimeter, its lower extremity has the configuration of a dihedron (4). Two vertical symmetric grooves (5) are dug on its external face up to half of its height. The device according to the invention is intended for the replacement of lost natural dental roots in odonto-stomatology.

Description

REPLACEMENT DENTAL ROOT

- 1 -

The present invention relates to a non-biodegradable biocompatib implant intended to replace as artificial root one or more teeth, either immediately after extraction, or in a delayed manner. The present invention also aims in its odonto-stomatological application, to serve as a substitute part for any loss of bone substance at the maxillary or mandibular level resulting from an alveolo-dental attack.

We know that the healthy tooth is embedded in the alveol to which it is attached by the alveolo-dental ligament.

The construction of the alveolar bone is linked to the existence and eruptive sequences of the teeth. During the extraction of one or more teeth there follows a lysis of the alveolar bone leading to a loss of substance at the site of the extraction.

It has already been proposed to replace missing or extracted teeth with the use of titanium implants, alumina ceramic or carbon carbon; on the other hand, to partially fill losses of alveolar substance, hydroxyapatite is used in various forms.

There are currently two imperatives in implantology: biocompatibility and resistance of the implant material.

To date, the implants used seem to have solved the problem of biocompatibility, the materials used seem to be more or less well tolerated by the bone; the mechanical resistance varying according to the material used.

It has already been proposed in French patent n ° 7918120 the use of corals as parts of a diaphysis prosthesis. The authors have proposed corals whose porosity allows osteon penetration into the implanted material which after 3 to 4 months was the object of a bone invasion with the formation of a Haversian system. The authors noted that it was sufficient for the pores to have a diameter of at least 30 microns for the osteopenetration to occur. The present invention is characterized in that it uses a calcium carbonate material with a structure crystalline, extremely hard, composing a coral of the Herpolit Sériatopora - Fongia - Pocillopora - Millepora and Octocorallial type Corallium Johnsoni Greay or any other coral having the characteristics mentioned above, whose pores are less than 10 microns. Indeed, there is a chemotaxis around the artificial root or the alveolo-dental substitution unit in calcium carbonate inducing a proliferation of osteons which can not penetrate the implanted material achieve with it a real synostosis. The crystal line composition of coral, essentially aragonite or calcite, close to bone, composed of calcium phosphate, which explains the biocompatibility of calcium carbonate.

The replacement dental root may be in the form of a slightly cylindroconical piece of very hard calcium carbonate with very low porosity, of variable size and diameter, approaching the roots of natural teeth.

According to a preferred embodiment and without this example being limiting, the device according to the invention is in the form of a stud of variable diameter and length, the slightly cylindroconical external face of which has a helical projection over its entire height, realizing a Z-shaped structure opposing the tearing and producing an immediate outfit. The edges of this projection are directed obliquely giving the general appearance of a tap. The external face of the device comprises, over half of its height, two symmetrical vertical notches intended to prevent, during bone filling, the rotation of the device according to the invention.

The device according to the invention is dug in the center of a cylindrical well. Its upper end has _a shoulder around its entire perimeter. Its lower end is machined in the shape of a dihedron allowing it a larger contact surface.

The device according to the invention may be in the form of a cylindrical post comprising over a part of its height a helical projection in the form of a Z and may not have a shoulder. The lower end over a height of 2 mm is smooth and has two symmetrical notches of variable depth intended to prevent rotation of the device according to the invention during bone filling. The following examples illustrate the invention without, however, limiting it. A choice of 12 laboratory animals (Beagles) was determined as well as 12 control animals.

Example 1 -

The device according to the invention, previously machined according to the preferential form mentioned above, treated with hypochlorite for 48 hours to rid it of all organic traces and debris, rinsed thoroughly with cold water, cold sterilized, is placed in an uninhabited cell after extraction. A mucosal suture is made isolating the artificial root from the oral environment.

Example 2 -

The device according to the invention, having machined and treated as above, is placed in a newly formed socket, a mucosal suture is made.

Example 3 -

The device according to the invention, treated as in Examples 1 and 2, is placed in the maxilla, in an uninhabited socket after extraction and also in a newly formed socket. The upper end emerging from 2 mm in the oral cavity Example 4 -

A fragment of the device according to the invention, treated as stated in the previous examples is placed under the muq-

»Palatal and in the vestibular region of two adult dogs.

Laboratory examinations (Calcemia - SV - Electrophoresis) carried out at regular intervals over a period of 3 months, are normal except for a slight increase in SV 48 hours after the intervention, which is mainly due to a normal transient bacteremia after any intervention in a septic environment.

Example 5 -

A laboratory animal after total alveolectomy received the device according to the invention cut into the shape of a parallelepiped with a volume equal to the loss of subtance.

Radiological examinations carried out at regular intervals have shown that in all cases after 16 weeks when the device according to the invention is produced in very hard coral with very low porosity (less than 10 microns), the coral fragments were intact and had not undergone any radiologically visible alteration. Experience has shown that when the size of the coral frag¬ ment was not made according to the shape of the device and that it was inserted in force into a cell, it underwent a push tending to expel it after 6 to 8 weeks depending on the case. This expulsion is explained by the fact that the osteogenetic forces at the bottom of the cavity were not counterbalanced by the retentive forces due to the preferential shape of the device according to the invention.

Indeed, this phenomenon does not occur when the device according to the invention is in the form of a slightly cylindroconical post having over its entire height and over its entire perimeter, a helical projection achieving a Z structure allowing immediate holding of the artificial root and promoting osteogenesis, inking around the device which opposes the vertical thrust.

The device according to the invention in another preferred embodiment can be in the form of alveolo-radicular parallelepiped units of 3 mm in thickness, of variable length ranging from 15 mm to 35 mm, with a width of 9 mm, the lower face of which has in its middle and over its entire length a dovetail of 4 mm at its base, and of 3 mm at its top and with a height of 3 mm. It is pierced with 1 or 2 orifices of variable diameter tapped with shapes and sizes allowing the insertion of the device according to the invention in its form of cylindrical post.

In humans, the device according to the invention has been tested in ten cases.

The device according to the invention was placed either immediately after extraction, or in newly formed cells. Example 1 -

5 subjects received the device according to the invention in newly formed cells. Biological and radiological examinations carried out at regular intervals showed on the one hand no alteration of the biological constants, on the other hand, a perfect integration of the device without absorption of the material used after 1 year.

Example 2 -

5 other subjects received the device according to the invention in uninhabited cells after extraction.

Radiological examinations showed perfect u ma uu nva ssemen bone u gre ¬ fon.

Example 3 -

The device according to the invention in its preferred form of alveolo-radicular unit has been tested in a dozen cases. After incision of the mucosa of the lower maxillary bone of a Beagle dog, a bony trench 4 mm wide and 3 mm deep over a length of 15 mm was made, as well as a newly formed threaded socket. The device according to the invention is inserted therein by its dovetail and held in place by any filling material, the mucosa being folded down, suturing is carried out.

The clinical and radiological examinations made it possible to verify a true fixation by its dovetail and by the artificial root.

Animal and human experimentation made it possible to see:

1) The osteogenetic push at the level of the graft, because of the preferential form of the device according to the invention does not cause its expulsion.

2) Whenever a graft has been removed or expelled, we note the presence of bone tissue on its surface proving the synostosis existing between the bone and the coral used on the one hand, and on the other hand, due to the speed of the repairing osteogenetic phenomenon, proof of osteoinduction caused by the very nature of the material used.

3 °) The low porosity of the material used gives it greater solidity and opposes the penetration of osteons thereby guaranteeing its integrity. 4 °) The mechanical and physical properties of the type of coral used are axima when it is soaked with a hypertonic solution of salt water or with physiological liquids and that, on the contrary, they are considerably reduced when the coral is used dry. These properties (elasticity, tensile strength under compression, shear and torsional forces) approximate those of natural dental root depending on the type of coral used.

The accompanying drawings illustrate the invention without, however, limiting it.

Figure 1.1 shows an overview of the device according to the invention.

The device shown in FIG. 1.1 includes a tap-shaped tenon having on its external face a helical Z-shaped sail¬ (1) a central well (2) intended to receive any pre-prosthetic suprastructure - an upper end with a shoulder (3) over its entire perimeter allowing the positioning of any pre-prosthetic suprastructure - a dihedral-shaped lower extremity (4) - two symmetrical vertical grooves (5) are hollowed out on the half . FIG. 2 represents an overall view of the device according to the invention in the form of an alveolo-radicular substitution element.

The device shown in Figure 2 consists of a parallelepipedic element (1) 15 mm long by 9 mm wide, 3 mm thick, the underside has a dovetail (2) over its entire length 3 mm thick and measures 4 mm at its base and 3 mm at its top. It is pierced with a threaded orifice (3) allowing the insertion of the artificial root.

Claims

- 7 -

1) Replacement dental root characterized in that it is made of calcium carbonate of natural origin.

2) Replacement dental root according to claim characterized in that it has a very slightly porous structure.

3) Replacement dental root according to any one of the preceding claims, characterized in that the pores are less than 10 microns.

4) Replacement dental root according to any one of the preceding claims, characterized in that the material is aragonite or calcite.

5) Replacement dental root according to any one of the preceding claims, characterized in that the material consists of very hard madreporal coral skeleton.

6) Replacement dental root according to any one of the preceding claims, characterized in that the coral is Herpolita - Pocillopora - Fongia - Seria-topora - Millepora, white, pale pink, brown or black in color , Corallium J. Greay.

7) Replacement dental root according to any one of the preceding claims, characterized in that it is in the form of a slightly cylindroconical post of variable size and dimension comprising on its external face a helical projection carrying out a structure in Z.

8) Replacement dental root according to any one of the preceding claims, characterized in that it is hollowed out in the center of a vertical well.

9) Replacement dental root according to any one of the preceding claims, characterized in that it is hollowed out on its external face with two symmetrical vertical notches over half of its height.

10) Replacement dental root according to any one of the preceding claims, characterized in that its ^~ upper end has a shoulder sur.tout its perimeter

11) Replacement dental root according to any one of the preceding claims, characterized in that its lower end is in the form of a dihedral. 12) Replacement dental root according to any one of the preceding claims, characterized in that it is also in the combined form of an alveolo-root piece of parallelepipedal shape pierced with 1 or 2 orifices allowing the insertion of '1 or 2 artificial roots.

13) Replacement dental root according to any one of the preceding claims, characterized in that it is cold sterilized by gamma radiation or trioxymethylene.

14) Replacement dental root according to any one of the preceding claims, characterized in that it is stored in a sterile hyper.tonic salt solution.

15) Replacement dental root according to claims 1 to 14, characterized in that it constitutes the replacement part for the loss of one or more natural dental roots or of the alveolar segment.