FR2600246A1 - REPLACEMENT DENTAL ROOT - Google Patents

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
The present invention relates to a non-biodegradable biocompatible 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 replacement 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 encased in the alveolus 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 the 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.

 I1 has already been proposed in French patent ne7918120 the use of corals as parts of diaphyseal prosthesis. The authors proposed corals whose porosity allowed penetration of osteons into the implanted material which after 3 to 4 months was the object of a bone invasion with formation of the Haversian system. The authors noted that it was enough for the pores to have a diameter of at least 30 microns for osteopenetration to take place.

 The present invention is characterized by the fact that it uses a calcium carbonate material of crystal structure, extremely hard, composing a coral of the Herpoli -ta - Sériatopora -Fongia - Pocillopora - Millepora and Octocoral type Coral type Johnson or Griy any other coral with the characteristics mentioned above, whose pores are less than 10 microns. Indeed, there is a chemotaxis around the artificial root or the alveolo-dental calcium carbonate substitution unit inducing a proliferation of osteons which cannot penetrate the implanted material achieve a real synostosis with it.The crystalline composition of the coral, essentially aragonite or calcite brings it closer to the bone, composed of calcium phosphate, which explains the biocompatibility of calcium carbonate .

 The replacement dental root can be in the form of a slightly cylindrical-shaped 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 post of variable diameter and length, the slightly cylindroconical external face of which has a helical projection over its entire height, realizing a Z structure opposing the tearing and realizing an immediate holding. 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 form of a dihedral allowing it a larger contact surface.

 The device according to the invention is carefully polished so as to present a perfectly smooth surface.

 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, sterilized in the cold, 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 been 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 palatal mucosa 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 in the shape of a parallelepiped with a volume equal to the loss of substance.

 Radiological examinations carried out at regular intervals have shown that in all cases at the end of 6 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 n ' had undergone no radiologically visible alteration.

 Experience has shown that when the size of the coral fragment was not made according to the shape of the device and that it was forcefully inserted into a cell, it underwent a push tending to expel it after 6 to 8 weeks as appropriate. 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 preferred form of the device according to the invention.

Indeed, this phenomenon does not occur when the device according to 1 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 structure in
Z allowing immediate holding of the artificial root and promoting osteogenesis, inking around the device opposing the vertical thrust.

 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.

 The radiological examinations showed a perfect integration of the material used without bone invasion of the graft.

Animal and human experimentation has shown:
1 ") The osteogenetic thrust at the level of the graft, due to the preferential shape of the device according to the invention does not cause its expulsion.

 20) 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.

 30) The low porosity of the material used gives it greater solidity and prevents the penetration of osteons thereby guaranteeing its integrity.

 40) The mechanical and physical properties of the type of coral used are maximum when it is soaked with a hypertonic solution of salt water or with physiological fluids and that, on the contrary, they are considerably reduced when the coral is used dry.

 These properties (elasticity, resistance to tensile compression, to shear and twisting 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 shows an overview of the device according to the invention.

 The device shown in FIG. 1 comprises a tap-shaped tenon having on its external face a helical Z projection (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 lower end in the form of a dihedron (4) - on two half of the external face are dug two symmetrical vertical grooves (5).

 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 parallelepiped element whose upper face is slightly convex (1) the lower face is slightly concave (2).

 I1 is pierced with two fixing holes (3). In its center is the insertion hole (4) of the replacement root of variable diameter.

Claims (15)

 1) Replacement dental root characterized in that it is made of calcium carbonate of natural origin.  2) Replacement dental root according to claim 1 characterized inC / equwelle has a very slightly porous structure.  3) Replacement dental root according to the preceding claims, characterized in that the pores are less than 10 microns.  4) Replacement dental root according to the preceding claims, characterized in that the material is Aragomite or calcite.  5) Replacement dental root according to the preceding claims characterized in that the material consists of very hard madreporal coral skeleton.  6) Replacement dental root according to the preceding claims, characterized in that the coral is Herpolita - Pocillopora - Fongia - Seriatopora - Millepora, white, pale pink, brown or black in color Corallium J.Greay.  7) Replacement dental root according to the preceding claims, characterized in that it is in the form of a slightly cylindroconical post of variable size and dimension having on its external face a helically coiled projection carrying out a Z-structure.  8) Replacement dental root according to the preceding claims, characterized in that it is hollowed out in the center of a vertical well.  9) Replacement dental root according to 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 the preceding claims characterized in that its upper end has a shoulder over its entire perimeter.  11) Replacement dental root according to the preceding claims, characterized in that its lower end is in the form of a dihedral.  12) Replacement dental root according to the preceding claims characterized in that it is also in the form of alveolo-radicular piece of parallelepiped shape.  13) Replacement dental root according to the preceding claims, characterized in that it is cold sterilized by gamma radiation or by trioxymethylene.  14) Replacement dental root according to the preceding claims, characterized in that it is stored in a sterile hypertonic saline 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.