FR2812537A1 - Dental instrument for removing prosthetic crown has oval tip exercising vertical force as it is rotated - Google Patents

Abstract

The instrument has an oval-section tip (D) connected by a shank to a handle. The tip is inserted into a slot (2) previously made between the prosthetic crown (4) and the upper surface of the natural or artificial stump (3) to which it is fitted. As the handle of the instrument is rotated the tip exerts forces against the facing surfaces of the stump and crown, lifting the crown from the stump. Variants use a tip which can be expanded by a change in temperature, or one which is operated automatically.

Description

<Desc / Clms Page number 1>
The present invention aims to provide an alternative or complementary solution to dentists and stomatologists to deposit unitary crowns, bridge supports and other sealed prostheses. Most of the existing solutions are either complex to implement, or expensive, in particular because they entail, on the one hand, the destruction of the crown (4), on the other hand, considerable wear of the cutters and the fatigue of rotary instruments. In addition, it is often an unpleasant or even painful operation for the patient.

It will be noted beforehand that: - If, in practice, a tooth is never vertical in the strict sense of the term, for reasons of clarity in our explanations, we will take as reference in terms of verticality, the vertical axis of the tooth (F) as shown in Figures 16, 17 and 18 - Figure 16 shows a section of the tooth along the sagittal plane while Figures 17 and 18 show a section of the tooth along the frontal plane.

 In the field of dental crown removal, one of the means was the instrument patented in 1982 under the name of Dental instrument intended for the removal of crowns and pivot teeth (Publication no .: 2,522,494 , National publication no .: 82 03435, filing date: 02. 03. 1982). This consisted mainly of a handle, and a rod whose front part was curved. This tool and the method used had the advantage of effecting a leverage between the stump (3) and the crown (4), sparing the gum, and allowing, when the operation was successful, to recover the crown ( 4). However, the shapes and dimensions of the instrument, and the method used, meant that the torque generated to obtain the lifting of the crown (4) was effected, on the one hand, on the occlusal surface of the stump (3 ), on the other hand, at the upper level of the notch (1) made in the face of the crown (4). However, if the support on the occlusal surface of the stump (3) was located in the vertical axis (F) of the tooth, the force produced on the wall of the crown (4) was, on the other hand, an offset movement relative to the vertical axis (F) of the tooth. This therefore resulted in the exercise of lateral effort which was detrimental to the tooth.

The present invention, on the other hand, makes it possible to obtain a couple of forces limiting or s up pni ni ant any lateral force, owing to the fact that the latter is carried out in an axis which is wholly or almost completely merged with the vertical axis ( F) of the tooth.

<Desc / Clms Page number 2>

 The present invention consists of an instrument comprising a notched intermediate part (C) and a working part (D). Inserted into a groove (2) previously made by the practitioner, the. working part (D) makes it possible to generate a couple of forces substantially in the vertical axis (F) of the tooth between the occlusal faces of the stump (3) on the one hand, and the underside of the crown (4) on the other hand, causing the removal of the crown (4). Until the crown (4) is loosened, the shapes and dimensions of the indented intermediate part (C) allow the latter not to obstruct the lifting of the notched side wall of the crown (4), and not to do not exert lateral forces on the crown (4).

The invention requires, in its mode of use, four operations common to all of its variants [see fig. 16, 17 and 18]: - The use of the instrument first requires the creation of a notch ( 1) crossing the thickness of the crown (4) on its most accessible face (in general, the vestibular face). This notch (1) must be of a width greater than or equal to the diameter of the indented intermediate part (C). This notch (1) must be created on a plane substantially parallel to the occlusal surface of the crown (4), at the supposed level of the occlusal part of the stump (3).

- In a second step, this notch (1) is extended using a cutter (of the cylindrical crack type) to create a groove (2) by carrying out a partial or total sweep of the surface of the stump (3). This groove (2) must have dimensions allowing the complete introduction of the working part (D).

- As a third step, it is necessary to slide the working part (D) of the instrument into the groove (2) thus created, until the notched intermediate part (C) coincides with the notch (1) of the crown (4).

- Finally, the crown lifting process (4) is activated, which can result from an expansion phenomenon, rotation of the working part (D) or any other process resulting in a couple of forces substantially in the axis of the tooth, between the occlusal faces of the stump (3), on the one hand, and the underside of the crown (4), on the other hand.

Thus, appropriate use of the instrument makes it possible to obtain a loosening of the crown (4) with a minimum of lateral forces, which are ineffective, painful and dangerous for safeguarding the stump (3) and the tooth.

Furthermore, in the method used, the crown (4) is incised on a plane substantially parallel to the occlusal surface of the crown (4), which makes it possible not to destroy the crown (4). Indeed, the notch (1) made in the crown (4) keeps at

<Desc / Clms Page number 3>

 this its rigidity and does not alter its cervical crimping, which allows it to be recovered for possible rest. It will then suffice, after refitting the crown (4), to proceed to (shutter Ventaille (1) with suitable materials.

The list of procedures for achieving the exercise of a couple of forces between the occlusal faces of the stump (3) and the underside of the crown (4) is not exhaustive. We will therefore describe a limited quantity of embodiments with regard to the number of technically feasible processes.

By way of nonlimiting examples, in addition to the embodiments described below, the invention may take the following forms: - an instrument, the working part of which (D) will be made of a material offering possibilities of controlled expansion , the substantially vertical expansion of which will be obtained, for example without limitation, by variation of the temperature], - an instrument whose working part (D) will consist of a membrane, the expansion of which will be obtained by injection of a pressurized fluid not a nozzle constituting the scalloped intermediate part (C).

In fact, all the physical processes inducing a substantially vertical expansion of the working part (D) can be envisaged, as soon as the instrument is characterized by the presence of a notched intermediate part (C) allowing the free lifting of the crown (4) and the absence or limitation of lateral forces. The handle (A) and the intermediate section (B) will only be incidentally required to hold or activate the working part (D) in the groove (2), depending on the expansion system used (for example, the handle (A) and the tapered intermediate section (B) are necessary for maintaining and rotating the working part (D) of 1I.DR described later).

For easier use, the invention may be provided with a mechanism allowing an easy or even automatic return to the rest position of the working part (D).

 The instrument may require adaptation to the variety of situations encountered (size and more or less accessible position of the tooth to be treated). This adaptation may be manifested by a modulation in the alignment of its different parts or in the shapes and dimensions of the latter. The instrument can therefore advantageously be presented in the form of a set of interchangeable tips integrating one or more parts of the instrument.

<Desc / Clms Page number 4>

 We will endeavor to describe more precisely three embodiments of the invention: -An instrument for loosening by rotation (IDR) -A variant using the overlap of two inclined planes (CDP1.) [See fig.17] -A variant to vertical expansion (EV) [see fig.18] The IDR is divided into 4 parts (fig.1 and 2) A handle (A).

A tapered intermediate section (B). An indented intermediate part (C). A working part (D) The handle (A) of the I.D.R has an ergonomic shape adapted to the grip as well as to the rotation of (instrument, comparable to the handle of a syndesmotome.

The only function of the tapered intermediate section (B) of IZ.D.R is to pass from the handle section (A) to a section close to that of the indented intermediate part (C). Its shapes and dimensions can therefore be diverse.

The indented intermediate part (C) of 17.D.8 is in the form of a segment having a preferably cylindrical shape. Its diameter is a function of the dimensions of the notch (1) made in the crown (4). Its length is a function of the thickness of the crown (4) and the depth of the groove (2).

The working part (D) of lZ.D.R. can take the most varied forms, since, by rotation of fLDR, they will generate a couple of forces between the occlusal faces of the stump (3), on the one hand, and the underside of the crown (4), on the other hand. This implies that the distance between the lateral ends of the working part (D) is greater than the height of the groove (2).

 Whether in its section, its face or its profile, we can thus confer on the working part (D) of the I.D.R. particular but non-limiting rectangular, ovoid, triangular, the shape of a snail or a diamond).

Furthermore, the working part (D) can have different shapes and sizes, the I.D.R can advantageously be in the form of a set of interchangeable tips. Depending on the location you choose to operate the securing system, each tip can integrate one or more parts of the instrument.

<Desc / Clms Page number 5>

 The angles between the axes A ', B', C 'and D' of the different parts of the I.D.R. may be different, so that all parts of the I.D.R. may be either on the same axis [see fig.l and 2], or on different axes for easier handling in the mouth, for example for posterior teeth [see fig.12, 13, 14 and 15].

Figures 3 and 4 show a variant tip of I.D.R. having a working part (D) whose face (fig. 3) and profile (fig. 4) are respectively rectangular, the ends being diametrically and symmetrically opposite with respect to the axis of rotation (C ') of the intermediate part indented (C).

Figure 5 shows a variant tip of I.D.R. having a working part (D) in the form of "blank key". The axis of rotation (D ') of the working part (D) is parallel to that (C') of the notched intermediate part (C), but it is distinct from it.

Figure 6 shows a variant of I.D.R. having a working part (D) whose profile has a rectangular shape with rounded edges.

Figures 7, 8, and 9 show a variant tip dI.D.R. having a working part (D) whose face (fig. 7), profile (fig. 8) and section (fig. 9) are ovoid.

FIG. 10 represents a variant of the working part (D) dZ.D.R. whose section is snail-shaped. This form has the advantage of obtaining a couple of regular forces, substantially vertical and very close to the vertical axis (F) of the tooth.

Figure 11 shows the section of a notched intermediate part (C) of cylindrical shape of an I.D.R ..

 Figures 12 and 13 show a variant of I.D. R, the axes A 'of the handle (A) and B' of the tapered intermediate section (B) form the angles a. l from the front and [i l from the side.

Figures 14 and 15 represent a variant of IDR whose axes A 'of the handle (A) and B' of the tapered intermediate section (B) form the angles a.2 from the front and [32 in profile and whose axes B 'and C' of the indented intermediate part (C) form the angles u3 from the front and [33 in profile.

FIG. 16 represents a variant of IDR whose working part (D) has a rectangular section which, inserted in the groove (2), allows, by a rotary movement, to generate a couple of forces between the lower surface of the occlusal side of the crown (4) and the occlusal side of the stump (3). Figure 16 shows a section of the tooth along the sagittal plane.

<Desc / Clms Page number 6>

 After making the notch (1) and the groove (2), the working part (D) of fI.D.R. in the groove (2) so that the notched intermediate part (C) is positioned at the level of the notch (1) made in the prosthesis. The shapes and dimensions of the indented intermediate part (C) allow it to freely perform rotational movements which it transmits to the working part (D).

 The work thus produced makes it possible to transmit to the working part (D), the rotational movements successively printed by the practitioner at the level of the handle (A).

The variant using the overlap of two inclined planes (Le C.D.P.I.). includes: -A handle (A).

-A tapered intermediate section (B). - A scalloped intermediate part (C).

-A working part (D) split in (D 1) and (D2).

The handle (A) of the C.D.P.I. has characteristics substantially identical to those of fLDR. . However, it also includes the insertion of a mechanism enabling the working half-part (D2) to be actuated. This mechanism may also include a system allowing the C.D.P.I. an automatic return to the rest position.

The characteristics of the tapered intermediate section (B) of the C.D.P.I. are substantially identical to those of fLD.R .. However, this includes, in addition, the insertion of the device making it possible to actuate the movement of the working half-part (D2).

The middle indented part (C) of the C.D.P.I. consists of two parts sliding one on the other or one inside the other. The first (CI) is integral on the one hand with the tapered intermediate section (B), on the other hand with the bottom pentahedron (D1) of the working part (D). The second (C2) is integral, on the one hand, with the mechanism inserted in the handle (A) which imparts the movement and which crosses the tapered intermediate section (B), on the other hand, the high pentahedron (D2) of the working part (D). The dimensions and shapes of the indented intermediate part (C) must allow a vertical translation of the crown (4).

The working part (D) of the C.D.P.1. consists of two half-parts (D1) and (D2), each having an inclined plane, the sum of which, when the C.D.P.I .. is at rest, forms a rectangular parallelepiped. Each of the two half-parts (D1) and (D2) is generally in the form of a pentahedron.

<Desc / Clms Page number 7>

 As in the case of the LD.R., after having made the notch (1) and the groove (2), the working part (D) of the C.D.P.1 is introduced. at rest in the groove (2) so that the notched intermediate part (C) comes to be positioned at the level of the notch (1) made in the prosthesis.

When, using the device inserted in the handle (A), a traction is applied to the pentahedron D2, the latter, by overlapping the pentahedron Dl rises regularly, so that the pentahedrons D 1 and D2 generate a substantially vertical expansion of the working part (D). The pentahedron D1 being pressed against the occlusal face of the stump (3), and the pentahedron D2 being pressed against the occlusal face of the underside of the crown (4), a couple of forces is obtained between the two faces.

The vertical expansion variant (E.V.) [see fig.18] includes: -A handle (A).

- A rod (E).

-A tapered intermediate section (B). - A scalloped intermediate part (C).

- A working part (D) split (D3) and (D4).

The handle (A) of YEN. has characteristics substantially identical to those of I'LD.R .. However, it also includes the insertion of a mechanism allowing the actuation of a rod (E) extending into the working part (D). This mechanism could also include a system allowing 1EN. an automatic return to the rest position.

The rod (E) is inserted into YEN. . It has an enlarged end (E1), so that, when traction is exerted on the rod (E) from the handle (A), the enlarged end (El) is inserted between the polyhedra (D3) and (D4) to cause it to spread.

The characteristics of the tapered intermediate section (B) of the EN. are substantially identical to those of fLD.R. . However, it also includes the insertion of the rod (E).

The lower part of 1BN. has characteristics substantially identical to that of the I.D.R. . However, it also includes the insertion of the rod (E).

The working part (D) of YEN. is composed of two polyhedra (D3) and (D4) having two inclined planes facing the enlarged end (El) of the rod (E). When the rod (E) is pulled between the inclined planes, their progressive spacing is obtained, and therefore, the substantially vertical expansion of the working part (D).

<Desc / Clms Page number 8>

 We carry out in the same way as for the LD.R. , a notch (1) and a groove (2). We insert the entire working part (D) of 1EN. in the groove (2), so that the notched intermediate part (C) is positioned at the notch (1). By actuating the mechanism located in the handle (A), a pull is exerted on the enlarged end (E1) of the rod (E). The enlarged end (E1) causes the progressive separation of the two polyhedra (D3) and (D4) until the torque of forces is obtained between the occlusal face of the lower surface of the crown (4), on the one hand, and the occlusal surface of the stump (3), on the other hand.

<Desc / Clms Page number 9>

Claims (10)

 CLAIMS 1) Instrument used to deposit a crown (4) characterized in that it comprises an indented intermediate part (C), and a working part (D). Inserted into a groove (2) previously performed by the practitioner at the supposed level of the occlusal face of the stump (3) along a plane substantially parallel to the occlusal surface of the crown (4), this working part (D) allows by an action physical exercise of a couple of forces substantially in the vertical axis (F) of the tooth, between the occlusal face of the stump (3), on the one hand, and the occlusal face of the underside of the crown (4) , on the other hand [fig.l6, 17 and 18]. 2) Instrument according to claim 1 characterized in that it has a scalloped intermediate part (C) whose shapes and dimensions allow it, during the exercise of the couple of forces between the respective occlusal faces of the stump (3) and the lower surface the crown (4), on the one hand. not to obstruct the vertical translation of the notched wall of the crown (4), on the other hand to limit the lateral forces on the crown (4) [fig.16.à 18]. 3) Instrument according to claims 1 and 2 characterized in that the indented intermediate part (C) and the working part (D) follow a handle (A) and a tapered intermediate section (B) [fig. let 2]. 4) Instrument according to claims 1, 2 and 3 characterized in that the indented intermediate part (C) and the working part (D) enter integrally in rotation with a tapered intermediate section (B) and a handle (A) by action of the practitioner on the handle (A), and having a working part (D) whose shapes and dimensions [fig.3 to 10 and fig.16], allow it during a rotational movement, to generate a couple of forces substantially in the vertical axis (F) of the tooth, between the occlusal face of the stump (3), on the one hand, and the occlusal face of the underside of the crown (4) on the other.  5) Instrument according to claims 1, 2 and 3 characterized in that the working part (D) is composed of two pentahedrons (D1) and (D2) which, when at rest, form a rectangular parallelepiped that the can be inserted into the groove (2), and, when their progressive overlap is actuated using a mechanism located in the handle (A) and crossing the tapered intermediate section (B), generate an expansion of the part working (D) substantially in the vertical axis (F) of the tooth [fig.17]. <Desc / Clms Page number 10>  6) Instrument according to claims 1, 2 and 3 characterized in that the working part (D) is composed of two pentahedrons (D3) and (D4) which, when actuating their spacing using a mechanism located in the handle (A) actuating the pull of a rod (E) having an enlarged end (El), and t-aversant the tapered intermediate section (B) and the notched intermediate part (C) generates an expansion of the part working (D) substantially in the vertical axis (F) of the tooth [fig.18]. 7) Instrument according to claims 1 and 2 characterized in that the working part (D) is constituted by a membrane into which a fluid under pressure is injected by a nozzle constituting the scalloped intermediate part (C). 8) Instrument according to claims 1 and 2 characterized in that the working part (D) is made of a material offering possibilities of controlled expansion, and whose vertical expansion can, for example, be obtained by varying the temperature. 9) Instrument according to any one of the preceding claims, characterized in that it is in the form of a set of interchangeable tips incorporating one or more parts of the instrument. 10) Instrument according to any one of the preceding claims, characterized in that it is provided with a device allowing the automatic return of the working part (D) to its rest position.