WO2013004703A1

WO2013004703A1 - A modular apparatus for dental implants

Info

Publication number: WO2013004703A1
Application number: PCT/EP2012/062942
Authority: WO
Inventors: Edoardo Maria CALVI
Original assignee: CALVI Raffaella
Current assignee: CALVI Raffaella
Priority date: 2011-07-04
Filing date: 2012-07-03
Publication date: 2013-01-10
Anticipated expiration: 2014-01-04
Also published as: ITAN20110089A1

Abstract

The present invention relates to an apparatus for dental implants provided with high versatility because it makes use of an implant able to cooperate indifferently with long and short stumps.

Description

Description A modular apparatus for dental implants

The present patent for industrial invention relates to a modular apparatus for realization of dental implants (prostheses).

The peculiarities and advantages of the invention will be more evident following to a short description of the prior art.

Dental implants are used in the patient's oral cavity to replace one or more teeth that have fallen out.

According to such a technology, the dentist inserts a metal pin (technically defined as "implant") in the patient's bone, which acts as root for the artificial tooth to be installed.

Once the implant has stabilized in the bone, a metal stem, usually defined as "stump" is fixed on it by means of a screw.

In turn, such a stump is adapted to support the dental prosthesis (the so-called "crown"), i.e. the metal capsule coated with ceramic that reproduces the natural tooth that is missing.

Most implants are provided with anti-rotational index that is adapted to act as stabilizer for the stumps and facilitate the dentist's work in the prosthetic works.

In order to additionally stabilize the coupling between the mouth of the implant and the corresponding end of the stump, an anti-rotational prismatic coupling is established between them.

Such a fact is considered in view of the high stress that might be transmitted to such a dental implant during mastication, with the risk of creating undesired clearance between implant and stump.

Said coupling is currently of the type normally defined as "flat to flat", according to which a prismatic coupling is obtained between a faceted appendage (which recalls the head of a bolt) provided on one of the components to be coupled and a corresponding faceted seat provided on the other component. Technically speaking, said prismatic coupling between the two cooperating components generates an "anti-rotational index"; it being provided that triangles, hexagons, octagons and dodecagons are the most used geometrical shapes.

Said "flat to flat" dental implants can be alternatively made according to the external or internal connection principle.

In case of dental implants with external connection, said faceted appendage is obtained on the top of the implant, whereas the seat is obtained at the base of the stump.

Instead, in case of dental implants with internal connection, said faceted appendage is obtained on the base of the stump, whereas the seat is obtained on the top of the stump.

According to such an alternative solution, dental implants with external connection are preferred for their versatility and easiness of use, which substantially derive from the fact that said faceted appendage provided on the top of the implant has a reduced height.

When using such a technology, it is very easy to take the impression of a dental implant (also in case of multiple disparallel implants), obtain passive frames and, finally, realized prosthesis screwed without using the intermediate components that are known as MUA (multi-unit abutment).

In view of said advantages, a dental implant with external connection is however impaired - in view of the reduced height of said faceted appendage of the implant - by a high tendency to unscrewing and a higher incidence of breakage of the prosthetic screw, being the most stressed component.

Dental implants with internal connection are preferred because the faceted appendage provided on the stumps is usually given a considerable height, such that a higher height can also be given to said anti-rotational index, i.e. prismatic coupling between implant and stump.

Therefore, implants with internal connection give a satisfactory resistance to undesired rotational stress. However, it must be said that the higher height of said faceted appendage is to the detriment of versatility of use of such a component, which actually requires the use of said MUA to realize screwed prostheses.

More generally, it must be noted that said "flat to flat" technology generates, both in the version with internal and external connection, with two important problems.

First of all, it must be noted that in order to obtain the desired prismatic coupling between implant and stump, it is always necessary to provide certain tolerance between the two components to be coupled, i.e. the faceted appendage and the corresponding seat.

Nevertheless, such a tolerance inevitably tends to generate certain mobility of the stump with respect to the implant, when the stump is subject to the oblique loads that are frequently generated during mastication.

Another problem derives from the fact that the tolerance necessary between the prismatically coupled components may generate small empty spaces (due to imperfect centering) that easily tend to be colonized by bacteria that may generate inflammations of the peri- implantar bone.

Also in view of these drawbacks, an alternative technology is largely used, according to which dental implants are obtained by means of conical coupling between implants and stumps.

In view of the above, each stump is provided in lower position with a conical appendage, technically defined as "Morse cone", whereas the implant is provided on top with a conical cavity.

When the Morse cone of the stump is exactly inserted into the corresponding cavity of the implant, the two components are stabilized, preferably with a screw that crosses the entire stump and is engaged on the bottom of the implant.

It appears evident that such a conical coupling avoids teh generatation of undesired empty spaces between stump and implant, which can be colonized by bacteria. On the other hand, it appears evident that such a coupling is not able to guarantee the anti-rotational effet between stump and implant, especially in case of short stumps, where contact conical surfaces are small.

To that end, a perimeter prismatic profile is obtained externally on the apical area of the Morse cone of the stump with conical connection

(where it achieves its maximum tapering), said prismatic profile being adapted to be exactly inserted into a corresponding seat obtained on the bottom of said conical cavity of the implant.

Using the aforementioned terminology, it can be said that an "apical index" is established between the stump with conical connection and the implant.

Another advantage of such a conical connection consists in the fact that the stump tends to be - especially if the connection with the implant is sufficiently long - totally unaffected by the stress, including the strong stress caused by transversal loads.

Moreover, the mastication stress is distributed along a higher height of the implant, thus avoiding stress peaks for the crown area of the implant (i.e. on top) that could easily cause the unscrewing and breakage of the implant, as well as an excessive transmission of the load for the cortical bone.

However, it must be noted that said conical coupling technology is impaired by some drawbacks.

In particular, it must be said that the presence of the antirotational index in apical position makes it very difficult to take impression for prosthetization of a dental implant (especially in case of multiple disparallel implants). Moreover, it requires the use of said MUA to obtain screwed prostheses.

In view of the short presentation of the prior art, it is easy to understand that no "perfect" dental implant type is currently available, which can be easily adapted to all different requirements.

Therefore, the dentist is obliged to user the different types of prostheses alternatively, trying to reach the best compromise between advantages and disadvantages according to the specific requirements of the clinical case.

In view of the above, the dentist is obliged to keep a large stock with multiple implant lines, in order to have the necessary components always available according to the specific case.

Evidently, this is a drawback, both in terms of economic resources and daily handling of such a large implant stock.

Starting from these critical evaluations, the modular apparatus of the invention has been devised, which intends to remedy the drawbacks of the prior art in two different aspects.

The first purpose is to realize dental implants provided with the main advantages of the various traditional techniques, but without the corresponding drawbacks.

The second purpose is to allow dentists to configure the apparatus of the invention at their discretion in such manner to obtain, from time to time, a dental implant with the most suitable structural and functional features according to the specific requirements.

More precisely, it must be said that the apparatus of the invention makes it possible to obtain a dental implant providing for conical connection between stump and implant, and at the same time guarantees that an effective prismatic coupling or "anti-rotational index" is established between these two parts (comparable to the type known as "flat to flat").

Such an anti-rotational index is established at the height of the crown section of the implant. Such a fact is extremely advantageous because it facilitates the dentist's work, with special reference to making the impression.

Likewise, it must be noted that said anti-rotational crown index is obtained in such manner to guarantee - unlike in the traditional "flat to flat" technology - perfect "sealing" between the interfaced surfaces of each stump and relevant implant, in order not to leave any space for bacterial settlement. Such sealing has been obtained by providing - at level of said anti- rotational crown index - the cooperating of suitable inclined surfaces that also favor perfect stability between implant and stump.

However, as mentioned above, the additional interesting feature of the apparatus of the invention is the fact that it can be used to make dental implants adapted to be indifferently provided with short or long stumps, where the higher or lower length of said stumps is actually referred to the length of their Morse cones.

For explanatory reasons, the description of the invention continues with reference to attached drawings, which only have an illustrative, not limiting value, wherein:

- Fig. 1 is an exploded axonometric view of the cooperation modes of three parts of the apparatus of the invention;

- Fig. 2 is a cross-sectional view of the parts of Fig. 1 after being assembled completely;

- Fig. 3 is an axonometric view of the stump shown in the preceding figures;

- Fig. 4 is the same of Fig. 1 , except for it shows different parts;

- Fig. 5 is a cross-sectional view of the parts of Fig. 4 after being assembled completely;

- Fig. 6 is an axonometric view of the stump shown in figures 4 and 5;

- Fig. 7 is an axonometric view of the implant shown in the preceding figures 1 , 2, 4 and 5.

First of all, it must be noted that the modular apparatus of the invention is composed of a plurality of parts adapted to be used in combination or alternatively.

Referring to Figs. 1 , 2 and 7, the first of these parts consists in an implant (1 ) usually consisting in an externally threaded cylindrical stem provided, in correspondence of its opening (otherwise definable as "crown section"), with a conical seat (10) with side walls (1 1 ) converging towards the apical section of the implant (1 ). Said side walls (1 1 ) are provided with substantially U-shaped impressions (12) disposed along the height and regularly spaced.

In particular, the back wall of said impressions (12) has an inclined profile such that the depth of each of said impressions increases from the opening of the implant (1 ) towards the apical section of the same.

The bottom (10a) of said conical seat (10) is joined with a conical hole (13) provided with smooth walls, which ends into a cylindrical hole (14) with threaded walls.

The second part of the apparatus of the invention consists in a first stump (2), usually consisting in a tubular cylindrical stem provided in apical position (i.e. in correspondence of the end facing the implant) with enlarged head (20).

From the center of the head (20) a collar (21 ) protrudes in lower position - configurable under all aspects as a Morse cone - provided with height compatible with the depth of said seat (10) of the implant (1 ).

Said collar (1 ) is crossed by a hole (20a) defined by a perimeter shoulder (20b) on the inside of said stump (2), as shown in Fig. 2.

Said collar (21 ) is provided with conicity both on the internal walls (21 a) and the external walls (21 b); it being also provided that the outlet hole (21 c) of said collar (21 ) has the same section as the opening section of said conical hole (13) of the implant (1 ).

In particular, said external walls (21 b) of said collar (21 ) have suitably conicity to exactly match the conicity of the side walls (1 1 ) of the seat (10) of the implant (1 ).

In correspondence of said external walls (21 b) of the collar (21 ) a series of substantially U-shaped projections (22) is obtained with shape and profile compatible with the impressions (12) of the seat (10) of the implant (1 ).

The front wall of each said projections (22) is provided with a sloping profile, such that projections (22) have a growing section consistently with the depth of said impressions (12) of the implant (1 ). With reference to said internal walls (21 a) of said first stump (2), it must be noted that they have such a conicity to exactly match with the conicity of the walls surrounding said conical hole (13) of the implant (1 ).

Such a stump (2) is adapted to be coupled with male-female coupling with the implant (1 ), as shown in Fig. 2.

In particular, such coupling is completed when said head (20) of the stump (2) is stopped against the mouth edge (15) of the implant (1 ).

In the meantime, in fact, the collar (21 ) of the stump (2) is perfectly engaged into said conical seat (10) of the implant (1 ), in such a condition that projections (22) are exactly housed into corresponding impressions (12) of the implant (1 ).

Naturally, such a prismatic coupling between projections (22) and impressions (12) realizes the desired "anti-rotational index" between stump (2) and implant (1 ), exactly at the height of said crown section of the latter.

The third part of the apparatus of the invention is a screw (3) adapted to provide stable coupling between the implant (1 ) and said first stump (2), as shown in Figs. 1 and 2.

The peculiarity of the screw (3) is that it is provided, immediately under the enlarged head (30), with a stem comprising an upper conical section (31 ) with smooth walls, which is joined with a lower cylindrical section (32) with threaded walls.

Fig. 2 shows the installation mode of the screw (3).

The screw (3) is inserted into the stump (2), in such manner that its stem penetrates inside the implant (1 ).

In this phase the threaded section (32) of the screw (3) is adapted to be progressively engaged into the threaded cylindrical hole (14) of the implant (1 ).

Such a helicoidal coupling favors the progressive descending travel of the screw (3) towards the bottom of the implant (1 ) until its enlarged head (30) is stopped against the shoulder (20b) internally defining the hole (20a) that crosses the collar (21 ) of the stump (2). In such a condition, the additional consequence is that the conical section (31 ) of the screw (3) is exactly engaged and simultaneously engaged inside the hole (20a) of the collar (21 ) of the stump (2) and inside the cylindrical hole (13) of the implant (1 ).

Such a perfect conical coupling considerably reduces the possibility that empty spaces are left between said implant (1 ) and said first stump (3), which may favor proliferation of dangerous bacteria.

The apparatus of the invention also comprising a fourth part, basically consisting in a second stump (4) adapted to be fixed to said implant (1 ) in alternative to the first stump (2), as shown in Figs. 4, 5 and 6.

The second stump (4), usually consisting in a tubular cylindrical stem, is provided with tapered end (40), crossed by a cylindrical hole

(41 ) , configurable under all aspects as a Morse cone.

Said tapered end (40) is composed of a first section (42) with conical profile, joined with a second thinned section (43) equally provided with conical profile.

The two sections (42, 43) are joined in correspondence of a perimeter shoulder (44) interposed between them.

In particular, said first section (42) of the second stump (4) is adapted to be exactly engaged into said conical seat (10) of the implant (1 ), before said shoulder (44) provided in lower position is stopped against the bottom (10a) of the conical seat (10), such to generate forced coupling.

In view of the above, the conicity of the walls of said first section

(42) of the second stump (4) corresponds to the conicity of the walls surrounding said conical seat (10) of the implant (1 ).

Said second section (43) of the second stump (4) is adapted to be engaged into the conical hole (13) provided on the implant (1 ) under the conical seat (10). In view of the above, the conicity of the walls of said second section (43) exactly corresponds to the conicity of the walls surrounding the conical hole (13) of the implant (1 ).

After the male-female coupling of implant (1 ) and second stump (4), as described above, the two parts are firmly fixed with a traditional cylindrical screw (V).

After penetrating the stump (4) and crossing its tapered end (40), the stem of said screw (V) can be normally engaged into said threaded hole (14) provided towards the bottom of the implant (1 ).

Also in this case, the fixing of the screw (V) is completed when the head of the screw (V) is stopped against the shoulder (45) defining the cylindrical hole (41 ) crossing the tapered end (40) of said second stump (4).

It must be noted that also the second stump (4) is provided, on the external walls of the first section (42) of its tapered end (40), with a series of projections (22) perfectly matching the ones provided on said first stump (2) and likewise adapted to be exactly engaged inside said impressions (12) obtained on the walls defining said conical seat (10) provided on the opening of the implant (1 ).

In view of the above, it is understood that also with the use of said second stump (4), the dental implant is provided with an efficient anti- rotational index - obtained by means of said coupling between projections (22) and impressions (12). Moreover, because of the exact coupling between said second section (43) of the stump (4) and the cylindrical hole (13) of the implant (1 ), the formation of empty spaces, which can be attacked by bacteria, between the cooperating parts.

Although it has been so far assumed that said first stump (2) is provided with said perimeter projections (22), an alternative constructive version can be realized, wherein said tapered end (21 ) is provided with perfectly smooth external walls (21 b) devoid of said projections (22).

Likewise, it must be noted that said implant (1 ) is internally provided, along its axial hole, also with a perimeter prismatic seat (16), formed of a series of vertical ribs, adapted to be used for screwing, by means of a tool, the implant into the patient's bone.

Claims

1 ) A modular apparatus for dental implants, characterized in that it comprises the following modular parts,

- an implant (1 ) consisting in an externally threaded cylindrical stem provided, in correspondence of its opening, with a conical seat (10) with side walls (1 1 ) converging towards the apical section of the implant (1 ); it being provided that said side walls (1 1 ) are provided with basically U- shaped impressions (12) disposed along the height and regularly spaced, each of them being provided with a back wall with inclined profile such that the depth of each of said impressions (12) increases from the opening of the implant (1 ) towards the apical section of the same; it being also provided that the bottom (10a) of said conical seat (10) is joined with a conical hole (13) in lower position, provided with smooth walls, and ending into a cylindrical hole (14) with threaded walls, both being axially obtained in the center of the implant (1 )

obtained in the center of the implant (1 )- a first stump (2) consisting in a tubular cylindrical stem provided in apical position with enlarged head (20) from which a conical collar (21 ) protrudes, being centrally crossed by a hole (20a) defined by a perimeter shoulder (20b) on the inside of said first stump (2); it being provided that said conical collar (21 ) is adapted to be exactly engaged into said conical seat (10) of said implant (1 ) and also provided with a perimeter series of projections (22) adapted to be exactly engaged into said impressions (12) obtained in correspondence of the perimeter walls (1 1 ) of the conical seat (10) of the implant (1 ); it being provided that said collar (21 ) is provided with outlet hole (21 c) provided with same section as the opening section of said conical hole (13) of the implant (1 ), as well as internal walls (21 a) provided with suitably conicity to exactly match the conicity of the walls (1 1 ) that define said conical hole (13) of the implant (1 ) and external walls (21 b) provided with conicity exactly matching the conicity of the side walls (1 1 ) of the conical seat (10) of the implant (1 ); - a screw (3) adapted to provide stable coupling between said implant (1 ) and said first stump (2) and suitably provided with enlarged head (30) adapted to stop against said shoulder (20b) of the first stump (2), a conical section (31 ) with smooth walls, adapted to be exactly and simultaneously engaged inside said hole (20a) of the collar (21 ) of the first stump (2) and inside said conical hole (13) of the implant (1 ), as well as a cylindrical section (32) with threaded walls, adapted to be helicoidally engaged into said threaded cylindrical hole (14) of the implant (1 );

- a second stump (4) consisting in a tubular cylindrical stem provided with tapered end (40) crossed by a cylindrical hole (41 ) and also composed of a first section (42) with conical profile joined, with interposition of a perimeter shoulder (44), with a second thinned section (43) equally provided with conical profile; it being provided that said first section (42) is adapted to be exactly engaged into said conical seat (10) of the implant (1 ) and said second section (43) is adapted to be exactly engaged inside said conical hole (13) of the implant (1 ); it being also provided that said first section (42) of said tapered end (40) of the second stump (4) is externally provided with a series of projections (22) adapted to be exactly engaged inside said impressions (12) obtained in correspondence of the perimeter walls (1 1 ) of said conical seat (10) of the implant (1 ).

2) An apparatus as claimed in claim 1 , characterized in that said implant (1 ) is internally provided with perimeter prismatic seat (16).