DESCRIPTION

This patent application for industrial invention relates to a dental implant for the rehabilitation of patients affected by complete or partial edentulism, that is to say the loss or absence of one or more teeth.

Dental implantology is now an established therapeutic practice based on the principle of osseointegration. The high level of predictability and success of the existing implant therapies has led to an evolution of surgical and prosthetic protocols.

As it is known, a conventional dental implant according to the prior art comprises a cylindrical or conical screw, normally made of titanium, to be screwed in a suitable threaded seat previously formed in the mandibular or maxillary bone of the patient. The screw will then undergo a process of osseointegration, that is to say the process of integration into the bone tissue, thus forming an artificial root for an artificial tooth, commonly defined as dental prosthesis, which is applied, by means of a stump screwable in a suitable seat of the screw, once the osseointegration process has been completed.

The success of such an implant and the long-term maintenance of the implant's osseointegration is especially determined by the quantity of maxillary bone or of mandibular bone of the patient. In fact, in presence of a scarce quantity of bone, particularly of cortical bone, in the area where the implant is to be installed, then the screw cannot have at its disposal a sufficient gripping surface and may get loose, meaning that the screw comes out of its seat with consequent loss and removal of the implant.

In order to overcome the abovementioned shortcomings, implantology studies have focused on finding a rapid and reliable solution capable of exactly solving the cases in which the quantity of mandibular or maxillary bone available for the implant is not sufficient for an implant such as the one described above. The same applicant devised a solution described in the patent application EP3062731 capable of remedying the cases in which the quantity of mandibular or maxillary bone is not sufficient for the realization of a traditional implant. The patent application EP3062731 is briefly described below with reference to Fig. 1 , which is a perspective view of the dental implant, and with reference to Figs. 2A to 3D, which show two alternative installation methods of the dental implant of Fig. 1 .

The patent application EP3062731 , in the name of the same applicant, discloses a dental implant (1 ) comprising a main body (2) suitable for being implanted in a primary implant seat (N1 ) formed in the mandibular or maxillary bone of a patient, and an auxiliary plate (10) suitable for realizing additional fixing points with the bone of the patient in additional secondary bony fixing zones with respect to the primary implant seat. The auxiliary plate (10) comprises one or more projecting portions (11 ) (in Fig. 1 only one projecting portion (11 ) is shown) that are flexible and therefore can be adapted to the shape of the patient's bone, in such a way to be positioned in correspondence with the abovementioned secondary bony fixing zones.

Said projecting portions (11 ) permit to fix the dental implant (1 ) in a plurality of bony fixing zones, ensuring a high retainability of the dental implant. Second through holes (13) are provided on the projecting portions (11 ) for the insertion of fixing screws (12) implanted in auxiliary implant seats (N2) formed in said secondary bony fixing zones.

The auxiliary plate (10) is fixed to the main body (2) by means of a reinforcing portion (17) comprising a fixing opening (16) suitably configured to be coupled with a fixing portion (15) of the main body (2).

In order to install such an implant (1 ), firstly a primary implant seat (N1 ) (as shown in Fig. 2A and 3A) is to be provided, wherein the main body (2) is to be positioned and fixed. In order to provide the primary implant seat (N1 ), a gingival flap is to be opened, a lead-in is to be formed in the cortical bone and drilling is to be performed in such a way to form the primary implant seat.

With reference to Figs. 2A and 3A, then the auxiliary implant seats (N2) are to be provided. The auxiliary implant seats (N2) can be provided by following steps substantially analogous to the ones described with reference to the primary implant seat (N1 ).

Successively, as shown in Fig. 2B and 3B, the auxiliary plate (10) is suitably positioned in such a way that the reinforcing portion (17) is positioned with the fixing opening (16) in coaxial position relative to the primary implant seat and the second through holes (13) are positioned in correspondence with the secondary implant seats.

With reference to Figs. 2C and 3C, then the main body (2) is inserted in the primary implant seat through the fixing opening (16) of the auxiliary plate (10). In such a case, the main body (2) is to be inserted and implanted until the fixing opening (16) and the fixing portion of the main body (2) are coupled.

After coupling the main body (2) with the auxiliary plate (10), the fixing screws (12) are screwed and fixed in the secondary implant seats, as shown in Figs. 2D and 3D.

The gingival flaps are then closed and sutures are made, if required.

Such a solution is impaired by some drawbacks, especially when the auxiliary implant seats or the auxiliary implant seat (N2) must be made at a long distance with respect to the insertion point of the implant, that is to say with respect to the zone where the artificial tooth (DA) is to be positioned.

Two different solutions can be adopted in such a case.

A first solution, which is defined as supracrestal and is shown in Figs. 2A to 2D, provides for using an auxiliary plate (10) provided with portions (11 ) with a high length and the reinforcing portion (17) in supracrestal position, that is to say in correspondence with the insertion point.

Such a solution is invasive, cumbersome and not optimal for a patient because of the presence of long metal flexible portions (11 ) that extend from the insertion point until the secondary zones.

A second solution, which is defined as subcrestal and is shown in Figs. 3A to 3D, provides for using an auxiliary plate (10) wherein the reinforcing portion (17) is coupled with the main body (2) in a subcrestal position, that is to say in a distal position with respect to the insertion point and in a proximal position with respect to the secondary zones. In view of the above, the length of the flexible portions (11 ) is considerably reduced and the dental implant (1 ) is less cumbersome.

In such a case, during the installation of the dental implant, an access is to be formed on the bone in a radial direction relative to the axis of the primary implant seat (N1 ) in such a way that, before inserting the main body (2) in the primary implant seat (N1 ), the reinforcing portion (17) is inserted through said access so that the fixing opening (16) is disposed in coaxial position relative to the primary implant seat, as shown in Fig. 3B. During the insertion of the main body (2), the main body (2) passes through the fixing opening (16) until the fixing opening (16) and the fixing portion of the main body (2) are coupled.

In spite of the considerable reduction of the dimensions of the auxiliary plate (2) and of the length of the projecting portions (11 ), such a solution is impaired by some drawbacks.

In particular the radial access must be formed with extreme care and precision so that the reinforcing portion (17) is positioned exactly at a pre calculated level that coincides with the position wherein the fixing portion (15) of the main body (2) is to be placed once the main body (2) is implanted in the main seat (N1 ). Therefore, such a solution is extremely complicated and for this reason it is adopted in an extremely small number of cases.

In addition, the aforementioned dental implant (1 ) necessarily requires the presence of surfaces formed on the fixing opening (16) of the auxiliary plate (1 ) and on the fixing portion (15) of the main body (2) shaped in such a way as to be coupled. Therefore, such a solution is not versatile as it is not adaptable to all types or shapes of main bodies (2) or screws.

US2004/161725A1 discloses a dental implantation system for securing a dental prosthesis to a patient's alveolar ridge. The dental implant fixture can be positioned in the patient's alveolar ridge and can have an upper end to receive the dental prosthesis. The dental implant support can be connected to the dental implant fixture in a laterally spaced apart relation therefrom and against the alveolar ridge.

US2002031747A1 discloses a dental implant containing a bi-cortical anchor apparatus, arranged for insertion into a jawbone, said bi-cortical anchor apparatus including a tool receptor, at the proximal-most end of said proximal portion, for interacting with a tool, to facilitate the insertion of said apparatus. An implant member arranged for insertion into a jawbone includes a cervix arranged to secure a dental prosthesis thereto and a through conduit arranged to support a bi-cortical anchor apparatus.

The purpose of the present invention is to overcome the drawbacks of the prior art by disclosing a dental implant that ensures a high retainability even in presence of a scarce quantity of bone and is suitably configured in such a way that the auxiliary plate can be installed simply and rapidly also in subcrestal position, that is to say at a long distance from the insertion point of the artificial tooth.

Another purpose of the present invention is to disclose a dental implant that is easy to make and is capable of facilitating the installation of said dental implant in a patient.

These and other purposes are achieved according to the invention with the characteristics of the appended independent claim 1 .

Advantageous embodiments appear from the dependent claims.

The dental implant according to the invention is defined by claim 1 .

For clarity purposes, the description of the dental implant according to the invention continues with reference to the attached drawings, which only have an illustrative, not limiting value, wherein:

Fig. 1 is an exploded axonometric view of the dental implant according to the prior art;

Figs. 2A and 2D are diagrammatic views of the operating steps of a first installation process of the dental implant according to the prior art;

Figs. 3A to 3D are diagrammatic views of the operating steps of a second installation process of the dental implant of the prior art;

Fig. 4 and Fig. 5 are two exploded axonometric views of two alternative embodiments of the dental implant according to the invention;

Fig. 6 is a diagrammatic sectional view of the main body, of a portion of the auxiliary plate and of the connection element of the dental implant shown in Fig. 4; Fig. 6A is a diagrammatic view of the main body, of a portion of the auxiliary plate and of the connection element of Fig. 6 in coupled condition;

Fig. 7 is a diagrammatic sectional view of the main body, of a portion of the auxiliary plate and of the connection element of the dental implant shown in Fig. 5;

Fig. 7A is a diagrammatic view of the main body of a portion of the auxiliary plate and of the connection element of Fig. 7 in coupled condition;

Fig. 8 is a longitudinal sectional view of the main body in an alternative embodiment according to the invention, wherein said main body is provided with two connection seats.

With reference to Figs. 4 to 8, a dental implant according to the invention is disclosed, which is generally indicated with reference letter (D).

The dental implant (D) is suitable for being applied in the mandibular or maxillary bone of a patient affected by complete or partial edentulism and therefore requires the implantation of one or more artificial teeth.

With reference to Figs. 4 and 5, the dental implant (D) comprises a main body (20) with elongated shape and longitudinal axis (Y).

The main body (20) has a truncated conical, cylindrical or partially cylindrical shape and is suitable for being implanted in a suitable primary seat (N1) formed on the mandibular or maxillary bone of the patient. The primary implant seat (N1) is obtained by means of suitable dental instruments, such as drills or the like.

Preferably, in order to ensure a stable anchoring of the main body (2) in the primary implant seat (N1), the main body (2) comprises an external thread (30) such that the main body (2) can be screwed into the primary implant seat (N1) which has been previously obtained by means of suitable dental instruments. Alternatively, said external thread (30) may be omitted and the main body (2) may be frictionally inserted into the primary implant seat (N1).

Therefore, the main body (20) acts as root for the artificial tooth (DA).

The dental implant (D) may further comprise a support (60) for the artificial tooth (DA) having an end (80) coupled to an end seat (40) formed in the main body (20). Preferably, the end seat (40) and the end (80) of the support (60) are configured in such a way as to advantageously have complementary shapes so as to prevent any relative rotation between the support (60) and the main body (20).

The end seat (40) of the main body (20) may be of internal type, i.e. forming a cavity, or of external type, i.e. having a suitably shaped projecting portion. Accordingly, said end (80) of the support (40) will be of projecting type and will be capable of fitting into the cavity, or will be of hollow type and will be capable of accommodating the suitably shaped projecting portion of the main body (20).

Additionally, in order to prevent the support (60) from axially coming out of the main body (20), the end (80) of the support (60) and the end seat (40) of the main body (20) may comprise threads suitable for mating with each other.

When the end (80) of the support (60) is completely screwed into the end seat (40), the support (60) is axially secured relative to the main body (20).

The main body (20) is preferably made of titanium or of a titanium alloy of different grades, as is the support (60). Moreover, the main body (20) may have different dimensions both axially and transversely based on the quantity of cortical bone available. Like the main body (20), also the support (60) can have different axial lengths according to the required specifications.

It should be noted that, although in Figures 4 and 5 the support (60) and the main body (20) are separate parts, the purposes of the present invention can be advantageously achieved also when said support (60) and said main body (20) are made in one piece.

The support (60) includes a head end (TC) suitably configured to be coupled by interference with a seat formed in the artificial tooth (DA).

With reference to Figs. 4 and 5, the dental implant (D) comprises an auxiliary plate (P) provided with a connection portion (170) connected to the main body (20), and one or more portions (110’, 110”, 110”’) that protrude laterally from the connection portion (170) and are suitable for being positioned in secondary bony fixing zones and spaced from the primary implant seat.

The dental implant (D) also comprises fixing means (120) of one or more projecting portions (110’, 110”, 110’”) of the auxiliary plate (P) in one or more auxiliary implant seats formed in the secondary bony fixing zones. Said auxiliary plate (P) and said means (120) generate anchoring points for the main body (20). Otherwise said, said auxiliary plate (P) and said means (120) are capable of anchoring the entire dental implant (D) in several different anchoring zones with respect to the main implant seat (N1 ) formed in correspondence with the insertion point of the artificial tooth (DA).

According to a preferred embodiment of the invention, said projecting portions (110', 110", 110") of the auxiliary plate (P) are flexible and plastically bendable in such a way that they can be positioned in the secondary bony fixing zones, and in such a way that they can be adapted to all types and configurations of mandibular or maxillary bone of the patient.

According to an alternative embodiment of the invention, said projecting portions (110', 110") may also be rigid and planar, or rigid and suitably preformed according to the specific configuration of the mandibular or maxillary bone of the patient.

Although in Figs. 4 and 5 the auxiliary plate (P) has three projecting portions (110', 110", 110"), the auxiliary plate (P) can have a different shape according to the necessities of the patient, with more or less projecting portions.

With reference to Figs. 6 to 8, the main body (20) comprises one connection seat (S) (as shown in Fig. 6 and 7), two connection seats (S) (as shown in Fig. 8) or a plurality of connection seats, each one having a radial axis (Ro, Ri) relative to the longitudinal axis (Y) of the main body (20) or having an axis parallel to a radial axis relative to the longitudinal axis (Y) of the main body (20). Otherwise said, said connection seats (S) have an axis (Ro, Ri) that can be incident to the longitudinal axis (Y) of the main body (20) or oblique to the longitudinal axis (Y) of the main body (20).

The connection portion (170) of the auxiliary plate (P) is connected to the main body (20) by means of a connection member (V) suitably configured to connect the connection portion (170) to said connection seat (S) of the main body (20). Preferably, the connection element (V) and the connection portion (170) are made in separate connectable pieces. In particular, said connection portion (170) comprises a through hole (161 ) for the insertion of said connection element (V). The connection element (V) comprises a threaded shank (G) coupled with a thread (Sf) obtained on the connection seat (S), and a head (T) in contact with said connection portion (170). The auxiliary plate (P) is secured to the main body (20) by engaging the head (T) with the connection portion (170) of the auxiliary plate (P). If the aforesaid securing operation, which provides for engaging the head (T) on the connection portion (170), is not perfectly stable and safe, then said connection element (V) may comprise a fixing portion (F) interposed between the threaded shank (G) and the head (T) and suitably configured in such a way as to be rigidly coupled by means of interference with the through hole (161 ) of the connection portion (170)

For illustrative purposes, the fixing portion (F) and the through hole (161 ) may comprise a thread that provides a threaded coupling between the connection element (V) and the connection portion (170).

Alternatively, the fixing portion (F) and the through hole (161 ) may have a truncated-conical profile in such a way to provide a rigid truncated-conical coupling between the connection element (V) and the connection portion (170).

Additionally, said fixing portion (F) and the through hole (161 ) may comprise both the thread and the truncated-conical profile.

Although not shown in the appended figures, according to a possible embodiment of the invention, said connection element (V) and said connection portion (170) may be made in one piece.

With reference to Figs. 6A and 7A, the connection seats (S) may be a through seat and the connection element (V) may be configured in such a way to comprise an ending section (Vf) suitable for projecting from the main body (20) when the connection element (V) is coupled with a connection seat (S). The end section (Vf) can be screwed in a cortical bone and/or can act as a support for the membrane of the maxillary sinus in order to keep said membrane in raised position. By keeping the membrane in raised position, a bone regeneration will be induced by osseointegration effects around the main body (20), thus improving the retainability of the main body (20) and consequently the retainability of the dental implant (D)

Going back to Figs. 4 and 5, said connection portion (170) has an annular shape with said through hole (161 ) in central position. Advantageously, the connection seat (S) comprises a mouth section (S1 ) suitably configured to partially or totally accommodate the connection portion (170) of the auxiliary plate (P).

It should be noted that the connection portion (170) may comprise a more or less projecting section relative to the main body (1 ) from which the projecting portions (110', 110", 110") of the auxiliary plate (P) extend. In such a way, said connection portion (170) can act as spacer, thus making the implant (D) versatile and adaptable to any morphology and any zone of the patient's mandibular or maxillary bone.

With reference to Figs. 4 and 5, each projecting portion (110’, 110”, 110’”) comprises one or more second through hole (130) and said means (120) comprise fixing screws (121 ), each fixing screw (121) being inserted in one of said second through holes (130) and suitable for being coupled with one of said auxiliary implant seats (N2).

The abutting of the heads (121 ') of the fixing screws (121 ) in the second through holes (130) ensures that the auxiliary plate (P) is secured to the maxillary or mandibular bone of the patient. It should be noted that the fixing screws (121 ) can be used in a lower number with respect the second through holes (130) during installation. The number of the fixing screws (121 ) will depend on the patient's condition and the assessment made by the doctor on a case-by-case basis.

Preferably, the heads (121 ') of the fixing screws (121 ) and the second through holes (130) have a complementary configuration in such a way to be rigidly coupled by means of interference.

In particular, the heads (12T) of the fixing screws (121 ) and the second through holes (130) have a truncated-conical profile in such a way to obtain a rigid coupling of truncated-conical type between the fixing screw (121 ) and the auxiliary plate (P) by means of interference. Alternatively, the heads (121 ’) of the fixing screws (121 ) and the second through holes (130) comprise threads to obtain a threaded connection between the fixing screws (121 ) and the auxiliary plate (P).

Further, according to an additional alternative embodiment of the invention, the heads (121 ') of the fixing screws (120) and the second through holes (110', 110", 110") may comprise both the truncated-conical profile and the threads.

Preferably, said main body (20) comprises a planar lateral surface (Q) whereon the connection seat (S) ends. More precisely, said planar lateral surface (Q) perimetrally surrounds the mouth section (S1 ) of the connection seat (S). The connection seat (S) has an axis (Ro, Ri) that is perpendicular to the plane whereon said planar lateral surface (Q) lies.

The planar lateral surface (Q) may lie on a plane parallel to the longitudinal axis (Y) of the main body (as shown in Fig. 6), or on an inclined plane (as shown in Fig. 7) relative to the longitudinal axis (Y) of the main body (20).

Consequently, the axis (Ro, Ri) of the connection seat (S) will be an axis (Ro) orthogonal to the longitudinal axis (Y) of the main body, if the planar lateral surface (Q) lies on a plane parallel to the longitudinal axis (Y) of the main body (20) or will be an inclined axis (Ri) if the planar lateral surface (Q) lies on a plane inclined to the longitudinal axis (Y) of the main body (20).

Preferably, the planar lateral surface (Q) lying on an inclined plane is obtained in an end section (201 ) of the main body (20) in such a way that the main body (20) has a tapered profile going towards the tip.

With reference to Figs. 9A, 9B, 9C and 9D, a process for the surgical installation of the dental implant (D) according to the invention is described below.

Reference will be made herein to the process wherein the auxiliary plate (P) and the connection element (V) are separate connectable pieces and the support (60) is formed in one piece with the main body (20). With reference to Fig. 9A, firstly, the process provides for a step of preparing the primary installation seat (N1 ), wherein the main body (2) is to be positioned and fixed.

Such a step can provide for the following substeps:

- opening a gingival flap,

- forming a lead-in in the cortical bone,

- drilling the bone where the main body (20) is to be installed by means of drills or the like, in order to form the primary implant seat; if necessary, threading the primary implant seat by means of a tapping tool;

Said step of threading may be omitted if the thread (30) of the main body (20) is not provided, in which case the main body (20) will be inserted by friction.

With reference to Fig. 9A, the process also provides for a step of preparing the auxiliary implant seat or seats (N2). The auxiliary implant seats may be constructed with substantially equivalent steps to those used for the provision of the primary implant seat.

At this point, once the primary implant seat and the auxiliary implant seat(s) have been prepared, the process provides for a step of inserting the main body (20) in the primary implant seat (N1 ), as shown in Fig. 9B.

The main body (20) is implanted in such a way that the planar lateral surface (Q), and consequently the mouth section (S1 ) of the connection seat (S), lies parallel to a bone or is disposed in correspondence with a previously formed hole or opening. If the hole or opening is not formed previously, then the hole or opening will be formed after installing the main body (20) in the point where the mouth section (S1 ) of the connection seat (S) is positioned.

It should be noted that the step of preparing the auxiliary implant seats can be performed indifferently either before or after the step of inserting the main body (20) in the primary implant seat.

With reference to Fig. 9C, then a step of connecting and positioning the auxiliary plate (P) is performed, wherein the auxiliary plate (P) is connected to the main body (2) by means of the aforementioned connection element (V) in such a way that the second through holes (130) are arranged in correspondence with the auxiliary implant seats (N2).

If said projecting portions (110', 110", 110") are of flexible type, then said projecting portions (110’, 110”, 110’”) can be bent in such a way that they fit the bone and the secondary through holes (130) are perfectly aligned with said secondary implant seats (N2).

Additionally, said projecting portions (110', 110") can also be positioned in such a way that free spaces are provided between the bone and the auxiliary plate to encourage the bone regeneration.

With reference to Fig. 9D, the process provides for a step of inserting and implanting the fixing screws (121 ) in said auxiliary implant seats in such a way as to securely connect the auxiliary plate (P) to the bone.

Finally, the gingival flaps are closed and sutures are made, if required.

If the support (60) and the main body (20) are made in separate pieces, and not in one piece, then a step of connecting the support (60) with the main body (20) will follow. The connection of the support (60) to the main body (20) can be performed immediately after the installation of the main body (20) and of the fixing screws (120) (one-stage immediate-load procedure) or at a later time (two-stage delayed-load procedure), which allows for an osseointegration of the main body (20) before the application of the support (60), namely before the dental implant (D) is stressed during the mastication of the patient.

According to an alternative embodiment of the invention, the dental implant (D) may also comprise a plurality of main bodies (20) connected by means of the auxiliary plate.

According to an additional alternative embodiment of the invention, if a plurality of connection seats (S) is formed on the main body (2), a plurality of auxiliary plates (P) may be connected to the main body (2), each one by means of a corresponding connection portion (170), or a single auxiliary plate (P) may be connected by means of multiple connection portions (170) to the same single auxiliary plate (P).

Finally, although the appended figures always show a monolithic connection portion (170) obtained in one piece with the auxiliary plate (P), the purposes of the present invention can be achieved also if, instead of being in one piece, said connection portion (170) is composed of two separate connectable elements, namely a first external element that is integral with the auxiliary plate (P), and a second internal element provided with said through hole (161 ). In such a case, the internal element and the external element can be connected and rigidly coupled by means of a threaded or truncated conical coupling, or in any case by means of a coupling that prevents the relative rotations between the two elements once they are firmly connected.

In such an instance, during the installation process of the system, it will be possible to first connect the internal element of the connection portion (170) to the main body (20) by means of said connection element (V) and subsequently couple the second element to the main body (20) with the projecting portions (110', 110") integral with the second element.

As a result of the foregoing description, the advantages and strengths of the dental implant (D) according to the present invention as compared to the dental implant (1 ) of the prior art become apparent.

First of all, the coupling of the auxiliary plate (P) with the main body (20) by means of said connection element (V) is safer and easier to perform during dental surgery.

In fact, whereas the dental implant (1 ) of the prior art required to position with extreme care and precision the fixing opening (16) of the auxiliary plate (10) in axis with the primary implant seat, before inserting and implanting the main body (2) in the primary implant seat, now it is sufficient to simply implant the main body (20) and then connect the auxiliary plate (P) according to the position of the mouth section (S1 ) of the connection seat (S). It appears evident that such a solution is extremely simpler and faster to perform.

Furthermore, the dental implant (D) is extremely versatile since screws or main bodies of any shape and any kind can be used as main body (20).

More precisely, whereas in the dental implant (1 ) of the prior art the fixing portion (15) of the main body (20) had to be suitably shaped in order to match with the fixing opening (16), now in the dental implant (D) according to the invention no specific configurations of the main body (20) are necessary and therefore any implant element or any fixing screw provided with said connection seat (S) formed with suitable tools can be used as main body (20).

Additionally, because of the provision of the connection seat (S) or of a plurality of connection seats (S), the dimensions of the projecting portions (110', 110") can be reduced also in the case of a large distance between the insertion point and the secondary bony fixing zone.

Numerous variations and modifications may be made to the present embodiment of the invention, within the scope of a person skilled in the art, but in any case within the scope of the invention as expressed by the appended claims.