Abstract:
This invention refers to a device exploitable within the scope of dental implantology, with specific reference to the set up and to the installation of a multi-teeth fixed prosthesis, either partial or total. The said invention specifically concerns a connection device ( 1 ) between a dental implant and the prosthesis. In particular, this invention concerns a connection device ( 1 ) including a bearing element ( 2 ) and a prosthesis connecting element ( 3, 3′ ), with the said connecting element ( 3, 3′ ) being matchable with the aforementioned bearing element ( 2 ), wherein the bearing element ( 2 ) includes a base portion ( 7 ) on which a conical portion ( 8 ) is further positioned and is characterized by the fact that between the base portion ( 7 ) and the conical portion ( 8 ) a shoulder ( 12 ) with a stop portion ( 13 ) is formed to prevent relative rotation of the connecting element ( 3, 3′ ) with respect to the bearing element ( 2 ).

Description:
FIELD OF THE INVENTION 
       [0001]    This invention refers to a device exploitable within the scope of dental implantology, with specific reference to the set up and to the installation of a multi-teeth fixed prosthesis, either partial or total. The said invention specifically concerns a connection device between a dental implant and the prosthesis. 
       BACKGROUND ART 
       [0002]    The techniques normally employed for the construction and the installation of a dental prosthesis, both partial and total, are complex and generally require very long spans of time. After the implant has been positioned in the gingival arch, the procedure is based on several steps including getting the dental impression, installing a temporary prosthesis and substituting the latter with a permanent one. In addition to the fact that the patient is thus obliged to undergo several dental sessions, the procedure requires great skill on the side of the operator as well as of the dental technician, in charge of the material realization of the prosthesis. 
         [0003]    Recently, more sophisticated techniques have been gradually gaining ground, which are based on a digital imprint, that is to say on a digital image obtained directly from the patient&#39;s mouth. This technique obviously requires very high precision levels. 
         [0004]    For a fixed total prosthesis, it is not necessary to proceed with the implant of every single tooth. Indeed, only three or four implants -on whom the complete dental arch prosthesis will be then fixed- can be positioned in the patient&#39;s jaw and mandible. 
         [0005]    A dental implant consists of a bio-compatible screw, typically in titanium, covered if need be with substances enhancing cohesion, osteointegration and resistance to microbial attack. The implant includes a base section intended to emerge out of the gingival and including an internal thread to fix a connection device the dental bridge will be put on. It is quite rare that the various dental implants necessary for prosthesis reconstruction are positioned in parallel. Typically, the longitudinal axes of dental implants, and, consequently, those of the corresponding connection devices, will be divergent, thus making even more difficult prosthesis design and installation. In particular, after the dental impression has been obtained and the prosthetic bridge has been realized, the correct repositioning of the connection devices functional to the subsequent bridge fixing is practically rather complex. 
       SUMMARY OF THE INVENTION 
       [0006]    This invention aims at realizing a device exploitable all through the various steps of multi-teeth fixed partial or total prosthesis implantology as well as making available a new prosthetic technique able to overcome, at least in part, the difficulties of the prior art. 
         [0007]    The said problem is overcome thanks to a connection device for dental implants, as discussed in the attached claims, whose definitions form an integral part of this description. 
         [0008]    An object of this invention is thus a connection device for dental implants allowing for an easy assembling on the implant as well as for an equally easy removal and making the subsequent repositioning precise and reproducible. 
         [0009]    A further object of the invention is a kit exploitable for multi-teeth fixed prosthesis repositioning and fixing to dental implants. 
         [0010]    An additional realization configuration is a method for the design and the production of a multi-teeth fixed prosthesis that relies on the invention&#39;s connection device. 
         [0000]    Further features and advantages of this invention will result from the description of some embodiments—deemed to be illustrative, but not exhaustive—here below, with specific reference to the following figures. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  represents an exploded perspective view of the invention connection device; 
           [0012]      FIG. 2  represents a perspective view of a detail of the connection device displayed in  FIG. 1 ; 
           [0013]      FIG. 3  represents a perspective view of a second detail of the connection device displayed in  FIG. 1 , according to a different embodiment; 
           [0014]      FIG. 4  represents a perspective view of the connection device during the assembling step on a dental implant; 
           [0015]      FIG. 5  represents a perspective view of a patient&#39;s jaw; 
           [0016]      FIGS. 6A, 6B and 6C  represent perspective views of a sequence of steps aimed at the realization of a fixed total prosthesis; 
           [0017]      FIG. 7  represents a perspective view of the assembling step of a fixed total prosthesis with the invention connection devices; 
           [0018]      FIG. 8  represents a perspective view in transparency of a fixed total prosthesis assembled on a patient&#39;s jaw. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0019]    With specific reference to  FIGS. 1-4 , the invention connection device, denoted in its entirety by number  1 , includes a bearing device  2 , a connection device  3  with a prosthesis, a first fixing screw  4  to anchor the bearing device  2  to a dental implant  6  and a second fixing screw  5  of the connection device  3  to the bearing device  2 . 
         [0020]    The bearing device  2  includes a base section  7 , on which a conic section  8  is located. 
         [0021]    The base section  7  includes a lower surface  7   a , whose structure and dimensions are adaptable to the most widespread implant screw types available for sale and further has a hole  9   a.    
         [0022]    The conic section  8  has a first hole  9  aligned with hole  9   a  belonging to the base section  7  and forming a channel with the latter. Furthermore, the conic section  8  also includes a second hole  10  whose X axis is inclined relative to the Y axis of the first hole  9 . The conic section  8  includes a conic surface  11 , whose generatrixes go through a generic point of the X axis. 
         [0023]    The second hole  10  is threaded internally. 
         [0024]    Between the base section  7  and the conic section  8  a shoulder  12  with a block portion  13  is formed, whose major aim will be clarified further ahead in this description. 
         [0025]    The block section  13  can be practically realized by changing the slope of the shoulder surface  12  to form a convex profile or a wedge (as shown in the pictures), or a concave or “V” profile. Alternatively, a tooth, a notch or any other blocking element could also be used for that purpose. 
         [0026]    The threaded hole  10  has an external edge  14  whose conicity is relatively more marked compared to that of the conic surface  11 . 
         [0027]    The connection device  3  includes a coupling portion  15  with the bearing device  2 , from which an anchor portion  16  for a prosthesis reaches out. 
         [0028]    The connection device  3  includes a longitudinal through hole  17  allowing for the introduction of the corresponding fixing screw  5  to the bearing device  2 . 
         [0029]    The coupling portion  15  has a shape that is complementary to conic portion  8  of the bearing device  2  and further has an edge  18  whose profile shape perfectly matches the shoulder  12 . 
         [0030]    Based on the embodiment shown in the figures, the edge profile  18  has a V-shaped portion  19  complementary to the wedge profile of the shoulder&#39;s  12  block portion  13 . 
         [0031]    The anchor section  16  has a substantially cylindrical or slightly frusto-conical shape and has a reference mark  20  on the external surface. 
         [0032]    The fixing screw  4  connecting the bearing device  2  to the implant is a screw like those commonly used for this type of implementation and has a thread  21  matchable with the internal thread of the implant screw head and a head  22  with a notch suited to a Phillips screwdriver C 1  or of any other conventional type. 
         [0033]    The fixing screw  5  of the connection device  3  to the bearing device  2  is a screw like those commonly used for these types of implementations and has a thread  23  matchable with the threaded hole  10  of the bearing device and a head  24  which is substantially cylindrical and jutting out relative to the thread  23 , so as to function as a block device against a shoulder  25  within the connection device  3  hole  17 . The head  24  of the fixing screw  5  further includes a notch  26  suited to a Phillips screwdriver C 2  or, in other embodiments, to any other type of screwdriver. 
         [0034]    In a different embodiment, shown in  FIG. 3 , the connection device  3 ′ is identical in all respects to the one shown in  FIG. 1 , apart from the fact of including a through hole  27  on the coupling portion  15 , perfectly aligned with the hole  9  of the conic portion  8  of the bearing device  2 , whenever the latter and the connection device  3 ′ are assembled together. 
         [0035]    As displayed in  FIG. 4 , the through hole  27  of the connection device  3 ′ allows for the screwing or the unscrewing of the bearing device  2  of the implant I, with no need to remove the connection device  3 ′ preliminarily. The advantage of this solution will be clarified further ahead in this description. 
         [0036]    The bearing device  2 , the connection device  3 ,  3 ′ and the corresponding fixing screws  4 ,  5  are typically realized in titanium or titanium alloys (e.g. grade 5 titanium), medical chromium, or any other bio-compatible material suited to these implementations. 
         [0037]    We will now describe the design and realization method of a multi-teeth fixed prosthesis in line with this invention, for instance, to replace a mobile prosthesis (bridge or total), once the dentist has provided for the installation of the necessary implant screws  6  within a patient&#39;s oral cavity. 
         [0038]      FIG. 5  displays as an example a patients&#39; jaw M, on which a temporary prosthesis or an old bridge P are present. Three reference points  28  are attached on the gum (only two reference points  28  are visible, the third being approximately located in a symmetrical position with respect to the first point on the right). 
         [0039]    In certain embodiments, the reference points  28  are made up of small semi-spheres, for instance in some plastic material, stuck on the mucosa through stick adhesives, like for instance medical grade cyanoacrylate or polymethacrylate. 
         [0040]    At this point, you perform a first digital vestibular scan of both jaw M with three reference points  28 , and of the mandible (not drawn), so as to obtain a digital image of the vestibular oral cavity of the patient. 
         [0041]    In some realization configurations the three reference points  28  can be placed also or only on the mandible. 
         [0042]    The digital scan can be performed by means of a scanner or a camera of the type used in dental applications. 
         [0043]    After the implant screws  6  (usually four in the case of a fixed total prosthesis) were fixed on the gingival arch of a patient, if not already present, on each of them is screwed the bearing element  2 . Onto the support element  2  can be screwed in advance the drilled connection element  3 ′. Indeed, thanks to the hole  27  it is possible to insert the fixing screw  4  into the hole  9 - 9   a  of the bearing element  2  ( FIG. 4 ), possibly using the anchoring portion  16  of the connection element  3 ′ as a handle of the device. In fact, being the bearing element  2  small and therefore difficult to handle, its mounting on the screw implant  6  may present difficulties. 
         [0044]    The jaw of the patient M on which were mounted the bearing elements  2  associated with the drilled connection elements  3 ′ is shown in  FIG. 6A . Also visible are the three points of reference  28  still positioned on the gingival mucosa. As can be seen, the axes of the connecting elements  3 ′ are not parallel. 
         [0045]    The presence on the bearing elements  2  of the stopping portion  13 , which interacts with the edge  18  of the connection element  3 ′, allows to avoid the rotation of the latter about the axis X, thus making reproducible and uniquely determined its position relative to the support element  2 . The reference notch  20  present on the surface of the anchoring portion  16  allows the identification of the correct position of the connection devices  1  in the oral cavity. 
         [0046]    At this point, you perform a second digital scanning of the whole mouth, so as to obtain a digital image of the total of the oral cavity with the connection devices  1  mounted. The three reference points  28  allow the comparison of this digital image with that taken earlier. 
         [0047]    A bar  29  of a ductile material (resin or metal, preferably with a non-circular section) is shaped so as to connect the various connection devices  1  mounted on the jaw M, then the shaped bar  29  is affixed thereto, for example by means of a self-curing resin, so as to obtain a jig  30  ( FIG. 6B ). 
         [0048]    We proceed to the removal of the jig  30  from the oral cavity of the patient. This operation involves first the unscrewing of the various connecting elements  3 ′ by the respective bearing elements  2 , so as to remove the jig  30 . Such removal, as well as the subsequent repositioning, is permitted by the coupling between the conical connection elements  3 ′ and bearing elements  2 , despite the fact that the various connecting elements  3 ′ are offset with respect to one another. Subsequently, the individual bearing elements  2  are in turn unscrewed from relative implants  6  and removed from the oral cavity. 
         [0049]    The bearing elements  2  are then mounted on analogues of the implant screws  6  present in the patient&#39;s mouth and then the jig  30  is repositioned on them. The jig  30  with the bearing elements  2  is then placed on a base  31 , on which the analogs of the implant screws  6  are fixed for example by means of a self-curing resin, obtaining the exact repetition of the implant positions (between them) inserted in the oral cavity a model  32  ( FIG. 6C ) M of the jaw of the patient. 
         [0050]    Using an appropriate CAD/CAM software, of the type used in dental applications, we will proceed with the following steps: 
         [0051]    i) comparison of the digital vestibular images of the patient&#39;s oral cavity arising from the first and second scan; 
         [0052]    ii) design of multiple fixed prosthesis  34  through CAD/CAM systems on the basis of the comparison of step i) in order to create a project file; 
         [0053]    iii) execution of multiple fixed prosthesis on the basis of the design at point ii). 
         [0054]    In step ii), the comparison between the images of the first and second scan allows to design the prosthesis together with the holes  33  adapted to mate with the connection devices  1  of the invention, in particular with the respective connection elements  3 . 
         [0055]    The realization of the prosthesis according to step iii) can be made according to conventional methods known to skilled dental technician or by automated methods of milling (removal of material) or 3D printing (adding material) from the project file prepared in step ii). 
         [0056]    The method then provides for the following steps: 
         [0057]    removing from the template model  32  the jig  30  with the drilled connecting elements  3 ′ and mounting on its bearing elements  2  of the model  32  the non-drilled connecting elements  3 ; 
         [0058]    mounting the prosthesis  34  on the connecting elements  3  of the model  32  by inserting the connecting elements  3  into the respective holes  33  ( FIG. 7 ) and securing it for example by gluing with dental sealants; 
         [0059]    unscrewing the elements of connections  3 , and then the prosthesis  34  rigidly coupled thereto, from the model  32 ; 
         [0060]    reassembling the jig  30  with the drilled connecting elements  3 ′ on the model  32 ; 
         [0061]    Removing from the model  32  the jig  30  together with the bearing elements  2 , using the hole  27  of the connecting elements  3 ′ to unscrew them from the analogues of implant screws  6 ; 
         [0062]    repositioning in the patient&#39;s mouth the jig  30 , fixing the bearing elements  2  to the implant screws  6 ; 
         [0063]    Removing the jig  30  by unscrewing the connection elements  3 ′ from the bearing elements  2 ; 
         [0064]    Mounting on the bearing elements  2  in the oral cavity of the patient the prosthesis  34 . 
         [0065]    The same process will be repeated on the mandible. 
         [0066]    The process described above provides a digital imprint made by the digital scanning of the patient&#39;s oral cavity and the related acquisition of digital images. The process of the invention that uses the connection devices  1  described above can however also be adapted in case you want to follow a traditional method for the replacement of a fixed prosthesis with a mobile prosthesis, once the clinician has put in the patient&#39;s mouth the implants  6 . In this case it will be possible to go through the following operational steps: 
         [0067]    A) mounting on the implant screws  6  positioned on a gingival arch of the oral cavity of the patient the bearing elements  2  together with the drilled connection elements  3 ′ as shown in  FIG. 4  and as previously described. Before tightening, the bearing elements  2  must be turned on implants  6  so as to make the relative connection element  3 ′ assume the more palatal position as possible; 
         [0068]    B) adapting the old denture or a copy thereof to the drilled connecting elements  3 ′ mounted, making on it special holes  33 ; 
         [0069]    C) performing additional holes in the old prosthesis or its copy in cestibular and palatal positions; 
         [0070]    D) replacing in the patient&#39;s mouth the drilled connecting elements  3 ′ with not-drilled connecting elements  3 ; 
         [0071]    E) mounting the old denture drilled according to B) and C) on the non-drilled connecting elements  3  and fixing it to them, for example through self-curing resin; 
         [0072]    F) taking the impression of gingival mucosa by inserting into the vestibular and palatal holes according to phase C) some prosthetic silicone; 
         [0073]    G) removing the old mobile denture with the footprint of the gingival mucosa by unscrewing the connecting elements  3  by the respective bearing elements  2 , thus realizing a jig with the mucous imprint and the bite registration between the maxillary and mandible using the occlusal surface of the old prosthesis; 
         [0074]    H) mounting on the jig created in step G) analogues of implant screws  6  fixed to the bearing members  2 ; 
         [0075]    I) realizing the plaster model of the dental arch of the patient and his antagonist. 
         [0076]    Obviously the same process can be performed both starting from the jaw or from the mandible and thereby realizing the plaster model also of the antagonist, according to conventional techniques well known to the expert dental technician. 
         [0077]    The process described above allows the use of the old prosthesis as a template for repositioning and as individual print-holder for the construction of the plaster model. 
         [0078]    A further object of the invention is a kit for the design and the realization of a multiple fixed prosthesis comprising: 
         [0079]    One or more bearing elements  2 ; 
         [0080]    One or more non-drilled connecting elements  3 ; 
         [0081]    One or more drilled connecting elements  3 ′; 
         [0082]    Optionally, one or more bars  29  of a ductile material, such as a resin or a metal; 
         [0083]    Optionally, one or more base tablets  31 ; 
         [0084]    Optionally, one or more fixing screws  4 ,  5  for the bearing elements  2  to an implant  6  and for the connection elements  3 ,  3 ′ to the bearing elements  2 ; 
         [0085]    Optionally, an amount of auto-locking resin. 
         [0086]    The connection device  1  according to the invention simplifies the assembly and design/construction of a fixed prosthesis, allowing a precise repositioning without errors of the connecting elements  3 ,  3 ′ on the bearing elements  2  and of the latter on the implant screws. 
         [0087]    It&#39;s obvious that have been described only some particular forms of embodiment of the present invention, where the expert of the art will be able to make all those modifications necessary for its adaptation to particular applications, without thereby departing from the scope of protection of the present invention.