Abstract:
A dental implant system is provided including an improved drive arrangement for enhancing the wall strength of the dental implant and for providing a reduced number of indexing points without reducing wall strength of the dental implant.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 61/130,163, filed on May 28, 2008. 
     
    
     FIELD 
       [0002]    The present disclosure relates to a dental implant system and more particularly, to a dental implant with an improved implant to abutment engagement geometry. 
       BACKGROUND AND SUMMARY 
       [0003]    This section provides background information related to the present disclosure which is not necessarily prior art and provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features. 
         [0004]    Dental implants are screwed or otherwise inserted into a prepared site in a jaw bone and serve as a fixture on which a prosthetic tooth or other dental appliance can be mounted. Dental implants have been in clinical use as a predictable treatment modality for more than 40 years and are well known in the art. Dental implants have various external shapes and generally fall into one of three categories including threaded (with different thread geometry and configurations), cylinders (with or without various features such as grooves, holes, etc.) and stepped. Additionally, dental implants can also be classified into two categories depending upon the connection at the neck into two broad categories including implants with external connections with different shapes, designs and configurations including hex, square, etc and implants with internal connections with different shapes designs and configurations including hex, octagon, tri-lobe and double helix. 
         [0005]    Dental implants are inserted into the jaw bone via a surgical procedure where the bone is drilled and an osteotomy site is prepared to certain dimensions depending on the implant design, size, and shape. To deliver the implant into the osteotomy site, a carrier mechanism is needed to connect the implant to a ratchet, torque device, or dental handpiece. This carrier mechanism can be in the form of a driver or a surgical mount. Certain indexing features are needed to provide anti-rotational characteristics during the insertion process. For externally connected implants such as the externally hexed implants, a driver or mount with a slightly larger but matching hexed concavity is used to fit over the external hex of the implant. This driver is secured with a fastener screw sometimes to provide a secure connection and help drive the implant to the site. For internally connected implants, the driver or mount relies on internal configurations for anti-rotation to deliver the implant to the site. Drivers can rely on internal hexes, octagons, or other features to engage the implant. The drivers and mounts generally have a similar shape but slightly smaller dimension to the inside of the implant in order to fit inside the implant. For example, an implant with an internal octagon concavity can use a driver with an octagon cross-section with a slightly smaller dimension as a driver and so on. In terms of patient safety, the implant is the only implantable part of the system and should have the entire system designed to maximize its efficacy and safety. The jaw bones of patients come in different densities with the lower jaws of higher density than upper jaws. Depending on the bone density, the osteotomy preparation, and the external shape of the implant, extremely high torque values can be reached during the implant insertion process. 
         [0006]    One potential problem with dental implants having internal connections is that the interior cavity that defines the internal connection is surrounded by a thin wall portion. It is desirable to maintain the implant with as small of a size as possible for adequately supporting a prosthetic tooth while maintaining sufficient strength to withstand the torques applied to the dental implant during insertion and to provide a strong connection between the dental implant and the prosthetic tooth. 
         [0007]    According to one aspect of the present disclosure, a dental implant includes a threaded shank portion and a head portion extending from the shank portion and including a recessed cavity in an axial end thereof. The recessed cavity has a cone shaped region extending from the axial end of the head portion and a multi-sided region extending from the cone shaped region in a direction extending away from the axial end of the head portion. The geometry of the multi-sided region provides for improved wall strength while maintaining a small head profile. 
         [0008]    Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
     
    
     
       DRAWINGS 
         [0009]    The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. 
           [0010]      FIG. 1  is a side plan view of a dental implant according to the principles of the present disclosure; 
           [0011]      FIG. 2  is a cross-sectional view taken longitudinally of the dental implant of  FIG. 1 ; 
           [0012]      FIG. 3  is a detailed enlarged view of the head portion of the dental implant shown in  FIG. 1 ; 
           [0013]      FIG. 4  is an enlarged detail view of a portion of the threaded shank of the dental implant shown in  FIG. 1 ; 
           [0014]      FIG. 5  is an end view of the head portion of the dental implant shown in  FIG. 1 ; 
           [0015]      FIG. 6  is an end view of the threaded shank portion of the dental implant shown in  FIG. 1 ; 
           [0016]      FIG. 7  is a perspective view of a digital abutment according to the principles of the present disclosure; 
           [0017]      FIG. 8  is a cross-sectional view showing the attachment of the digital abutment to a dental implant according to the principles of the present disclosure; 
           [0018]      FIG. 9  is a cross-sectional view of an exemplary prosthetic screw according to the principles of the present disclosure; 
           [0019]      FIG. 10A  is a partial perspective view of a first end of an abutment having a modified octagonal shape according to the principles of the present disclosure; 
           [0020]      FIG. 10B  illustrates the first end of the abutment shown in  FIG. 10   a  inserted into the recessed cavity of an implant according to the principles of the present disclosure; 
           [0021]      FIG. 11A  is a partial perspective view of a first end of an abutment having an octagonal shape; and 
           [0022]      FIG. 11B  illustrates the end of an octagonal abutment inserted in a modified octagonal recess of an implant according to the principles of the present disclosure. 
       
    
    
       [0023]    Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. 
       DETAILED DESCRIPTION 
       [0024]    Example embodiments will now be described more fully with reference to the accompanying drawings. 
         [0025]    Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail. 
         [0026]    The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed. 
         [0027]    When an element or layer is referred to as being “on,” “engaged to,” “connected to,” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to,” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
         [0028]    Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments. 
         [0029]    Spatially relative terms, such as “inner,” “outer,” “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. 
         [0030]    With reference to  FIGS. 1-6 , a dental implant  10  according to the principles of the present disclosure will now be described. The dental implant  10  includes a threaded shank portion  12  and a head portion  14  extending from the shank portion  12 . The threaded shank portion  12  can include a standard cutting thread form. The threaded shank portion can have a sand blasted surface with a surface finish of bio-coat MPS 041 which is well known in the implant industry. The end portion  16  of the threaded shank portion  12  can be provided with tapping threads  18  as best illustrated in  FIGS. 1 and 6 . The tapping threads  18  can be spaced at predetermined intervals. In the embodiment shown, 120 degree intervals are provided between the tapping threads  18 , although other intervals can be utilized. 
         [0031]    In the embodiment shown, as illustrated in  FIG. 4 , the thread of the threaded shank portion  12  has a major diameter d 1  of approximately 0.157 inches and a minor diameter d 2  of 0.13 inches. Furthermore, the thread pitch P is approximately 0.028 inches while the thread angle “a” is approximately 70 degrees. It should be understood that the dimensions provided herein are for exemplary purposes only and other dimensions can be utilized. With reference again to  FIG. 6 , is it noted that the tapping threads  18  are defined by a radially inwardly extending cut region that is spaced a distance “s” of approximately 0.03 inches from the axis A of the dental implant. Furthermore, with reference to  FIG. 1 , the cut sections defining the teeth  18  are provided at an angle a 2  of approximately 25 degrees relative to the axis A. 
         [0032]    With reference to  FIG. 3 , a detailed enlarged view of the head portion  14  of the dental implant  10  is shown. The head portion  14  tapers slightly inward from the end  20  toward the shank portion  12 . By way of example, the maximum diameter dmax of the head portion  14  can be approximately 0.1636 inches toward the end  20  while the minimum diameter dmin of the head portion can be 0.158 inches at the end proximal to the shank portion  12 . The implant  10  can have multiple sizes with the maximum diameter dmax varying for each implant size, while the size and shape of the recessed cavity  26  remain the same for each size implant. The head portion  14  can be provided with a series of recessed grooves  22  in which bone growth can penetrate for securing the implant in the patient&#39;s jaw. The recessed grooves  22  can be defined by a radiused groove having a radius of approximately 0.005 inches. According to one aspect of the present disclosure, the first groove  22  closest to the end  20  of the head portion  14  can be spaced a distance D 3  of approximately 0.022 inches from the end  20 ; the second groove  22  can be spaced a distance D 4  of approximately 0.045 inches from the end  20 ; the third groove  22  can be spaced a distance D 5  of approximately 0.069 inches from the end face  20 ; and the fourth groove  22  can be spaced a distance D 6  of approximately 0.092 inches from the end face  20 . 
         [0033]    With reference to  FIG. 2 , the head portion  14  can have a length L 1  of approximately 0.109 inches while the total length of the implant can be approximately 0.512 inches. The head portion  14  can have a chamfered surface  24  adjacent to the end face  20  that can have an electropolished finish. With reference to  FIG. 2 , the dental implant  10  includes a recessed cavity  26  extending axially from the end face  20 . The recessed cavity includes a cone-shaped region  28  extending from said axial end  20  of the head portion  14  and a multi-sided region  30  extending from the cone-shaped region  28  in a direction extending away from the axial end  20  of the head portion  14 . A shoulder  32  is provided at the end of the multi-sided region  30  and an internally threaded bore  34  extends from the shoulder  32 . 
         [0034]    With reference to  FIG. 5 , the multi-sided region  30  can include a plurality of concave curved portions  38  separated by intermediate corner portions  40  wherein the concave curved portions  38  define the largest diameter portions of the multi-sided region. In the embodiment shown, four concave curved portions  38  are provided with four corner portions  40  disposed therebetween. The multi-sided region  30 , as described herein, can include other forms including square, triangle, hex, octagon, pentagon, and other shapes, however, it has been found that the arrangement as shown in  FIG. 5  having four indices instead of six, is easier for purposes of allowing the prosthetic device to be designed based upon the orientation of the indices of the present design as opposed to a six-sided hex or other forms with larger numbers of indices. Furthermore, with the curved concave portions  38 , defining the outermost diameter of the multi-sided region, the design of the present disclosure avoids sharp edges at the outermost portion that would otherwise define stress concentrations at the locations of the smallest wall thickness. With the curved concave portions  38 , the stress concentrations can be avoided at these locations in order to strengthen the wall of the recessed cavity  30  and to allow for a minimized size of the head portion  14  of the implant  10 . 
         [0035]    In the embodiment shown, the concave curved portions  38  are spaced at 90 degrees from one another and spaced at 45 degrees from the corner portions  40 . As shown in  FIG. 10B , the modified octagonal shape provides four distinct indexing positions for accurate transfer and repeated placement of an abutment  42  ( FIG. 10A ) having a corresponding exterior configuration. The modified octagonal shape (four protrusions) provides for four distinct indexing positions of the abutment  42  as opposed to eight, thus simplifying the design and installation procedure. Furthermore, the modified octagonal shape of the multi-sided region  30  can also receive an octagon shaped abutment  44 , as illustrated in  FIGS. 11A-11B . Thus, the modified octagonal shape of the multi-sided region  30  of the dental implant  10  allows for flexibility in options using abutments that can have 4 or 8 different indexing positions depending upon desired applications. By way of example only, the diameter D 7  between the concave curved portions  38  can be 0.1058 inches while the diameter D 8  between the corner portion can be 0.1014 inches. Furthermore, the angle of the corner portions  40  relative to a line passing through the apex of the corner portions  40  and through the center axis can be an angle b of 67.5 degrees. It should be understood that all of the dimensions provided herein are exemplary dimensions and that larger and smaller dimensions could be utilized for a desired application. 
         [0036]    With reference to  FIG. 2 , it is noted that the cone-shaped region  28  of the recessed cavity  26  has an outer diameter D 9  that can be 0.126 inches while the cone angle C can have an angle of between 14 and 40 degrees and more particularly 26 degrees such that the wall of the cone-shaped region  28  is angled relative to a central axis by between 9 and 16 degrees, and more particularly 13 degrees to allow improved removability of the abutment without sacrificing wall strength of the implant. 
         [0037]    The dental implant  10  cuts threads into a pre-drilled hole in a patient&#39;s jaw bone. A driver having a multi-sided end that corresponds to the multi-sided region of the recessed cavity is inserted into the recess cavity  26  and drives the implant into the bone. The material for the dental implant  10  can be Ti 6 Al 4 V. The inside surface of the recessed cavity  26  can have an electropolished finish. 
         [0038]    With reference to  FIGS. 7 and 8 , a digital abutment  50  is shown including a first end  52  having a multi-sided region  54  and a cone-shaped region  56  for receipt in the recessed cavity  26  of a corresponding dental implant  10 . The multi-sided region  54  can include a modified octagonal shape having four curved convex portions  54   a  disposed between four intermediate corner portions  54   b , as illustrated in  FIGS. 10   a ,  10   b . The digital abutment  50  includes a second end  58  having a recessed cavity  60  therein. The recessed cavity  60  includes a multi-sided region  62  that is identical to the multi-sided region of the implant  10 . The configuration of the multi-sided region  62  allows for a digital three-dimensional impression to be taken of the digital abutment  50  within a user&#39;s mouth with the orientation and alignment of the multi-sided region  30  of the recessed cavity  26  in the dental implant being duplicated at the top of the digital abutment  50 . A prosthetic tooth can then be designed, machined, and placed on a prosthetic abutment without the need for an open or closed tray impression procedure based upon the scanned digital image of the digital abutment within the user&#39;s mouth. 
         [0039]    The digital abutment  50  includes a shoulder portion  64  disposed at a bottom of the recessed cavity  60  and an aperture  66  extending from the shoulder to the first end  52  of the digital abutment. The shoulder  64  provides a surface against which a head portion  68  of a prosthetic screw  70  (see  FIG. 9 ) can seat against. The prosthetic screw  70  includes a threaded portion  72  which is threadedly engaged with the threaded bore  34  in the dental implant  10  for securing the digital abutment  50  to the dental implant  10 . With prior designs, the orientation of the multi-sided region of the recessed cavity in the dental implant  10  was unknown while the abutment was in place, whereas with the digital abutment of the present disclosure, the multi-sided region of the recessed cavity of the dental implant  10  is now reproduced at the end of the digital abutment  50  for use in designing and manufacturing a prosthetic abutment and prosthetic tooth. 
         [0040]    It should be noted that the multi-sided region  54  of the digital abutment can be designed to engage other shapes of multi-sided recesses such as triangular, square, rectangle, hex, octagon, and other shapes. However, it has been found to be particularly advantageous to utilize the specific orientation as described with reference to  FIG. 5  above. The concept of the digital abutment  50  does not depend upon the specific geometry of the recessed cavity  26  of the implant and the recessed cavity  60  of the digital abutment, other than the fact that the recessed cavity  60  in the digital abutment needs to replicate the orientation and geometry of the multi-sided region  30  of the recessed cavity  26  in the dental implant  10 . The digital abutment  50  can receive a temporary crown so that the digital abutment can remain in place for preserving the gingival architecture while waiting for the final crown and the final abutment. 
         [0041]    The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the invention, and all such modifications are intended to be included within the scope of the invention.