Abstract:
A dental abutment having a coronal portion for supporting a prosthesis separated from a post for seizing, galling or cold welding in a dental implant by a cylindrical portion and hemispheric base portion of length less than the combined length of the prosthetic head and locking taper post portions. The hemispherical portion of the abutment having a sloping shoulder with a surface that forms a small angle with a perpendicular to the cylindrical surface. A dental prosthesis system including such dental abutments.

Description:
FIELD 
       [0001]    The present disclosure concerns dental implant abutments. 
       BACKGROUND 
       [0002]    Dental implants are often the best treatment for missing teeth. When a damaged or decayed tooth is removed, both the visible part of the tooth, called the crown, and the root are lost. 
         [0003]    A dental implant can be placed in the jawbone so that it can be fused with natural bone and become a strong and sturdy foundation for replacement teeth. Implants can be used to replace an individual tooth or for an implant-supported bridge or denture containing multiple teeth. 
         [0004]    A dental implant abutment is a device that connects the prosthetic tooth/teeth to the dental implant. The replacement tooth is custom made to match a patient&#39;s natural teeth and is sometimes referred to as a crown or dental prosthesis. 
       SUMMARY OF THE INVENTION 
       [0005]    This disclosure describes dental abutments that can not only be used for all conventional restorative techniques, but can also be readily scanned digitally, which enables precise restorations of a tooth or teeth to be fashioned more easily and conveniently than abutments whose geometry preclude the use of digital scanning or require modification or interpretation of scanned images for use. This feature supports the movement of the dental implant field toward precise customizable prosthetic restorations and digital dentistry with the increased use of CAD/CAM technologies. 
         [0006]    The dental abutments described within can also include anti-rotational features for the prosthetic component (i.e. crown) that allows the patient&#39;s prosthesis to have a precise fit. Grooves on opposite sides of the coronal end of the abutment (i.e. longitudinal end of abutment located farthest from the bone in the implanted site) provide the anti-rotation element. Each groove is generally of a constant depth that slopes toward the shoulder to end the anti-rotational element. The sloping of the groove is symmetric to reduce material stress. The coronal end of the abutment can also have a rough surface (e.g., a grit-blasted surface) to facilitate retention. For example, grit blasting can provide asperities up to 300 microns in size. The term “asperities” is used to indicate sharp, rough, or rugged projections extending from a surface. 
         [0007]    The described dental abutments have a post in the area of the apical end of the abutment (i.e. longitudinal end located closest to the bone in the implanted site) that is received by the open end of the dental implant. The post allows for a 360° of rotation during seating to increase the likelihood of correct orientation of the abutment, or abutment-restoration unit, either intra-orally or extra-orally. This 360° rotation also facilitates parallelism for angled abutments. The post and implant connection utilizes a friction fit connection which is a locking taper. Once fully engaged, this mechanism limits or prevents unintentional rotation between the dental abutment and implant and can provide a bacterially sealed connection. The post has a cylindrical shape for simplicity and compatibility with a large number of dental implants. 
         [0008]    Some dental abutments include a coronal portion that slopes to a shoulder of the dental abutment after a fixed distance of at least a 15° angle to allow for the scanning to be performed without any additional modifications or interpretations to the scan. The distance from the coronal end to the shoulder and the shoulder width has a ratio of less than seven with a shoulder width of greater than 0.02 inches. The team that developed the present dental abutments has found that the width of the shoulder and the ratio between the distance from the coronal end to the shoulder and the shoulder width to be particularly significant in providing an abutment that is conducive to digital scanning The coronal portion slopes toward the shoulder of the dental abutment at about a 3° angle to allow the anti-rotational element to work properly. 
         [0009]    In some dental abutments, the distance from the bevel at the coronal end to the top of the hemispherical shoulder is long enough to allow all the edges of the dental abutment to be digitally scanned without additional modifications or interpretations. In contrast, other dental abutments have margins that are not smooth and/or not visible on scans so users manually draw in the margin on the scan results. 
         [0010]    The geometry of these dental abutments also allows for one conventional recording sleeve configuration to suffice for registering multiple different abutment dimensions, since different abutment sizes and angulations are independent of the prosthetic attachment aspect of the abutment. Conventional dental impression materials can be used to record and represent multiple different abutment dimensions prosthetically. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0011]      FIGS. 1A and 1B  show a dental implant and dental abutment before and after the addition of a crown, respectively. 
           [0012]      FIG. 2A  is a side view of a dental abutment.  FIGS. 2B and 2C  depict the cross section and coronal views of the abutment in  FIG. 2A , respectively. 
           [0013]      FIGS. 3A and 3B  show two dental abutments of different sizes with and without a crown. 
           [0014]      FIGS. 4A and 4B  show two dental abutments of different configurations with and without a crown. 
           [0015]      FIGS. 5A-5C  show a dental prosthesis supported by multiple dental abutments. 
           [0016]      FIGS. 6A and 6B  are, respectively, a front view and a side cross-sectional view of an angled dental abutment 
       
    
    
     DETAILED DESCRIPTION 
       [0017]      FIG. 1A  shows a dental abutment  100  engaged in a dental implant  110  which has been placed in a patient&#39;s jawbone  112 .  FIG. 1B  shows the dental abutment  100  and the dental implant  110  after a crown  114  has been placed on the dental abutment  100 . 
         [0018]    The dental abutment  100  in  FIG. 1A  extends from the apical end  116  (i.e. toward the jaw) to the coronal end  118  (i.e. toward the crown) in the longitudinal direction. The dental abutment  100  has a post  120 , which is designed to be received by the open end of the dental implant  110 . The post  120  extends from the apical end  116  of the dental abutment  100  to a retention element  122 . The dental abutment  100  also has a coronal portion (or head)  123  which designed to support the crown  114 . The coronal portion  123  extends from the coronal end  118  of the dental abutment  100  to the retention element  122 . 
         [0019]    The dental abutment  100  can be made out of a variety of materials, including titanium alloy or polyether ether ketone (PEEK). 
         [0020]      FIGS. 2A-2C  shows the dental abutment  100  in isolation to more clearly illustrate features of the dental abutment  100 . 
         [0021]    The post  120  is substantially cylindrical, which allows for the 360° rotation of the dental abutment  100  while it is being seated into the dental implant  110  (see  FIGS. 1A and 1B ) in order to facilitate a dentist&#39;s correct orientation of the prosthesis or crown  114  (see  FIG. 1B ), either intra-orally or extra-orally. This cylindrical shape provides the opportunity for the prosthesis to be used to orient and initially seat the abutment in the well of the implant. The simplicity of the cylindrical shape affords for improved manufacturability and also makes the dental abutment  100  compatible with a number of different types of dental prostheses. While substantially cylindrical, the post  120  is tapered to provide a friction fit connection which is a locking taper between the post  120  and the dental implant  110  (see  FIGS. 1A and 1B ). This configuration can facilitate seizing, galling or cold welding between the post  120  and the dental implant  110 . 
         [0022]    Once fully engaged, this mechanism limits or prevents unintentional rotation and micro-movement between the dental abutment  100  and dental implant  110  (see  FIGS. 1A and 1B ). The locking taper can also provide a bacterial seal between the two components. The angle α between sides of the post  120  and a longitudinal axis  124  of the dental abutment  100  is approximately 1.3°. Depending on the dental abutment variant, the angle between sides of the post  120  and a longitudinal axis  124  of the dental abutment  100  is typically between 1.1° and 1.6°. The geometry of the dental abutment  100  is symmetrical along the longitudinal axis  124 . 
         [0023]    The retention element  122  extends from the post  120  to the coronal portion  123 . The retention element  122  has a base  128  and a shoulder  130  which meets the base  128  at a margin  132 . The transition between the base  128  and the post  120  is a curve  134  with a radius of curvature  136  (see  FIG. 2B ) of approximately 0.02 inches. In some dental abutments, the radius of curvature  136  is more or less than 0.02 inches (e.g., between 0.01 and 0.03 inches) which can reduce stress factors and resulting fractures. The surface of the base  128  has a radius of curvature  138  (see  FIG. 2B ) of approximately 0.08 inches. In some dental abutments, the radius of curvature  138  is more or less than 0.08 inches (e.g., between 0.08 and 0.15 inches). The shape of the base  128  provides for the consistent confrontation of what is an approximation of a hemispherical contour to tissues in the proximity to the periosteum. This confrontation in turn can stimulate osteoblastic activity and subsequent bone growth. 
         [0024]    Between the hemisphere and the shoulder  130 , the side of the abutment extends for a length L 1  to the margin  132 . The perimeter (e.g., circumference) of the dental abutment increases at 1-2° in this portion of the dental abutment as distance from the apical end  116  of the dental abutment  100 . In the dental abutment  100 , the length L 1  is 0.16 inches (4 mm). As discussed in more detail below with reference to  FIGS. 3A and 3B , some dental abutments are configured in which the length L 1  is more or less than 0.16 inches (4 mm) (e.g., between 0.05 (1.3 mm) and 0.32 inches (8.1 mm)). This variability provides the opportunity to use the same inferior or post and superior or head contours on the abutment, while providing the flexibility to use with implants placed at different depths within the jaw bone. 
         [0025]    The diameter of the dental abutment at the margin  132  is 0.24 inches (6 mm). In some dental abutments, the diameter of the dental abutment at the margin  132  is more or less than 0.24 inches (6 mm) (e.g., between 0.16 inches (4 mm) and 0.31 inches (8 mm). 
         [0026]    An angle β is defined between the shoulder  130  and a plane  140  that is perpendicular to the longitudinal axis  124 . In dental abutment  100 , the angle β is approximately 15°. In some dental abutments, the angle β is more or less than 15° (e.g., between 10° and 20°). It has been found that dental abutments in which the angle β is approximately 15° allow the scanning to be performed without any additional modifications or interpretations to the scan. 
         [0027]    The coronal portion  123  includes a neck  142 , an anti-rotation portion  144 , and a bevel  146  at the coronal end of the dental abutment  100 . The neck  142  has a length L 2 . The neck  142  is substantially cylindrical with sides that are substantially parallel to the longitudinal axis  124  of the dental abutment  100 . Some dental abutments have necks with other shapes such as, for example, with rectangular or octagonal (rather than circular) cross-sections. 
         [0028]    In contrast, the anti-rotation portion  144  of the coronal portion  123  is tapered with a cone angle γ such that the perimeter (e.g., circumference) of the coronal portion  123  at the coronal end of the anti-rotation portion  144  is smaller than the apical end of the anti-rotation portion  144 . In dental abutment  100 , the cone angle γ is approximately 3°. In some dental abutments, the angle γ is more or less than 3° (e.g., between 2.5° and 3.5°). It has been found that dental abutments in which the angle γ is more than 2.5° help enable scanning to be performed without any additional modifications or interpretations to the scan. 
         [0029]    The surface of coronal portion  123  can be either rough or smooth based on the individual needs dictated by the procedure. A roughened surface can be achieved, for example, through the use of grit blasting. This provides a better surface for the adhesion of dental materials, such as opaque (i.e., composite dental resin that is used to cover unsightly dentition), as well as the crown  114  or prosthesis to the coronal portion  123 . In particular, the roughened surface can facilitate the mechanical retention of chemical bonding agents such as opaque layers of composite resins or prosthetic cementing agents. 
         [0030]    The structure of the coronal portion  123  provides the dental abutment  100  with a configuration that can be easily scanned. The perimeter (e.g., the circumference) of the dental abutment  100  increases monotonically from the coronal end  118  to the margin  132  defined between the base  128  and the shoulder. The edge between the bevel  146  and the anti-rotation portion  144  is smaller than the edge between anti-rotation portion  144  and the neck  142 . The edge between the anti-rotation portion  144  and the neck  142  is smaller than margin  132  between the neck  142  and the base  128 . As can be seen best in  FIG. 2C , the shoulder  130  is visible and clearly delineated which makes the shoulder  130  easy to record during digital scanning In addition, the length L 3  (from the bevel  146  to the neck  142  of the coronal portion  123 ) is long enough that when present in concert with angle γ, allows all the edges of the dental abutment to be observed with a digital scanner without additional modifications or interpretations to the scan. Unlike abutments whose geometry preclude the use of digital scanning or require modification or interpretations of scanned images for use, the abutments presented in this application allow for easy digital scanning which enables the rapid and precise restorations of a tooth or teeth. This feature supports movement of the dental implant field toward customizable restorations or prostheses and digital dentistry with the increased use of CAD/CAM technologies. 
         [0031]    The geometry of these dental abutments not only facilitate their recording by digital scanning technologies, but also allows for a singular conventional recording sleeve configuration to suffice for registering multiple different abutment dimensions. Further conventional dental impression materials can be used to record and represent their multiple different abutment dimensions prosthetically. 
         [0032]    The anti-rotation portion  144  of the coronal portion  123  includes anti-rotation features in the form of two grooves  148  on opposite sides of the coronal end  118 . The anti-rotational features help control the orientation of a prosthetic component or crown  114  which helps provide a precise fit of the prosthesis. The grooves also guide the prosthetic component or crown  114  into the correct orientation. 
         [0033]    The anti-rotation grooves  148  located on opposite sides of the coronal end  118  of the dental abutment  100  are generally of a constant depth that slopes toward the shoulder to end the anti-rotational element. The sloping of the groove is symmetric to reduce material stress. 
         [0034]    The length L 3  (see  FIG. 2A ) of the anti-rotation portion  144  and the grooves  148  are nominally 0.125 inches (3.2 mm). The width W (see  FIG. 2A ) of the grooves  148  is nominally 0.055 inches (1.4 mm). The depth D (see  FIG. 2B ) of the grooves  148  is nominally 0.02 inches (0.51 mm). As discussed above, the anti-rotation portion  144  of the coronal portion  123  is tapered with an angle γ of approximately 3°. The angled surface allows the anti-rotational element (e.g., grooves  148 ) to work properly. In addition, the sloping surface facilitates attaching other components as it is difficult to attach additional components to parallel surfaces, 
         [0035]    Some dental abutments have grooves  148  in which the length L 3  is more or less than 0.125 inches (3.2 mm) (e.g., between 0.1 (2.5 mm) and 0.3 inches (7.6 mm)), the width W is more or less than 0.055 inches (1.4 mm) (e.g., between 0.04 inches (1 mm) and 0.06 inches (1.5 mm)), and/or the depth D is more or less than 0.02 inches (0.51 mm) (e.g., between 0.010 inches (0.254 mm) to 0.030 inches (0.76 mm)). Some dental abutments include other anti-rotation features such as, for example, hexagonal or multi-sided flat surfaces and/or a variety of slots or grooves. 
         [0036]    As discussed above, some dental abutments are configured in which the length L 1  (between the hemispherical portion of the base  128  and the margin  132 ) is more or less than 0.16 inches (4 mm) (e.g., between 0.06 inches (1.5 mm) and 0.32 inches (7 mm)). 
         [0037]      FIGS. 3A and 3B  compare the dental abutment  100  with a dental abutment  200  that has a length L 1  that is 0.24 inches (˜6 mm). The dental abutment  100  and the abutment  200  have identical configurations except for the differences in the length L 1 . In particular, the dimensions of the post  120  are the same in both the dental abutment  100  and the abutment  200  such that a single type of dental implant can be used with either abutment. This configuration allows a dentist to set the position of the coronal portion  123  of the dental abutment  100 ,  200  relative to the gum above an implant regardless of the implant&#39;s axial position in the jawbone  112 . 
         [0038]    Some dental abutments have retention elements  122  that have different perimeters (e.g., diameters for the illustrated dental abutments).  FIGS. 4A and 4B  compare the dental abutment  100  with a dental abutment  300  in which both length L 1  and the diameter of the retention element are smaller than those of the dental abutment  100 . It accommodates implant wells that are more parallel for greater retention or wider for greater strength and resistance to metal fatigue and breakage. 
         [0039]    This specification has described a dental prostheses system including versatile abutments with numerous advantages. Dentists may now make numerous uses and modifications of and departures from the specific embodiments and techniques disclosed herein without departing from the inventive concepts. For example, multiple dental abutments as described above can be used to support a single dental prosthesis.  FIGS. 5A-5C  show a system in which four dental abutments  100  are used to support a single dental prosthesis  114 . In another example, dental abutments can be formed with the features described above but with the post set at angle relative to the coronal portion.  FIGS. 6A and 6B  show a dental abutment  400  in which an axis  124 ′ of the post  120  set at angle relative to an axis  124 ″ of the coronal portion  123 . Consequently, the claims are to be construed as embracing each and every novel feature and novel combination of features presented in or possessed by the apparatus and techniques herein disclosed. 
         [0040]    There has been described novel apparatus and techniques in connection with dental implanting. It is evident that those skilled in the art may make numerous modifications of and departures from the specific apparatus and techniques herein disclosed without departing from the inventive concepts. Consequently, the invention is to be construed as embracing each and every novel concept and combination of concepts disclosed herein and limited only by the spirit and scope of the appended claims.