Abstract:
A ceramic and metallic dental abutment for use with a dental implant is disclosed. The abutment can generally include a body having a base region, a coronal region, and a transgingival region disposed between the base and coronal regions. The body regions can define a longitudinal axis. The base region can include an anti-rotational feature such that, when engaged with the dental implant, an anti-rotational connection exists. The coronal and transgingival regions can include a ceramic exterior surface. The abutment can further include a metal contact portion having an annular shape and positioned to engage the dental implant. The metal contact portion can include a conical outer contact surface, disposed at an oblique angle with respect to the longitudinal axis, to match an angle of a chamfer of the dental implant.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 13/425,706, filed Mar. 21, 2012, and issued as U.S. Pat. No. 8,439,680 on May 14, 2013; which is a continuation of U.S. patent application Ser. No. 12/853,792, filed Aug. 10, 2010 and issued as U.S. Pat. No. 8,142,191 on Mar. 27, 2012; which is a continuation of U.S. patent application Ser. No. 11/362,236, filed Feb. 24, 2006 and issued as U.S. Pat. No. 7,780,446 on Aug. 24, 2010, each of which is incorporated herein in its entirety for all purposes. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to dental prosthetics and, in particular, to a ceramic/metallic abutment for use with a dental implant as part of a prosthodontic restoration. 
     DESCRIPTION OF THE RELATED ART 
     Dental implants are commonly used as anchoring members in prosthodontic restorations to provide prosthetic teeth at one or more edentulous sites in a patient&#39;s dentition at which the patient&#39;s original natural teeth have been lost or damaged. Typically, known implant systems include a dental implant made from a suitable biocompatible material, such as titanium. The dental implant is typically threaded into a bore which is drilled into the patient&#39;s mandible or maxilla at the edentulous site. The implant provides an anchoring member for a dental abutment, which in turn provides an interface between the implant and a dental restoration. The restoration is typically a porcelain crown fashioned according to known methods to replicate the shape of the tooth being replaced. 
     Many current dental implant surgeries are performed in two stages. In the initial or first stage, an incision is made in the patient&#39;s gingiva at an edentulous side, and a bore is drilled into the patient&#39;s mandible or maxilla at the edentulous site, followed by threading or impacting a dental implant into the bore using a suitable driver. Thereafter, a cap is fitted onto the implant to close the abutment coupling structure of the implant, and the gingiva is sutured over the implant. Over a period of several months, the patient&#39;s jaw bone grows around the implant to securely anchor the implant in the surrounding bone, a process known as osseointegration. 
     In a second stage of the procedure following osseointegration, the dentist surgically reopens the gingiva at the implant site and secures an abutment and optionally, a temporary prosthesis or temporary healing member, to the implant. Then, a suitable permanent prosthesis or crown is fashioned, such as from one or more impressions taken of the abutment and the surrounding gingival tissue and dentition. In the final stage, the temporary prosthesis or healing member is removed and replaced with the permanent prosthesis, which is attached to the abutment with cement or with a fastener, for example. 
     Typically, abutments are made from a biocompatible metal, such as titanium, or from a ceramic material. Advantages of titanium abutments include structural strength and relative ease of manufacture. However, if recession of the gingival tissue occurs around the implant and abutment after implantation, there is the potential that a portion of the metal of the abutment beneath the crown may become exposed, such that the grey color of the titanium is visible, which is aesthetically disadvantageous. 
     Ceramic abutments are harder than titanium abutments, and have the additional advantage of providing a light, tooth-like color such that, in the event of gingival recession, the light color of any exposed portions of the abutment substantially match the color of the crown and appear tooth-like to preserve aesthetics. 
     What is needed is an abutment which is an improvement over the foregoing. 
     SUMMARY OF THE INVENTION 
     The present invention provides a ceramic/metallic dental abutment for use with an implant, the abutment generally including a ceramic body portion having a base region, a transgingival region, and a supragingival region. The base region includes an anti-rotational implant interface, such as an external polygonal fitting, for engaging a cooperating internal polygonal fitting of an implant to prevent relative rotation between the abutment and the implant. The ceramic abutment body portion additionally includes a metal implant contact portion for contacting the implant and providing a load-bearing, metal-on-metal interface between the abutment and the implant. 
     In one embodiment, the implant contact portion is provided in the form of an annular metal ring made of titanium, for example, which is attached to the abutment via a press-fit connection, an adhesive connection, a shrink-fit connection, a brazed connection, or in another suitable manner. The implant contact portion is disposed substantially at the interface between the base region and the transgingival region of the abutment, and is dimensioned such that, when the abutment is connected to the implant, the implant contact portion is substantially entirely contained within the outer periphery of the open proximal end of the implant. Therefore, after attachment of the abutment to the implant, the implant contact portion is not visible and does not contact soft tissue surrounding the abutment. 
     In one embodiment, the proximal end of the implant includes an annular chamfer disposed at an oblique angle with respect to the longitudinal axis of the implant and abutment, and the implant contact portion of the abutment includes a contact surface disposed at a cooperating angle for engagement with the implant chamfer. The internal polygonal fitting of the implant may be greater in length than the external polygonal fitting of the abutment such that, upon receipt of the external polygonal abutment fitting into the internal polygonal implant fitting, relative rotation between the abutment and implant is prevented while axial loads from the abutment, such as occlusal and/or mastication loads, for example, are transferred to the implant only through the implant contact portion for improved resistance to wear. 
     In one form thereof the present invention provides a dental abutment, including a ceramic body portion defining a longitudinal axis, and including a base region with an anti-rotational implant interface, a transgingival region, and a supragingival region; a bore extending through the body portion along the longitudinal axis; and a metal implant contact portion attached to the body portion and disposed adjacent the implant interface. 
     In another form thereof, the present invention provides a dental abutment, including a ceramic body portion having a longitudinal axis, a bore extending through the body portion along the longitudinal axis, and an anti-rotational implant interface; and metal implant contact means attached to the body portion for axial load-bearing contact with an implant. 
     In a further form thereof, the present invention provides, in combination, a dental implant, including an externally threaded body having a distal end and a proximal end; a bore extending into the proximal end, the bore including a threaded portion and a first anti-rotational interface; and a dental abutment, including a ceramic body portion including a second anti-rotational interface cooperable with the first anti-rotational interface of the implant whereby relative rotation between the abutment and the implant is prevented; and a metal contact portion abuttable with the proximal end of the implant. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention itself will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein: 
         FIG. 1  is a perspective, interproximal view of a ceramic/metallic abutment in accordance with the present invention; 
         FIG. 2A  is a sectional view of the abutment of  FIG. 1 ; 
         FIG. 2B  is a fragmentary view of a portion of  FIG. 2A ; 
         FIG. 3  is a sectional, exploded view showing the abutment together with an implant and an abutment screw; 
         FIG. 4  is a sectional view of the implant, abutment, and abutment screw of  FIG. 3 , with the implant implanted within a jawbone and a crown secured to the abutment; 
         FIG. 5  is a sectional view of an angled abutment according to a further embodiment; and 
         FIG. 6  is an enlarged fragmentary view of a portion of an abutment according to another embodiment. 
     
    
    
     Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate preferred embodiments of the invention, and such exemplifications are not to be construed as limiting the scope of the invention any manner. 
     DETAILED DESCRIPTION 
     Referring first to  FIGS. 1 ,  2 A, and  2 B, a ceramic/metallic dental abutment  10  according to the present invention is shown, which may be used with a dental implant  12 , such as that shown in  FIGS. 3 and 4  and described below, to provide a prosthetic tooth at an edentulous site in a patient&#39;s dentition at which a natural tooth has been lost or damaged. In  FIG. 1 , an interproximal view of abutment  10  is shown, which includes a facial side  14  and an opposing lingual side  16 , as well as a mesial side  18  and an opposing distal side (not visible in  FIG. 1 ). Abutment  10  also generally includes a base region  20  for interfacing with implant  12 , an emergence profile region or transgingival region  22  which extends through soft gingival tissue, and a coronal region or supragingival region  24  extending superiorly of transgingival region  22  to which a prosthetic tooth or crown  26  may be attached, as shown in  FIG. 4 . 
     Abutment  10  includes a body portion  28  made of a suitable ceramic material, such as aluminum oxide or zirconium oxide, for example, and body portion  28  additionally includes an implant contact portion  30 , described below, which may be made of a suitable biocompatible metal, such as titanium, for example. As shown in  FIG. 2A , body portion  28  of abutment  10  includes a central bore  32  therethrough extending along the longitudinal axis L 1 -L 1  of abutment  10 , with bore  32  including step  34  for abutting engagement by the head of an abutment screw to secure abutment  10  to implant  12  in the manner described below. Although transgingival region  22  and supragingival region  24  of abutment  10  extend substantially along the direction of longitudinal axis L 1 -L 1  in the embodiment shown in  FIGS. 1-4 , in other embodiments, transgingival region  22  and/or supragingival region  24  of abutment  10  may be angled away from bore  32  and longitudinal axis L 1 -L 1  as needed to conform to the anatomical orientation of the tooth being replaced. 
     For example, referring to  FIG. 5 , an angled abutment  90  is shown which, except as described below, is substantially identical to abutment  10 , and the same reference numerals are used to designate identical features therebetween. In abutment  90 , central bore  92  thereof is disposed along central longitudinal axis L 1 -L 1  of abutment  90 , while supragingival region  94  of abutment  90  is oriented or disposed along an axis L 2 -L 2  which angled with respect to central bore  94  and longitudinal axis L 1 -L 1 . 
     Base region  20  of abutment  10  includes an implant interface, shown herein as an external polygonal fitting  36  having a hexagonal shape. In other embodiments, abutment  10  could include an internal polygonal fitting and/or a polygonal fitting which includes more or less than six sides. Referring additionally to  FIG. 2B , at its upper end adjacent transgingival region  22 , polygonal fitting  36  terminates at shelf  38  adjacent a notch  40  disposed substantially at the transition of base region  20  and transgingival region  22 , with notch  40  including annular rim  42  and annular base wall  44  within which implant contact portion  30  is fitted, as described below. 
     Referring to  FIG. 1 , transgingival region  22  of abutment  10  includes concave surface  46  extending toward margin shoulder  48  of transgingival region  22  on facial side  14  of abutment  10 , and another concave surface  50  extending toward margin shoulder  48  on lingual side  16  of abutment  10 . Margin shoulder  48  is disposed substantially at the gingival or gum line, is contoured to follow the gingival line based on the anatomy of the tooth being replaced, and includes concave recesses  52  on each of its sides which merge into the outer profile of supragingival region  24 . 
     Referring to  FIGS. 1 ,  2 A, and  2 B, abutment body portion  28  additionally includes an implant contact portion  30 , shown herein in the form of an annular metal ring, for example. Implant contact portion  30  may be made of substantially the same material as implant  12 , such as a suitable biocompatible metal, for example, titanium. As best shown in  FIG. 2B , implant contact portion  30  generally includes annular inner surface  54  and annular top surface  56  disposed against rim  42  and base wall  44  of notch  40  of abutment body portion  28 , respectively, as well as an implant contact surface  58  disposed at an oblique angle with respect to longitudinal axis L 1 -L 1  of abutment  10 , which surface contacts implant  12  in the manner described below. 
     Implant contact portion  30  may be attached to abutment body portion  28  via a press-fit connection, in which implant contact portion  30  is pressed with force onto rim  42  and against base wall  44  within notch  40  to firmly retain same on body portion  28  of abutment  10 ; an adhesive connection, in which a suitable adhesive or cement is applied between notch  40  and implant contact portion  30  which, when cured, firmly secures implant contact portion  30  to abutment body portion  28  within notch  40 ; a shrink-fit connection, in which implant contact portion  30  is heated, pressed onto rim  42  against base wall  44  within notch  40 , and is then cooled to shrink the diameter of implant contact portion  30  slightly such that same is firmly retained to abutment body portion  28 ; or a brazed connection, in which implant contact portion  30  is pressed around rim  42  against base wall  44  within notch  40  and is then heat brazed to body portion  28 . 
     Referring to  FIGS. 3 and 4 , implant  12  includes a threaded body  15  which is implanted into a tapped bore in the jawbone  60  ( FIG. 4 ) of a patient according to known surgical techniques. After implant  12  is allowed to osseointegrate within jawbone  60 , abutment  10  is initially seated on implant  12  by inserting external polygonal fitting  36  of abutment  10  into an internal polygonal fitting  62  of implant  12 . Also, when abutment  10  is seated on implant  12 , implant contact portion  30  of abutment  10  engages an internal annular chamfer  64  at the proximal end  17  of implant  12 . Implant contact surface  58  of implant contact portion  30  of abutment  10  and chamfer  64  of implant  12  are complementary angled at an oblique angle relative to longitudinal axis L 1 -L 1  of abutment  10  and implant  12 . 
     As may be seen in  FIG. 4 , external polygonal fitting  36  of abutment  10  is slightly shorter along the direction of longitudinal axis L 1 -L 1  of abutment  10  and implant  12  than internal polygonal fitting  60  of implant  12 , such that an axial clearance space  66  is provided within internal polygonal fitting  62  of implant  12  distally of external polygonal fitting  36  of abutment  10 . In this manner, the engagement between external polygonal fitting  36  of abutment  10  and internal polygonal fitting  60  of implant  12  prevents rotation of abutment  10  with respect to implant  12  without supporting the weight of abutment  10  and crown  26  or bearing loads along the direction of longitudinal axis L 1 -L 1  of abutment  10 . Rather, the metal-on-metal contact between implant contact portion  30  of abutment  10  and chamfer  64  of implant  12  supports the weight of abutment  10  and crown  26 , as well as loads imposed upon abutment  10  and crown  26  along or divergent from the direction of longitudinal axis L 1 -L 1  of abutment  10 , such as occlusal and/or mastication loads, for example. 
     An abutment screw  68 , shown in  FIG. 3 , is provided for securing abutment  10  to implant  12 , and generally includes head  70  with instrument engagement structure such as an internal polygonal fitting  71 , for example, as well as shank portion  74  extending from head  70  and having threads  76  thereon distally of head  70 . In use, abutment screw  68  is inserted through central bore  32  of abutment  10 , and threads  76  of abutment screw  68  are threaded into internally threaded region  78  of implant  12  with head  70  of abutment screw  68  initially seating against step  34  within internal bore  32  of abutment  10 . 
     Thereafter, further tightening of abutment screw  68  presses head  70  thereof against seat  34  to firmly engage abutment  10  to implant  12  and, more specifically, to firmly press implant contact portion  30  of abutment  10  into engagement with chamfer  64  of implant  12 , such that the loads imposed via abutment screw  68  along the direction of longitudinal axis L 1 -L 1  of abutment  10  are transferred to implant  12  directly through implant contact portion  30 . The firm engagement between implant contact portion  30  of abutment  10  and chamfer  64  of implant  12  minimizes micromotion between abutment  10  and implant  12 . 
     After abutment screw  68  is tightened, abutment  10  is securely retained to implant  12  via the engagement of implant contact portion  30  of abutment  10  with chamfer  64  of implant  12 , wherein a small gap may be present between external polygonal fitting  36  of abutment  10  and internal polygonal fitting  60  of implant  12  such that direct contact between the ceramic material of external polygonal fitting  36  of abutment  10  and the metal of internal polygonal fitting  60  of implant  12  is minimized. Advantageously, the metal-on-metal contact between implant contact portion  30  and implant  12  provides increased resistance to wear therebetween, due to the similarity or identity of the materials of implant contact portion  30  and implant  12 . 
     After abutment  10  is secured to implant  12  in the manner described above, crown  26  may be attached to supragingival region  24  of abutment  10  via cement, for example, to complete the restoration. Advantageously, as can be seen in  FIGS. 3 and 4 , implant contact portion  30  of abutment  10  is disposed substantially entirely within the open proximal end  17  of implant  12  such that implant contact portion  30  is not visible externally of the prosthetic and, in the event of recession of gingival tissue  80  around transgingival region  22  of abutment  10 , implant contact portion  30  will not be visible. Further, receipt of implant contact portion  30  substantially entirely within the open proximal end  17  of implant  12  as shown in  FIG. 4  prevents the metal of implant contact portion  30  from contacting the soft gingival tissue  80  around abutment  10  and implant  12 . 
     As shown in part in  FIGS. 1 and 2B , ceramic body portion  28  and/or implant contact portion  20 , in the area of base region  20  and/or transgingival region  22  of abutment  10 , may be coated with a thin coating  82  of gold or other metallic or non-metallic coating, such as by electroplating or sputtering techniques, for example, such as for providing a light, tooth-like coloring for aesthetics. 
     Referring to  FIG. 6 , a portion of an abutment  100  according to another embodiment is shown which, except as described below, is identical to abutment  10  described above, and the same reference numerals are used to indicate identical or substantially identical features therebetween. Abutment  100  includes contact portion  102  similar to contact portion  30  described above, and which may be attached to abutment  100  in the same manner as contact portion  30  is attached to abutment  10 . Contact portion  102  includes an annular outer end surface  104  dimensioned to seat on a proximal, outer annular rim  106  of implant  12 , which a small clearance space  108  present between contact portion  102  and chamfer  64  of implant  12 , wherein load are transferred from abutment  100  to implant  12  via outer end surface  104  of contact portion  102  to the proximal, outer annular rim  106  of implant  12 . 
     While this invention has been described as having a preferred design, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.