Patent Publication Number: US-2009233256-A1

Title: Band of Connective Tissue Grooves for Use with a Dental Implant or a Separate Abutment for a Dental Implant

Description:
CROSS-REFERENCE TO PRIOR APPLICATIONS 
     The present application claims priority to U.S. patent application Ser. No. 10/404,700 filed Apr. 1, 2003, now U.S. Pat. No. 7,097,453, and to U.S. patent application Ser. No. 11/420,379 filed May 25, 2006, currently pending, both of which are incorporated herein by reference. 
    
    
     BACKGROUND 
     The present invention is a band of connective tissue rings and grooves for use with a dental implant system. The band may be part of a dental implant or part of a separate abutment that is used in conjunction with a dental implant, and is designed to minimize tissue loss and to reduce the risk of bacterial infection in the implant site. The band is intended to be positioned on the portion of the implant or the abutment such that when the dental implant system is mounted within a patient&#39;s jawbone, the connective tissue band is positioned within the connective tissue layer and adjacent to the bone. 
     Dental implants are embedded in the jaw bone and serve to anchor one or more artificial teeth or dentures. Typically, the implant is set in the bone and an abutment is mounted on the implant. Important to the success of such devices is the rigid anchoring of the implant in the bone, and several journal articles and patents have proposed various methods for achieving rigid anchoring (see U.S. Pat. No. 5,344,457 and incorporated herein by reference). For example, U.S. Pat. No. 4,713,003, issued to Symington et al. describes an implant that has a tapered external body, resulting in a better distribution of the stresses acting on the device in situ than is achieved with cylindrical body implants. U.S. Pat. No. 5,344,457, issued to Pilliar et al, describes an implant that has a body with a non-porous surface on the upper portion of the implant and a porous surface on the lower portion of the implant. The porous surface provides interstices into which bone is permitted to grow once the implant is accommodated within the bone. 
     As reported in U.S. Pat. No. 6,454,469, issued to Hollander et al, and incorporated herein by reference, it is known to provide a variety of surface effects to enhance osseo-stability of the implant within bone. In the &#39;469 patent a device is taught that has a collar portion consisting of proximal and distal cylindrical sub-segments, one having a surface effect adapted for the promotion of growth of soft tissue and the other adapted for the promotion of bone or hard tissue growth. Specifically, the &#39;469 patent teaches a dental implant having a distal segment with a surface that defines an ordered microgeometric repetitive surface pattern in the form of a multiplicity of alternating ridges and grooves, each having a fixed or established width in a range of about 2.0 to about 25 microns and a fixed or established depth in the range of about 2.0 to about 25 microns. While the device of the &#39;469 patent recognizes that bone and soft tissue react differently with implant surfaces, it fails to recognize that academic studies have demonstrated that pore sizes of 10 microns or less lead to little or no fibrous ingrowth, and that a pore size of greater than about 30 microns is needed to give sufficient blood supply for adequate blood vessel ingrowth. This ingrowth is believed to be a factor in impeding epithelial migration toward the boney region of the implant site, and the less epithelial migration into the site, the lower the probability of infection development. 
     As is known in the art, the abutment of the dental implant generally has a first portion that abuts the implant and that is preferably positioned so as to lie within the connective tissue layer, a second portion that abuts the first portion and is preferably positioned so as to lie within the attached epithelial layer, and a third portion that abuts the second portion and is preferably positioned so as to lie within the sulcular epithelial layer. Each of the tissue layers are generally believed to be about 1 mm in depth. 
     Because of its proximity to the bone, it is imperative that the connective tissue forms a tight bond with the first portion of the abutment. If gaps remain between the connective tissue and the abutment, bacteria may penetrate into the gap and into the boney region, causing infection. The prior art has recognized the need for the connective tissue segment of the abutment to have a surface designed to encourage tissue attachment to the abutment. For example, U.S. Pat. No. 6,527,554, issued to Hurson, et al., teaches a dental implant system that has a “soft tissue attachment zone”. To promote attachment of connective soft tissues, the soft tissue attachment zone is preferably roughened, and is “at least about twice as rough as the smooth machined and/or polished surfaces of prior art abutments in the transgingival region.” U.S. Pat. No. 6,419,491, issued to Ricci, et al., teaches a dental implant with a “platform section” that has a first ordered microgeometric repetitive surface pattern at a distal section and a second ordered geometric pattern at a proximal portion. The second ordered geometric pattern, which exhibits “a width of about 2 to about 25 microns and a depth in a range of about 2 to about 25 microns”, is deemed to be “more suitable for purpose of tissue (as opposed to bone) adhesion or interface”. U.S. Pat. No. 6,981,873, issued to Choi, et al., teaches a dental implant with a “settling portion” formed between an abutment portion and a fixture portion, wherein the average surface textures of the settling portion is between about 1.0 μm to about 2.0 μm. 
     Although progress has been made with respect to addressing the adhesion of connective tissue to dental implants, the implants of the prior art still fail to promote the degree of adhesion needed to reduce the risk of bacterial infection. 
     SUMMARY OF THE PREFERRED EMBODIMENT 
     The present invention is a dental implant system comprising a band of connective tissue rings and grooves on an external surface of the dental implant system positioned such that that when the dental implant system is mounted within a patient&#39;s jawbone, the connective tissue band is positioned within the connective tissue layer and adjacent to the bone. It is intended that the connective tissue band be located on the stem of the dental implant system. The connective tissue band may be located on a dental implant device or on an abutment used in conjunction with a dental implant. The connective tissue band comprises a plurality of a repetitive pattern of rings and grooves wherein the rings define a ring width of from greater than about 25 μm to about 600 μm, and more preferably from about 30 μm to about 450 μm, and the grooves define a groove width of from greater than about 25 μm to about 600 μm, and more preferably from about 30 μm to about 150 μm. The rings and grooves further define a groove depth of from greater than about 25 μm to about 600 μm, and more preferably from about 30 μm to about 400 μm. To minimize the risk that contamination can transverse into the implant site, each groove is preferably isolated from its neighboring grooves. The dental implant may further comprise bone locking grooves having a depth approximately twice the depth of the connective tissue grooves thereby allowing the implant to be “locked” into the bone with resultant stabilization of the implant. 
    
    
     
       DESCRIPTION OF FIGURES 
         FIG. 1  is a perspective view of a dental device made in accordance with the present invention anchored in a lower jaw bone; 
         FIG. 2  is a side view of the dental device of  FIG. 1 ; 
         FIG. 3  is a detailed view of the connective tissue rings and grooves of the abutment section and of the bone locking rings and grooves of the implant section of the dental device of  FIG. 2 ; 
         FIG. 3A  is an expanded view of the connective tissue rings and grooves of the abutment section of the dental device of  FIG. 2 ; 
         FIG. 4  is a first embodiment of the connective tissue grooves made in accordance with the present invention; 
         FIG. 4A  is a cross-sectional view taken along line  4 A- 4 A of the connective tissue grooves of  FIG. 4 ; 
         FIGS. 5A-5H  are alternative embodiments of connective tissue grooves made in accordance with the present invention; 
         FIG. 6  is an alternative embodiment showing the connective tissues grooves at an angle; and 
         FIG. 7  is perspective view of an abutment having connective tissues grooves made in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The dental devices depicted in the various Figures are selected solely for the purposes of illustrating the invention. Other and different dental devices may utilize the inventive features described herein as well. The illustrations are not intended to be representative with respect to dimensions. 
     Reference is first made to  FIGS. 1 through 3A  in which a dental device is constructed in accordance with the present invention is generally noted by the character numeral  10 . The dental device  10 , which defines a distal abutment end  11  and a proximal end  32 , has as major components an abutment section  20  and an implant section  30 . The abutment section  20  comprises a first portion or stem  22 , a second portion or collar  24 , and a third portion or head  26 . The abutment section  20  may be fixedly joined to the implant section  30 , so the dental implant device is a one-piece unit; or, the abutment section  20  may be provided separate from the implant section  30  but adapted to be reversibly joined to the implant section  30 . 
     The stem  22  of the abutment section  20  is adjacent to the implant section  30 . The implant section  30  comprises a neck  12  and a body  15 . In the embodiment of  FIG. 2 , the body  15  includes two different types of surface textures for inserting the implant  30  into the bone  90 ; however, the implant  30  may have any type of surface texture or configuration that is known in the art of dental implants to function as intended. As is known in the art, the implant section  30  includes a bore (not shown). The implant section  30  has an axial length, L, defined as the distance between an abutment end  36  and the proximal end  32 . A midline, m, is defined through the axial center of dental device  10 . 
     As shown in  FIG. 1 , the dental device  10  is mounted in a cavity bored into the jaw bone  90  of the patient such that the body  15  extends into the jaw bone  90 . After the dental device  10  is anchored in the jaw bone  90 , a bridge or artificial tooth  94  can be secured to the device  10 , as is known in the art. The device  10  can be formed from any smooth hard material commonly known in the art as being suitable for dental implants, including but not limited to metals, ceramic-based materials, zirconium-based materials, and composites of these materials. In one embodiment, the device  10  is machined from a titanium alloy. The device  10  can be inserted into the cavity  92  by being screwed in or hammered in, techniques which are known in the art. 
     As shown in  FIGS. 2 ,  3  and  3 A, the abutment section  20  is adjacent to the implant section  30  such that the stem  22  abuts the neck  12 . In an exemplary embodiment, the stem  22  defines a diameter at the stem&#39;s widest point wherein the stem diameter is smaller than either the diameter of the collar  24  or the diameter of the neck  12 . When the dental device  10  is properly inserted into the jaw bone  90 , the stem  22  will lie essentially at the upper edge of the bone and within a connective tissue layer  92 . 
     Referring again to  FIGS. 2 ,  3  and  3 A, the stem  22  has length L 1  of about 0.2 mm to about 2 mm, and comprises a band of rings  61  and grooves  60 . As used herein, the band of rings  61  and grooves  60  comprise the connective tissue band. Each groove  60  is formed between a pair of neighboring rings  61 . The connective tissue rings  61  and grooves  60  serve to help form a tight band of connective tissue around the stem  22 . This can minimize the risk of bacterial invasion and can potentially limit bone loss. This may further mimic the Sharpey fiber attachment that is present on a natural tooth. 
     Each ring  61  of the stem  22  defines an outer diameter and each groove  60  defines an inner diameter. The difference between the outer diameter and the inner diameter defines a connective tissue groove depth, d c . In the dental device  10 , the groove depth d c  is from greater than about 25 μm to about 600 μm, and more preferably from about 30 μm to about 400 μm. In an exemplary embodiment, the groove depth is about 50 μm. 
     The rings  61  circumscribe the stem  22  so as to lie essentially parallel, and they are preferably essentially equally spaced relative to each other. The rings  61  may lie essentially perpendicular to the midline m, i.e. they can form a series of neighboring rings encircling the stem  22 , as shown in  FIG. 4 , or they may lie at a slight angle relative to the midline m, thereby giving the stem  22  a “spiraled” appearance, as shown in  FIG. 6 . Optionally, the rings  61  may be essentially planar or may have a slight “wave” so as to more closely match the bone contour. The rings  61  serve to isolate the grooves  60  so that bacteria and/or other contaminants cannot transverse the axial length of the dental device  10 . 
     As shown in  FIGS. 3 and 3A , each ring  61  has a face  63 , an upper edge  62 , and a lower edge  64 . The angle of the edges  62 ,  64  relative to the face  63  may vary from a slight angle to essentially a right angle. The edge may be “beveled” or rounded slightly to eliminate sharp edges. The upper edge  62  has a groove end  62 G and a face end  62 F; the lower edge  64  has a groove end  64 G and a face end  64 F. The width of the ring  61 , w ring , is defined as the distance from the upper edge groove end  62 G to the lower edge groove end  64 G, and ranges from greater than about 25 μm to about 600 μm, and more preferably from about 30 μm to about 450 μm. 
     Each groove  60  defines a groove face  60 F. A groove width, w g , is defined to be equal to the length of the groove face  60 F, and can range from greater than about 25 μm to about 600 μm, preferably from about 30 μm to about 150 μm, and more preferably from about 30 μm to about 135 μm. 
     In one embodiment, the ring width w ring  and the groove width w g  and the connective tissue groove depth d c  are essentially identical. In a second embodiment, the ring edge  62  is approximately at a right angle to the face  63 . In a preferred embodiment, the stem  22  has about fourteen grooves  60  covering a length of about 0.7 mm along the stem  22 , and the ring width w ring  and groove width w g  and connective groove depth d d  are each approximately 50 μm. 
     Referring again to  FIGS. 2 and 3 , the stem  22  lies adjacent to the neck  12  of the implant section  30 . The neck  12  comprises a plurality of bone locking grooves  50 . The neck  12  and bone locking grooves  50  may form only a relatively short portion along the implant section  30 , as shown in  FIG. 2 , with macro grooves  14  or other surface textures as are known in the art covering the body  15 . Alternatively, the neck  12  and bone locking grooves  50  may extend from the stem  22  to the proximal end  32  of implant section  30 . In a preferred embodiment, the neck  12  has an axial length, L 2 , of from about 0.1 mm to about 16 mm. 
     In the embodiment shown in  FIG. 2 , the dental device  10  has an essentially cylindrical shape. However, other configurations known in the art, such as implants with a frusto-conical shape, can apply the band and groove technology described herein. As shown in  FIG. 2 , the dental device  10  is a one-piece unit comprising an abutment section  20  and an implant section  30 . Optionally, the dental device  10  may be divided into separate pieces that can be reassembled to create the device  10 . For example, it is anticipated that the device  10  could be divided into an abutment section  120  having connective tissue grooves, as shown in  FIG. 7 , and having a separate implant section (not shown), the division being made along the abutment end  36 . The stem  22 , neck  12  and other exterior faces of the dental device  10  may have a smooth, porous, coated, treated, textured, roughened, machined or beaded surface comprised of a network of discrete particles which provides interstices into which bone is permitted to grow once implant  10  is accommodated within the bone  90  (such as described in U.S. Pat. No. 6,379,153, issued to Schroering, and incorporated herein in its entirety by reference, or roughened by other techniques known in the art). 
     Several optional features, known in the art and not shown herein, may be included in the implant  10 . For example, the implant  10  may be self-tapping to allow the implant  10  to enter the jaw bone more easily and/or may include a cutting thread. Cutting threads are commonly used to help seat the dental implants. 
     The ring and groove designs disclosed herein are anticipated to be applicable to implant designs other than the implant depicted in  FIG. 2 . For example, in the implant described in U.S. Pat. No. 6,379,153 issued to the applicant, the smooth-surfaced neck ( 44 ) can be replaced by the bone locking grooved neck  12  taught herein and the abutment section  20 , comprising the stem  22  with the connective tissue rings  61  and grooves  60 , can be adjoined to the implant ( 10 ). The resulting dental device would provide for a tapered body with a beaded finish between the bone locking grooves  16  and the proximal end  32 . 
     Further, it is anticipated that the band of rings  61  that form the connective tissue band may vary in design and/or that the surface may be roughened. For example, as shown in  FIGS. 4 and 4A , the rings  61  may be in the form of parallel rings with slightly rounded edges. Alternatively, the rings may have a variety of edge designs, such as shown in  FIGS. 5A-5G . 
     It is understood that, in light of a reading of the foregoing description and drawings, those with ordinary skill in the art will be able to make changes and modifications to the present invention without departing from the spirit or scope of the invention, as defined herein. For example, those skilled in the art may accomplish the band and groove patterns by using bands with tips of a different design or configuration.