Implant with internal multi-lobed interlock
A dental implant for supporting a dental prosthesis comprises a body portion and a top surface. The implant further comprises an internal cavity with an opening located at the top surface. The internal cavity comprises an interlock chamber having a depth measured from the top surface equal to a first distance. The interlock chamber comprising a cylindrical portion and plurality of semi-circular channels arranged around a periphery of the cylindrical portion. A threaded chamber that includes threads is located below the post-receiving chamber. The cylindrical portion has a first radius and the channels have a second radius, a ratio of the first radius to the second radius being between approximately 4:1. and 2:1.
The present application claims priority and benefit under 35 U.S.C. §119(e) of U.S. Provisional Patent Application Ser. No. 60/156,198, filed Sep. 27, 1999.
BACKGROUND OF THE INVENTION1. Field of the Invention
The present invention relates generally to dental implants and, more particularly, to an improved implant with an improved internal interlock for supporting other dental implant components with corresponding interlock structures.
2. Description of the Related Art
Implant dentistry involves the restoration of one or more teeth in a patient's mouth using artificial components. Such artificial components typically include a dental implant and a prosthetic tooth and/or a final abutment that is secured to the dental implant. Generally, the process for restoring a tooth is carried out in three stages.
Stage I involves implanting the dental implant into the bone of a patient's jaw. The oral surgeon first accesses the patient's jawbone through the patient's gum tissue and removes any remains of the tooth to be replaced. Next, the specific site in the patient's jaw where the implant will be anchored is widened by drilling and/or reaming to accommodate the width of the dental implant to be implanted. Then, the dental implant is inserted into the hole in the jawbone, typically by screwing, although other techniques are known for introducing the implant in the jawbone.
The implant itself is typically fabricated from pure titanium or a titanium alloy. Such materials are known to produce osseointegration of the fixture with the patient's jawbone. The dental implant fixture also typically includes a hollow threaded bore through at least a portion of its body and extending out through its proximal end which is exposed through the crestal bone for receiving and supporting the final tooth prosthesis and/or various intermediate components or attachments.
After the implant is initially installed in the jawbone, a temporary healing cap is secured over the exposed proximal end in order to seal the internal bore. The patient's gums are then sutured over the implant to allow the implant site to heal and to allow desired osseointegration to occur. Complete osseointegration typically takes anywhere from four to ten months.
During stage II, the surgeon reassesses the implant fixture by making an incision through the patient's gum tissues. The healing cap is then removed, exposing the proximal end of the implant. Typically, an impression coping in attached to the implant and a mold or impression is then taken of the patient's mouth to accurately record the position and orientation of the implant within the mouth. This is used to create a plaster model or analogue of the mouth and/or the implant site and provides the information needed to fabricate the prosthetic replacement tooth and any required intermediate prosthetic components. Stage II is typically completed by attaching to the implant a temporary healing abutment or other transmucosal component to control the healing and growth of the patient's gum tissue around the implant site.
Stage III involves fabricating and placement of a cosmetic tooth prosthesis to the implant fixture. The plaster analogue provides laboratory technicians with a model of the patient's mouth, including the orientation of the implant fixture relative to the surrounding teeth. Based on this niodel, the technician constructs a final restoration. The final step in the restorative process is replacing the temporary healing abutment with the final restoration.
As mentioned above, the implant typically includes a hollow threaded bore for receiving and supporting the final tooth prosthesis and/or various intermediate components or attachments. The implant also typically includes anti-rotational means, which are typically located on the proximal end of the implant. These anti-rotational means are designed to mate with corresponding anti-rotational means formed on the various mating components (e.g., a healing abutments and/or an impression coping). These anti-rotational means primarily serve to prevent relative rotation between the mating component and the implant.
Such anti-rotational/indexing means frequently take the form of a hexagonal boss or recess (“hex”) formed on the proximal portion of the implant. For externally threaded implants, the hex may also be used to engage a driving tool for driving the implant into an internally threaded bore or osteotomy prepared in the patient's jawbone (mandible or maxilla). When the implant is fully installed in a patient's jawbone, the hex or other indexing means is typically exposed through the crestal bone so that accurate indexing may be provided between the implant and the final prosthesis and/or various intermediate mating prosthetic components.
SUMMARY OF THE INVENTIONOne aspect of the present invention includes the realization that prior art anti-rotational means typically include sharp corners. When the implant and mating component are subjected to a rotational force, these sharp corners are subject to high concentrations of stress. The high stress concentrations can cause the sharp corners to chip or wear away. This can cause the anti-rotational means to take on a circular shape, which reduces the ability of the anti-rotational means to resist rotation. The chipping or wearing away can also result in fitting errors between the implant and the mating components. In some cases, the high stress concentrations can also cause the implant to crack at or near the corners of the anti-rotational means thereby shortening the life of the implant.
Another aspect of the present invention includes the realization that prior art anti-rotational means typically offer little resistance to lateral forces. That is, prior art anti-rotational means typically do not prevent the mating component from “tipping” off the implant. Furthermore, prior art anti-rotational means typically provide little or no tactile feedback to the oral surgeon to indicate that the mating component is properly seated in the implant.
Yet another aspect of the present invention is the recognition that traditional anti-rotation means, such as a hexagonal recess, are difficult to machine. Specifically, a special reciprocating tool, such as a broach, typically must be used to form a hexagonal recess.
Accordingly, it is a principle object and advantage of the present invention to overcome some or all of the above-mentioned limitations in the prior art. Thus, one aspect of the present invention provides for a dental implant for supporting a dental prosthesis comprises a body portion and a top surface. The implant further comprises an internal cavity with an opening located at the top surface. The internal cavity comprises an interlock chamber having a depth measured from the top surface equal to a first distance. The interlock chamber comprising a cylindrical portion and plurality of semi-circular channels arranged around a periphery of the cylindrical portion. A threaded chamber that includes threads is located below the post-receiving chamber. The cylindrical portion has a first radius and the channels have a second radius, a ratio of the first radius to the second radius being between approximately 4:1. and 2:1.
Another aspect of the present invention provides for a prosthodontic assembly for installing a prosthetic tooth. The prosthodontic assembly comprises a first prosthodontic component and a second prosthodontic component. The first prosthodontic component comprising a body portion and a top surface. The first prosthodontic component further comprising an internal cavity with an opening located at the top surface. The internal cavity comprising an interlock chamber having a depth measured from the top surface equal to a first distance. The interlock chamber comprising a cylindrical portion with a plurality of semi-circular channels arranged around a perimeter of the cylindrical portion. A threaded chamber that includes threads is located below the interlock chamber. The cylindrical portion has a first radius and the channels have a second radius. A ratio of the first radius to the second radius is between approximately 4:1. and 2:1. The second prothodontic component comprising an interlock area comprising a plurality of semi-circular protrusions configured to mate with channels of the first prosthodontic component.
Yet another aspect of the present invention provides for a dental implant for supporting a dental prosthesis. The dental implant comprising a body portion and a top surface. The implant further comprising an internal cavity with an opening located at the top surface. The internal cavity comprising an interlock chamber having a depth measured from the top surface equal to a first distance. A threaded chamber that includes threads and is located below the post-receiving chamber. The interlock channel being formed as a single continuos curve having substantially no internal corners.
Still yet another aspect of the present invention provides for a prosthodontic assembly for installing a prosthetic tooth. The prosthodontic assembly comprises a first prosthodontic component and a second prosthodontic component. The first prosthodontic component comprising a body portion and a top surface. The first prosthodontic component further comprising an internal cavity with an opening located at the top surface. The internal cavity comprising an interlock chamber having a depth measured from the top surface equal to a first distance. The interlock chamber being formed as a single continuos curve having substantially no internal corners. A threaded chamber that includes threads is located below the post-receiving chamber. The second prothodontic component comprising an interlock area having a shape that corresponds to the shape of the interlock chamber.
For purposes of summarizing the invention and the advantages achieved over the prior art, certain objects and advantages of the invention have been described herein above. Of course, it is to be understood that not necessarily all such objects or advantages may be achieved in accordance with any particular embodiment of the invention. Thus, for example, those skilled in the art will recognize that the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein.
All of these embodiments are intended to be within the scope of the invention herein disclosed. These and other embodiments of the present invention will become readily apparent to those skilled in the art from the following detailed description of the preferred embodiments having reference to the attached figures, the invention not being limited to any particular preferred embodiment(s) disclosed.
BRIEF DESCRIPTION OF THE DRAWINGSThese and other features of this invention will now be described with reference to the drawings of a preferred embodiment which is intended to illustrate and not to limit the invention. The drawings contain the following figures.
FIGS. 4A-C are schematic illustrations of preferred shapes of the interlock regions of the dental implant of
As best seen in
The body portion 12 of the implant 10 is also preferably acid-etched. Acid-etching produces a rougher surface, which increases the surface area of the body portion 12. The increased surface area promotes osseointegration. Alternatively, the body portion 12 of the implant can be coated with a substance that increases the surface area of the body portion 12. Calcium phosphate ceramics, such as tricalcium phosphate (TCP) and hydroxyapatite (HA), are particularly suitable materials.
As best seen in
The neck 14 and the collar 16 form a “variable placement zone”. The length and configuration the variable placement zone allows for “variable positioning” of the dental implant 12. That is, the surgeon can vary the height of the implant 10 with respect to the crest of the jawbone. For example, as shown in
It should, however, be noted that several advantages of the present invention can be achieved with an implant 10 that (i) does not include a variable placement zone or (ii) includes variable placement zone that is smaller or larger than the preferred embodiment. For example, several advantages of the present invention can be achieved with an implant without the neck 14 and/or the collar 16. Similarly, the neck 14 and/or collar 16 can have dimensions that are smaller or larger than the illustrated embodiment. However, the illustrated embodiment, with the neck region 14 and collar 16, is preferred because it best allows for the flexibility described above.
As best seen in
With reference to
The cylindrical portion 35 has a first radius R1 and the semi-circular channels 36 have a second radius R2. The ratio α1 of the first radius R1 to the second radius R2 preferably is between 2:1 and 4:1. In the preferred embodiment the ratio α1 is about 3:1. This arrangement is preferred to minimize the stress concentrations in the dental implant 10, as will be explained below. To reduce stress concentrations further, the interfaces 39 between the channels 36 and the cylindrical portion 35 are preferably rounded.
The interlock chamber 34 is preferably dimensioned to be as large as possible without significantly compromising the structural integrity of the vertical side wall 26. This arrangement is preferred because it increases the surface area of the interlock chamber 34. The larger surface area results in a more stable connection between the implant 10 and the mating dental component. Accordingly, the interlock chamber 34 has a third radius R3, which is approximately equal to the first radius R1 plus the second radius R2. The third radius R3 is sized such that the thickness Ti (i.e., the radius R4 of the implant minus R3) of the vertical wall 26 is greater than a minimum value, which provides sufficient structural integrity for the implant 10. For an implant made of dental grade titanium alloy, the preferably minimum value is approximately 0.4-0.8 millimeters. Another preferred aspect of the shape of the interlock chamber 34 is the ratio between the radius R4 of the implant 10 and the radius R2 of the channels 36. More specifically, the ratio between the radius R4 of the implant and the radius R2 of the channels 36 is preferably between 4:1 to 5:1. In the preferred embodiment, the ratio is about 4.5:1.
The internal socket 28 also preferably includes a post-receiving chamber 32, which lies between the interlock chamber 34 and the threaded chamber 30. The post-receiving chamber 32 is preferably substantially cylindrical. The diameter of the post-receiving chamber 32 is preferably less than the diameter of the interlock chamber 34. The post-receiving chamber also preferably includes a chamfered region 37, which is adjacent the threaded chamber 30.
One aspect of the present invention is that the implant 10 provides significant resistance to lateral (i.e., “tipping”) forces. Accordingly, the interlock chamber 34 preferably has a depth D1 as measured from the top surface 24 that is greater than about 1 millimeter (see
As best seen in
The illustrated shape of the abutment 32 can be used as an healing abutment, which is typically used during the second healing period to shape the patient's gums. However, as mentioned above, the abutment 38 can be modified or otherwise formed into many different types of dental components. Therefore, it should be appreciated that the upper and curved regions 40, 42 of the abutment can be formed into any desirable shape.
As best seen in
With continued reference to
Below the interlock area 44 is the post 46. The post 46 is preferably substantially cylindrical and is configured to fit within the post-receiving chamber 32 of the implant.
Turning now to
The coupling screw also preferably includes a hexagonal recess 70 located on a top surface 72 of the screw 60. The hexagonal recess 70 allows for the insertion of a hexagonally shaped tool such as a conventional Allen® wrench to remove the coupling screw 60 from the implant body 10.
As mentioned above, during stage I surgery, the dental implant 10 is typically inserted into a pre-made hole formed in the patient's jawbone. A driving tool (not shown) is typically used to screw the implant into the pre-made hole. Accordingly, a distal end of the driving tool is preferably configured to mate with the interlock chamber 34 of the implant 10. That is, the distal end of the driver is preferably configured substantially the same as the interlock region 44 of the abutment 38 described above. When the driving tool is mated to the implant 10, the distal end of driver can be used to transmit torque to the implant through the interlock chamber 34 so as to drive the implant 10 into the pre-made hole. If the implant 10 is self-tapping, a particularly large amount of torque is required to drive the implant 10 into the bone. For conventional implants with hexagonal recesses, this large amount of torque can cause the implant to crack at the apexes of the hexagonal recesses. This reduces the strength of the implant and can cause fluids and bacteria to enter the implant.
An advantage of the illustrated implant 10 and mating abutment 38 is that when subjected to rotational forces the stress concentrations in the implant 10 and the abutment 38 are minimized. Stress concentrations refer to areas of large stress caused by geometric discontinuities (i.e., stress risers) and/or the application of large loads over a small area or at a point (e.g., at a corner or apex). Areas of large stress concentrations are often the starting point of material damage, which can ultimately lead to material failure by fracture (i.e., cracking). Thus, by minimizing stress concentrations, the durability of the implant 10 and the abutment 38 can be increase. The reduction in stress concentration derives from the particular preferred shape of the interlock chamber 34 of the implant 10 and the mating interlock region 44 of the abutment 38.
FIGS. 4A-C are schematic representations of the shape 78 of the interlock chamber 34 and the interlock region 44.
Another advantage of the illustrated arrangement is that the abutment 38 and the implant 10 offer improved resistance to lateral or “tipping” forces. This improved resistance to lateral forces is due primarily to the depth of the interlock chamber 34 and the post-receiving chamber 32. The improved resistance to lateral forces also prevents the coupling screw 60 from loosening, thereby virtually eliminating movement between the implant 10 and the abutment 38.
Yet another advantage of the illustrated arrangement is that the interlock chamber of the implant 10 can be machined using a conventional end mill. That is, because of circular shape of the cylindrical portion 35, it can be machined with a conventional end mill. Moreover, the semi-circular channels can also be machined with a conventional end mill. This reduces the complexity of manufacturing especially as compared to the machining of a conventional hexagonal recess, which typically requires a reciprocating tool, such as, for example, a broach.
The illustrated arrangement of the implant 10 and abutment 38 also provides improved tactile confirmation that the blank abutment 38 is properly seated on the implant 10. That is because of the depth of the post-receiving chamber 32, the oral surgeon can feel the abutment 38 engaging the implant 10. This tactile confirmation is especially important for posterior prosthetics where visibility and working space are often compromised.
The lower region 87 of the final abutment 86 is substantially identical to the lower region of the blank abutment 38 described above. Accordingly, the lower region 87 comprises a lower surface 50, an interlock region 44 with protrusions 64, and a post 46. As with the blank abutment 38, the interlock region 44 with protrusions 64, and the post 46 that are sized and dimensioned to fit within the interlock chamber 34 and post-receiving chamber 32 of the implant 10.
Down the center of the final abutment 54 is an bore 48. The inner bore 48 is preferably divided into two regions: a first chamber 50 and a second region 52. Preferably, the diameter of the first chamber 50 is slightly larger than the second chamber 52. A screw passes through the screw receiving chamber 50 and engages the threads of the threaded region 52 and the first chamber 22 of the implant 10. Accordingly, the final abutment 54 can be permanently attached to the implant. Alternatively, the final abutment 54 could be cemented to the implant 10 using methods well known in the art.
The upper surface 88 of the final abutment 86 is formed to receive a prosthetic tooth. Accordingly, the prosthetic tooth (not shown) has an inner surface configured such that the prosthetic tooth can fit over the final abutment 86. The prosthetic tooth is typically cemented to the final abutment 86.
Although this invention has been disclosed in the context of certain preferred embodiments and examples, it will be understood by those skilled in the art that the present invention extends beyond the specifically disclosed embodiments to other alternative embodiments and/or uses of the invention and obvious modifications and equivalents thereof. In addition, while a number of variations of the invention have been shown and described in detail, other modifications, which are within the scope of this invention, will be readily apparent to those of skill in the art based upon this disclosure. It is also contemplated that various combination or subcombinations of the specific features and aspects of the embodiments may be made and still fall within the scope of the invention. Accordingly, it should be understood that various features and aspects of the disclosed embodiments can be combine with or substituted for one another in order to form varying modes of the disclosed invention. Thus, it is intended that the scope of the present invention herein disclosed should not be limited by the particular disclosed embodiments described above, but should be determined only by a fair reading of the claims that follow.
Claims
1-36. (canceled)
37. A dental implant for mating with a dental abutment, the dental implant comprising:
- a body portion;
- a top surface;
- an interlock chamber with an opening located at the top surface, the interlock chamber having a depth measured from the top surface equal to a first distance, the interlock chamber configured to mate with a dental abutment having cylindrical post, which has a plurality of semi-circular protrusions arranged around a periphery of the cylindrical post, wherein the cylindrical post has a first radius and the protrusions have a second radius, a ratio of the first radius to the second radius being between approximately 4:1 and 2:1; and
- a threaded chamber located below the interlock chamber, the threaded chamber including at least one thread.
38. The dental implant as in claim 37, wherein the ratio of the first radius to the second radius is approximately 3:1.
39. The dental implant as in claim 37, wherein the first distance is greater than 1 millimeter.
40. The dental implant as in claim 37, wherein the interlock chamber includes at least three channels that are arranged around the perimeter of the interlock chamber such that each of the channels are approximately 120 degrees apart from one another.
41. The dental implant as in claim 37, wherein the top surface of the dental implant has a third radius and a ratio of the third radius to the second radius is between approximately 5:1. and 4:1.
42. The dental implant claim 41, wherein the ratio of the third radius to the second radius is approximately 4.5:1.
Type: Application
Filed: Dec 14, 2004
Publication Date: May 5, 2005
Inventor: Steven Hurson (Yorba Linda, CA)
Application Number: 11/011,513