Dentistry – Prosthodontics – Holding or positioning denture in mouth
Reexamination Certificate
2000-09-27
2004-05-11
Shaver, Kevin (Department: 3732)
Dentistry
Prosthodontics
Holding or positioning denture in mouth
Reexamination Certificate
active
06733291
ABSTRACT:
BACKGROUND OF THE INVENTION
1. 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 model, 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 INVENTION
One 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 compo
Bumgarner Melba
Knobbe Martens & Olson Bear LLP.
Nobel Biocare USA, Inc.
Shaver Kevin
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