Dentistry – Prosthodontics – Holding or positioning denture in mouth
Reexamination Certificate
2001-06-15
2004-01-06
Wilson, John J. (Department: 3732)
Dentistry
Prosthodontics
Holding or positioning denture in mouth
C433S173000, C433S180000
Reexamination Certificate
active
06672871
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to dental restorations and, more particularly, to a coping that is used to form a dental prosthesis.
2. Description of the Related Art and Summary of the Invention
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.
After the implant is initially installed in the jawbone, a temporary healing cap can be secured over the exposed proximal end in order to seal an internal bore of the implant. The patient's gums are then sutured over the implant to allow the implant site to heal and to allow the desired osseointegration to occur. Complete osseointegration typically takes anywhere from four to ten months.
During Stage II, the surgeon reaccesses 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. The interior of the implant is thoroughly cleaned and dried. The surgeon can then attach a final abutment to the implant. To accurately record the position, the orientation and the shape of the final abutment within the mouth, the surgeon takes a mold or impression of the patient's mouth. Stage II is typically completed by securing a protective cap to the abutment with temporary cement. Alternatively, a conventional temporary restoration can be attached to the abutment.
Stage III involves fabricating and placement of a final restoration to the implant fixture. A laboratory technician makes the stone plaster model of the patient's mouth from the impression that was taken in Stage II. To create the model, the technician typically repositions an analogue of the final abutment into the impression. The technician then pours plaster into the impression to create a hard stone plaster model of the patient's mouth. Based on this model, the technician constructs a final restoration. The final restoration typically includes an internal cavity that is configured to fit over the final abutment. Typically, the final step in the restorative process is securing the final restoration to the final abutment with cement.
To ensure that there is adequate space for the cement, the internal cavity of the final restoration generally is slightly larger than the final abutment. To create the slightly larger internal cavity, the technician typically paints a die spacer onto the analogue. The die spacer typically has a thickness of approximately 25 to 50 microns. The analogue is then covered with wax. The wax can then be used in an investment casting process to create a metal coping. The spacer die ensures that the internal cavity of the metal coping has an internal cavity that is 25 to 50 microns larger than the final abutment. To form the prosthesis, the metal coping is typically covered with a tooth-like material, such as, for example, porcelain.
SUMMARY OF THE INVENTION
Because the internal cavity of the coping is 25 to 50 microns larger than the final abutment, a gap exists between the coping and the final abutment. This gap provides room for the cement. Without this gap, the prosthesis would not sit all the way down upon the final abutment due to the added thickness of the cement. Moreover, the size of the gap is important for achieving the desired cement thickness between the prosthesis and the final abutment. If the gap is too large, the cement thickness becomes too thick and the integrity of the cement is impaired. If the gap is too small, the cement thickness becomes too thin and the cement will have poor resistance to shear stresses. Also, the variability of the thickness of the spacer die and the pressure applied by the dentist during the cementing process can cause the final restoration to sit unevenly upon the final abutment and/or sit too low or high. Thus, there is a need for a more predictable method of forming the required gap between the coping and the final abutment.
Accordingly, one aspect of the present invention is a final restoration for a prosthodontic assembly. The restoration comprises a body portion having a proximal end, a distal end and an inner surface that defines an internal cavity and at least one standoff that extends from the inner surface towards a center of the internal cavity.
Another aspect of the present invention is a coping for creating a final restoration. The coping comprises a body portion having a proximal end, a distal end and an inner surface that defines an internal cavity and at least one standoff that extends from the inner surface towards a center of the internal cavity.
Yet another aspect of the present invention is a method for creating a final restoration. A coping is provided. The coping has a body portion that includes a proximal end, a distal end and an inner surface that defines an internal cavity and at least one standoff that extends from the inner surface towards a center of the internal cavity. An analogue of a final abutment is also provided. The analogue and the final abutment each have an upper region configured to fit within the internal cavity of the coping. The coping is placed over the upper region of the analogue. A material suitable for investment casting is applied to an outer surface of the coping. The coping and the material suitable for investment casting are encased in an investment material. The coping and the material suitable for investment casting are melted. The coping and the material suitable for investment casting are removed from the investment material and a cavity within the investment material is filled with a material suitable for forming a part of a final restoration.
Another aspect of the present invention is a method for creating a final restoration. A coping is provided. The coping has a body portion made of a material suitable for forming a final restoration. The body portion comprises a proximal end, a distal end and an inner surface that defines an internal cavity and at least one standoff that extends from the inner surface towards a center of the internal cavity. A toothlike material is attached to the coping to form a final restoration. The final restoration is attached to a final abutment.
Still yet another aspect of the present invention is a method for forming a final restoration. A transfer coping is provided. The transfer coping has a body portion comprising a proximal end, a distal end and an inner surface that defines an internal cavity, a flanged region, and at least one standoff that extends from the inner surface towards a center of the internal cavity. The transfer coping is placed over an upper region of a final abutment that is secured to a dental implant within a patient's mouth. An impression of the patient's mouth is formed by placing impression material around the transfer coping and the final abutment. The impression and the transfer coping are removed from the patient's mouth. Model material is poured into the impression to form a model of the patient's mouth and the upper region of the final abutment.
Another aspect of the present invention is a final restoration for a prosthodontic assembly. The restoration comprises a body portion having a proximal end, a distal end and an inner surface that def
Nobel Biocare AB
Wilson John J.
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