Dentistry – Prosthodontics – Holding or positioning denture in mouth
Reexamination Certificate
2001-10-15
2002-12-24
Lewis, Ralph A. (Department: 3732)
Dentistry
Prosthodontics
Holding or positioning denture in mouth
Reexamination Certificate
active
06497573
ABSTRACT:
FIG. 1
shows a prior art dental restorative system described in U.S. Pat. No. 5,685,714 entitled “Support Post for Use in Dental Implant System.” The system generally includes a dental implant
10
and a support post or abutment
12
. The implant is embedded into the jawbone leaving a gingival end
14
exposed through the bone. This gingival end includes a threaded recess
15
and a multi-sided male projection
16
for abutting with the abutment
12
.
The abutment has a cylindrical configuration with an elongated upper portion
18
and a lower transgingival portion
20
. The abutment serves several functions but generally provides a structure for extending the implant above the gum-line. In this regard, one end of the abutment connects to implant while the other end connects to a prosthesis
22
.
A passageway
24
extends through the abutment and provides a recess
26
at the transgingival portion
20
for engaging the projection
16
of the implant. A screw
28
abuts against a shoulder
30
and engages the threaded recess
15
to hold the abutment to the implant. The prosthesis
22
is fabricated around the upper portion and typically connects to the abutment with either a separate screw (not shown) or cement.
Typically, the abutment is made of metal, such as titanium. An entirely metallic abutment, however, can be visible through the prosthesis and can result in a dark, unattractive shadow within the prosthetic structure. In order to alleviate this particular problem, the abutment shown in
FIG. 1
is made from two different materials. An outer portion
34
is made from ceramic and an inner portion, shown as an insert
36
, is made from titanium or its alloys. The ceramic shields the shadow of the metallic abutment through the prosthesis.
The restorative system shown in FIG.
1
and other prior abutments present numerous disadvantages. The outer portion
34
of the abutment is made of ceramic, typically aluminum oxide. Ceramic, however, is not always a desirable material for use in an abutment. Ceramics, for example, are very brittle and not easily repaired when damaged. If a ceramic component is damaged, for instance chipped, broken, or scratched, it is replaced with a new component. Furthermore, splinted, multiple-tooth ceramic prostheses are very difficult to fabricate because of the hard, brittle nature of the ceramic material. Ceramic components are also difficult to fabricate with precision because of the shrinkage of the ceramic that occurs as the ceramic material is sintered. Further yet, ceramics have a hardness even greater than that of titanium. Once these materials permanently harden, they cannot thereafter be softened and can be re-shaped only by grinding.
The prosthesis
22
is preferably made of porcelain. A porcelain prosthesis bonds well with a ceramic abutment but also is not always a desirable material. Like ceramic, porcelain cannot be easily repaired. If a porcelain prosthesis becomes chipped, for instance, it is replaced and typically not repaired. Additionally, porcelain also permanently hardens once cured. It cannot thereafter be softened and re-shaped. As a further disadvantage, porcelain has a hardness greater than natural teeth. As a result, a porcelain prosthesis will tend to wear an opposing natural tooth during chewing.
The present invention solves the problems discussed above with prior dental restorative systems and provides further advantages.
SUMMARY
The present invention is directed toward a dental restorative system having an abutment formed from two different materials. The abutment includes a metallic core and a polymeric cuff. The core has a cylindrical configuration with an end abutting against a gingival end of a dental implant. The cuff surrounds the outer surface of the core and connects to a prosthesis. The prosthesis is also formed from a polymer and bonds to or abuts the cuff.
The present invention has numerous advantages. For example, both the cuff of the abutment and the prosthesis are made from polymer. These components can be readily repaired if they become chipped, broken, or scratched. Such a repair may occur even after the polymer is hardened and the abutment and prosthesis are placed in the mouth of a patient. Further, the polymeric prosthesis generally will not have a hardness greater than any opposing natural teeth in the patient. As such, the prosthesis will not wear or damage natural teeth as a porcelain prosthesis will. Furthermore, the polymeric cuff can be made to more closely resemble the color of natural teeth than can the traditional metal abutments. As a result, the final restoration will have greatly improved esthetics.
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Riley Robert L.
Tysowsky George
Wagner William R.
Centerpulse Dental Inc.
Lewis Ralph A.
Lyren Philip S.
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