Dentistry – Prosthodontics – Holding or positioning denture in mouth
Reexamination Certificate
1998-12-01
2001-01-16
Wilson, John J. (Department: 3732)
Dentistry
Prosthodontics
Holding or positioning denture in mouth
C433S174000
Reexamination Certificate
active
06174167
ABSTRACT:
FIELD OF INVENTION
The present invention relates generally to the field of implant dentistry, and more particularly to the design of one- and two-stage endosseous implants.
BACKGROUND OF THE INVENTION
Endosseous, i.e., intra boney, implants are commonly used to support fixed or removable prostheses where a patient's natural roots have been lost, and as a consequence, support is lacking to provide an adequate foundation onto which the dentist can rebuild a dentition. As the aging population retains more of their natural teeth, and as the younger generations want to take advantage of more conservative approaches offered by implant dentistry, e.g., using a single implant rather than cutting down adjacent teeth to support a short span bridge to replace a missing tooth, implant dentistry has gained more and more popularity and has moved into the mainstream of dentists worldwide.
The current implant design is based on an endosseous fixture, a titanium screw that acts as an artificial root. Br{dot over (a)}nemark,
Tissue
-
Integrated Prostheses
(1985). Modifications made to the endosseous fixture have centered on the macro structure of the implant (e.g., by exchanging the screw with a press-fit/cylindrical implant, a stepped screw or cylinder, or a tapered screw or cylinder), (Brunski J. B.,
Biomechanics Of Oral Implant,. Future Research Directions
NIH Consensus Development Conference on Dental Implants, 1988; Kirsch A. et al.,
The IMZ Osseointegrated Implant System
, Dent. Clin. North Am. 1989 (4), 33:733-791; Niznick G. A., A
Multimodal Approach To Implant Prosthodontics
, Dent. Clin. North Am. 1989 (4), 33:869-878; Wennerberg A. et al.,
Design And Surface Characteristics Of
13
Commercially Available Oral Implant Systems, Id.
1993:8:622-633; Siegele D. et al.,
Numerical Investigations Of The Influence Of Implant Shape On Stress Distribution In The Jaw Bone, Id
., 1989:4:333-340; Olsson M. et al.,
MkII
-
a Modified Self
-
Tapping Br{dot over (a)}nemark Implant:
3-
Year Results, Id.
at 1995:10:15-21; Langer B. et al.,
The Wide Fixture: A Solution For Special Bone Situations And A Rescue For The Compromised Implant, Part
1
, Id.,
1993:8:400-408; Schnitman P. A. et al.,
Implants For Partial Edentulism, NIH
Consensus Development Conference On Dental Implants, 1988), on the micro structure (e.g., surface modifications such as use of machined titanium, blasted titanium, titanium alloy, acid-etched titanium, plasma-sprayed titanium and hydroxyappatite coating, growth factors, and proteins), (Baier R. E. et al.,
Future Directions In Surface Preparation Of Dental Implants
, NIH Consensus Development Conference On Dental Implants, 1988; Young F. A.,
Future Directions In Dental Implant Materials Research, Id
.; Krauser J.,
Hydroxylappatite
-
Coated Dental Implants
, Dent. Clin. North Am. 1989, 33:4:879-903; Buser D. et al.,
Tissue Integration Of One
-
Stage ITI Implants
: 3-
Year Results Of A Longitudinal Study With Hollow
-
Cylinder And Hollow
-
Screw Implants
, Int. J. Oral Maxillofac. Implants, 1991:6:405-412), on one-vs-two-stage designs, (Weber H. P. et al.,
Comparison Of Healed Tissues Adjacent To Submerged And Non
-
Submerged Unloaded Titanium Dental Implants
, Clin. Oral Impl. Res. 1996:7:11-19; Busser D. et al.,
Tissue Integration Of One
-
Stage ITI Implants
: 3-
Year Results Of A Longitudinal Study With Hollow
-
Cylinder and Hollow
-
Screw Implants
, Int. J. Oral Maxillofac Implants 1991:6:405-412), and on modifying the connection between the implant and its abutment (e.g, either internal hex, external hex, standard hex, tall hex, wide hex, etc.), (U.S. Pat. No. 4,960,381; U.S. Pat. No. 5,407,359; U.S. Pat. No. 5,209,666; U.S. Pat. No. 5,110,292).
Irrespective of the design variables discussed above, current systems have two general characteristics in common: First, the abutment-implant interface is planar; and second, the area intended for bone apposition, i.e., osseointegration, terminates parallel to the abutment-implant interface, 360 degrees around the implant.
Traditionally, endosseous implants were designed for treatment of the fully edentulous patient. In general, this particular patient population exhibits reduced bone-tissue volume, both in height and width when compared to the partially edentulous patient with recent or impending tooth loss. However, the bone-tissue morphology of partially edentulous patients significantly differs from that of fully edentulous patients, in that the naturally occurring supporting bone structures reveal a scalloped architecture around the tooth.
Currently available implant technology does not take the different bone-tissue morphologies into consideration. Heretofore use of an implant with an intended bone-tissue apposition surface parallel to a flat abutment-implant interface has led to either (1) placement of soft-tissue intended parts of the implant within bone-tissue, leading to bone-tissue resorption in these areas, and/or (2) exposure of hard-tissue intended surfaces to the soft tissue, resulting in possible peri-implant infections due to bacterial colonization around the rough surface and potential loss of the implant.
SUMMARY OF THE INVENTION
Novel endosseous implants, which are structured to better maintain hard and soft-tissue in the area where the implant exits from the bone-tissue and transverses the soft-tissue. More particularly, the implants of the present invention are designed so that areas intended for hard- and soft-tissue apposition exhibit a scalloped appearance, including convex and/or concave patterns, disclosed approximate the naturally occurring bone morphology. Thus, the implants of the present invention provide substantially increased attachment possibilities for both bone-tissue and soft-tissue, thereby facilitating bone-tissue and soft-tissue preservation and maintenance.
The present invention will enable the surgeon to place an implant into residual bone with the surface of the implant intended for bone-tissue contact and apposition (machined or roughened, surface coated or textured, altered with biologic modifiers such as proteins and growth factors, or any combination thereof) being substantially in contact with bone-tissue, and with the surface intended for soft-tissue apposition (polished/treated with soft tissue specific surface modifications) being substantially in contact with soft-tissue.
More specifically, the implant, according to an embodiment of the present invention, is a substantially cylindrical shaft made from a biocompatible material having a distal end and a proximal end. A bone-tissue/soft-tissue transition region and a abutment-implant interface are both disposed towards the proximal end of the shaft. The bone-tissue/soft-tissue transition region is defined as the approximate region of the shaft and/or the abutment-implant interface where the implant exits the bone-tissue and transverses into the soft-tissue. The bone-tissue/soft-tissue transition region has a bone-tissue apposition surface configured to approximate the physiological contours of the alveolar bone. In a two-stage implant, the abutment-implant interface may be either substantially planar, approximately 90° to the longitudinal axis of the shaft, or contoured to approximate the contour of the alveolar bone. In a one-stage implant the abutment is permanently attached to the abutment-implant interface, or an integral part of the implant itself. The abutment, in both one-and two-stage implants, has an abutment-crown interface, which is either substantially planar or contoured to approximate the contour of the alveolar bone, and a chimney onto which the crown is secured.
An implant constructed according to the principles of the present invention facilitates hard- and soft-tissue maintenance, increases longevity of the implant and improves its aesthetic appearance. As will be readily apparent to the skilled artisan, the present invention may be applied to numerous prosthetic applications, such as, but not limited to, a single tooth replacement, an abutment for a bridge (fixed partial denture) regardless o
Bumgarner Melba
Pennie & Edmonds LLP
Wilson John J.
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