Dentistry – Prosthodontics – Holding or positioning denture in mouth
Reexamination Certificate
1999-04-22
2001-09-11
Lewis, Ralph A. (Department: 3732)
Dentistry
Prosthodontics
Holding or positioning denture in mouth
Reexamination Certificate
active
06287117
ABSTRACT:
This invention relates to root-form one-part and two-part endosseous dental implants for insertion into an opening in the jawbone of a patient that include a healing screw and an optional implant extender.
Such one-part implants include a neck/abutment portion that is sufficiently long to extend through the gum tissue atop such an opening; an internally-threaded shaft inside the implant; an optional implant extender, preferably about 1 to about 4 mm in length, that fits atop the neck/abutment portion; and a healing screw with a threaded shank of sufficient length to pass through a longitudinal passage inside the implant extender, and to engage the internally-threaded shaft inside the implant.
The healing screw holds the extender to the implant, and covers the proximal opening into the longitudinal passage of the extender. If the extender is omitted, the healing screw, upon insertion into the internally-threaded shaft of the implant, covers the opening into the shaft. In some embodiments, these extenders include a distal end portion that fits over the neck/abutment portion of the implants, and a top portion that replicates the top portion of the implants, at least where the healing screw seats upon the implant's top end, and, optionally, where an abutment would sit atop the implant.
Two-part dental implants include an implant and a separate abutment, and require a two-stage surgical protocol. The first stage comprises inserting an implant, such as the CORE-VENT®, SCREW-VENT®, MICRO-VENT®, BIO-VENT® and BRANEMARK® implants, into the jaw bone, and burying it beneath the mucosal gum tissue for a submerged healing period. See, generally, U.S. Pat. No. 4,960,381, whose contents are incorporated herein by reference as though fully set forth here. Such implants include an externally-threaded or unthreaded, tapered or untapered body portion, and an internally-threaded shaft, with an internally-threaded region of sufficient length to accommodate an optional implant extender, and a healing screw with a threaded shank of sufficient length to pass through a longitudinal passage inside the extender, and to engage the internal threads of the implant.
The second stage comprises exposing the top of the submerged implant to allow attachment of an abutment. The abutment has a portion that extends above the gum tissue to allow attachment of a prosthesis. Submerged body implants and even non-submerged implants with a body and neck are usually two-part implants, requiring attachment to the implant of a separate abutment to support a prosthesis.
Many two-part implants include, at the top, a wrench-engaging surface, such as an internal or external hex or spline. Such wrench-engaging surfaces may be used for insertion of threaded implants into an opening in a patient's jawbone, or for connection of one-part or multi-part, screw-retained abutments that engage the wrench-engaging surface to provide anti-rotational stability to the abutment. Such a connection provides a stable base for attachment of a cemented single tooth restoration. All of these implants include an internally-threaded shaft extending downwardly from the top of the implant, and terminating inside the implant. This shaft is of sufficient length, and includes a threaded region of sufficient length, to engage the threaded distal end of the healing screw with, or without an implant extender atop the implant. The overall length of these implants, whether one-part or two-part, is preferably at least about 8 mm, with the internally threaded shaft region of the internal shaft preferably at least about 4-5 mm in length, to accommodate the implant extender and healing screw.
The implant/implant extender/healing screw combination is preferably packaged in an enclosed vial with a stopper that engages all three parts of this combination, but the implant extender may be packaged alone or with a healing screw. Such a stopper includes, at its distal end, a multi-sided male member that fits snugly into multi-sided internal wrench-engaging surfaces of the implant. The stopper also includes a body portion that fits into, and frictionally engages, the opening into a vial for the implant. An external annular flange on the stopper seats on the rim of the vial opening at its proximal end. This stopper includes an internal passage from its proximal end that receives and frictionally or otherwise engages the healing screw and the implant extender. The extender may include a threaded region in its longitudinal passage to engage the threads on the shank of the healing-screw. The stopper then serves as a delivery tool for delivering the extender and healing screw together to an implant after its placement in a jawbone site.
The one-stage surgical protocol comprises inserting an implant, e.g., Straumann's ITI® implant or a Screw-Vent® II implant (see FIG.
1
), with its cylindrical neck portion extending through the gum tissue at time of implantation, avoiding the need for a second stage of surgery. Such implants may have a neck portion alone that extends through the gum tissue, or a neck/abutment portion for support or retention of a prosthesis.
One-part, root-form, endosseous dental implants are disclosed in U.S. patent application Ser. No. 08/887,463, filed Jul. 2, 1997, in the United States Patent and Trademark Office. The contents of that application are incorporated herein by reference as though fully set forth here. Such one-part implants may include a body portion adapted to be inserted into an opening in a patient's jawbone, and to become attached directly to bone at that site through a process called osseointegration. The body portion of these implants may be wholly or partly externally threaded or unthreaded, as in the SCREW-VENT® or BIO-VENT® dental implants; may include a hollow basket structure, as in the CORE-VENT® dental implant; or a ledge-type structure, as in the MICRO-VENT® dental implant. Preferably, the body portion is similar to the body portion of the SCREW-VENT® implant. Preferably, such body portions are tapered, and have externally-threaded surfaces with outside/inside thread diameters of 3.3 mm/2.8 mm, 3.7 mm/3.2 mm, and 4.7 mm/4.2 mm.
The optional implant extenders increase the available jawbone placement options with both one-part root-form endosseous dental implants and two-part root-form endosseous dental implants. With one-part root-form endosseous dental implants, the dental professional can place the implant in a jawbone site with the neck or neck/abutment portion of the implant projecting above the crestal bone and through the mucosal tissue atop the site, thus avoiding the trauma and cost of the second surgery required with two-part implants. Such placement in posterior jawbone sites may be satisfactory, but is likely less desirable in anterior jawbone sites. For such sites, the dental professional can use a one-part, root-form, endosseous dental implant by placing the implant in the jawbone site such that the neck or neck/abutment portion does not extend above the mucosal tissue, and then use the optional implant extender to extend the implant above the mucosal tissue.
Following healing, the extender can be removed, and a tapered abutment or abutment adapter attached to the implant to allow fabrication of a crown with its margin below the tissue for aesthetics. Since the implant extenders have a top surface that substantially mimics or replicates the top surface of the implant, a dental professional's restoration options are unimpeded by differences between the top surface of the implant itself and the top surface of the extender for attachment of a ball or tapered screw abutment.
The wrench-engaging surfaces, internally-threaded shaft, or both may be connected to a one-part or multi-part abutment, whether ball-shaped, tapered (straight or angled), atop the neck/abutment portion of a one-part implant. Such abutments may provide anti-rotational support, or retention for cemented restorations or overdentures, thus expanding clinical applications.
External wrench-engaging surfaces may be multi-sided, mul
Bright Patrick F.
Lewis Ralph A.
Sulzer Dental Inc.
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