Dentistry – Prosthodontics – Holding or positioning denture in mouth
Reexamination Certificate
2001-09-11
2004-06-01
Wilson, John J. (Department: 3732)
Dentistry
Prosthodontics
Holding or positioning denture in mouth
C433S172000, C411S055000, C411S061000, C411S071000
Reexamination Certificate
active
06743018
ABSTRACT:
TECHNICAL FIELD OF INVENTION
The present invention is directed to developments in the dental field, with particular regard to dental restoration apparatus. Typically, apparatus of this type includes a prosthetic implant, an abutment and a fastener apparatus. In use, the implant is adapted to be implanted within an anchor site fashioned within the bone of the jaw of a patient. The abutment is adapted to be mounted on the implant to provide a support surface for a tooth restoration. And, the fastener apparatus functions when engaged with both the implant and abutment in a mounted orientation to secure the structures in a manner to positively resist relative movement of the abutment and implant both axially and rotationally.
BACKGROUND OF THE INVENTION
It is common practice in dentistry and dental surgery to use a prosthetic device characterized as an implant to serve as a base to support a tooth restoration in the process of replacing a natural tooth lost for some reason. In this practice the implant is imbedded in a site referred to as an anchor site created in the bone within the jaw of the patient. It is hoped that the implant, during a healing process, will become secured to and integrated with living bone cells juxtaposed thereto, thus becoming immobilized within the anchor site.
Implants of the prior art have been designed variously in order to achieve a level of securement during a process of biological cementation, known as “osseointegration,” when the implant attaches to and integrates with living bone cells in position in situ within the anchor site. Generally, the implant includes a body formed either of circular cross-section or of gradually tapered outline from a trailing end toward a leading end. It is intended that implants fabricated in these body shapes when received in the anchor site become immobilized in the seated, final disposition to function as a final, stable and secure base for mounting an abutment and tooth restoration.
Many prior art designs of dental restoration apparatus and its component parts function adequately in carrying out the intended use. However, many designs of implant are known to suffer from a number of well documented difficulties and shortcomings that continue to require attention of those involved in the art of tooth restoration.
Many of these difficulties and shortcomings are attendant to factors including the consequences of and the reaction to the force of loading upon the implant/abutment interface during the initial or integration phase, particularly with forces such as those generated during eating, and the consequences of and the reaction to the lack of adequate surface area of the body of the implant in contact with viable tissue and bone cells within the anchor site.
Another difficulty and shortcoming has its genesis in the placement of threaded implants in dense or poorly vascularized bone, or in loose, poorly organized bone with excess fatty bone marrow. In the former, the pressure of threading an implant into a tapped, dense, hard bone may cause pressure necrosis at the implant bone interface, resulting in failure or a total loss of the implant due to bone necrosis and subsequent fibrous integration of the implant to the bone. In the latter case, implants threaded into bone of poor quality, such as loosely organized bone with fatty bone marrow generally are inadequately stabilized. The inadequacy of stabilization will subsequently lead to failure of the implant.
The body surface of the body of many implants of the prior art is smooth throughout. This is the case irrespective of whether the implant is of circular cross-section or of a configuration tapered from a trailing toward a leading end. The implant of each configuration is pressed fit into the anchor site to the final, seated disposition. Thus, the anchor site within which the body is received is specially fashioned to accommodate the implant whatever the size of the body and whatever its outline. If the anchor site is not properly sized problems will occur. For example, if the anchor site is oversized, the implant will not be supported properly during the healing process. Any movement of the implant when subjected to a force, such as a loading force acting at the implant/abutment interface during the initial healing or integration phase, or within another location during chewing or other oral functions will impede the process of osseointegration. On the other hand, if the anchor site is undersized, the body of the implant likely will cause damage to the cellular bone structure within the anchor site as the implant is pressed fit or threaded (screwed) to the final, seated disposition. Damage represented by crushed bone and fibrous tissue formation should be avoided as best as possible. Thus, the dentist or dental surgeon strives to fashion an anchor site to a size that closely tolerates movement of the implant during implantation, and presents a maximum amount of surface area within the wall of bone that ultimately will reside in intimate contact with the surface of the body of the implant. Adverse characteristics, including those that are the resultant of a poorly prepared anchor site, a poor quality of bone within the anchor site and/or any capability of movement of the implant during healing must be reduced substantially or totally eliminated.
The consequences of loading evidence themselves rather dramatically.
In the past, implants were used by dentists and dental surgeons as anchors for denture/bridge constructions for replacement of multiple, natural teeth. The prior art included implants specifically designed and generally suited for that purpose. Recently, however, dental professionals are being asked to respond to requests related to other aspects of dental surgery, namely that of replacement of individual teeth with tooth restorations that appear more like the natural tooth that was lost. Prior art implants, typically, were fabricated with a body providing only a few millimeters of interface diameter for support of a crown or other restorative structure. The range may be 4 mm or less measured between the occlusal margins. It is not unusual, however, for the dentist or dental surgeon to work with a crown or other restorative structure having an occlusal loading surface much larger in interface diameter. For example, the occlusal loading surface of a molar is in the range of about 6-7 mm by 10-12 mm. Oftentimes, failure and resultant breakdown occurs at the interface of implant and abutment. This may be evidenced by a ditching effect around the cervical margin of the implant, a resultant or associated bone loss, and a loosening or fracture of the body of the crown or tooth structure.
Still further, the emergence profile of the crown as it comes through the gum tissue generally is not aesthetically pleasing. This is because the large size of crown associated with a small diameter implant has an unnatural appearance. Furthermore, periodontal disease may develop as a result of the unnatural undercut of the relatively large crown as it tapers to meet the relatively small body of implant.
In addition, fastener assembies used in prior art to connect the implant and abutment and, then, maintain the connection so that the abutment cannot loosen itself from the condition of engagement with the implant suffer from various difficulties and shortcomings. If the fastener assembly is incapable of maintaining integrity between the abutment and implant, the prosthesis can be damaged, and possibly require replacement. In addition, the loss of integrity of the connection between abutment and implant resulting in microvibratory movement of structures and deterioration of bone cells and tissue within and around the anchor site will encourage a growth of bacteria, leading to gum disease. The effect is cervical bone loss around the neck or shoulder of the body of the implant, and ultimately bone loss along the longitudinal length of the body.
Threaded fasteners, such as screws and bolts for securing workpieces together are well known in the art and have been utilized in a wide v
Morrow Intellectual Properties, LLC
Stoll Keenon & Park, LLP
Wilson John J.
LandOfFree
Dental restoration apparatus does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Dental restoration apparatus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Dental restoration apparatus will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3365906