Dentistry – Method or material for testing – treating – restoring – or...
Reexamination Certificate
1999-11-30
2002-06-11
Lewis, Ralph A. (Department: 3732)
Dentistry
Method or material for testing, treating, restoring, or...
C433S173000, C623S016110
Reexamination Certificate
active
06402518
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to dental surgical procedures in general and, more particularly, to a method and apparatus for augmenting a patient's alveolar ridge or jaw bone using bone graft material.
BACKGROUND OF THE INVENTION
According to a National Survey on Oral Health, conducted by the National Institute of Dental Research, approximately 42 percent of Americans over 65 years of age and four percent of those 35 to 64 are totally edentulous. Moreover, those over 65 years old who are not totally edentulous have nevertheless lost an average of 12 of their 28 teeth, and persons aged 55 to 64 have lost an average of 9 of their 28 teeth.
When an extracted or otherwise missing tooth is not immediately grafted or replaced with an implant, atrophy of the jaw bone occurs over time. Consequently, individuals who have been partially edentulous for an extended period of time are left with an atrophic alveolar ridge that can not securely support a denture. Furthermore, the edentulous individual faces deteriorated aesthetics and a compromised ability to chew leaving the quality of the individual's oral life in an unfortunate state.
FIGS. 1 through 3
illustrate the deteriorating effect of tooth extraction on the alveolar ridge.
FIG. 1
illustrates a tooth of a patient, comprised of a crown
10
and root
20
seated in the alveolar bone or jaw bone
30
. The buccal and lingual portions of the alveolar bone are surrounded by a layer of tissue known as the gingiva or gum
40
. The crown
10
and root
20
are supported by the elevated portion of the alveolar ridge or jaw bone
30
and gingiva
40
which, in the ideal case, hold all of the teeth in place such that a level gum line
50
and crown line
60
are maintained. When such a tooth or series of teeth become infected, damaged or otherwise hygienically dangerous, such that the extraction of the crown
10
and root
20
are required, the root is removed from the alveolar bone
30
by separating the surface of the root
20
from the periodontal membrane
70
.
FIG. 2
represents the portion of the jaw bone shortly after extraction of the crown
10
and root
20
. As is shown, the periodontal membrane clots such that bleeding ceases and a socket
90
remains in the alveolar bone
40
in the shape of the extracted root
20
.
The buccal and lingual portions of the alveolar bone
30
are composed of soft trabecular bone which has the unique characteristic of being capable of absorbing the shocks caused by the movement of teeth during speech, eating, etc. The removal of a tooth and the resulting absence of frequent bone pressure stimuli in the area, causes the alveolar bone
30
to shrink in that area, with the subsequent loss of 40 to 60 percent of the alveolar ridge's former height measured at the gum line
50
.
FIG. 3
shows an endulous extraction site with loss of buccal and lingual portions of the alveolar bone
30
, two years after the extraction of the tooth represented in FIG.
1
. After initial 40-60% loss, the alveolar bone
30
continues to atrophy at a bone loss rate of one-half to one percent per year.
Bone replacement graft material has been used to immediately fill a socket
90
at an extraction site after a root
20
extraction, in order to promote bone growth and therefore avoid this atrophy. Bone growth is promoted via the bone graft material's intermixing with the patient's own marrow blood at the extraction site
90
. While methods of applying bone graft materials to a newly extracted root site are known, a method for applying bone graft materials to an area of jaw bone which has already atrophied is not known and would have obvious benefits.
Because an application of synthetic bone replacement materials during a ridge augmentation procedure would not be preceded by a root extraction, such a method must allow the bone graft material to come into contact with the alveolar bone marrow such that the synthetic bone graft material and the alveolar bone can fuse together to create dense lamina bone a in the area where augmentation is desired. Furthermore, a method of shaping the alveolar ridge following the implantation of bone graft material in the augmentation area is required to properly maintain the shape of the implanted bone graft material consistent with the overall desired shape of the reconstructed alveolar ridge.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a method and apparatus for performing ridge augmentation on an atrophied jaw bone using synthetic or other bone replacement materials. It is a further object of the invention to provide a method and apparatus for constructing a provisional denture-stent to be used in the augmentation process either with or without implant insertion. Because the disclosed procedure involves surgery, it is also an object to provide post-operative instructions and recommended clinical follow-up procedures.
According to an aspect of the invention, a method for performing ridge augmentation on an atrophied alveolar ridge of the jaw bone of a patient utilizing synthetic bone alloplast comprises the steps of (1) constructing a denture-stent with a fitted hollow space on the underside of the stent conforming to the desired height, width and extent of ridge augmentation, (2) reflecting gingiva tissue covering the alveolar ridge at the site to be augmented, (3) inserting synthetic bone or other graft material into reflected gingiva tissue of the alveolar ridge and onto the bleeding cortical plate of the jaw bone in the area where ridge augmentation is desired, (4) suturing the reflected gingiva tissue, (5) placing the preconstructed stent over the area of the alveolar ridge containing the synthetic bone graft material immediately after the area has been sutured and (6) fixing the stent denture to the jaw bone when necessary.
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Darby & Darby
Lewis Ralph A.
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