Dentistry – Prosthodontics – Holding or positioning denture in mouth
Reexamination Certificate
2001-10-02
2004-04-20
O'Connor, Cary E. (Department: 3732)
Dentistry
Prosthodontics
Holding or positioning denture in mouth
C433S215000
Reexamination Certificate
active
06722884
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to dental procedures in general and, more particularly, to a method and apparatus for installing bone graft material and an implant in a tooth root extraction socket following a root extraction.
BACKGROUND OF THE INVENTION
According to the 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 still have some of their teeth have lost an average of 12 of their 28 teeth, and persons aged 55 to 64 have lost an average of nine of their 28 teeth.
When an extracted or otherwise missing tooth is not replaced, atrophy of the jaw bone occurs over time. Consequently, individuals who have been partially or fully edentulous for an extended period of time are left with an atrophic alveolar ridge that can not securely support a full or partial denture or support the placement of a dental implant. Furthermore, the edentulous individual faces a continuing deterioration of 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. Turning to
FIG. 1
, a tooth of a patient, comprised of a crown
10
and root
20
, are shown seated in the alveolar (or jaw) bone
30
. The buccal and lingual portion of the alveolar bone is surrounded by a layer of tissue known as the gingiva or gum
40
. The crown
10
and root
20
are supported by the alveolar ridge or jaw bone
30
and the gingiva
40
which, in the ideal case, is adjacent to the tooth at a level gum line
50
over the underlying bone. Crown height line
60
is shown. When such a tooth or series of teeth become infected or otherwise dentally compromised such that the extraction of the crown
10
and root
20
are required, the root
20
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 alveolar bone
30
shortly after extraction of the crown
10
and root
20
. As is shown, the alveolar bleeding clots, such that bleeding ceases and a root extraction socket
90
remains in the alveolar bone
30
in the shape of the extracted root
20
.
The buccal and lingual portions of the alveolar bone
30
are composed of bone which has a unique characteristic, i.e., being capable of absorbing the shocks caused by the stress movement of teeth during speech, eating, etc. The removal of a tooth and the resulting absence of frequent use pressure in the area causes the alveolar bone
30
to shrink (i.e., be resorbed) in that area where pressure is no longer applied (the extraction site) with the subsequent loss of 40 to 60 percent (in a 2 to 4 year time) of the alveolar ridge's former height measured at the gum line
50
(i.e., “disuse atrophy”).
FIG. 3
shows an extraction site with various degrees of loss of buccal and crestal alveolar bone
30
two years after the extraction of the tooth represented in FIG.
1
. The jaw bone continues to atrophy at a bone loss rate of one-half to one percent per year until death of the patient.
Bone graft substitute material has been used to immediately fill a root extraction socket
90
at an extraction site after a root
20
extraction in order to promote bone growth and to avoid the expected bone atrophy, i.e., Ridge Preservation. Bone growth is promoted via the bone graft material's intermixing with the patient's own marrow blood which seeps through the root extraction socket
90
. After an appropriate time period to allow alveolar bone regeneration (approximately 12 to 18 months) dense lamina bone forms in the extraction socket area. The patient may then be considered for a denture prosthesis.
The method of applying bone graft material to a newly extracted root site is known. What is desired is a method for installing an implant in a root extraction socket and backfilling the socket area immediately after extraction, i.e., immediate post-extraction implant installation. What is alternately desired is a method for backfilling a root extraction socket with bone graft material immediately after extraction and then delaying installation of an implant in the root extraction socket until bone graft material has promoted sufficient bone growth in the root extraction socket, i.e., delayed post-extraction implant installation.
SUMMARY OF THE INVENTION
It is accordingly an object of the present invention to provide a method and apparatus for immediate post-extraction installation of an implant by (a) immediately installing an implant in a root extraction socket following root extraction and (b) filling the remaining space in the socket with bone graft material to encourage new bone growth in the extraction site and subsequent osseointegration of the implant.
According to an aspect of the invention, a method and apparatus for preserving the alveolar ridge around a newly extracted root socket and providing an implant comprises the steps of installing a dental implant apically 3 to 6 mm to the root extraction socket, filling the remaining open area of the root extraction socket with bone graft material and retaining the bone graft material during initial healing of the bone and gingiva with a restraint such as sutures, or a collagen or a surgical foil dressing.
It is a further object of the present invention to provide a method and apparatus for delayed post-extraction installation of an implant by filling the root extraction socket with bone graft material immediately after root extraction and, after sufficient new bone growth has been promoted by the bone graft material in the root extraction socket, installing an implant in the new bone growth utilizing known methods and apparatus for installing an implant in a normal, non-atrophied jaw bone.
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A. Norman Cranin, et al., Abstract:“The Use of a Particulate, Microporous, Calcified Copolymer as a Ridge Maintenance Device in Dogs,” Joural of Veterinary Dentistry, 12(2):53-58, (Jun. 1995).
U.S. patent application Ser. No. 09/248,079, Ashman et al.
Darby & Darby
O'Connor Cary E.
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