Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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CAP TACK BONE GRAFT DEVICE
BACKGROUND
Referring to Fig. 1, an implant is illustrated in an ideal position which
means that the
implant is inline with the tooth root. The problem is that after extraction
most dental
ridge resorb and lose about 3mm or 30% of the ridge width.
Referring to Fig. 2, in a dental resorb ridge a bone graft is often needed to
achieve ideal
position. Compromise leads to poor loading control with long teeth on short
implants
and poor esthetics with long looking front teeth.
There are two main bone grafting options a particulate graft and a block of
bone taken
from chin or corner of the jaw. The particulate graft is done simultaneously
with implant
placement (I full surgery). This can be done with a "self bone" from other
site in mouth
i.e. corner of jaw or commercial. sources (bovine HA crystals, human donor
products,
etc.). The block of bone can be taken from chin or corner of jaw and it is
placed before
implants so requires 2 full surgeries; block placement and then implant
placement.
The concept of space preservation is the key to bone graft success. A bone
graft resorbs
unless there is a barrier membrane to prevent soft tissue in growth. Fibrous
tissue
matures about 4 x faster than bone and bone needs to be separated from soft
tissue and
space provided for bone formation. Space is needed for bone to grow. Some
membranes
such as collagen are soft so do not hold space very well.
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Space is needed for bone to grow. Dissolving membranes such as collagen are
soft so
they do not hold space very well, but are forgiving surgically if exposed.
Durable
membranes of GoretexTM hold space but if exposed become growth surface for
bacteria.
Fig. 3 illustrates a simultaneous bone graft. In the simultaneous bone graft
procedure a
bone graft can be done simultaneously with the implant. Autogenous bone from
another
site in mouth and commercial HA ceramic bone could be used. A barrier is
needed to
keep bone from mixing with soft connetive tissue of the flap. This barrier can
be soft
collagen or durable GortexTM. Both of which have disadvantages: soft membranes
do not
works to build out bone space as well; and GoretexTM is very technique
sensitive.
The most common membranes are resorbable collagen or resorbable polygalactic
acid.
These have forgiving property that post surgical exposures rapidly resorb and
so do not
track bacteria into the wound. These membranes resorb at about 4 weeks, so
removal is
not required making second re-open surgery easier.
However, these types of membranes do have disadvantages, they do not hold
space, so
bone grafting with these is limited to 1-2mm volumes. Also, they are not
capable of any
vertical bone gain.
GoretexTM ,( eptfe) once considered the gold standard for membrane in bone
grafting is
non resorbing. However, exposure leads to bacteria tracking along membrane
into
wound. GoretexTM is made with thin ribbing of titanium and provides space
maintenance
so it can rebuild large defects and even gain lost vertical bone. However,
GoretexT"4 can
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be a dual edge sword. It is very technique sensitive with any exposure leading
to bacteria
wicking along membrane. The flaps must be "stretched" over wound since the
bone
volume is now wider than pretreatment. These flaps must be well adapted with
inverted
margins or epithelium will grow down along the contact margins and block full
wound
closure. This is typically beyond the skill of general dentists. GoretexTM is
stopping
eptfe dental membranes as of Aug 2411 in part because of the expansion of
general
dentist doing implants and the lack of skill in Goretex1"'T use.
Fig. 4 illustrates the use of collagen where gain is only within contours of
the jaw and the
use of GoretexTM with the gain extending beyond contour of the jaw.
to Fig. 5 illustrates an implant in an ideal position and a bone graft.
Fig. 6 illustrates an implant with the bone and GoretexTM in place.
Fig. 7 illustrates the implant 3 months later.
Fig. 8 illustrates the bone building potential of GoretexTM
However, the use of GoretexTM is technique sensitive. The membrane must be
tacked on
both sides. This is tricky and not readily in skill set of general dentist.
Additionally, the
membrane must then also be removed and getting the pin out means doing a
second
large surgery.
GoretexTM holds space but is hard to use so general dentists, the larger
market place, are
not doing this procedure. Collagen is easy to use but does not work to build
out bone.
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A small titanium sheet held over implant, ti mesh has been used but is hard to
fix over
implant. Most mesh and or barriers fix to bone and wrap over implant. Some
ideas have
been suggested to fix titanium mesh to the top of the implant but they require
custom
casting and complex, costly machining to get it to tit in each internal part
of different
implant system because the internal section of each implant is proprietary.
DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS
Referring to Figs. 9- 11, in one aspect, an implant 10, a cover screw 20, a
cap tack 30 and
a membrane 40 can be provided.
The implant 10 is inserted into the jaw of the patient. The implant 10 can
include a
aperture 12 that will eventually be used to hold a artificial tooth in place
when the
implant 10 is fully healed and osseointegrated with the patient's jaw bone.
However,
until this occurs, the cover screw 20 is inserted in the aperture 12 of the
implant 10 can
covers the aperture 12 and the top of implant 10 until it heals. A driver hole
22 is used to
insert the cover screw 20 into the implant 10 by allowing the surgeon to
insert a tool in
the driver hole 22 and turn the cover screw 20, securing it in place in the
implant 1Ø
The cap tack 30 is connected to the membrane 40. The membrane 40 can be a
titanium
mesh and in one aspect the titanium mesh can be treated with a bioactive
surface to allow
tissue to grow over it. The cap tack 30 is attachable to the cover screw 40 by
providing
an attachment to the driver hole 22 on the cover screw 20. The cap tack 30
will use a
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friction lock tack 32 to engage the driver hole 22 of the cover screw 20.
Rather than
attaching to the aperture 12 of the implant 10, the driver hole 22 of the
cover screw 20 is
more universal, with only a few variations such as hex-shaped and square
shaped driver
holes. The friction tack 32 will "hammer-in" to the driver hole 20 of the
cover screw 20
and hold down the membrane 40 over the implant 10.
In one aspect, the membrane 40 can be thin and bendable allowing it to be cut
and shaped
to tit the defect. In one aspect, the membrane 40 can be cut and shaped to the
desired
shape to provide the necessary space before being connected to the implant 10
by the
attaching the cap tack 30 to the cover screw 10 inserted in the implant 10.
The membrane
40 can be covered with a collagen barrier or it can be treated with a
bioactive surface to
allow tissue to grow over it.
The foregoing is considered as illustrative only of the principles of the
invention.
Further, since numerous changes and modifications will readily occur to those
skilled in
the art, it is not desired to limit the invention to the exact construction
and operation
shown and described, and accordingly, all such suitable changes or
modifications in
structure or operation which may be resorted to are intended to fall within
the scope of
the claimed invention.
