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| In 1952, A Swedish orthopedic surgeon named Per
Ingvar Branemark was doing research on the microscopic healing of bony
defects. His subjects were rabbits, and he and his team were
studying healing bone by using specially designed microscope heads made
out of titanium metal with lenses at the tips. These were placed
firmly in holes drilled into thighbone of the anesthetized animals, and
left in place in order to photograph the microscopic events during
healing. |
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After the experiments, he attempted to retrieve
the microscope heads and found that they he could not remove them. Further
study convinced him that the titanium metal was biocompatible and had actually
integrated into the bone. He called this phenomenon "osseointegration".
He spent the next 25 years trying to convince the scientific community that he
had finally discovered a metal that would integrate when implanted in bone, and not
be rejected by the body's immune system.
Today implants are used fairly commonly in
dentistry. They have a good success rate, and can sometimes mean the
difference between a patient having teeth, or going without anything. They
are especially good for people who cannot wear a full denture because they
gag,
or because of severe
bone
resorbtion They can be used to replace individual missing teeth,
and in situations in which a standard bridge
would not work, such as replacing back teeth where no
posterior
abutment is available for a retainer .
In my own practice, I have chosen not to do
rootform implants. This is
not because I don't think highly of them, but because of their high cost, and the
fact that they are generally not covered by dental insurances. This tends to place them out of
reach for most of my patient base. The ones that cross my path are referred
to experienced prosthodontists who do them all the time. I have, however,
recently begun to place mini
implants for the retention of lower dentures.
The Endosseous Implants (rootform implants)
When people think of implants, this is the type they have in
mind. Above are images of three different "rootform" endosseous
implants. Endosseous means that this type of implant is actually placed in
a hole drilled in the bone and are then allowed to integrate, just as
Branemark's microscope heads integrated into the rabbit bone. The two
implants on the left are made of pure titanium. The one furthest left is
the one refined by Branemark himself. The implant in the middle has been
sandblasted with silicone oxide to produce a rough surface. This rough
surface has been shown to help in bony integration. The one on the right has been plasma
coated with hydroxyapatite, the same substance that makes up the enamel on our
teeth. hydroxyapatite has been shown to allow osseo-integration like pure
titanium. The choice of implant type depends on the preferences of the
dentist placing them.
Case before surgery
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insertion of implant into bone
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Panorex showing the case post- operatively
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6 months post-op immediately after uncovering the implants
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The image to the left above shows the special abutments and
screws used to secure them to the implants, as well as the crowns which are
cemented over them. The image on the right is what the finished case
looks like (after the patient has been wearing temporary crowns for an
additional 8 weeks). You can see that the anatomy of the gums
surrounding the implant teeth looks different than that of the gums surrounding
the natural teeth. This is because there is no direct attachment of the
soft gum tissue to the implants as there is to natural teeth.
Implant retained dentures
As you can see from the series of images above, the lower jaw
can undergo some serious deterioration after the teeth are removed, leaving very
little to retain a denture. The ball attachments placed on a pair of
rootform implants can reverse the situation permanently. This solution is
limited to patients with enough bone mass to allow the full width of each
implant to be buried in the bone
MDI mini implants for the retention of lower dentures
 The
image to the right is a schematic of a lower denture retained in position by
four mini implants. Mini implants, unlike standard implants can be placed
in the jawbone in a one hour procedure that generally does not involve cutting
an incision in the gums. These implants are about the size of a round
wooden toothpick, are made out of a very strong titanium alloy which
osseointegrates quite well, and are of the sandblasted variety. The
denture (usually an old denture) is then retrofitted with tiny housings that
contain a rubber o-ring made to slip over the implants. The denture then
snaps into position over the implants and the patient can wear, and use the
denture immediately upon walking out of the office. The cost of this
procedure is much less than the cost of retrofitting a denture with standard
implants, and since the surgery is much less invasive, it can be performed on
nearly any patient with nearly any medical condition. Click on the image
to read more.
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