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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 have become the most rapidly
growing dental service in the world. Properly done, their immediate
success rate borders on 100%, and their ten year success rate is about 95%.
A tooth with a root canal, post and core and crown has ten year success rate of
about 90%. (Unlike natural teeth, implants are not subject to decay,
fracture or failed root canals, but like natural teeth, they can still be lost
to poor oral hygiene leading to periodontal disease.)
Dental implants can be
placed immediately after the extraction of a tooth, and, like the natural teeth
they are meant to replace, they preserve the bone
height wherever they are placed. They can also be used to retain full
dentures in patients who cannot ordinarily wear them due to
gagging,
or because there is not enough bony anatomy to retain them due to severe
bone
resorbtion. They
can be used to replace individual missing teeth, or serve as abutments for a
bridge
.
Finally, unlike traditional
bridges, they have the added advantage of being
able to replace a missing natural tooth without damaging adjacent teeth.
The Endosseous Implants (rootform implants)
When people think of dental implants, they generally are
thinking about endosseous rootform implants. 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 is 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 silicon oxide to produce a rough surface. sandblasted and
etched titanium has become the industry standard. 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 osteointegration like pure
titanium, however, experience has shown that better results are obtained using
sandblasted titanium alone. Most dentists work with a specific brand of
implant since all the drills and wrenches, as well as the implants themselves
are company proprietary.
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 the abutment after it is screwed firmly into the implant itself.
Much more on this process will be
found on the next page. The image on the right is what the finished case
looks like after healing is complete.
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.
Ball abutments placed on a pair of rootform implants can reverse the situation permanently.
When should a patient choose an implant over
preservation of a damaged natural tooth?
Nothing beats a healthy tooth with a live nerve if it surrounded
by healthy gums. Natural teeth are meant to last you all your life,
especially if you have reasonably good
oral hygiene and do not use
sugar
to excess. Even if the tooth has large fillings, or a well done root
canal, it may last for a the rest of your life. For teeth with a root
canal, this is true only if it is
protected with a
post and core followed by a
crown.
A fairly intact tooth with a root canal, a post and core and a
crown has about a 90% ten year survival rate while an implant has about a
95% ten year survival rate. (These figures are industry standards and were
published recently in Dental Economics.) Neither of these statistics takes into account
the vast majority in both categories which survive for twenty or more years.
In most instances, it is wiser to do the root canal, if necessary, on a good, intact tooth with
no gum disease rather than to extract it and replace it with an implant. On the other hand, a patient presenting with
a very badly broken down tooth
above the gum line, or with a tooth that needs a root canal and also has
moderate to severe gum disease, might be wise to extract the tooth and place an
immediate implant instead.
When a dentist suggests an extraction followed by an implant
rather than repairing the natural tooth, he or she is simply calculating the
relative expense vs. the long term prognosis for each option. In other words, twenty years from the
day the procedures are finished, the dentist believes the implant tooth is more likely than the
natural tooth to be in place and functioning. The implant tooth will
never get decay, there is no post and core that may break out, there is
no root canal to fail, and, unlike the roots of a natural tooth with a root
canal, the implant itself will never fracture. (Unfortunately, poor
oral hygiene will cause the implant to fail, just like a natural tooth.)
Finally, the dentist and the patient must consider the expense
side of the equation.
The implant, along with the abutment and bone grafting
that may be necessary will probably cost about 30% to 80% more
than repairing the natural tooth with a root canal, post and core and crown,
but when you consider the probability of that tooth's long term survival, the
costs even out. Furthermore, there are now many ways to finance even an
expensive dental treatment plan. Things have begun to change drastically
in the world of dentistry.
Factors that cause implants to fail
A properly done implant is one of the most predictable
procedures in dentistry. Unfortunately several health related factors can
contribute to peri-implant disease (which is the implant version of periodontal
(gum) disease disease).
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Smoking and smokeless tobacco increase the likelihood
of peri-implant disease by a factor of 5. In other words, if you are a
smoker, or if you chew or dip tobacco, you are 5 times as likely to lose
your implant than persons who do not have these habits.
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Uncontrolled diabetes is a serious risk factor for
implant failure. This is not the case for well controlled diabetics
who's success rate with implants is nearly as high as persons without
diabetes.
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Immunosuppressed patients may have a higher risk of
implant failure. This does not apply to HIV patients who's
symptoms are in remission during implant surgery and healing. Patients
on immunosuppressive drugs for cancer should wait until they are they
have stopped their therapy and are in remission. Patients taking
corticosteroids for chronic conditions are more prone to implant failure.
Patients taking IV bisphosphonates for cancer are poor candidates for
implants. Patients taking oral bisphosphonates (Fosamax, Boniva
Actonel, etc.) are NOT at risk. See my
page on
Bisphosphonates for more on this subject.
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Untreated periodontal disease can predict implant
failure since the same factors which cause
periodontal disease (poor oral hygiene,
smoking etc) can cause peri-implant disease. If you want implants, you
still have to carefully brush and floss or you can lose them.
Dental Implants vs. Fixed bridges A
fixed bridge (fixed
partial denture) is the traditional method of replacing one or more missing
teeth if there remains at least one healthy natural abutment tooth on either
side of the edentulous (empty) space. The dentist prepares (changes the
shape of) the remaining natural teeth on either side of the space and takes an
impression. The lab returns a bridge, which consists of crowns that
replace the anatomy of the abutment teeth with a pontic (false tooth) attached
between them.
The cost of doing a three unit bridge is the same as the cost of
doing three crowns, which, it turns out is about the same as the cost of doing a
single implant with its associated abutment and crown.
However, implants have a number of serious advantages over the fixed bridge,
and consequently, implants are becoming the tooth replacement of
choice. The long term success rate of an implant is, in fact greater than
the success rate for a three unit bridge. Implants also
prevent the loss
of the bone that used to support the extracted tooth,
while the bridge does not.
Bone continues to disappear under a pontic leaving more and more
space between the gums and the false tooth where food can become
trapped.
|
Factor |
3-unit bridge |
single tooth implant |
| Success rate: |
50% fail within 10
years |
97%+ are successful
after 10 years |
| Decay |
Most common cause of
failure |
No risk of decay |
| Risk of needing root canal |
15% of abutment teeth
require root canal |
No risk of needing
root canal |
Failure of abutment teeth
due to fracture, abscess etc. |
12% at 10 years, 30%
at 15 years |
no additional risk
since implants never fracture, or need root canals |
| Prevents loss of bone at site of
extraction |
No |
Yes |
| Can be done if replacing the last
tooth in the arch or in an area where there are no
adjacent teeth. |
No |
Yes |
Financing an expensive dental treatment plan
Dentists are not banks. They have no means of checking
your credit history, and even if they did, they have no legal status as lenders.
They simply cannot finance your dentistry. Until recently, patients either
had to pay for their dental plans all at once, or do a little at a time until it
was all finished. This often lead to financial hardship, unfinished
treatment plans or dental work that never ended.
But things began to change when financiers figured
out that patients are customers too. When that patient goes into an
automobile dealership and purchases a car, he doesn't have to pay for it all at
once out of pocket. Nor does he make arrangements to drive the car only
when he happens to have the cash to pay that month. He makes a financial
agreement with a bank or finance company to take a loan. He then gets to
pay a fixed amount monthly, the dealer gets his money upfront, and the
patient/customer gets his new car.
Today we have several finance companies which do the same thing
for dentistry that they do for car dealerships. Now,
Care
Credit, Wells Fargo,
Henry Schein and several other large banks will
arrange loans that can be used at any medical facility, including physicians,
dentists, ophthalmologists, podiatrists and veterinarians. You don't have
to make your own arrangements. The doctor's staff can apply for you
over the internet. The finance company checks the patient's credit and
makes an immediate decision about granting the loan. If the patient is
approved, he or she signs an agreement, the money goes immediately to the
medical provider, and the patient gets his or her treatment from beginning to
end with no waiting or dragging out his or her wallet at each visit. In
most instances, the medical provider will even pay the interest on the loan
during the first twelve months for the patient.
How are implants done, and How much do they cost?
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