Dental Implants are structures that are implanted into the gum
or bone to help support tooth replacements. Over the past
centuries, a spectrum of designs have come and gone in man's
pursuit to permanently replace teeth.
The Early Years
Man has been quite ingenious in developing tooth replacements
independent of other teeth. Egyptians buried gold roots into the
gums. Thousands of years later, dentists drilled holes into the
gums to snap removable dentures in for additional retention. In
Europe and America, dentists started to open the gums, drill
troughs into the bone and place metal structures to support teeth.
These implants were shaped as flat plates or vents and were usually
subject to biting forces shortly after placement.
Other large implants, requiring two surgeries, were placed on
top of broad areas of bone but under the gums. The first surgery
was performed to get an impression of the bone. After a laboratory
created the implant, a second surgery was performed to place the
implant on the bone. Usually these implants were surrounded by scar
tissue or fibrous encapsulations, which were often unstable and
susceptible to deep infections. Additionally, significant
procedures were performed to remove the implants, resulting in
additional loss of bone or gum.
One fairly stable system, which enjoyed some success and
popularity, was called the trans-mandibular staple. Two to four
long metal screws were placed through the lower jawbone using a
surgery from under the chin and in the mouth. A plate was fastened
to the base of these screws and over the jaw but under the gum.
These two to four screws served to anchor dentures, which may have
been unstable without the implants. The most widely encountered
objection to this system was the relatively involved surgery and
limited applications. This procedure was mainly used in the lower
front jaw.
Discovery Of Osseointegration Advances Implants Treatment
In the 1950's and 60's, a Swedish orthopedic surgeon, Dr. P. I.
Bränemark, performed research on bone circulation in rabbit tibias.
He implanted titanium metal screws with optic chambers to evaluate
circulation in bone when select conditions were created. He
discovered that these titanium chambers were difficult to remove
after healing.
Dr. Bränemark then performed a series of research studies in
dogs to determine the potential applications for implants to
replace teeth. The basic difference between this system and past
designs included an approach that emphasized the protection of
living bone around the implants. This approach required minimal
damage to the bone supporting the implants. Dr. Bränemark
discovered that time was required to allow for growth of bone
directly to the implant surface. This resulted in a direct
bone-implant interface that Dr. Bränemark named OSSEOINTEGRATION.
Implants that successfully integrated to the bone functioned
predictably and comfortably for long time periods. In the 1960's,
human studies were initiated to test dental implants to support
bone anchored dentures. These patients were followed over thirty
five years with success rates near ninety six percent success
rates!
Modern Implants:
Implants were still so unpredictable in the 1970s that at a
consensus meeting held at Harvard University in 1978 it was
determined that an implant system was considered acceptable if 75%
of the implants were still functioning after five years. In
contrast, today's systems enjoy success rates ranging 90 to 98%
over time periods from 5 to 35+ years.
Most of today's dental implant systems are designed around the
same concepts that Dr. Bränemark developed. These implant systems
are placed into the jawbone, allowed to integrate with living bone,
and then used to anchor tooth replacements. Most are screw-shaped
with internal openings that allow teeth to be attached. Most
systems are made with a roughened titanium surface to increase
implant surface area and improve bone integration, and increase
chances for success in bone with poor density. This implant surface
is growing in popularity as research shows improved success rates.
Some dentists use an implant surface coated with chemicals as
research shows this can improve the speed and quantity of
connection of the implant to bone.
Research continues today to find chemical treatments that
further enhance the quality and quantity of bone-to-implant
connection.