Dental Implants: An Historical Look at Tooth Replacement

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.