Early Historical Developments:
Replacing lost teeth with a “bone anchored device” is not a new concept at all. Archeological evidence was found that the ancient Egyptian and South American civilizations already experimented with “re-implanting” lost teeth with hand-shaped ivory substitutes.
In the 18th century lost teeth were sometimes replaced with extracted teeth of other “donors”. The implantation process was probably somewhat crude and the success rates extremely low due to the strong immune reaction of the receiving individual.
In 1809, Maggiolo fabricated a gold “implant” which was placed into fresh extraction sockets to which he attached a tooth after a certain healing period. In 1887, a physician named Harris tried the same procedure with a platinum post, instead of gold; and in 1886 Edmunds was the first to implant a porcelain crown mounted on a platinum disc in the US at the First District Dental Society of New York. Several other attempts were made along the same line, experimenting with different metal alloys and porcelain formulations, however on the whole the long-term success rates were very poor.
Strock placed the first somewhat successful oral implants in 1937 at Harvard University. Strock published a paper on the physiological effects of cobalt-chromium-molybdenum alloy (vitallium) in bone, and thus placed a series of vitallium implants into test animals and humans. These implants were immediately implanted after an extraction and no untoward post-operative complications were reactions were recorded. Histologic sections from the test animals showed remarkable, complete toleration. He followed some of his patients successfully for fifteen years, until he died. Certain types of implants used today are often still cast from vitallium.
Modern Historical Developments:
The time span from the mid-1930s to the present represents the period one begins to see the emergence of implant concepts developed into those that are presently the most refined and popularly utilized. These methods include the Subperiosteal, the Endosteal Blade, the Ramus Frame and the Endosteal Root-form or Cylindrical Implant.
The Subperiosteal Implant has been successful in treatment during the past 30 years according to several publications. The first Subperiosteal Implant was placed in 1948 by Gustav Dahl and was constantly improved in its design since then.
The Endosteal Blade Implant, introduced independently in 1967 by Leonard Linkow and Ralph and Harold Roberts also proved to be a very viable form of patient care with respect to implant reconstruction.
The quantum leap in Implant Dentistry was achieved in 1952 in the Laboratory of Vital Microscopy at the University of Lund, Sweden, by a Swedish research team headed by Per Ingvar Branemark, an Orthopedic Surgeon. One of their research projects was to study the microscopic “healing events” in bone. Their test subjects were rabbits. Dr. Branemark’s team designed an optical chamber housed in a titanium metal cylinder, which was screwed into the rabbit’s thighbone. Once the experiment was completed after several months, they realized that the titanium cylinder had “fused” to the bone. He named this phenomenon Osseointegration. Based on this observation, Dr. Branemark’s research shifted more towards the use of titanium appliances in human bone, including the use of titanium screws as bone anchors for lost teeth. Many experiments and trials by himself and colleagues from other disciplines and institutions would head in that direction providing adjunctive expertise in physics, chemistry, biomechanics, medicine and physiology. The Osseointegration concept evolved closely coupled with the design of a cylindrical titanium screw with a specific surface treatment to enhance its bioacceptance.
Many animal and, subsequently human clinical trials were performed to test the success rate, the concept and the design of this implant. Dr. Branemark battled the doubts of the scientific community for many years with continuing clinical trials. In fact, it was not until 1981 when enough long-term data was available to his team to publish a landmark paper for the scrutiny of an intrigued scientific community.
In 1982 the Toronto Conference on Osseointegration in Clinical Dentistry laid down the first parameters on what is to be considered successful implant treatment within the stringent confines of the scientific community. This “Conference” also catalyzed the acceptance and use of dental implants in North America.
Since then many other foreign as well as domestic implant systems have surfaced. Most of them are very similar in design to the original “Branemark Titanium Screw”. However, many improvements have been made since then by many different companies, and research continues to influence future designs and concepts.
Although the FDA has been regulating all medical devices in the US since 1976, oral or dental implants have only recently been placed in a Class III (premarket approval) category. This will require the implant companies to furnish enough data from controlled clinical and preclinical studies to satisfy the stringent restrictions of the FDA, in order for their product to gain their full approval. This will ultimately enhance marketing ethics and benefit the patients in terms of higher standards of care.