The Toronto Conference – Osseointegrated Dental Implants - 44 years later

A new "light" at the bone-implant interface in 1982.

This seminal event was held in Toronto, at the Four Seasons Hotel, from May 9 to 11. The year was 1982. Thus, 44 years have passed.

By coincidence, in the same month of Per-Ingvar Brånemark birthday, born in May 3rd.

For the first time, the “Swedish squad” of dental scientists and surgeons, over the leadership of Prof. Dr. Per-Ingvar Brånemark, and invited by Prof. George Zarb (University of Toronto, Canada), provided in depth what was really achieved with the contemporary titanium dental implant (fixture) and the so-called bone anchored dental prostheses.

At the same time, professionals from respected, local universities were there to witness the new area of oral rehabilitation with contemporary dental implants.

Also, those lectures were published as series of articles found in the Journal of Prosthetic Dentistry. The year was 1983 (see at the end of this article).

For the newer generations, such an event cannot be simply denied.

For classic generations, a pivotal masterpiece that brought hope for the edentulous predicament and refreshed the complete denture teaching.

To be edentulous meant to be an oral invalid?

The expression “oral invalid” or “handicapped” soon captured the dental profession and pointed out that the alveolar bone without teeth would progress to the atrophic state, being further compromised in case of long-term wearing of complete, removable dentures (prosthesis).

In this way, “to cope or not to cope” was the biological dilemma.

Meanwhile, it is true that techniques such as “the neutral zone” or the use of lingualized occlusal settings” already exist, but even thus the height/width of the residual alveolar bone still posed considerable challenges.

Those oral problems also resulted in social problems: imagine an entire generation (maybe most grandpas and grandmas at that time) prevented from interacting well with their families.

What means the word “osseointegration”: a possible answer

For the first time, the bone tissue was really approaching (with capital A) the screw-thread, titanium dental implant.

And these were not anecdotal observations: now, the evidence was mounted on light microscopy, scanning microscopy, transmission microscopy, radiographs, animal studies, and especially from human beings (with at least 10 years of use).

Also, vital microscopy revealed the importance of nutrition (capillaries) and the reformation of the Haversian bone layers throughout the whole process.   

According to official records, there were more than 4,000 dental implants with consistent documentation installed in humans.

Different from other metals, titanium has a dielectric constant value similar to water (it can hold similar electric charges avoiding repulsion).

Still, at its periphery, there is the oxide layer that changes over time, transiting molecules, ions, and another species.

Simply speaking, “at the end of day”, an apatite layer like the natural bone will approach the titanium surface, a fact not seen in any known metal used in dentistry.

No magic, just real science. For the good of mankind.

More than 80% success in the maxilla, more than 90% success in the mandible. A new dental hope was on the way for America.

Surgical and prosthodontic principles: the tenets were established

Since then, the Brånemark protocol was a term used to describe the sequence of surgical and prosthetic interventions.

Curiously, at the very beginning, no mentions on torque insertion values were found, but minimal trauma was advocated to avoid bone resorption using a precise technique and gentle insertion of the dental fixtures.

From the biomechanical standpoint, since the bone-implant interface formed a continuum of different elastic moduli, overload of the entire system (prosthesis too) would have to be counteracted by better implant distribution and reduced cantilevered units.

Thus, preventive measures were taken.

Years ahead: the world of the dental implants would never be the same

It is a fact that this therapy evolved to more esthetic abutments (partial, single cases) and new prosthetic material/designs, as well as new dental implant surfaces with varied nanometric roughness, and the use of flapless and guided surgery modalities, and all sorts of implant-abutment connections.

Also, new dental implant centers and companies were created all over the world to provide their own, customized solutions. Finally, more scientific periodicals started to publish and reflect on how implant dentistry and the other dental disciplines would benefit each other.   

Even after all those years, it´s still remarkable how such initiative was made and how a tiny piece of titanium changed forever the lives of millions.

A very special thank you to Profs. P-I Brånemark and George Zarb.

Suggested readings

Zarb GA. Introduction to osseointegration in clinical dentistry. J Prosthet Dent. 1983 Jun 49(6):824.

Zarb GA. The edentulous milieu. J Prosthet Dent. 1983 Jun;49(6):825-31. https://doi.org/10.1016/0022-3913(83)90358-x.

Kasemo B. Biocompatibility of titanium implants: surface science aspects. J Prosthet Dent. 1983 Jun;49(6):832-7. https://doi.org/10.1016/0022-3913(83)90359-1.

Parsegian VA. Molecular forces governing tight contact between cellular surfaces and substrates. J Prosthet Dent. 1983 Jun;49(6):838-42. https://doi.org/10.1016/0022-3913(83)90360-8.

Skalak R. Biomechanical considerations in osseointegrated prostheses. J Prosthet Dent. 1983 Jun;49(6):843-8. https://doi.org/10.1016/0022-3913(83)90361-x.

Eriksson AR, Albrektsson T. Temperature threshold levels for heat-induced bone tissue injury: a vital-microscopic study in the rabbit. J Prosthet Dent. 1983 Jul;50(1):101-7. https://doi.org/10.1016/0022-3913(83)90174-9.

Hansson HA, Albrektsson T, Brånemark PI. Structural aspects of the interface between tissue and titanium implants. J Prosthet Dent. 1983 Jul;50(1):108-13. https://doi.org/10.1016/0022-3913(83)90175-0.

Bergman B. Evaluation of the results of treatment with osseointegrated implants by the Swedish National Board of Health and Welfare. J Prosthet Dent. 1983 Jul;50(1):114-5. https://doi.org/10.1016/0022-3913(83)90176-2.

Lekholm U. Clinical procedures for treatment with osseointegrated dental implants. J Prosthet Dent. 1983 Jul;50(1):116-20. https://doi.org/10.1016/0022-3913(83)90177-4.

Adell R. Clinical results of osseointegrated implants supporting fixed prostheses in edentulous jaws. J Prosthet Dent. 1983 Aug;50(2):251-4. https://doi.org/10.1016/0022-3913(83)90026-4.

Albrektsson T. Direct bone anchorage of dental implants. J Prosthet Dent. 1983 Aug;50(2):255-61. https://doi.org/10.1016/0022-3913(83)90027-6.

Lundqvist S, Carlsson GE. Maxillary fixed prostheses on osseointegrated dental implants. J Prosthet Dent. 1983 Aug;50(2):262-70. https://doi.org/10.1016/0022-3913(83)90028-8.

Zarb GA, Symington JM. Osseointegrated dental implants: preliminary report on a replication study. J Prosthet Dent. 1983 Aug;50(2):271-6. https://doi.org/10.1016/0022-3913(83)90029-x.

Brånemark PI. Osseointegration and its experimental background. J Prosthet Dent. 1983 Sep;50(3):399-410. https://doi.org/10.1016/s0022-3913(83)80101-2.