Section II Biologic Considerations

Section II Biologic Considerations
Hard Tissue–Implant Interface
Osseointegration is the key biologic and biophysical process that has made dental implant therapy predictably
effective for replacing missing teeth. Histologically defined, osseointegration is the direct structural and functional
connection between organized, living bone and the surface of a load-bearing implant without intervening soft tissue between the implant and bone. The discovery of this process occurred by accident when Swedish bone
researchers placed chambers into the bone of animals to examine the vasculature of the bone. Hoping to minimize
the potentially damaging effects of chamber insertion on the bone they wanted to study, they prepared the site for
the chamber using a series of sharp drill bits and drilled at very low speeds, while carefully irrigating the drills to
minimize thermal damage. The chambers they used were made of pure titanium, known to be well-tolerated by
animal tissues. When they sought to remove the chambers for use in other animals, they discovered that the
bone had adhered to the chamber surface so well that they had to fracture the bone to remove the chamber.
The investigators realized that such a tight bond of metal implant to bone could be used to anchor implants in
jawbones to support prosthetic teeth and to provide anchorage in other parts of the face and body.
The primary goal in implant placement is to achieve and maintain an intimate bone-to-implant connection. This
concept is known as dental osseointegration. Dental osseointegration is defined clinically as the asymptomatic
rigid fixation of an alloplastic material (the implant) in bone with the ability to withstand occlusal forces (Fig II-1).
The factors that the Swedish researchers found key to successful implant osseointegration were as follows:
1. Use of biologically compatible material such as pure titanium
2. Implant surface free of contamination and implantation site free of infectious and other diseases
3. Use of an atraumatic insertion technique that minimizes heat damage to bone adjacent to the implant surface
A. Sharp drill bits
B. Gradual increase in width of implant site using graduated drills
C. Cooling of drill bit during drilling
D. Ultra-low speed, high torque drill for implant site tapping and implant insertion
4. Close approximation of the implant surface to the surrounding bone
A. Precision in site development and implant insertion
B. Tapping of dense cortical bone
5. Delayed implant loading (prosthesis placement), giving time for the biologic process of osseointegration to
occur