Sequential morphometric evaluation at UnicCa® and DCD® implant surfaces. An experimental study in the dog.

Abstract

To study tissue components adjacent to implants with nanotechnologically modified surfaces at different periods of healing. In 12 beagle dogs, two different implant systems with different surface configurations were randomly installed in the edentulous premolar regions of the mandible. One surface was first acid-etched and subsequently, nanotechnologically modified with calcium ions (UnicCa® ), while the other was first sandblasted and acid-etched, and then additionally treated with a nanometer calcium phosphate deposition (discrete crystalline deposition; DCD® ). The implants were fully submerged; surgeries and sacrifices were planned to harvest biopsies after 1, 2, 4 and 8weeks of healing (n=6 per period). A morphometric evaluation of percentages of new and old bone, bone debris/particles and clot, new soft tissues (provisional matrix and immature marrow), mature bone marrow and vessels was performed in the spongiosa compartment adjacent to the implant surface up to a distance of about 0.4mm from the surface. After 2weeks of healing, the soft tissues were represented by 41.0% at the UnicCa® and 37.9% at the DCD® surfaces, in both cases mainly being composed of provisional matrix. These percentages decreased over time, being composed of greater amounts of immature bone marrow, and disappeared after 8weeks. New bone increased progressively between 1 and 8weeks of healing from 9.7±6.3% to 70.0±8.4% and from 8.2±3.5% to 67.0±6.1% at the UnicCa® and DCD® surfaces, respectively. Pristine bone was progressively resorbed. Throughout the periods of healing observed, the formation of a provisional matrix followed by the formation of new bone and marrow was revealed in a similar fashion as for other modified surface configurations.