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

AIM: To study tissue components adjacent to implants with nanotechnologically modified surfaces at different periods of healing. MATERIAL & METHODS: 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 8 weeks 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 0.4 mm from the surface. RESULTS: After 2 weeks 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 8 weeks. New bone increased progressively between 1 and 8 weeks 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. CONCLUSIONS: 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