Influence of Different Implant Surfaces on Peri-Implant Osteogenesis: Histomorphometric Analysis in Sheep Marco Franchi,* Beatrice Bacchelli,* Gianluca Giavaresi, † Viviana De Pasquale,* De ´sire ´e Martini,* Milena Fini, † Roberto Giardino, † and Alessandro Ruggeri* Background: The present study investigated peri-implant osteogenesis and implant biologic fixation in different zirconia sandblasted endosseous titanium surfaces (SLA-60 and SLA- 120) and a turned titanium surface (T) 2 and 4 weeks after surgery. Methods: Seventy-two implant screws were implanted in tibia of six sheep. Histologic sections of implants (2 and 4 weeks after surgery) were analyzed with light microscopy for histomorphometric analysis of bone-to-implant contact (BIC), bone ingrowth (BI), and bone surface (BS/BV). Histo- logic blocks were used to perform bone microhardness studies next to the implants. Some implants were also observed with scanning electron microscopy (SEM) and transmission elec- tron microscopy (TEM). Results: In general, the highest values of BIC, BI, BS/BV, and Vickers hardness number (HV) were measured in SLA-60 samples, followed by SLA-120 and T implants. Two weeks after surgery, all the implants appeared biologically fixed by a newly formed woven bone arranged in thin bone trabeculae and filling the gap between implant and host bone. Four weeks after implantation, the thickness of the woven bone trabeculae had increased, especially around the SLA-60 and SLA-120 implants by a gradual deposition of parallel-fiber bone. Conclusions: Our results suggest that, in the early period of peri-implant healing, the implant surface morphology that seemed to influence the increase of peri-implant osteogenesis, bone turnover, and peri-implant bone maturation was SLA- 60. We suggest that this surface, characterized by moderately deep titanium cavities very similar to the osteocyte lacunae, could act as a microscopic scaffold for mesenchymal and/or osteoblast-like cells adhesion. J Periodontol 2007;78:879-888. KEY WORDS Dental implantation, endosseous; histology; microscopy, electron; osseointegration; titanium; zirconium oxide. S hape, chemical composition, and macro/microtopography of the implant surface have been widely studied as major factors positively influ- encing implant osseointegration. Titanium is the most commonly used material for orthopedic and endosseous dental im- plants because of its good mechanical properties and biocompatibility, 1,2 good resistance to corrosion, no cell toxicity, and very poor inflammatory response in peri-implant tissues. 1,3-5 Implant surface topography plays an important role in favoring early peri- implant bone deposition. 6-11 Rough sur- faces increase the implant area in contact with the host bone, favoring both implant primary stability 12,13 and peri-implant bone formation more than smooth sur- faces. 14-20 Titanium implant screws with roughened surfaces, with or without a coating, can enhance the osteoblast ac- tivity, favoring the rate and the degree of osseointegration through the deposi- tion of new bone directly on the implant surface. 10,14,15,21,22 All experimental studies on peri-im- plant osseous healing around different implant surfaces aim to find the implant surface that can best improve osseointe- gration of the medical device, allowing early implant loading. 14,22-31 In recent years, various roughened uncoated sur- faces obtained by removal techniques such as sandblasting treatment have been pro- posed to reduce the time of peri-implant healing. Structural and functional proper- ties of components of osteoblast adhesion * Department of Human Anatomical Sciences and Physiopathology of Locomotory Apparatus, University of Bologna, Bologna, Italy. † Department of Experimental Surgery, Codivilla-Putti Research Institute, Rizzoli Orthopedic Institute, Bologna, Italy. doi: 10.1902/jop.2007.060280 J Periodontol • May 2007 879