title: Early cellular responses in cortical bone healing around unloaded titanium implants: an animal study.
abstract: BACKGROUND
  A clear understanding of the early cellular events leading to osseointegration of implants is currently lacking. To gain better insight, titanium implants were inserted in a rabbit model and histologic and histomorphometric analyses were performed at early time points after insertion.
  
  
  METHODS
  Thirty-six cylindrical implants were inserted in the tibial diaphysis of six rabbits and left to heal for 1 to 42 days. Samples were processed into paraffin or methylmethacrylate sections, on which the surface of new bone, region of altered nuclear morphology, relative surface of basic multicellular units (BMUs) and blood vessels, and bone-to-implant contact were measured.
  
  
  RESULTS
  After coagulum formation, osteoclasts and osteoblasts were observed at the bone surface 1 week after healing. In the preexisting bone, osteocytic lacunae appeared to be devoid of cells. This region of altered nuclear morphology continued to extend for 28 days (P <0.05) after implant insertion. This expansion was accompanied by an invasion of the damaged bone by BMUs that initiated intensive bone remodeling, which reached its maximum after 4 weeks (P <0.05) but was ongoing after 6 weeks of implant insertion.
  
  
  CONCLUSIONS
  This study evaluated the early cellular events in cortical bone surrounding titanium implants. The insertion of an implant into bone initiates a series of biologic processes, including the formation of a hematoma, altered nuclear morphology of the osteocytes surrounding the implantation site, intensive bone remodeling, and the formation of new bone, eventually leading to the osseointegration of the implant.
authors.affiliation: Department of Prosthetic Dentistry, BIOMAT Research Group, Catholic University Leuven, Leuven, Belgium.
authors.forename: Elke
authors.initials: E
authors.lastname: Slaets
authors.forename: Geert
authors.initials: G
authors.lastname: Carmeliet
authors.forename: Ignace
authors.initials: I
authors.lastname: Naert
authors.forename: Joke
authors.initials: J
authors.lastname: Duyck
mesh_terms: D000818:Animals; D001857:Bone Matrix / Q000098:blood supply / Q000166:cytology*; D003758:Dental Implantation, Endosseous; D015921:Dental Implants; D023421:Models, Animal; D016348:Osseointegration / Q000502:physiology*; D010011:Osteocytes / Q000166:cytology*; D011817:Rabbits; D014025:Titanium
chemical_list: D015921:Dental Implants; D014025:Titanium