Microvascular changes after placement of titanium implants: Scanning electron microscopy observations of machined and titanium plasma-sprayed implants in dogs

Background: The purpose of this study was to clarify the osseointegration process of titanium implants through study of the vascular architecture and bone apposition. The smooth machined-surface implant is tightly fixed to the bone by its threads. The rough titanium plasma-sprayed (TPS) coated implants give a scaffold for new bone. Methods: Twelve beagle dogs were used, and 2 surface types of implants were inserted in the mandible. Vascular injection was given 14, 30, and 120 days after surgery. The soft; tissue was digested by proteinase solution, and specimens were examined by scanning electron microscope (SEM). Results: Fourteen days after placement of machined implants, new vessels could be seen branching out from the vascular network of the bone marrow. In TPS implants, a vascular network was seen between the bone-implant interface. At 30 days, the vessels were arranged in a groove corresponding to the machined fixture. With TPS implants, new bone was visible along the surface of the fixture, and the vascular network was buried in the bone. At 120 days after placement of machined implants, bone had formed a smooth surface. A few blood vessels were arranged along the bone surface. With TPS implants, a rough bone surface and flat vessels were observed on its surface; Conclusions: Implants become osseointegrated in different ways, depending on their structures and the characteristics of their surfaces. From the microcirculation point of view, the vessels are an important factor for the remodeling of bone.