Osseointegration and Bioscience of Implant Surfaces - Current Concepts at Bone-Implant Interface

The high success rates for the dental rehabilitation of patients with endosseous implants have resulted from many research approaches with the aim of enhancing and accelerating bone anchorage to the implant, thereby providing optimal support for the intraoral prosthetic devices. This revolutionary breakthrough has first evolved from the research efforts of the Brånemark group in the late 1960s by pioneering the insertion of machined screw-type commercially pure titanium (cpTi) implants with minimum surgical trauma and a consolidation period for the healing of the bone (Albrektsson et al., 1981; Brånemark et al., 1969). This first endosseous titanium implant was produced with an industrial turning process, which led to surfaces with minimally rough topographies at the micron level. The bone bonding ability, termed as “osseointegration” by Brånemark et al. (1977), of this machined implant was mainly the result of the proper surgical technique providing macrostability to the implant and the biocompatible nature of the bulk titanium. In the past three decades, much has been learned about the concept of osseointegration and significant improvements on the design and surface of implants were done to eliminate the important challenges of the implant dentistry. Osseointegration was first defined as a direct contact between living bone and the surface of a load-carrying implant at the histological level (Brånemark, 1983) and, in clinical terms, as a biomechanical phenomenon whereby clinically asymptomatic rigid fixation of the implant is achieved and maintained in bone during functional loading (Albrektsson & Johansson, 2001). Typically, an implant is considered to be osseointegrated when there is an absence of movement between the implant and bone under normal conditions of loading following a defined healing period. This clinical state is the result of direct bone apposition to an implant surface without formation of a poorly vascularised collagenous capsule, termed as fibrous encapsulation. Although the concept of “osseointegration” was first put forth to define the connection between bone and titanium, it has been shown that bone anchorage can also be achieved with the use of other materials without an adverse tissue reaction (Wenz et al., 2008). Thus, osseointegration is currently accepted as a general term for boneimplant surface contact. However, the quality of the host bone/foreign implant interface is