Define osseointegration and its theories.

Osseointegration implies that "it is a contact established without interposition of non bony tissue between normal remodeled bone and an implant at the light microscopic level, entailing a sustained transfer and distribution of load from the implant to and within the bone tissue". Osseointegration can also be defined as "a direct structural and functional connection between ordered, living bone and the surface of a load carrying implant" Creation and maintenance of osseointegration, therefore, depends on the understanding of the tissue's healing , repair, and remodeling capacities. Branemark's Theory of Osseointegration Branemark proposed that implants integrate such that the bone is laid very close to the implant without any intervening connective tissue. Branemark also stated that the implant should not be loaded and left out of function during the healing period for osseous integration to occur Weiss's Theory of Fibroosseous fixation Weiss' theory states that there is a fibro-osseous ligament formed between the implant and the bone and this ligament can be considered as equivalent to the periodontal ligament found in the gomphosis. He defends the presence of collagen fibers at the bone-implant interface. Biointegration - dePutter observed that there are two ways of implant anchorage or retention: mechanical and bioactive.