The structure of bone is an important consideration for the size, type, and surface of dental implants. Haversian canals are microscopic tubes or tunnels in cortical bone that house nerve fibers and a few capillaries. This allows bone to get oxygen and nutrition without being highly vascular. These canals also communicate with bone cells using special connections, or canaliculi. This connection facilitates the deposit and storage of mineral salts, which essentially gives bones their strength. Haversian canals are formed by lamellae, or concentric layers of bone, and are contained inside osteons. Osteons are cyndrylical structures that transport oxygenated blood to bone, and they are arranged parallel to the surface of the bone, along the long axis. Osteons that have intact Haversian canals comprise about 45% of cortical bone, or a little less than half. Haversian canals and osteons are part of the Haversian system, which allows nutrients to pass between the blood and bone.