Teeth essentially can be thought of as having two main parts, the crown, the part above the gum tissues, and the root, the part that is suspended in the bone by the periodontal ligament (peri-around, odont-tooth) which keeps the tooth in place. A dental or endosseous implant (endo – inside, osseous – bone) is actually a root replacement, but unlike the root of a tooth it becomes anchored in the bone of the jaw, formerly occupied by a tooth or teeth. The amazing thing about currently used dental implants is that they actually fuse with, or “integrate” into the bone, a process known as “osseo-integration” (osseo-bone, integrate – to become part of). They are for the most part made of commercially pure titanium, a metallic substance used for many years in medicine and dentistry because it is not rejected by the body, being osteophilic (bone loving). The actual process of osseo-integration is essentially a biochemical fusion of living bone cells and bone substance to an oxide layer that forms on the surface of the titanium.
The illustration shows the assembly necessary to restore an implant with a crown. The assembly consists of an abutment with a screw that fits into the implant and a permanent crown which is then cemented onto the abutment.