In simplest terms, a dental implant is a device that replaces the root of a missing tooth. After placement, an implant can be used to hold a crown while multiple implants can support a bridge or aid in securing a removable denture. 
The vast majority of dental implants are fabricated of bio-compatable titanium alloy (similar to hip or knee replacements) and are cylindrical structures that are placed into the bone. Less common are blade or plate form implants which are broad, flat devices placed in narrow bone and subperiosteal implants which are larger and form "saddles" that are placed over the jaw bone.

Placement of dental implants has become a routine, well documented procedure in modern dentistry. It is an in-office procedure performed with local anesthetic and often with a mild sedation.