Dental implants are titanium screws placed directly into bone structure to provide support for a single missing tooth, multiple teeth or for the entire dentition.
A single missing tooth would require a single implant to provide an anchor to a single crown. The alternative treatment would require cutting the adjacent teeth to have a fixed bridge replace the single crown. Missing multiple teeth or entire dentition would require multiple implant structures to provide anchors to multiple units either as a fixed bridge (for a few missing teeth) or as anchors to stabilize a removable denture for missing teeth of entire arch.
Most implants will require 3-4 months to allow osseointegration (bone to fuse with implants) before final restorations can be placed on the implants.