Implants are artificial roots. They are used to replace a missing tooth by a new, artificial one.
This sounds easy, but for an implant bone is needed and when a tooth is missing the volume of the bone in this area will decrease, a problem that can be avoided, if the missing tooth is replaced in time, because the implant can preserve the bone level. The reconstruction of missing bone volume is possible, but this is another kind of treatment.
For this reason, early implantations are recommended.