There are many reasons why implants fail. You can not do a bridge connecting an implant to natural teeth. You will either need to have the implant replaced or do a 6 unit lower bridge. Talk to your dentist to determine which will be the best option for you.
Implant replacement or go for the bridge
you have failed implant, you either go for anew implant , after 3 months at least, again,and wait another 5 months, before you load it, and then you can do the 4 unit bridge,
or just go for a 6 unit bridge, and leave that implant without loading it , its called to have a implant put to sleep, and will preserve the bone.this is when patients do not want to go through another surgery, or waiting time.obvoiusly if the teeth besides are good and have good support for a bridge.
You will not be able to do an implant Bridge without successfully replacing the failed implant. This may require a bone graft in order to achieve a site that can accept the new implant which needs to be placed. Your other options are to do a 6 unit fixed bridge from canine to canine or a removable partial denture.
Douglas Jopling, DDS
Dallas, Texas area