My husband had one done about 18 months or so ago. He lost the tooth almost 2 years ago, when it cracked in half. They went in to see about a crown or whatever, and it just crumbled, so it all came out. Set him up for an implant about 4 months (?) after the extraction. It is surgery. They put them "under". What they actually do is drill into the jaw bone and implant-really they screw it into the bone-- a titanium "root". The bone and titanium actually will fuse over time. Once the implant procedure is done, there is a short waiting period (a couple of months ?) for the implant to heal. The put a little cap thingee on it (not like getting your teeth capped, but like a little cover thing that is very temporary) until it is healed. Once healed, they take the tooth replacement (which they mold during the interim) which is I think made up of the same stuff they make tooth colored fillings (not sure on that part, it might be ceramic)... anyway.. They pop that on the titanium "root" and they are done.
My husband hasn't had one tiny issue of any kind, since the actual tooth was removed. No issues with the implant procedure. No issues with the recovery. No issues with the tooth part. Nothing.
Yeah.. it was pricey. Altogether, including the extraction, it cost around $3400. The extraction was done by our regular dentist. He referred him out to an implant surgeon (specialist) for the rest.
ETA: How long has she had the bridge? Over time, the bone (that the implant would be screwed into) deteriorates if there is no tooth/implant in place after an extraction or lost tooth. She may not have sufficient bone left to DO a proper implant. Here's more info that might help explain: http://www.baltimorecosmeticimplantdentist.com/bone_densi...