Do dental implants cause bone loss?
 

I've been doing a lot of reading about implants and I'm a bit confused. All the adverts seem to imply that they will last a lifetime and have no side effects but others say they cause all sorts of problems including bone loss around the implant. Also that they will never last a lifetime and cannot be replaced when they finally fail. Which is true? I thought getting an implant is recommended to prevent bone loss after an extraction.