I have 5, not done all at once. It is a long procedure, first remove the bad tooth have to wait a few months till that heals if its upper they have to take bone from below and also use cadaver bone then put a screw in so the implant will screw on. It takes a total of about 14 months maybe less maybe more.
They put me to sleep each time and it really didn't hurt much after or when it was healing.
Yes it is very expensive,but worth it.