Having a dental implant placed could aptly be described 'as like having a tooth extracted in reverse'.
As such unfortunately there is pain and discomfort after placement just like when having a tooth removed.
If they are placed in hospital by an oral surgeon or maxillofacial surgeon then this gone be done under GA.
If placed in an implant clinic outside of hospital practice then implants can be placed under sedation or sometimes just local anaesthetic alone.
I know some people who have dental implants and all of them have stinky breaths. They are always in pain and ends up by the dentist to have the implants remove for a cleaning.