Sydney,
What you are describing is an abcess and/or cyst that formed around the circumference of the dental implant. This condition can occur from any residual infection that was present in the bone prior to the implant surgery.

If a tooth is extracted and the periodontal ligament is not thoroughly removed from the tooth socket during the extraction, the remnants of the ligament can lead to residual infection. Any time the tooth socket is not thoroughly debrided of all necrotic material during an extraction, it can lead to residual infection.

Sometimes during the implant surgery in the upper jaw, the implant is placed too close or even into the sinus cavity. If the implant is left like that, it will lead to infection and ultimate failure of the implant.

Other times, the surgery was not done under adeqaute sterile conditions and bacteria entered the surgical site via an instrument, etc.

If the implant is placed in healthy bone and it fails due to infection, then the culprit could be that the implant crown was ill fitting. If the margins on the implant crown were open in any way, then bacteria will get in there and work it's way up into the bone causing an infection and ultimate implant failure.

I hope the second one is successful for him!

Bryanna