Retrograde peri-implantitis is a term used specifically to describe an infection at the apex of an implant deep in the bone. Fortunately such an infection is rare but it usually occurs very soon after implant placement, typically within the first 3 weeks and results in an intense throbbing pain. Such an infection does not normally occur after one month, so if problems present after this time it is probably not a retrograde peri-implantitis.
Retrograde peri-implantitis is thought to result from bacteria left over from a chronic tooth abscess which exist in a quiescent state in the bone and become disturbed on implant placement. Equally it is known to be a complication of immediate implant placement when an implant is placed directly into a fresh extraction socket, where bacteria related to the failed tooth can cross infect the deeper bone during the drilling preparation for the implant. More often than not this infection will respond to strong antibiotic therapy but occasionally it is necessary to undertake a surgical decontamination of the area, which usually arrests the condition although it is associated with some post-operative discomfort.