Retrograde peri-implantitis of dental implants

Retrograde peri-implantitis, or implant periapical lesion, is a radiolucent lesion at the apical portion of a dental implant. Typically one will develop in the first few months post insertion.

What is the cause of retrograde peri-implantitis?

The cause is bone death and or infection. We believe this is often due to bone necrosis from overheating. The cases in the literature often seem to have another factor in common and that is minimal bone in area of lesion. This makes sense as very thin bone is more likely to necrosis from the trauma of the surgery due to it being cortical bone with low blood supply.

These lesions consist of active and inactive.

Active lesions are symptomatic and include signs of gingival swelling, pain, swelling, and presence of a fistula. While surgical treatment may be necessary it is our experience that this can resolve on own without intervention.

Inactive retrograde peri-implantitis lack symptoms. We monitor these lesions for changes, both clinically and radiographically. The retrograde peri-implantitis lesion below went from active on 8/8 to inactive on 9/3. It is still currently in the inactive state. It is my opinion that case has a lesion because a bone expander was used in close proximity to the buccal cortical bone. You can view the CBCT of the case on our Youtube channel here or at the bottom of the page.

How do we treat active lesions?

There are two methods for treatment of retrograde peri-implantitis. One involves accessing and cleaning the implant and the other involved removing a portion of the dental implant.

Surgical access and cleaning of an implant with retrograde peri-implantitis

Surgical access and curettage and irrigation of the implant. Much like the treatment of peri-implantitis the methods of cleaning the threads are many. A guided bone regeneration (GBR) finishes up the procedure.

Apicoectomy treatment approach

One can also simply remove the lesion and the offending apical portion of the dental implant as Balshi 2007 JOMI does. This method may be better if the dental implant is apically outside the bone contours or very close. This is somewhat likely as the real reason there is an apical radiolucency may be perf or near perf with the dental implant. This can even be seen in some papers. Not sure these are true retrograde peri-implantitis though.

Is retrograde peri-implantitis real or a result of slightly less than ideal surgery?

Some of the cases in the literature and ones we have seen are clearly the result of less than ideal placement resulting in the apical portion outside the bone or in an area with very thin cortical bone only. The x-ray below is from an article in Dentistry Today Oct 2019. Does this x-ray show retrograde peri-implantitis or simply less than ideal placement? It seems obvious to me this implant is simply too far buccal but depends on where this screen shot is taken from as we move around the arch. It may look better or worse than this as one scrolls through the axial view.