Retrograde peri-implantitis

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 and is multi-factorial. We believe this is often due to bone necrosis from overheating or from lingering endodontic infection. The cases in the literature often seem to have another factor in common and that is minimal bone in the area of the 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. Poor ability to heal due to minimal blood supply in thin cortical bone, existing bacteria from lingering endodontic infection, and trauma from the surgery itself are likely the trifecta of causes.

These lesions consist of active and inactive.

Active lesions are symptomatic and include signs of gingival swelling, pain, swelling, and/or the 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 and may simply be a part of the healing process. 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.

X-rays from a retrograde peri-implantitis case study.

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 involves removing a portion of the dental implant. That assumes the neighboring teeth are vital.

Retrograde peri-implantitis decision tree

Decision tree from Sarmast, who puts out a lot of good research on the topic.

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.

Retrograde peri-implantitis

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 of the implant being outside the bone or in an area with very thin cortical bone only. Quirynen COIR 2005  states that retrograde peri-implantitis should be distinguished from non-integration of the apex and this is exactly what we see in some studies. 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.

Retrograde peri-implantitis x-ray or poor placement?

The Sarmast JOE 2019 case studies bring up an interesting issue of inactive lesions near teeth needing endo. Placing an implant in either a site with a previous root canal or near a tooth needing a root canal increases the likelihood of a retrograde lesion. Lefever J Clin Perio 2013

Case of retrograde apical peri-implantitis that is almost certainly due to thin cortical bone at apex, trauma of surgery, and preexisting endodontic lesion.

This implant below is slightly too buccal and is likely partially the reason for the retrograde peri-implantitis lesion. We did wait 6 weeks post extraction to place. Maxillary premolars are the site with the highest occurrence of retrograde apical peri-implantitis according to Park 2004 Int J Perio Rest Dent.

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