Peri-implant mucositis, which resembles gingivitis around natural teeth, may progress to peri-implantitis, a pathological inflammatory condition that occurs in the coronal portion of dental implants and leads to progressive loss of supporting bone. Prevalence of these conditions is high, with peri-implantitis occurring in nearly 20% and peri-implant mucositis in nearly half of all patients; up to 10% of all implants placed must be removed due to peri-implantitis. Increased risk of developing peri-implantitis has been linked to a history of chronic periodontitis, poor plaque control and a lack of regular peri-implant maintenance treatment.

Typically, retrograde peri-implantitis, limited to the periapex of osseointegrated implants, leads to the failure of the implant to completely osseointegrate. Retrograde peri-implantitis presents with radiographic bone loss associated with the apical area of the osseointegrated implant, resulting in clinical signs of inflammation with or without an abscess or sinus tract anytime from a few days to 4 years after implant placement.

Etiology of retrograde peri-implantitis remains unclear, but current literature suggests it may be caused by 1 of the following:

  • an endodontic infection of an adjacent tooth
  • residual microorganisms present after extraction of the infected tooth
  • excessive heat or compression at implant placement
  • implant apex contamination at implant placement

Some articles have also suggested viral infections as a possible factor. Treatment often includes surgery on the affected implant.

Sarmast et al from the University of Texas Health Science Center at Houston recently reported the successful nonsurgical treatment of 2 patients with retrograde peri-implantitis.


A 58-year-old man, referred for possible implant therapy on severely resorbed posterior mandibular edentulous ridges, underwent guided bone regeneration at sites #18 and #19. At the same time, tooth #20 received a buccal subepithelial connective tissue

graft to cover a cervical defect and achieve root coverage. Two implants were placed 7 months later.

When the implants were uncovered 9 months later, imaging revealed a periapical radiolucency at the apex of tooth #20 and the apex of the implant at #19. Subsequent testing revealed that tooth #20 suffered from pulp necrosis and asymptomatic apical periodontitis, while implant #19 was diagnosed with retrograde peri-implantitis.

The patient and practitioner decided to attempt a nonsurgical treatment. Orthograde root canal treatment was performed on tooth #20. Following a 2-visit treatment, tooth #20 was restored with a crown. Radiographs showed evidence of healing of the periapical radiolucency at both tooth #20 and at implant #19.


A 66-year-old man underwent guided bone restoration prior to implant placement at sites #29 and #30. Although tooth #28 was asymptomatic, tested normal, and failed to show problems either clinically or radiographically, it was diagnosed with pulp necrosis and asymptomatic apical periodontitis when the implants were due to be uncovered. Imaging showed a periapical radiolucency at the apex of tooth #28 and at implant #29. Orthograde root canal therapy was performed on tooth #28; at follow-up, both periapical radiolucencies had resolved.


At follow-up (2 years for the first patient and 6 months for the second), the patients remained asymptomatic. With the chance of developing retrograde peri-implantitis in an implant adjacent to a tooth with an apical lesion at about 1 in 4, a nonsurgical endodontic approach should be the first treatment option to resolve retrograde peri-implantitis.

Sarmast ND, Wang HH, Sajadi AS, et al. Nonsurgical endodontic treatment of necrotic teeth resolved apical lesions on adjacent implants with retrograde/apical peri-implantitis: a case series with 2-year follow-up. J Endod 2019;doi:10.1016/j.joen.2019.01.002.