The goal of this clinical trial is to compare non-surgical treatment by mechanical debridement with air-polishing in peri-implantitis. The main question it aims to answer is:

• Does non-surgical treatment of peri-implantitis with an air-polishing devise (Perioflow® EMS, Nyon Switzerlad) provide a better treatment result than conventional cleaning with mechanical instruments?

Participants will receive non-surgical treatment of peri-implantitis either with mechanical debridement and with an air-polishing devise.

Researchers will compare pocket depth and bleeding/suppuration on probing in implants treated with the two methods to see if either of them is more efficient in treatment of peri-implantitis.

Inclusion Criteria:

• Referred to TkNN (Tannhelsetjenestens kompetansesenter for Nord-Norge) for treatment of peri-implantitis
• Participants should have at least one implants with peri-implantitis according to the diagnostic criteria from the 2017 Chicago Consensus Meeting.

Exclusion Criteria:

• Cemented prosthetic reconstructions, individuals smoking more than 10 cigarettes per day, individuals with diabetes and poor control of blood glucose levels, antibiotic treatment during the past threee months, and implants that are preferably to be extracted due to prognosis or function, are excluded.

A periodontist that is not involved in the treatment and who is blinded to the treatment received will evaluate the treatment results.