For this retrospective analysis, standardized clinical record forms of a total of 39 partially/fully edentulous patients (25 female and 12 male) exhibiting 57 implants were screened. All patients had attended the Department of Oral Surgery, Heinrich Heine University, Düsseldorf, Germany for the treatment of peri-implantitis between 2007 and 2010, and were under regular implant maintenance care. The mean follow-up time was 41.9 ± 34.75 months (range 6 to 126 months). Some patients were also participating in a randomized prospective clinical study, which aimed at investigating the effects of two surface decontamination methods on the clinical outcomes following combined therapy [14].

A data extraction template was generated and used for the anonymous acquisition of demographic study variables/implant site characteristics and baseline as well as follow-up clinical measurements after surgical therapy. The study was in accordance with the Helsinki Declaration, as revised in 2013 and approved by the local ethics committee.

For patient selection, the following inclusion criteria were defined:

Partially or fully edentulous patients rehabilitated with fixed or removable implant-supported prostheses;

Presence of at least one screw-type (one or two part) titanium implant diagnosed with peri-implantitis;

Respective implants had received a combined surgical peri-implantitis treatment;

No implant mobility;

Presence of at least 2 mm of keratinized mucosa;

Treated chronic periodontitis and proper periodontal maintenance care;

A good level of oral hygiene as evidenced by a plaque index (PI) at the implant level < 1;

No systemic diseases which could influence the outcome of the therapy (i.e., diabetes (HbA1c < 7), osteoporosis, antiresorptive therapy);

No history of malignancy, radiotherapy, chemotherapy, or immunodeficiency within the last 4 years and;

Non-smoker or light smoking habits (< 10 cigarettes per day);

Complied with at least 6 months of follow-up;

Information on the initial bone grafting procedure and protocol at the respective implant site was available.

Patients whose data files lacked information on the bone grafting procedures at the implant site or lacked information on augmentation protocols (i.e., lateral ridge augmentation or sinus floor elevation; one- or two-stage approach), and patients who did not comply with at least 6 months of follow-up were not included in the analysis.