20-25 Year Follow-Up on Regenerative Bone Procedures for Peri-Implantitis

The aim of this 20-25 year observational follow-up study is to investigate the outcomes of bone regenerative surgery in peri-implantitis. The study compares two approaches: Group 1: surgery with a bone substitute alone (Algipore) and Group 2: surgery with a bone substitute (Algipore) combined with a membrane (Osseoquest). Both groups received systemic antibiotics-Amoxicillin 375 mg three times a day combined with Metronidazole 400 mg twice a day for 10 days, starting the day before surgery.

The objective of this observational study is to gain insights into the long-term effects of bone regenerative surgery in patients with peri-implantitis and to determine if there is a difference.

The patients were enrolled in a strict maintenance program with supportive therapy every third months with a yearly evaluation.

In this study, patients will examined of the surgically treated implant(s) after 20-25 years. The examination will include a clinical assessment, measuring probing pocket depths at each implant to the nearest millimeter using a standardized probing force of 0.25 N (Hawe-Click Probe, Kerr Hawe SA Bioggio, Switzerland). The prevalence of pus, full-mouth bleeding on probing, and bleeding grades will be recorded around the implant(s) at four sites per tooth and implant(s) as follows: 0 = no bleeding, 1 = point of bleeding, 2 = line of bleeding, and 3 = drop of bleeding. The plaque index will be defined as either visible or not visible at the implant site using an erythrosine dye (TopDent Lifco Dental AB, Enköping, Sweden). All clinical assessments will be performed by the same periodontist (AMRJ).

Data from the clinical treatment were registered in patient records. In parallel, clinical data were documented in a study protocol and saved in a safe in accordance with standard operation procedure at the clinic.The protocol with medical records were not opened until the study was completed and only by authorized persons with access to the data in the study such as, principal investigator and statisticians.

In accordance with an international working group diagnosis of peri-implantitis should include pocket depth, bleeding, and bone loss (X-ray). Thus, in this study the primary outcomes are radiographic evidence of bone fill and changes in probing depths at implants treated.

Parametric tests (independent t-tests, equal variance not assumed), and non-parametric tests (Mann-Whitney U-test, Wilcoxon test) will be performed to assess differences over time and between groups. Statistical significance will be declared at p \<0.05. The Kolmogorov- Smirnov test will be used to define if the data presented with normal distribution or not. The SPSS PASW 29.0 statistical software (SPSS Inc., Chicago, IL, USA) for Apple computer will be used in the analysis.

Patients that will participate in the study will consecutively be given an ID code. and data will be registered in the ordinary patient journal. The code list will be placed in a locked up space, at the clinic.

All patients will be given oral and written information about the study and will sign a written informed consent. The patients will be informed that they could drop off when ever they want without any explanations. The ethical board approved the study.