Immediate Versus Delayed Surgical Reconstruction of Peri-implantitis Intra-bony Defects.

Inclusion Criteria: * Systemically healthy adults * Age ≥ 18 years * The patient must be able to perform good oral hygiene * With at least one implant with either cement or a screw-retained prosthesis demonstrating a diagnosis of peri-implantitis at an implant in function for a minimum of 1 year with a prosthesis installed. * In cases where previous radiographic records are available: presence of bleeding and/or suppuration on gentle probing, increased probing depth compared to previous examinations, and radiographic evidence of bone loss beyond initial crestal remodeling. (Berglundh 2018). * In cases where baseline radiographs are not available: presence of PPD ≥6 mm with BOP and/or suppuration (SUP) and radiographically detectable marginal bone loss (MBL) exceeding 3 mm on an implant in function forfor at least 1 year (Berglundh 2018). * Target implants have to also demonstrate the presence of a peri-implant intra-bony defect with a depth ≥3 mm and width ≤4 mm, as assessed on radiographs and confirmed intra-surgically. In addition, the bony defect should present with a minimum of two walls . No implant mobility and no evidence of occlusal overload. In patients presenting with more than one implant meeting the inclusion criteria, a single implant will be randomly selected for inclusion in the study. Exclusion Criteria: * Short implants (≤ 6mm) * Contraindications for undergoing oral surgery. * Patients pregnant or attempting to get pregnant (self-reported), or nursing women. * Untreated/active periodontitis, or other untreated acute infections at the surgical site. * Untreated malignancies at the surgical site. * Self-reported current smoking, or active tobacco chewing, or chronic vaping. * Taking long-term (\>1yr) NSAID, prednisone or other anti-inflammatory prescription drugs * Patients with any known history of blood disorders or complications such as abnormal concentration of thrombin and factor XIII in plasma, or hemophilia. * Patients with significant co-morbidities, such as obesity, uncontrolled diabetes, immunosuppression, severe endocrine-induced bone diseases, signs of malnourishment, those receiving immunosuppressive therapy, poor tissue oxygenation or perfusion, and pre- or post-operative radiation. * Unable to give consent for participation.