Open flap debridement and surface decontamination with titanium brush (n = 30/Control), or additional insertion of PTG (n=33/Test) was performed for reconstruction of 3- or 4-wall intra-osseous peri-implant defects with at least 3 mm defect depth and circumferential (≥270°) morphology. Patients were given amoxicillin and metronidazole for 8 days. Radiographic and clinical assessments were performed at baseline and 6 months.