BACKGROUND The restoration of damaged periodontium, especially one-wall intrabony defects, is a major challenge for clinicians. Concentrated growth factors (CGF) are a 100% autologous fibrin with multiple concentrated growth factors. The rigid fibrin structure of CGF makes it possible to preserve or reconstruct the initial bone volume. The aim of this study was to evaluate the clinical healing patterns after surgical application of CGF with and without a Bio-Oss graft in one-wall infrabony defects. MATERIAL AND METHODS We randomly divided 120 one-wall intrabony defects in 54 patients into 4 groups: flap surgery alone (Group 1), flap surgery with autologous CGF (Group 2), flap surgery with Bio-Oss (Group 3), and flap surgery with CGF+Bio-Oss (Group 4). Clinical parameters such as probing depth (PD) and clinical attachment level (CAL) change were recorded at baseline and at 6 and 12 months postoperatively. RESULTS At 12 months postoperatively, Group 2 showed significant improvement in clinical parameters over Group 1 (P<0.05) and the results were significantly greater in Groups 3 and 4 compared to the other groups (P<0.05). Although no significant difference was noted between Groups 3 and 4 in clinical parameters (P>0.05) compared to Group 3, the mean change of CAL at 6-12 months in Group 4 was not significant (P>0.05). CONCLUSIONS CGF reduced periodontal intrabony defects depth and, when mixed with Bio-Oss, CGF showed better results in the early period and the effect was more stable.