Objectives: Comparison of the clinical outcomes after regenerative periodontal surgery using either an enamel matrix derivative (Emdogain®) or a synthetic bone graft (Ostim®) in wide intrabony defects 12 months after treatment. Material and Methods: Thirty-eight patients with chronic periodontitis were recruited (Table 1). All patients showed intrabony defects of at least 4 mm depth and 2 mm width (Figure 4). Using a microsurgical technique a modified papilla preservation flap was prepared. After debridement, patients were randomly assigned to Emdogain group (control) or Ostim group (test) as schown in figures 2, 3. Assessments at baseline, after 6 and 12 months included bone sounding, attachment level, probing pocket depth, bleeding on probing, and recession (Figure 1). Early wound healing, adverse effects and patients perceptions were also recorded (Figure 5, 6). Results: Both treatment modalities led to significant clinical improvements. No significant differences between both groups were recorded. Change in bone fill 12 months after surgery was 1.6 mm (±1.2) in the test group and 1.6 mm (±1.3) in the control group, respectively. A clinical attachment gain of 1.4 mm (±1.8) in the test group and 2.1 mm (±1.6) in the control group was found. A reduction in probing pocket depth of 2.6 mm (±1.8) in the test group and 3.2 mm (±1.8) in the control group was recorded, table 2, 3. Two weeks after surgery primary closure was maintained in 100% of both test and control groups (Figure 5). No differences in patients' perceptions were observed (Figure 6). Conclusion: The results show comparable clinical outcomes following both treatment modalities 12 months after treatment. Further investigation is needed to identify factors influencing individual responses. Schlagwörter: enamel matrix derivative, intrabony defects, periodontal regeneration, randomized clinical trial