A polylactide-polyglycolide copolymer (Fisiograft®, Ghimas S.p.A., Italy) was recently used to treat closed bone defects and for sinus floor augmentations. The material is manufactured as gel, granules or sponge, displays a good handling during the surgery; degradation occurs through "bulk erosion" by hydrolysis. Objective of this clinical controlled study was to compare clinically the treatment of deep intrabony defects with the combination of flap surgery (FS)+ Fisiograft® to the FS alone. 13 patients with chronic periodontitis, displaying a total of 24 deep intrabony defects, were randomly treated either with FS + Fisiograft® (test) or with FS(control). Soft tissue measurements were made at baseline and six months following the surgery. The Wilcoxon paired-samples test was used to statistically evaluate the changes from baseline to six months;the Mann-Whitney U independent-samples test was used for comparison between the groups. No differences in any of the investigated parameters were observed at baseline between groups. Healing occurred uneventful in all patients. At six months after therapy, the test group showed a reduction in mean probing depth (PD) from 7.92 ± 1.88 mm to 3.83 ± 1.27 (p=0.002) and a change in mean clinical attachment level (CAL) from 8.58 ± 1.78 mm to 5.50±1.78 (p=0.003). In the control group, the mean PD was reduced from 7.08 ± 1.08 mm to 4.42 ± 1.44 (p=0.002) and the mean CAL changed from 8.00 ± 1.28 mm to 7.00 ± 2.13 (ns). The test treatment resulted in statistically higher PD reductions (p=0.024) and CAL gains (p=0.02) than the control group. In both groups, a minute or no radiographic defect fill was observed at six months after treatment. At six months after the surgery both therapies resulted in PD reductions and CAL gains.Treatment with flap surgery + Fisiograft® resulted in significantly higher CAL gains and PD reductions than treatment with FS alone. Schlagwörter: polylactide-polyglycolide, intrabony defects