Background: The aim of this clinical and radiographic study was to evaluate the effect of guided tissue regeneration using a bioabsorbable barrier in the treatment of intrabony defects in humans. Methods: Intrabony osseous defects (2 or 3 walls) around mandibular canines and premolars were treated in 10 systemically healthy patients with ages ranging from 35 to 56 years. Prior to the surgical phase, patients were enrolled in a strict maintenance program including oral hygiene instructions and scaling and root planing (presurgical PI and GI <10%). Patients were seen for professional prophylaxis during the duration of the study. Clinical measurements were performed with an electronic probe at baseline and at reentry 8 months following surgical therapy. Measurements included clinical attachment levels (CAL), gingival margin levels (GML), probing depths (PD), bone defect levels (BDL), and alveolar crest level (ACL). A split mouth design was used. Quadrants were randomly assigned for treatment by GTR (experimental) or open flap debridement alone (control). Standardized radiographs were taken at baseline and at reentry. Digital images were analyzed by subtraction to assess changes in area (A) and optical density (OD). Data were evaluated using paired t test. Results: Statistically significant differences were found in both groups when comparing baseline and post-treatment values for CAL, GML, PD, and BDL (P <0.01). Greater reductions in BDL and gain in A and OD were observed in the GTR group when compared to control (P <0.01). Both therapies were effective in improving the clinical parameters assessed. Conclusion: Clinical and radiographic findings from this study demonstrated more bone fill in sites treated with GTR.734353359