Objectives: The aim of this 5 year follow-up study was to evaluate clinically and radiographically the long-term results after GTR therapy of infrabony defects using non-resorbable and bioabsorbable barriers. Methods: In 12 patients suffering from advanced periodontitis 12 pairs of contralateral infrabony defects were treated. Within each patient one defect received a non-resorbable (ePTFE; control: C) and the other a bioabsorbable (Polyglactin 910; test: T) barrier by random assignment. At baseline, 6 and 60±3 months after surgery clinical parameters and standardized radiographs were obtained. Using digital subtraction analysis gain of bone relative density change (mean grey level change x area) within infrabony defects was assessed. Results: Eight of 12 patients were available for the 60-months re examinations. Six and 60±3 months after GTR therapy statistically significant (p Keywords: infrabony defects/therapy, guided tissue regeneration, membranes, artificial, membranes, barrier, polytetrafluoroethylene/therapeutic use, radiography, dental radiography, dental, subtraction