Volume 73 • Number 4 Case Series 450 Background: The aim of this 5-year follow-up case series was to clinically and radiographically evalu- ate the long-term results after guided tissue regener- ation (GTR) therapy of infrabony defects using non- resorbable and bioabsorbable barriers. Methods: In 12 patients with advanced chronic periodontitis 12 pairs of contralateral infrabony defects were treated. Within each patient one defect received a non-resorbable (expanded polytetrafluoroethylene [ePTFE]; control: C) and the other a bioabsorbable (polyglactin 910; test: T) barrier by random assign- ment. At baseline and at 6 and 60 ± 3 months after surgery clinical parameters and standardized radio- graphs were obtained. Gain of bone density within infrabony defects was assessed using subtraction radi- ography. Results: Eight of 12 patients were available for the 60-month reexaminations. Six and 60 ± 3 months after GTR therapy statistically significant (P <0.05) vertical attachment (CAL-V) gain was observed in both groups (C6: 2.6 ± 1.4 mm; C60: 1.6 ± 1.5 mm; T6: 3.0 ± 1.7 mm; T60: 3.0 ± 0.7 mm). However at 60 months, 2 infrabony defects in the control group had lost all the attachment that had been gained 6 months after therapy and a clinically relevant but statistically insignificant mean CAL-V loss of 1.0 ± 2.1 mm was observed from 6 to 60 months. The case series failed to show statistically sig- nificant differences between test and control regard- ing CAL-V gain 60 months after surgery. Also sub- traction analysis failed to reveal statistically significant differences regarding density gain between both groups 6 and 60 months postsurgically (C6: 26.4 ± 54.2; C60 62.8 ± 112.7; T6: 68.7 ± 72.8; T60. 84.1 ± 83.6). Conclusions: CAL-V gain achieved after GTR ther- apy in infrabony defects using both non-resorbable and bioabsorbable barriers was quite stable after 5 years in 14 of 16 defects. J Periodontol 2002;73:450- 459. KEY WORDS Bone density; guided tissue regeneration; membranes, artificial; membranes, barrier; membranes, bioabsorbable; polytetrafluoroethylene/ therapeutic use; follow-up studies. The principle of guided tissue regeneration (GTR) has histologically demonstrated the potential for estab- lishing a new connective tissue attachment after peri- odontal surgery using non-resorbable membranes 1-3 and bioabsorbable barriers. 4,5 Several clinical studies compared GTR therapy non-resorbable expanded polytetrafluoroethylene (ePTFE), § as well as bioab- sorbable barriers and conventional periodontal surgery, reporting more favorable results for GTR therapy in infrabony defects. 6-11 The removal of non-resorbable barriers requires a second surgical procedure after 4 to 6 weeks. Clinical studies comparing GTR therapy of infrabony lesions using non-resorbable and bioab- sorbable barriers demonstrated similar results for a short-term period of 5 to 6 months 6,12,13 and 12 months. 14-16 Results after longer observation periods are scarce. 17,18 There are long-term studies compar- ing results after use of non-resorbable and bioab- sorbable barriers in Class II furcation defects 19 but not in infrabony defects. The objective of this follow-up case series was to report the clinical and radiographic results of GTR periodontal therapy with non- resorbable and bioabsorbable barriers over a 5-year period in infrabony defects of a population that had been previously evaluated at 6 13 and 24 months. 16 CASE DESCRIPTION AND RESULTS Patient Population Twelve patients (3 male, 9 female) aged from 32 to 62 years (mean age 46.1 ± 10.1), under treatment for advanced chronic periodontitis at the Section of Peri- Long-Term Results of Guided Tissue Regeneration Therapy With Non-Resorbable and Bioabsorbable Barriers. II. A Case Series of Infrabony Defects Ti-Sun Kim,* Rolf Holle, † Ernest Hausmann, ‡ and Peter Eickholz* * Section of Periodontology, Department of Operative Dentistry and Periodontology, University Clinic of Dental Medicine Heidelberg, Heidelberg, Germany. † Gesellschaft für Strahlenforschung (National Research Center for Environment and Health), Institute of Medical Informatics and Health Services Research, Neuherberg, Germany. ‡ Computer Analysis Plus, Amherst, NY and Department of Oral Biology, School of Dental Medicine, University at Buffalo, Buffalo, NY. § Gore-Tex Periodontal Membrane, W. L. Gore & Associates, Inc., Flagstaff, AZ.