The microbial colonization of expanded polytetrafluoroethylene membrane by putative periodontopathogens at 3 minutes of intraoral manipulation was determined in 42 patients with 42 mandibular posterior two‐ to three‐wall defects. Twenty patients exhibited no periodontal pockets of ≥ 5 mm, other than the study site, and low levels of pathogens (group A). Twenty‐two patients revealed multiple periodontal pockets of 5 mm or more and numerous pathogens (group B). Within the preceding 3 months of regenerative surgery, group A patients had received apically positioned flap surgery with osseous recontouring (except for the study site), and group B patients had been enrolled in a non‐surgical maintenance program. The subgingival microbiota was examined prior to regenerative therapy, and the membrane microbiota was examined at 3 minutes and at the time of removal at 6 weeks by culture, DNA probes, and phasecontrast microscopy. The mean initial defect depth was 7.4 mm for group A and 7.2 mm for group B. At 6 months, the difference in mean clinical attachment gain was statistically significant (P < 0.001; group A: 3.4 mm; group B: 1.4 mm). At 3 minutes, putative pathogens were detected in seven (16.7%) membranes in group B (group Binfected), and the associated sites gained only 0.6 mm in clinical attachment at 6 months. Clinical attachment gain was modeled as a linear function of the explanatory variables (r2 = 86%). The presence of Porphyromonas gingivalis detected by DNA probe at 3 minutes was associated with 1.5 mm less expected gain (P = 0.0002). Total microbial counts and the percentage of Peptostreptococcus micros and Capnocytophaga species at baseline, and of motile rods on the membrane surface facing the gingiva at 6 weeks, were statistically significant negative predictors of clinical attachment. For each week the membrane remained covered, an additional 0.5 mm gain could be expected (P = 0.002); and for every 10 sites that exhibited bleeding on probing, the clinical attachment gain was 0.6 mm less at the site of regeneration (P < 0.0001). The present results showed that putative pathogens may colonize membranes within 3 minutes of intraoral manipulation. The patient group treated with periodontal osseous surgery revealed the lowest levels of periodontal pathogens in the membranes and exhibited the most gain in clinical attachment. J Periodontol 1996;67:694–702.

Clinical and microbiological features of periodontal healing in barrier membrane‐treated sites were determined in a randomized clinical trial. The study included 10 patients with advanced adult periodontitis and a minimum of one set of similar 2 to 3 wall intraosseous periodontal lesions with no furcation involvement. In each patient, one periodontal lesion was treated with a biodegradable membrane and a contralateral lesion with a nonresorbable barrier membrane. Within the preceding 3 months of regenerative therapy, all patients received full mouth osseous surgery except for the sites for regeneration, were instructed in oral hygiene, and were prescribed systemic ciprofloxacin and metronidazole (250 mg of each, TID, 8 days), starting 7 days before membrane placement. At baseline and at 6 months postsurgery, probing depth and clinical attachment level were assessed in each study site. The subgingival presence of suspected periodontal pathogens was determined by non‐selective and selective culture and by DNA probe analyses, and of human cytomegalovirus (HCMV) and Epstein‐Barr virus type 1 (EBV‐1) by a nested‐polymerase chain reaction detection method. At baseline, the barrier‐treated sites did not differ significantly in clinical and microbial parameters. Mean baseline probing depth was 7.8 ± 1.1 mm for bioabsorbable and 7.9 ± 1.3 mm for nonresorbable barrier‐treated sites. At 6 months, sites treated with bioabsorbable barrier revealed 4.6 ± 1.7 mm gain of clinical attachment (range: 1 to 7 mm) and sites treated with nonresorbable barrier 4.2 ± 2.0 mm (range: 1 to 8 mm). The 11 barrier‐treated sites that harbored 10% or less bacterial pathogens and were free of HCMV and EBV‐1 averaged significantly more clinical attachment gain than the 9 sites that yielded more than 10% bacterial pathogens and/or test viruses (5.6 mm versus 3.0 mm; P = 0.005). The present data suggest bioabsorbable and nonresorbable barriers provide similar clinical healing of 2 to 3 wall intraosseous periodontal lesions, emphasize the importance of controlling bacterial pathogens prior to and during periodontal healing, and point to the possible detrimental role of HCMV and EBV‐1 in periodontal repair. J Periodontol 1998;69:445–453.

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