THE DYNAMICS OF MICROBIAL COLONIZATION OF BARRIER MEMBRANES FOR GUIDED TISSUE REGENERATION

THE MICROBIAL COLONIZATION OF EXPANDED POLYTETRAFLUOROETHYLENE MEMBRAN E by putative periodontopathogens at 3 minutes of intraoral manipulati on was determined in 42 patients with 42 mandibular posterior two- to three-wall defects. Twenty patients exhibited no periodontal pockets o f greater than or equal to 5 mm, other than the study site, and low le vels of pathogens (group A). Twenty-two patients revealed multiple per iodontal pockets of 5 mm or more and numerous pathogens (group B). Wit hin the preceding 3 months of regenerative surgery, group A patients h ad received apically positioned flap surgery with osseous recontouring (except for the study site), and group B patients had been enrolled i n a non-surgical maintenance program. The subgingival microbiota was e xamined prior to regenerative therapy, and the membrane microbiota was examined at 3 minutes and at the time of removal at 6 weeks by cultur e, DNA probes, and phase-contrast 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 signific ant (P < 0.001; group A: 3.4 mm; group B: 1.4 mm). At 3 minutes, putat ive pathogens were detected in seven (16.7%) membranes in group B (gro up Bi,,,,,), and the associated sites gained only 0.6 mm in clinical a ttachment at 6 months. Clinical attachment gain was modeled as a linea r function of the explanatory variables (r(2) = 86%). The presence of Porphyromonas gingivalis detected by DNA probe at 3 minutes was associ ated with 1.5 mm less expected gain (P = 0.0002). Total microbial coun ts 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 predi ctors of clinical attachment. For each week the membrane remained cove red, an additional 0.5 mm gain could be expected (P = 0.002); and for every 10 sites that exhibited bleeding on probing, the clinical attach ment gain was 0.6 mm less at the site of regeneration (P < 0.0001). Th e present results showed that putative pathogens may colonize membrane s within 3 minutes of intraoral manipulation. The patient group treate d with periodontal osseous surgery revealed the lowest levels of perio dontal pathogens in the membranes and exhibited the most gain in clini cal attachment.