Colonization of retrieved polytetrafluoroethylene membranes: morphological and microbiological observations

Polytetrafluoroethylene membranes (ePTFE) used in guided tissue regeneration (GTR) are accessible to colonization by oral bacteria. The bacterial composition of the adherent biomass is unknown. We examined a total of 6 membranes that were retrieved after 4 to 6 weeks from human periodontitis sites, using optical and transmission electron microscopy (TEM) as well anaerobic cultivation. Five of the 6 membranes provided the microbiological data and microscopic data. TEM revealed an organized microbial mass covering the surfaces and also within the interstices of the open microstructure and occlusive portions of the membranes. Numerous bacterial forms including cocci, rods, and filaments with an interbacterial matrix, frequently in microcolonies, were identified. Anaerobic cultivation yielded Streptococcus and Actinomyces species with a minor component of Gram-negative facultative rods comprised mainly of Haemophilus species. Candida species was recovered from one membrane. These data show that ePTFE is heavily colonized by oral bacteria during retention. The impact of bacterial colonization of ePTFE is not known but it seems reasonable to assume that colonization of membranes may affect connective tissue regeneration. Further studies will be needed to examine the effect of systemic antimicrobials on ePTFE colonization and in turn to examine the effect on GTR.