title: Ultrastructure of plaque associated with polytetrafluoroethylene (PTFE) membranes used for guided tissue regeneration.
abstract: The purpose of the study was to examine the ultrastructure of plaque contaminating polytetrafluoroethylene (PTFE) membranes used for guided periodontal tissue regeneration. 8 patients treated with Gore-Tex membranes received daily antibiotics (650 mg x 2 Femepen) and rinsed with 10 ml 0.2% chlorhexidine during a healing period of 30 days. Following retrieval, the membranes were processed for electron microscopy. External aspects of 12 portions from 4 partially exposed membranes were selected for detailed ultrastructural examination. The plaque-membrane interface was characterized by the presence of fibrin or discontinuous accumulation of intermicrobial matrix. Adjacent plaque-free areas of membrane surface exhibited no detectable electron-dense material. 3 structurally different groups of bacterial aggregations were observed on the strips: (i) dense layers of gram-positive cocci and rods dominated the external aspect of the open microstructure portion; (ii) cocci, rods and filamentous microorganisms embedded in fibrin filled the spaces of the open microstructure; (iii) a loosely arranged mixed microbiota consisting of gram-positive cocci and rods as well as of gram-negative microorganisms and spirochetes were present on the occlusive portion. Areas with morphologically intact bacteria alternated with areas with empty bacterial cell walls. One specimen also displayed degenerated Candida-like blastospores. This study shows that oral micro-organisms may colonize and extensively invade the open microstructure of PTFE material and that adhesion of plaque to the membrane surface is mediated either by fibrin or a discontinuous layer of intermicrobial matrix.
authors.affiliation: Department of Periodontology, School of Dentistry, University of Bergen, Aarstadveien, Norway.
authors.forename: H J
authors.initials: HJ
authors.lastname: Grevstad
authors.forename: K N
authors.initials: KN
authors.lastname: Leknes
mesh_terms: D000328:Adult; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D002710:Chlorhexidine / Q000031:analogs & derivatives / Q000627:therapeutic use; D003773:Dental Plaque / Q000382:microbiology / Q000648:ultrastructure*; D005337:Fibrin; D006090:Gram-Negative Bacteria / Q000166:cytology; D006095:Gram-Positive Cocci / Q000166:cytology; D016987:Gram-Positive Rods / Q000166:cytology; D016557:Guided Tissue Regeneration, Periodontal; D006801:Humans; D008567:Membranes, Artificial; D008854:Microscopy, Electron; D010518:Periodontitis / Q000601:surgery; D011138:Polytetrafluoroethylene / Q000737:chemistry; D016062:Porosity; D013144:Spirochaetales / Q000166:cytology; D013499:Surface Properties
chemical_list: D000900:Anti-Bacterial Agents; D008567:Membranes, Artificial; D005337:Fibrin; D011138:Polytetrafluoroethylene; C010882:chlorhexidine gluconate; D002710:Chlorhexidine