Abstract
Non-resorbable polytetrafluoroethylene (PTFE) membranes, either expanded (e-PTFE) or dense (d-PTFE), are used in guided tissue regeneration (GTR), guided bone regeneration (GBR), and alveolar ridge preservation (ARP), yet oral exposure brings them into contact with the oral microbiome. This systematic review, registered in PROSPERO (CRD420261445702) and conducted per PRISMA 2020 and SWiM, synthesizes evidence on microbial colonization and biofilm formation on the membrane surface, appraising risk of bias with RoB 2, ROBINS-I (comparative non-randomized studies), and QUIN, and single-arm studies with a structured methodological appraisal. Among 48 included reports (47 independent studies)—25 therapeutic clinical (21 periodontal GTR, one also including GBR around implants, and 4 ARP with d-PTFE), 6 non-therapeutic intraoral exposure-model, and 17 in vitro—colonization was consistently observed following oral exposure: bacterial adhesion was detectable within 4 hours in exposure models, and, in therapeutic settings, complex pathogen-rich polymicrobial biofilms were consistently present on membranes examined at retrieval (typically four to six weeks), which reflects biofilm accumulation at removal rather than its development over time. In correlational GTR studies, heavier or pathogen-rich contamination was associated with lower attachment gain or bone fill. Antimicrobial adjuncts reduced, but did not eliminate, colonization. Surface roughness, micro-porosity, and surface free energy were associated with bacterial adhesion in vitro, and brand-level differences within the same material class suggest that product-specific microstructure may contribute to colonization intensity beyond the e-PTFE/d-PTFE distinction. The evidence is heterogeneous, predominantly descriptive, and insufficient to establish causality; standardized comparative studies are needed to clarify its clinical relevance.