Structure and composition of early health-associated biofilms formed on osseointegrated titanium implants is complex, diverse, subject-specific and dynamic

BACKGROUND/OBJECTIVES: Dental implants are increasingly used to replace missing teeth. The biofilm formation on dental implants is an orchestrated process involving diverse interacting microorganisms. The aim of this study was to characterize structure, composition and ecology of the early health-related implant-associated biofilms. METHODS: Confocal laser scanning microscopy was used in combination with high-throughput single-molecule real-time sequencing of full-length 16S rRNA gene amplicons to characterized biofilms. Application of retrievable healing abutments allowed characterization of biofilms in the area of implant penetration. Biofilms were studied in twelve individuals during the first three weeks of wearing the implants. RESULTS: Biofilm volumes showed tendency to increase during first two weeks (P = 0.052) and microbial colonization was higher on supramucosal areas. Biofilm structures and compositions were complex, diverse, subject-specific and dynamic. Epithelial cells were often found on implant surfaces. In total 371 different species-level phylotypes were detected, averaging 92 species per implant (SD = 3; range 28 - 148). Early biofilms were dominated by streptococci, but usually devoid of pathogens. Early dysbiosis was observed in single patient and was characterized by a consortium of Campylobacter, Capnocytophaga, Eikenella and Fusobacterium species. Difficult-to-culture species were prevalent. Core genera were Actinomyces, Shaalia, Streptococcus and Veillonella. Positive correlations and predicted interactions between biofilm members were commonly observed. The species detected had the potential to engage in food chains, exploitation of growth factors, enzyme sharing and cross-protection. CONCLUSION: Dynamics of biofilm structure and composition was revealed for early health-related implant-associated biofilms. Early biofilms form the ecological foundation upon which more pathogenic communities can develop later. How emergence of new colonization niches is prevented or favored and how personalized healthcare can control it require deeper ecological studies.