Microbial community composition on polytetrafluoroethylene tape retrieved from implant screw channels: A cross-sectional high-throughput 16S rRNA sequencing study.

OBJECTIVES

To identify the types of microorganisms colonizing the surface of polytetrafluoroethylene (PTFE) tape used for sealing the central screw channel in implant prostheses and to evaluate their association with the duration of prosthetic functional loading.

METHODS

A cross-sectional study design was adopted. Forty patients who had received single-tooth screw-retained implant restorations using the Straumann BL implant system were recruited and allocated into four groups (n = 10 per group) according to the time elapsed since prosthetic loading: 1 month (Group A), 3 months (Group B), 1 year (Group C), and ≥ 3 years (Group D). PTFE tape samples were aseptically retrieved from the central screw channels. Total genomic DNA was extracted, and the V3-V4 hypervariable regions of the 16S rRNA gene were amplified and sequenced using the Illumina NovaSeq platform. Bioinformatic analysis was performed using the QIIME2 pipeline with amplicon sequence variant (ASV) clustering, and taxonomic assignment was conducted against the SILVA database. Alpha diversity indices, including Chao1 richness, Shannon diversity, and Simpson indices, were compared among the four groups using the Kruskal-Wallis test with pairwise post-hoc comparisons.

RESULTS

The rarefaction curves for all 40 samples plateaued, indicating sufficient sequencing depth. At the phylum level, the ten most abundant taxa across all samples were Firmicutes, Actinobacteria, Proteobacteria, Bacteroidetes, Synergistetes, Fusobacteria, Patescibacteria, Campilobacterota, Spirochaetae, and Euryarchaeota. Comparative analysis of microbial diversity among Groups A, B, C, and D revealed no statistically significant differences in Chao1 richness, Shannon diversity, or Simpson indices (P > 0.05 for all comparisons).

CONCLUSION

Bacterial DNA was detected on PTFE tape across all groups, consistent with the hypothesis that microbial ingress into the screw channel via the implant-abutment interface or screw access opening is a frequent phenomenon. The diversity of the bacterial community detected on the PTFE tape within the central screw channel was not significantly influenced by the duration of prosthetic loading.