Probiotic-containing Nanofiber-based Dental Floss Suppresses Subgingival Red Complex Periopathogens: A Randomized Double-blind Crossover Study

The study aimed to validate a targeted subgingival delivery method using Ligilactobacillus salivarius-infused nanofiber floss. Participants received both floss types in a crossover design. Clinical parameters (Approximal Plaque Index and Sulcus Bleeding Index) and microbiological markers (presence of L. salivarius, red complex pathogens, total bacterial DNA) were measured at multiple timepoints. DNA analysis was performed using validated multiplex qPCR protocols. Statistical analysis included non-parametric tests and correlation models. The study was ethically approved and conducted prospectively, but is being registered retrospectively to ensure transparency and support future publication.

Retrospective Registration Note:

This study was originally designed as a method validation investigation to refine subgingival probiotic delivery techniques using a newly developed nanofibre dental floss containing Ligilactobacillus salivarius. At the time of ethics approval and initiation (February 2022), the study was not classified as a clinical trial. However, subsequent interpretation of NIH guidelines suggests that the randomized, blinded, crossover design involving a health-related behavioral intervention meets criteria for interventional clinical research. Accordingly, the investigators now recognize that the study should be registered as a clinical trial. The research team is submitting this retrospective registration to ensure transparency and support future publication. No participant-level outcomes have been modified post hoc, and all data were collected prospectively under full ethical oversight.