Number of operational taxonomic units (OTUs) that either disappeared from or appeared in the microbiota of each subject after periodontal therapy.

The OTUs detected in pre-therapy samples with more than two reads but not in post-therapy samples were defined as “disappeared OTUs” and the OTUs that were not detected in pre-therapy samples but detected in post-therapy samples with more than two reads were defined as “appeared OTUs.” Statistical differences were calculated using paired t-tests.