Bacteria located within the cheek, tongue mucosa, saliva, or untreated sites may contribute to reinfection of the pockets and explain the insignificant response to local tetracycline therapy.

The present study showed that at AST-positive sites, there is a higher prevalence and higher proportion of certain periodontal pathogens. Although only the correlation of P. gingivalis and AST values was statistically significant, the results imply that certain periodontal pathogens may be associated with elevation of AST levels in GCF.