The study examined profiles of free amino acids in saliva of patients with periodontitis and their relationship to clinical disease parameters. The research focused on dynamic changes in these amino acids as a response to non-surgical periodontal therapy. Periodontitis is an inflammatory disease of the periodontium that leads to loss of periodontal attachment and formation of periodontal pockets. Non-surgical periodontal therapy includes procedures such as periodontal scaling and debridement. The aim of the study was to determine whether salivary amino acid profiles change during treatment and whether they could serve as markers of therapy response. The research was conducted under the direction of a research team led by Yuwei Zhang and was successfully completed.