Clinical Research Directory

Inclusion Criteria Disease Group: 1. Adults aged 18 to 75 years; 2. No restrictions on sex or race; 3. Diagnosis of at least one target disease, including periodontitis or chronic kidney disease; 4. Ability and willingness to provide written informed consent; 5. Ability to understand the study procedures and comply with study requirements. Control Group: 1. Adults aged 18 to 75 years; 2. No restrictions on sex or race; 3. No history of diagnosis of periodontitis or chronic kidney disease; 4. Ability and willingness to provide written informed consent; 5. Ability to understand the study procedures and comply with study requirements. Exclusion Criteria 1\. Age \<18 years or \>75 years; 2. Pregnancy or lactation; 3. Current smoking, alcohol abuse, or betel nut chewing; 4. Unhealthy dietary habits, such as frequent intake of high-salt or high-fat foods; 5. Use of antibiotics or probiotics, or receipt of oral/gastrointestinal surgery, within the past 2 months; 6. Fewer than 8 natural teeth remaining; 7. Severe systemic diseases other than the target condition, mental illness, or other conditions that may affect study participation, compliance, or data interpretation; 8. Inability to understand the study procedures; 9. Current participation in another clinical trial.