The goal of this observational study is to investigate cellular heterogeneity and inflammatory microenvironment features in gingival tissues from patients with aggressive periodontitis compared to chronic periodontitis and healthy controls, using single-cell and spatial transcriptomics combined with whole-genome sequencing.

The main question(s) it aims to answer are:

What are the differences in cellular composition, mesenchymal stem cell subpopulations, and gene expression profiles between aggressive periodontitis, chronic periodontitis, and healthy gingival tissues? Which key molecular markers, signaling pathways, and spatially resolved microenvironment patterns distinguish aggressive periodontitis from the more common chronic form? Are there disease-specific genetic variants associated with aggressive periodontitis identified through whole-genome sequencing of peripheral blood DNA?

Participants (already scheduled for tooth extraction or periodontal surgery as part of routine clinical care) will undergo:

Standard clinical periodontal examination and CBCT imaging Collection of a small gingival tissue sample (~1×3×1 mm) during the planned extraction/surgery under local anesthesia Collection of 5 mL peripheral blood for DNA extraction No additional intervention, treatment, or follow-up visit is required beyond routine dental care.

Last updated: December 23, 2025

Inclusion Criteria:

Aggressive Periodontitis Patients:

1. Aged 20-35 years
2. Radiographic evidence of at least 30% vertical bone loss at ≥2 tooth sites
3. Can be classified as Stage III/IV, Grade C periodontitis according to the 2018 new classification of periodontitis
4. With or without family history of periodontitis
5. No significant local contributing factors (e.g., calculus, occlusal trauma, etc.)

Chronic Periodontitis Patients:

1. Aged 30-40 years
2. ≥3 sites with probing depth ≥5 mm
3. Can be classified as Stage I/II, Grade A/B periodontitis according to the 2018 new classification of periodontitis
4. No significant family history
5. Disease predominantly driven by local factors (dental plaque, calculus, etc.)

Healthy Controls:

1. Aged 20-40 years
2. Radiographic examination shows no significant alveolar bone loss
3. Clinically cannot be diagnosed with gingivitis or periodontitis

Exclusion Criteria:

1. Use of antibiotics within the past 3 months
2. Smoking >10 cigarettes per day
3. Uncontrolled severe diabetes (HbA1c level ≥6.7%)
4. Planning pregnancy, currently pregnant, or breastfeeding
5. Alcohol or drug addiction
6. Long-term use of immunosuppressive agents
7. Infectious diseases such as hepatitis or AIDS/HIV
8. History of malignant tumor, radiotherapy, or chemotherapy within the past 5 years

This cross-sectional observational study will recruit 9 adults (n=3 per group) from the Department of Periodontology, Second Affiliated Hospital, Zhejiang University School of Medicine. All participants are already scheduled for routine tooth extraction or periodontal surgery, allowing incidental collection of a small gingival tissue sample (~1×3×1 mm) and 5 mL peripheral blood during standard care. No extra procedures are added.

Aggressive Periodontitis (AP) Group (n=3) Age 20-35 years

• 30% vertical bone loss at ≥2 sites on radiographs Stage III/IV, Grade C (2018 classification) With or without family history Minimal local factors (negligible calculus/trauma) Chronic Periodontitis (CP) Group (n=3) Age 30-40 years
• 3 sites with probing depth ≥5 mm Stage I/II, Grade A/B (2018 classification) No family history Disease driven by plaque/calculus Healthy Controls (n=3) Age 20-40 years No significant bone loss on radiographs Clinically healthy periodontium (no gingivitis/periodontitis)