This project aims to construct an injectable self-healing hydrogel loaded with BMP-2, with optimized gelation time and mechanical strength to meet the requirements for periodontal pocket filling, for the treatment of periodontitis and acceleration of tissue repair, achieving a "bactericidal-anti-inflammatory-regenerative" trinity function. This project will provide a novel intelligent material for promoting alveolar bone regeneration in periodontitis and establish a theoretical paradigm for the precise intervention of oral infectious diseases.

Inclusion Criteria:

• Clinical Diagnosis: Meets the 2018 International Classification of Periodontal Diseases, diagnosed with Stage III or IV periodontitis.
• Bone Defect Characteristics: At least one affected tooth presents with a deep periodontal pocket (PPD ≥5 mm), and CBCT imaging confirms the presence of significant vertical bone resorption or angular bone defects (these defect types are most suitable for in-situ hydrogel filling and guided regeneration).
• Age and General Condition: Aged between 18 and 70 years, any gender, generally in good systemic health.
• Compliance and Consent: The subject is able to understand the study procedures, voluntarily sign the informed consent form, and commit to returning for follow-up visits as required (1, 3, 6, 12 months).

Exclusion Criteria:

• Systemic Interference with Bone Metabolism: Presence of poorly controlled diabetes (HbA1c > 7%), osteoporosis, or long-term use of medications affecting bone metabolism such as bisphosphonates or glucocorticoids within the past six months.
• Local Anatomical Limitations: The affected tooth has a vertical root fracture, severe periapical pathology, or a residual root that is deemed non-restorable and without preservation value.
• Factors Interfering with Healing: Heavy smokers (average > 10 cigarettes per day), as impaired microcirculation can significantly compromise the biological effects of the hydrogel.
• Special Physiological Periods: Pregnant or breastfeeding women.