Clinical Study of Minocycline Hydrochloride Injectable Hydrogel for the Treatment of Periodontitis

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. 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. * Drug Allergy: Known allergy to minocycline (MH), hyaluronic acid (HA), or similar chemical components.