The overall objective of this study is to evaluate the safety and efficacy of allogeneic human dental pulp stem cells (DPSCs) injected for the treatment of chronic periodontitis in humans. It aims to develop a stem cell injection therapy that promotes the regeneration of periodontal soft and hard tissues through a non-invasive (minimally invasive) procedure, thereby replacing traditional traumatic periodontal surgery.

Periodontitis, a chronic inflammatory disease, affects over 700 million people worldwide, leading to bone and soft tissue destruction as well as systemic inflammatory manifestations. For severe periodontitis, current treatments mainly rely on invasive surgical procedures such as guided tissue regeneration, combined with bone grafting and growth factors. However, such surgeries often cause significant pain and discomfort to patients, and tissue regeneration is frequently incomplete, with risks of infection and uncontrolled tissue growth.

As a type of mesenchymal stem cell, dental pulp stem cells (DPSCs) can be easily obtained through a non-invasive procedure from orthodontically extracted or removed wisdom teeth. Compared to bone marrow- or adipose-derived stem cells, DPSCs exhibit stronger proliferative capacity and are better able to resist oxidative stress and cellular senescence within the periodontitis microenvironment. DPSCs have low immunogenicity and can interact with T cells, B cells, natural killer cells, macrophages, and others. For example, they can induce T cell anergy by secreting relevant factors, or regulate the proliferation and differentiation of B cells, thereby reducing the risk of immune rejection after allogeneic transplantation.

In light of the above research status, the conduct of this study holds the following outstanding value at both the scientific exploration and clinical application levels: Currently, most studies on stem cell therapy for periodontitis still rely on traditional flap surgery for transplantation. The DPSC injection therapy focused on in this study pioneeringly achieves the promotion of periodontal soft and hard tissue regeneration through simple local injection (e.g., intra-periodontal pocket injection). This not only greatly improves patient comfort but also provides a more convenient and minimally invasive treatment option for patients with severe periodontitis who would otherwise require complex periodontal surgery. The pathogenic mechanism of periodontitis is complex, with the core being the disruption of local microenvironmental homeostasis. Exogenous DPSC injection not only acts as "seed cells" for tissue regeneration but also, through paracrine secretion of various cytokines, remodels the immune microenvironment, restores local homeostasis, and thus achieves the "dual benefit" of reducing periodontal pocket depth and repairing alveolar bone defects. Investigating its specific molecular targets and regulatory pathways holds high scientific value. Considering that DPSCs are abundantly available, easily scalable for expansion, and have extremely low immunogenicity, they possess great potential as "off-the-shelf" allogeneic stem cell drugs. Compared to maxillofacial tissue reconstruction surgeries using recombinant growth factors, the minimally invasive stem cell injection strategy not only has a lower technical barrier but also offers significant advantages in time cost and economic efficiency, effectively reducing the healthcare burden.

Inclusion Criteria:

• Disease Diagnosis: Clinically diagnosed with chronic periodontitis (typically Stage III or IV according to the latest periodontal disease classification).
• Target Tooth Requirements: At least two non-adjacent periodontal pockets with a Probing Pocket Depth (PPD) ≥5 mm.
• Clinical Attachment Level (CAL) loss ≥3 mm.
• Evidence of significant alveolar bone resorption on X-ray or CBCT (bone loss exceeding one-third of the root length).
• Age and General Condition: Typically aged 18-70 years, in good general health, and able to complete the 12-month follow-up.
• Oral Hygiene Awareness: Subjects are willing to receive conventional periodontal basic treatment (SRP) and demonstrate a good willingness to maintain oral hygiene (e.g., plaque index controlled at a low level).

Exclusion Criteria:

• Systemic Diseases: Presence of severe, uncontrolled systemic diseases (e.g., diabetes with HbA1c >7%, active hepatitis, tuberculosis). History of malignancy or immunodeficiency diseases (due to the proliferative potential of stem cells, cancer risk must be strictly excluded).
• Local Interfering Factors: Target teeth with severe mobility (Grade III mobility) or non-restorable residual crowns/roots. Received periodontal surgical treatment or systemic antibiotics within the past 3 months.
• Special Populations and Habits: Heavy smokers (typically defined as smoking >10 cigarettes per day), as smoking significantly inhibits the regenerative effect of stem cells and local blood supply. Pregnant or breastfeeding women. Individuals allergic to any components of the study preparation (e.g., specific biological carriers).