Concentrated growth factor (CGF) is relatively a new generation of platelet concentrate product, it contains more cytokines and growth factors compared with PRP and PRF also promotes the proliferation, migration, and differentiation of stem cells

Inducing bleeding to facilitate healing is a common surgical procedure. The blood clot formed after hemorrhage, acts as a scaffold and rich source of growth factors, and could play an important role in tissue repair in the canal. The growth factors could stimulate differentiation, growth, and maturation of fibroblasts, odontoblasts and cementoblasts, from the immature undifferentiated mesenchymal cells in the newly formed tissue matrix

Dry canals with paper points. A 10 ml of venous blood will be collected and transferred to sterile tubes without anticoagulant solutions by a trained nurse. The tubes will be centrifuged machine using a one-step centrifugation protocol at variable rpm, after centrifugation, four layers will be obtained: the first layer at the top is serum, second layer is the fibrin buffy coat, the third layer is the liquid phase containing growth factors, The concentrated growth factor was separated from the red blood cells and serum using sterile scissors.

CGF will be packed into canal to the full working length using sterile pluggers.

The coronal level of the CGF gel is near the cervical area above cementoenamel junction and white MTA placed as capping material after CGF, then GIC and composite restoration

The treatment will be considered to be clinically successful when. Absence of pain will record it by verbal question to patient/ parent. Absence of tenderness to percussion) will record it by percussion test (by the back of the dental mirror) Absence of swelling and fistula or sinus tract -- will record it by visual clinical examination

The treatment will be considered to be Radiographic Success when.

• Root elongation (increased root length): will be assessed in mm through a radiographic x-ray system measure from cementoenamel junction to the apex.
• Root maturation: increased root dentin thickness will be assessed in mm through a radiographic x-ray system for each case and will be calculated as the difference between the outer root area and the pulp space area.
• Absence or reduce in the size of periapical radiolucency: will be assessed in mm through a radiographic x-ray system.