Evaluation of Platelet-rich Fibrin for Revascularization of Immature Permanent Teeth Versus Standard Apexification

The goal of this clinical trial is to evaluate the effect of platelet-rich fibrin for revascularization of immature permanent teeth in comparison to standard apexification using calcium hydroxide (as a 12 months follow up for previous study) through using clinical outcomes and radiographically using cone beam computed tomography the main questions it aims to answer are * is the platelet-rich fibrin an effective mean for management of necrotic immature permanent teeth * is the platelet-rich fibrin has a superior clinical and radiographic effects than calcium hydroxide apexification participants were treated either by platelet-rich fibrin revascularisation or calcium hydroxide apexification