system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
Apexification is the treatment of choice for a permanent tooth with wide open apex when:
assistant
The correct answer is  Apexification is the process of inducing the development of the root and the apical closure in an immature pulpless tooth with an open apex.
The main aim of apexification is to preserve the Hertwig’s root sheath and apical pulp tissue.

Ref :Textbook of endodontics, Nisha Garg and Amit Garg, 3rd edition, pg no:548