Objective: To investigate treatment strategies for chronic periapical periodontitis in prematurely erupted premolars and provide guidance for managing pulp and periapical diseases in young permanent teeth with immature roots. Methods: A regenerative endodontic procedure (REP) was performed on a prematurely erupted maxillary left first premolar (tooth 24) at Nolla stage Ⅶ with chronic apical periodontitis, following standardized protocols including root canal irrigation, disinfection, and coronal sealing. The case was followed up, and a literature review was conducted. Results: Clinical resolution of symptoms was observed on tooth 24, with sustained root development. After a 20-month follow-up, the tooth had restored biological function. Literature synthesis revealed that periapical infections in prematurely erupted permanent teeth predominently arise from pulp exposure and bacterial infection, with retrograde infection being rare. For young permanent teeth with necrotic pulp, regenerative endodontic procedures has been established as the treatment of choice to promote apical closure and root maturation. The critical steps of regenerative endodontic procedures include thorough disinfection, induced bleeding to form a fibrin scaffold, and coronal sealing to facilitate stem cell recruitment and differentiation. Conclusion Regenerative endodontic procedures represents an effective and viable treatment option for prematurely erupted young permanent teeth with chronic periapical periodontitis.

Objective To use World Health Organization Family International Classifications (WHO-FICs) to explore the framework and approaches of development and research of guidelines of rehabilitation at levels of policies, community and services.Methods The important documents and tools of rehabilitation at international level, including United Nations Convention on the Rights of Persons with Disabilities, WHO World Report on Disability, Community-based Rehabilitation Guideline, Rehabilitation in Health Service System, and International Classification of Diseases (ICD), International Classification of Functioning, Disability and Health (ICF), and International Classification of Health Intervention (ICHI) of WHO-FICs, had been discussed.Results The framework, classifications, diagnosis and description of diseases and functioning, coding, intervention and functioning evaluation based on ICD-11, ICF and ICHI-β-2 had been established for development and implementation of rehabilitation guidelines and Cochrane rehabilitation.Conclusion The framework and systematic approaches of ontology, classification, terminology, coding, diagnosis and description of diseases and functioning, interventions and evaluations for the development and implementation of rehabilitation guidelines had been developed.