Orthograde Apical Barrier in Non-Vital Immature Permanent Teeth: A Narrative Review of Clinical Pathways, Procedural Determinants, and Evidence Gaps

Background/Objectives: Pulp necrosis in immature permanent teeth arrests root development, leaving an open apex, thin, divergent dentinal walls, and an unfavorable crown-to-root ratio that predisposes the tooth to fracture and complicates endodontic management. An apical barrier using hydraulic calcium silicate cements has become the first-line orthograde approach for these teeth when regenerative procedures are not indicated or feasible. This narrative review synthesizes current evidence on the complete clinical pathway for apical barrier placement in immature permanent teeth, with particular emphasis on the procedural determinants of barrier formation. It also critically appraises where the evidence is robust and where it remains uncertain. Methods: The relevant English-language literature on root development, the etiology of pulp necrosis in immature teeth, diagnosis, isolation, apical barrier methods, calcium silicate materials, and treatment outcomes was reviewed through targeted searches of PubMed/MEDLINE, Scopus, Web of Science, the Cochrane Library, and Google Scholar through June 2026. The literature search was completed in June 2026; therefore, studies published after this date were not included. Evidence was narratively synthesized according to the clinical sequence of diagnosis, treatment selection, isolation, disinfection, barrier formation, restoration, follow-up, and evidence gaps. Throughout, an explicit distinction was maintained between clinical and laboratory evidence. Results: Sensibility testing is widely considered unreliable in immature teeth, complicating diagnosis. Isolation is often challenging because of traumatic crown loss. Successful treatment depends on adequate chemical disinfection, judicious minimal instrumentation, a well-condensed apical barrier of at least 4–5 mm, and a definitive coronal seal that also addresses the weak cervical dentin. Calcium silicate cements—principally MTA, Biodentine, and pre-mixed bioceramic putties—achieve high clinical success. Observational evidence further suggests, as a hypothesis requiring prospective confirmation, that material choice may be less decisive than operator experience and the quality of the coronal restoration. Conclusions: Apical barrier placement with hydraulic calcium silicate cements is a predictable orthograde preservation approach for non-vital immature permanent teeth, particularly when regenerative endodontic procedures are not indicated, not feasible, or unlikely to yield predictable clinical outcomes. Well-designed randomized clinical trials with standardized reporting are needed.