Critical analysis of the "nanoleakage concept" in endodontics: a narrative review.

BACKGROUND: Microleakage models have historically defined leakage assessment in endodontics despite well-recognized methodological limitations, leading to increasing restrictions on their publication. Since the seminal description of the term nanoleakage, interest in nanoscale interfacial leakage has progressively expanded into endodontics, where achieving a bacteria-free seal is critical for treatment success.

OBJECTIVE: We aim to map and critically analyze the current evidence on nanoleakage in endodontics, identifying research trends, methodological approaches, and existing knowledge gaps across different clinical applications.

METHODS: A narrative review was conducted following a literature search to identify studies addressing nanoleakage within endodontic contexts. Eligible studies were screened and categorized according to their clinical application and methodological approach.

RESULTS: Evidence is derived from in vitro studies, mostly using a qualitative approach, with significant heterogeneity in experimental designs and interpretation criteria. Most studies rely on passive tracer-based methodologies, which may not adequately reflect the dynamic behavior of fluids and bacterial by-products at the nano-interface. Research was primarily focused on areas including the bonding of adhesives to coronal and radicular dentin as well as in retrograde filling and root canal filling.

CONCLUSIONS: Understanding nanoleakage is an important objective, yet endodontic models remain underdeveloped. The existing evidence is limited by methodological inconsistencies and a lack of clinical validation. Future research should prioritize the development of dynamic, clinically relevant models to better understand interfacial sealing and improve the predictability of endodontic outcomes.