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

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.

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.

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.

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.

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.