Variations in nasopalatine canal morphology across populations: a cone-beam computed tomography systematic review and proposed nomenclature system.

Background: The nasopalatine canal (NPC), also known as the incisive canal, is an interosseous conduit in the premaxilla located just behind the maxillary central incisors. Its variations must be carefully considered in dental and oral surgical procedures, especially with the higher aesthetic considerations inherent in the premaxilla. This study was aimed at assessing the morphology of the NPC and its variations across different populations, while also proposing a new classification system for naming and describing the NPC.

Materials and methods: Following the PRISMA guidelines, the Population, Intervention, Comparison, Outcome format was applied to formulate the focusedquestion. An electronic literature search was conducted in Google Scholar by using the following databases: Clarivate Analytics or ISI Web of Science, Elsevier's Scopus, and PubMed (MEDLINE). We restricted our search to studies published in or after 2013. The key words used were 'NPC morphology', 'incisive canal morphology', 'incisive foramen', 'NPC foramen', 'NPC shape', 'incisive canal shape', 'incisive canal', and 'NPC'. Outstanding full-text studies were assessed according to inclusion and exclusion criteria, and appropriate reports were nominated. The collected data was analysed and subjected to a risk of bias and quality assessment.

Results: Ten full-length papers with a total of 1,697 participants were included. Among them, the cylindrical shape, slant-straight course, and single canal were the most commonly observed in both sagittal and coronal views.

Conclusions: This review highlights the significant variability in the anatomical morphology of the NPC across different populations, a factor presenting challenges in establishing a standardised classification system. The current study introduces a new, adaptable naming system to be used in education, research, and by clinicians during the description of the NPC anatomy.