Morphology of the Physiological Foramen: A Systematic Review.

Objective: Accurate knowledge of apical morphology is crucial for determining the correct working length and achieving an optimal seal, both of which are vital for long-term endodontic success. This review summarizes and evaluates the current literature on the physiological foramen, focusing on its diameter and the distance between the anatomical apex and the physiological foramen. Materials and Methods: A systematic literature search was conducted using the databases PubMed (via Medline), Embase, LILACS, and Scopus. Studies addressing the anatomy of the physiological foramen were selected based on predefined inclusion criteria. A total of 743 records were identified. After removing 103 duplicates, the titles and abstract of 640 records were screened, with 625 being excluded as irrelevant. Fifteen full texts were assessed and six excluded for not meeting inclusion criteria. Five additional articles were found through manual search. In total, 14 studies were included in the review. The risk of bias was assessed using the AQUA tool. Results: Considerable variation in the diameter of the physiological foramen was observed across the included studies, ranging from 0.15 mm to 0.43 mm depending on tooth type and location. Additionally, the distance between the anatomical apex and the physiological foramen varied from 0.1 mm to 1.2 mm. Conclusions: The results demonstrate considerable heterogeneity in the dimensions and position of the physiological foramen, with oval shapes occurring more frequently than round or irregular ones. Standardized definitions and consistent terminology are essential to improve comparability across studies and to enhance the clinical applicability of research findings. Recognizing these anatomical variations optimizes endodontic treatment outcomes and minimizes procedural errors.