The anatomy of the maxillary sinus has been widely analysed over the last few years, specifically when it comes to its vascular anatomy, relationship to the teeth, and alveolar process. In fact, surgical procedures require the most accurate knowledge of anatomical structures, facilitated by the use of some state-of-the-art imaging technologies such as the cone beam computed tomography (CBCT). Such systems are constantly evolving in terms of quality, definition, image detail, and accuracy. This review aims to analyse the international literature of the last decade that has dealt with the topic of sinus anatomy, especially looking at the presence, percentage and localization of Underwood’s septa, with the aim of supporting dentists to diagnose these anatomical structures in as much detail as possible and to perform surgery in this area with greater confidence.