Ulm C W, Solar P, Krennmair G, Matejka M, Watzek G
Department of Oral Surgery, School of Dentistry, University of Vienna, Austria.
Int J Oral Maxillofac Implants. 1995 Jul-Aug;10(4):462-5.
A variable number of septa, also referred to as Underwood's septa, divide the floor of the maxillary sinus into several recesses and may thus cause various complications during sinus-lift procedures. The incidence of Underwood's septa was evaluated by examining 41 edentulous maxillas. In 13 of these maxillas (31.7% of the cases), sinus floors with at least one septum were observed. Most of the septa were located in the region between the second premolar and the first molar. A possible cause of septal formation could be the variable phases of maxillary sinus pneumatization of the empty alveolar process following tooth extraction.
