The maxillary sinuses are usually fluid‐filled at birth. Pneumatization, or filling of the sinus cavity with air, takes place during the later phase of growth as the permanent teeth develop and erupt. Pneumatization can be so extensive as to expose tooth roots with only a thin layer of soft tissue covering them. Later with tooth loss, further pneumatization can take place, leading to a reduced vertical height in the alveolar bone. This often requires sinus floor elevation procedures to allow the placement of dental implants.