The tuberosity of the maxilla is a rounded bony prominence located at the very back of the upper jaw, just behind the last molar teeth. It represents the most posterior part of the maxillary alveolar process, the section of the jawbone that holds the teeth.
Anatomical Location and Structure
The tuberosity of the maxilla is positioned on the lower portion of the infratemporal surface of the maxilla. It sits directly above the sockets of the upper third molars, often becoming more noticeable as these wisdom teeth develop.
It lies adjacent to the maxillary sinus, an air-filled cavity within the cheekbone. The tuberosity also shares proximity with the pterygoid plates of the sphenoid bone, which are wing-like bony extensions located behind the upper jaw.
Functional Role in the Jaw
The tuberosity of the maxilla supports the eruption and positioning of the upper wisdom teeth. The presence or absence of these teeth can influence the overall size and shape of the tuberosity.
It also acts as an attachment site for a portion of the medial pterygoid muscle, which is involved in chewing. The tuberosity also participates in the developmental growth of the upper jaw.
Clinical Significance in Dentistry
The tuberosity of the maxilla is significant in various dental procedures and potential complications. During the extraction of an upper molar, particularly a wisdom tooth, there is a risk of fracturing the tuberosity. This can occur due to factors such as bulbous or divergent tooth roots, ankylosis (fusion of tooth to bone), or thin surrounding bone.
A related concern during extractions is the possibility of creating an opening into the maxillary sinus, known as a perforation. The bone separating the tooth roots from the sinus can be very thin, making this area vulnerable. If a perforation occurs, patients might experience symptoms like air passing between their mouth and nose.
The tuberosity also serves as a guide for administering a posterior superior alveolar (PSA) nerve block. This injection technique numbs the upper molars by targeting the nerves that supply them. The needle is inserted superiorly, medially, and posteriorly to the last molar in the arch.
For individuals needing upper dentures, the maxillary tuberosity provides stability and support. It is considered a primary stress-bearing area for the denture, helping distribute chewing forces. If the tuberosity has an undercut (a section that bulges out), it can complicate denture fabrication and may require surgical reshaping or denture design modifications.
The bone of the maxillary tuberosity can also be used as a source for bone grafting procedures. This involves harvesting bone from the patient’s own body to augment deficient areas of the jawbone, often to prepare a site for dental implant placement. It is a convenient intraoral donor site, offering both particulate (small pieces) and block grafts with less discomfort at the donor site compared to other areas.