The maxilla, commonly known as the upper jawbone, is a large, paired bone that forms the central part of the face, supporting the upper teeth and contributing to the structure of the eye sockets, nasal cavity, and roof of the mouth. Within this complex bone structure lies a specific bony prominence known as the tuberosity of the maxilla, or tuber maxillae. This anatomical feature is a rounded area situated at the posterior end of the maxilla. Understanding the tuberosity’s location and composition is important, as it dictates its involvement in oral function and complex surgical planning.
Anatomical Location and Structure
The maxillary tuberosity is located on the lower portion of the infratemporal surface of the maxilla, which is the bone’s posterior-facing surface. It presents as a rounded eminence that becomes noticeable after the development of the third molar. This prominence sits directly behind the socket of the last upper molar, marking the distal boundary of the upper dental arch.
The structure is composed of cancellous, or spongy, bone tissue, which is relatively porous compared to the dense cortical bone found elsewhere in the jaw. On its lateral side, the tuberosity connects with the pyramidal process of the palatine bone. In some individuals, it may also form a direct connection with the lateral pterygoid plate of the sphenoid bone, anchoring the maxilla to the base of the skull.
Just above this bony bulge is a smooth area that forms the anterior wall of the pterygopalatine fossa, a small space containing nerves and blood vessels. Small openings called alveolar foramina are present on the tuberosity; these transmit the posterior superior alveolar nerve and blood vessels, which supply sensation and blood flow to the upper molar teeth.
Role in Oral Function and Support
The tuberosity provides structural integrity to the posterior segment of the upper jaw. It acts as a bony buttress that resists the heavy forces generated during chewing and grinding food. This structural support allows the molar teeth, which handle the bulk of masticatory load, to remain firmly anchored in the jawbone.
The prominence also functions as an anchor point for specific muscle fibers involved in jaw movement, particularly fibers of the medial pterygoid muscle. This muscle is one of the four main muscles of mastication, and its attachment contributes to the powerful closing and grinding motions of the mandible. The tuberosity helps distribute mechanical stresses across the facial skeleton during normal oral function.
Its presence ensures the stability of the entire posterior dental arch, preventing excessive movement during chewing. The dense fibrous connective tissue covering the tuberosity provides stability, making it a reliable area of support even after tooth loss.
Clinical Relevance in Dental Procedures
The tuberosity is utilized in various dental treatments. During the extraction of an upper third molar, the tooth roots are often encased within the dense bone of the tuberosity. Surgeons must carefully manage this bony support to remove the tooth without damaging the surrounding anatomy.
The tuberosity is particularly significant in prosthetics, especially for patients requiring a complete upper denture. It is considered a primary stress-bearing area, absorbing and distributing the forces from the denture during chewing. The tuberosity’s dense fibrous covering provides a stable foundation, and its size and shape are crucial for achieving the necessary suction and stability to keep the upper denture securely in place.
In modern implant dentistry, the tuberosity region has become a popular site for placing dental implants. This area often retains good bone height even after significant bone loss elsewhere in the jaw. This allows for the placement of longer implants without needing extensive bone grafting or sinus lifting. Furthermore, the tuberosity is a potential site for harvesting autogenous bone for augmentation in other areas.
Potential Complications and Management
The tuberosity’s location and structure present specific risks during surgical procedures. The most widely recognized complication is a fracture of the tuberosity, which can occur during the difficult extraction of a tightly anchored upper molar. Signs of this include a sudden crack or the mobility of the tooth and a segment of bone together, necessitating immediate stabilization or controlled removal of the fractured segment.
The close anatomical relationship between the tuberosity and the maxillary sinus is a major concern. The maxillary sinus is a large air-filled cavity situated directly above the upper back teeth. Aggressive manipulation of the tuberosity can easily perforate the sinus floor, creating an oroantral communication. This direct opening between the mouth and the sinus cavity must be promptly closed to prevent chronic sinusitis.
If the fractured segment is large and includes multiple teeth, management often involves stabilizing the bone back in place for several weeks to allow for healing before attempting the extraction again. Prompt management of any communication or fracture is essential for a good long-term outcome. Small oroantral communications may sometimes heal spontaneously, but defects larger than two millimeters typically require a surgical flap procedure to ensure a watertight closure.