What is Bennett movements in teeth?

Bennett movements of the mandible (also called side shift or lateral shift) are the horizontal movement of the mandible that occurs during lateral excursions. They are named after the American prosthodontist Norman G. Bennett, who described them in 1908.

Bennett movements are essential for maintaining proper occlusion during chewing and other functional movements. They allow the teeth to come into contact evenly and prevent them from grinding against each other. The amount of Bennett movement varies from person to person, but it is typically around 1-2 millimeters.

Bennett movements are caused by the inclination of the articular eminence, which is the part of the temporal bone that the mandible articulates with. The articular eminence is not perfectly flat, but rather slopes down and forward. This slope causes the mandible to move sideways as it opens and closes.

The Bennett movement is influenced by several factors including:

- The shape and size of the articular surfaces

- The slope of the articular eminence

- The length and orientation of the mandibular fossa

- The position of the condyle within the mandibular fossa

- The muscle tone of the muscles of mastication.

Bennett movements can be affected by a number of factors, including temporomandibular joint (TMJ) disorders, dental restorations, and orthodontic treatment. TMJ disorders can cause the articular eminence to become damaged or inflamed, which can lead to reduced Bennett movement. Dental restorations can also affect Bennett movement, by altering the shape of the teeth or the occlusion. Orthodontic treatment can also change Bennett movement, by moving the teeth into a new position.

In many clinical cases, Bennett movements are a critical factor in establishing a harmonious occlusion and preventing premature tooth wear or temporomandibular joint disorders.