Effects of the Bennett Movement On Cusp Height

So here's a bit of technical info on the effects of the Bennett movement of cusp height. Might help out some of you with TMJ problems, I know it's kind of hard to tell what's going on without pictures but yeah. Couldn't really find any accurate pictures.

In the Bennett movement is a bodily side shift of the mandible that occurs during final movements. During a ladder or excursion to the orbiting condyle moves downward, forward, and inward in the mandibular fossa around axes located in the opposite condyle.

The degree of inward movement of the orbiting condyle is determined by two factors: morphology of the medial wall of the mandibular fossa and in a horizontal portion of the TM ligament, which attaches to the lateral poll of the rotating condyle. If the TM ligament of the rotating condyle is very tight and the medial wall close to the orbiting condyle, a pure asking movement will be made around the axis of rotation in the rotating condyle. When this condition exists, there is no bodily side shift of the mandible. Such a condition rarely occurs. Most often there is some looseness of the TM ligament in the medial wall of the mandibular fossa lies medial to that to an arc around the axis of the rotating condyle. When this occurs the orbiting condyle is moved inwardly to the medial wall and produces a Bennett movement.

The Bennett movement has three attributes: amount, timing, and direction. The amount and timing are determined in part by the degree to which the medial wall of the mandibular fossa departs immediately from an arc around the axis in the rotating condyle. They are also determined by the degree of latter movement of the rotating condyle permitted by the TM ligament. The more medial the wall from the medial poll of the orbiting condyle, the greater will be the amount of Bennett movement; and the looser the TM ligament attached to the rotating condyle, the greater will be the Bennett movement.

The direction of Bennett movement depends primarily on the direction taken by the rotating condyle during the bodily movement.

The amount of Bennett movement is determined by the tightness of the inner horizontal portion of the TM ligament attached to the rotating condyle as well as the degree to which the medial wall of the mandibular fossa departs from the medial poll of the orbiting condyle. The looser this ligament and the greater its departure, the greater will be the amount of mandibular body of movement. As the Bennett movement increases the bodily shift of the mandible dictates that the posterior cusps be shorter to permit the mandibular shift without creating contact between the maxillary and mandibular posterior teeth.

The effect of the direction of Bennett movement on cusp height

The direction of shift of the rotating condyle during a Bennett movement is determined by the morphology and ligamentous attachments of the TM giant undergoing rotation. The movement occurs within a 60° kind whose Apex is located at the axis of rotation. Therefore in addition to lateral movement, the rotating condyle may also move in that superior, inferior, and cheerier or posterior direction. Furthermore, combinations of these can occur.

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