What occurs at the TMJ when chewing hard food on one side?

When chewing hard food on one side, the dynamics of the temporomandibular joint (TMJ) exhibit a specific response due to the mechanical forces involved. The correct understanding is that when the jaw is moved to one side for chewing, the side doing the chewing experiences increased compression because of the muscle activity and the load of the food. This compression occurs at the TMJ on the same side (the ipsilateral side).

Conversely, the opposite side (the contralateral side) experiences what is known as distraction. This is because the jaw moves in such a way that the joint on the opposite side is not engaged in weight-bearing activity. Therefore, the muscles around the contralateral TMJ do not exert the same compressive forces, resulting in a state of distraction in that joint.

This interaction illustrates the mechanics of mastication, where the repositioning of the jaw creates a differential loading pattern across the two TMJs. Chewing on one side leads to specific compression and distraction effects that are important for understanding how the joints respond to functional loads.