ABSTRACT
The recruitment of the craniomandibular muscles depends upon the oral function as the final end-product, or goal of the integrated motor response. In those oral functions which require the dentition, the system involves a close interaction between the sensory feedback from the periodontal region innervating the dentition, the sensory feedback from the bilateral temporomandibular joints, and the motor control developed through the coactivation pattern of the jaw-closing and jaw-opening muscles and generated by the central nervous system. The recruitment pattern for the craniomandibular muscles involved in a function using the occlu sion varies with two factors: (1) the direction of developing the loads within the periodontal and joint regions; and (2) the number, position, and bilateral balance of contacts in both the dentition and temporomandibular joints. The jaw-closing muscles are recruited maximally during contacts, which include the bilateral posterior teeth, but changing the direction of the force with the same contacts shifts those muscles which are most active. There is an interplay between the two factors which are dominant in determining the level of recruitment of the craniomandibular muscles: direction of forces and loading contact positions.
