The improvement in masticatory function following the correction of a posterior unilateral crossbite is best attributed to the restoration of:

 # The improvement in masticatory function following the correction of a posterior unilateral crossbite is best attributed to the restoration of:

A. Reduced muscle hyperactivity in the temporalis muscle

B. Elimination of a functional midline deviation

C. Bilateral, simultaneous grinding and mixing function

D. Ideal anterior guidance and disclusion

The correct answer is C. Bilateral, simultaneous grinding and mixing function

Posterior unilateral crossbite induces a functional mandibular shift toward the crossbite side in centric occlusion, resulting in asymmetric bolus manipulation, preferential unilateral chewing, and reduced efficiency in comminution (grinding) and food mixing. Orthodontic or orthopedic correction (e.g., via expansion or asymmetric mechanics) repositions the mandible to eliminate this shift, reestablishing symmetric occlusal contacts and enabling bilateral, coordinated mandibular excursions for optimal masticatory performance—as evidenced by improved electromyographic symmetry in masseter and temporalis muscles and enhanced particle size reduction in chewing cycles. While midline deviation (B) is eliminated as a byproduct, it's secondary to occlusal symmetry; temporalis hyperactivity (A) may decrease but isn't the primary driver; and anterior guidance (D) is unrelated to posterior crossbite dynamics.