How can a posterior crossbite affect occlusal function?

• A. It can cause symmetric condylar movement.
• B. It can cause asymmetric condylar movement, uneven muscle activity, and occlusal interferences.
• C. It eliminates muscle tension.
• D. It improves occlusion.

Answer: (B)

A posterior crossbite disrupts the balance of occlusion by causing the mandible to shift toward the crossbite side to achieve the best possible contacts. This results in asymmetric condylar movement because each condyle follows a different path during closure. The change in contact pattern also drives uneven muscle activity as muscles on one side work harder to maintain closure and balance, while the other side is less engaged. Premature contacts and bumps against the opposite teeth create occlusal interferences that prevent smooth, stable bite. Taken together, these factors compromise occlusal function rather than improve it. Other options would imply symmetry, elimination of muscle tension, or an improved bite, which do not reflect the typical effects of a posterior crossbite.