Patients with smaller jaw bones have less surface area and mechanical leverage for muscle attachment, resulting in decreased muscle mass and contraction force. This directly leads to reduced closing pressure during mastication compared to those with larger jaw bones. The size and morphology of the jaw significantly influence muscle efficiency and bite force generation. Thus, a smaller jaw limits the maximum occlusal force the muscles can exert, causing less closing pressure.

Reference: Clinical Oral Physiology, Gregory J. Van der Bilt, 2nd Edition.