Final answer:
Labial and buccal are terms that specifically refer to structures related to the mouth, with labial pertaining to the lips and buccal to the cheeks, and do not correspond to the paired directional terms mentioned.
Step-by-step explanation:
The terms labial and buccal can be substituted for not superior and inferior, anterior and posterior, medial and lateral, or proximal and distal. Instead, these terms refer specifically to structures concerning the mouth. Labial refers to the lips while buccal refers to the cheeks, more precisely to the side of the oral cavity enclosed by the cheeks. Neither of these terms is related to the relative directions like superior, inferior, anterior, posterior, medial, lateral, proximal, or distal, which describe the position of body parts with respect to each other.