Question

question 14
the tooth # for the mandibular left 2nd premolar is:
#20
#4
#13
#12

Explanation:

In dental numbering (Universal Numbering System), mandibular (lower jaw) left teeth are in the 17 - 24 range. The 2nd premolar in mandibular left: premolars are 4th and 5th from the midline in lower left. Calculating: midline (18,19), then 20 (1st premolar? No, wait: Universal system: upper right 1 - 16, lower left 17 - 32? Wait, correction: Universal Numbering: upper right is 1 (3rd molar) to 16 (3rd molar upper left), lower left is 17 (3rd molar lower left) to 32 (3rd molar lower right). Wait, no, standard Universal: upper right quadrant (teeth 1 - 8), upper left (9 - 16), lower left (17 - 24), lower right (25 - 32). So mandibular left (lower left) quadrant: teeth 17 (3rd molar), 18 (2nd molar), 19 (1st molar), 20 (2nd premolar), 21 (1st premolar), 22 (canine), 23 (lateral incisor), 24 (central incisor). Wait, no, premolars: in lower left, from midline (23,24 are incisors, 22 canine, 21 1st premolar, 20 2nd premolar? Wait, no, order from midline (lower left): central incisor (24), lateral (23), canine (22), 1st premolar (21), 2nd premolar (20), 1st molar (19), 2nd molar (18), 3rd molar (17). Yes, so mandibular left 2nd premolar is #20. The other options: #4 is upper right 2nd premolar, #13 upper left 2nd premolar, #12 upper left 1st premolar. So correct is #20.

Answer:

#20