For an adult horizontal premolar bitewing, position the image receptor so that the anterior edge lines up:

a. behind the distal half of the canine.
b. between the first and second premolars.
c. behind the distal half of the first premolar.
d. in front of the mesial half of the second premolar.

a. The premolar bitewing must image the distal portion of both the maxillary and the mandibular canines to image the mesial surface of the first premolar, one of the teeth of interest for this projection. The radiographer should align the anterior edge of the image receptor behind the distal edge of either the maxillary or the mandibular canine, whichever one is farther forward in the mouth (the most mesial canine).