The recommended vertical angulation for exposing a mandibular incisor periapical radiograph

using the bisecting technique is:

a. -10 degrees
b. -15 degrees
c. -20 degrees
d. -5 degrees

b. To obtain a radiograph with an accurate representation of the mandibular incisor, the central ray of the x-ray beam should be directed toward the imaginary bisector between the long axis of the canine and the plane of the image receptor in the vertical dimension at -15 degrees.