Which combining form denotes the angle formed by the junction of distal and buccal surfaces of a tooth?

• A. conjunctiv/o
• B. poster/o
• C. cerebr/o
• D. dist/o

Answer: (D)

In dental terminology, naming an angle formed by junctions of tooth surfaces uses combining forms for the surfaces involved. Distal describes the surface away from the midline toward the back of the mouth, and it is written as dist/o. The angle created by the junction of the distal and buccal surfaces is the distobuccal angle, so dist/o is the combining form that denotes the distal component of that angle. The other options refer to parts not used in this dental directional context (eye conjunctiva, brain, etc.), so they don’t fit the term describing the distobuccal angle.