What occlusal relationship describes teeth #12 and #20?

• A. End-to-end bite
• B. Normal occlusion
• C. Crossbite
• D. Open bite

Answer: (C)

Occlusal relationships describe how upper and lower teeth meet when the jaws close. A crossbite happens when an upper-tooth contacts a lower-tooth on the opposite side of the arch, meaning the upper tooth sits inside relative to its opposing lower tooth rather than ahead of it.

For the teeth in question, the way they meet is inside the opposite arch, which fits the pattern of a crossbite. This is different from normal occlusion, where the upper teeth are positioned slightly buccal to the lowers; from edge-to-edge contact, where upper and lower teeth meet bite-for-bite without overjet or overbite; or from an open bite, where there is a vertical gap between the upper and lower teeth when the back teeth are together.