Definition: When two adjacent teeth switch positions in the arch.
Location: Most commonly associated with the permanent canine.
Shape: Normal tooth shape.
Internal: Radiopaque and radiolucent. Same appearance as a normal tooth.
Number: Associated with two teeth.
(click image to enlarge)
(note the canine erupting adjacent to the central incisor)
(note the lateral incisor adjacent to the first premolar and the canine adjacent to the central incisor)