To determine whether an object or impacted canine is buccal or lingual, a second radiograph is taken with a changed horizontal tube angle. Using the SLOB rule, if the object moves in the SAME direction as the tube shift, it is located:

SLOB = Same Lingual, Opposite Buccal. When the tube head is shifted and the object moves the SAME direction as the beam, it lies lingual/palatal; if it moves the OPPOSITE direction, it lies buccal. Two films at different angles provide the third dimension.Other options: The rule specifically distinguishes lingual from buccal; sinus or extra-body location is not what SLOB determines.Key exam takeaway: SLOB: object moves the Same way as the tube = Lingual; Opposite = Buccal. Use the tube-shift (parallax) with two films.