Abstract: An improved dental x-ray aiming device for longitudinal radiographic analysis is provided. The device includes a bite block, a guiding rod, an aiming ring, and a supplemental ring. The bite block includes a film holder that is not perpendicular to a top surface of the bite block. The guiding rod is also attached to the bite block in a non-parallel relationship to accommodate the non-perpendicular arrangement of the film holder. As a result, a proper relationship is maintained between the aiming ring (and hence a dental radiography device) and the film holder. The aiming ring is attached to the guiding rod through a sliding member. The sliding member secures the aiming ring at a predetermined distance from the guiding rod, while allowing the aiming ring to move on an axis parallel with the guiding rod. The bite block includes a slot for receiving and holding a reference device for later density reference measurements.