Factors influencing the design of aiming devices for intraoral radiography and their practical application

Intraoral roentgenograms can be made according to the long-tube paralleling technique utilizing aiming devices. These instruments consist of a bite block, an indicator rod, and a collimator plate. For the position of the film in relation to the bite block surface, the following data are decisive and therefore studied: the length of the teeth to be radiographed, the enlargement as a result of the divergence of the x-ray beam, and the periapical area necessary for the interpretation and mounting of the roentgenograms. As a result, the bite blocks of the instruments were provided with three vertical steps to permit different film positions needed for the specific situation in the different regions of the mouth. The use of the correct film positions results in roentgenograms with a high diagnostic value. In order to reduce the patients radiation dose the aiming devices include a collimator plate. A description is given of the data used for the design of the plate.