[Lateral teleradiography of the cranium: the effect of head positioning in the interpretation of cephalometric tracings. An experimental study on a phantom].

PURPOSE: To assess the influence of head mispositioning during lateral teleradiography of the skull for cephalometric purposes. MATERIAL AND METHODS: We used a human dry skull fixed on a professional support at a three level angular scale to quantitate lateral and anteroposterior rotations and inclinations. We took 15 radiographs at different angles (-2 degrees and -4 degrees right rotation; +2 degrees and +4 degrees left rotation; -2 degrees and -4 degrees anterior roll; +2 degrees and +4 degrees posterior roll; -2 degrees and -4 degrees right pitch; +2 degrees and +4 degrees left pitch; + 2 degrees left rotation and -2 degrees anterior roll; +2 degrees left rotation and +2 degrees left pitch). RESULTS: The analysis of the 15 radiographic tracings compared with the one obtained with the head positioned correctly showed no substantial differences in angular and linear values; no difference was such as to invalidate tracing. DISCUSSION: When skull malpositioning limited within 4 degrees, the angular and linear measurements of the cephalometric tracing are reliable and accurate. Nevertheless, cephalometric findings must always be integrated with clinical and history data. CONCLUSIONS: We believe that even less than perfect teleradiographs of the skull should be used for cephalometric purposes because, even though they require more care of the dentist to analyze them, the results are reliable and the patient is spared further X-ray exposure.