Cephalometric analysis involves the evaluation and subsequent interpretation of both lateral and posterio-anterior views of skull.
Procedure: radiograph is taken in the Frankfort plane, ear posts positioned at the external auditory meatus and the teeth in centric occlusion. The central ray should pass through the ear posts. Most importantly, the the x-ray source to midsagittal plane distance and midsaggital plane to film distance should be standardised to facilitate reproducibility and to minimise magnification. To enhance the soft tissue profile, the beam intensity can be reduced by placing aluminium filter between x-ray source and the patient.
Uses of lateral cephalometric analysis -diagnostic aid -check treatment progress -to assess treatment and growth changes
As a diagnostic aid it serves to shed light on dental and skeleta;l characteristics of a malocclusion. Also serves as a reference point of pretreatment incisor position, especially if anterior-posterior movement is intended, providing a series of radiographs to compare and monitor treatment progress.
Chacking of unerupted teeth and identification of soft and hard tissue pathology and upper roots resorption.
As a means of checking treatment progress. During treatment with fixed and functional appliances.
Assessing treatment and growth changes: if films are to be compared, they must be superimposed on some stable landmarks/points. As orthodontic treatment is generally carried out during growth period, no natural fixed points/planes exist. However S-N can be considered to be a stable and close approximation of anterior cranial base Superimposing the position of the anterior vault of palate shows a good approximation of maxillary tooth position. Changes in mandibular tooth position may be assessed by superimposing structure of inner cortex of the inferior and lingual aspect of the symphysis and mandibular canal outline.