Localization of impacted maxillary canines using panoramic radiography.

We aimed to establish a reliable method of localizing an impacted maxillary canine on the sole basis of assessment of a single panoramic radiograph, and to determine the validity and reproducibility of the method. Panoramic radiographs of 50 subjects with a total of 68 impacted canines were analysed. The Canine Incisor Index (CII), Canine Canine Index (CCI), control Canine Incisor Index (c-CII), Zone (apical, middle, coronal) and Sector (I, II, III, IV) were determined on digitized panoramic radiographs. Comparison of the CII and CCI values of labially or palatally impacted canines revealed a statistically significant difference (P < 0.05). Comparison of labial and central canine impactions revealed no relation to CII or CCI (P > 0.05). There was a significant difference between palatal and central canine impactions in relation to CII (P < 0.05), but no significant difference between the two with respect to CCI (P > 0.05). Correct prediction of palatal canine impactions by differential magnification on a panoramic radiograph is possible in 77% of cases. Vertical and horizontal restrictions have no value in recognition of labiolingual position of impacted maxillary canines. The panoramic radiograph cannot be used as a sole radiograph for reliable localization of impacted maxillary canines.