Comparetive Evaluation of Spiral Tomography with Surgical Results in Determination of Position of Maxillary Impacted Teeth

Conventional radiographs are usually used for diagnosis of dental impaction, but these radiographs do not provide the dentist with complete information in 3rd dimension. In this situation, tomography or computed tomography is used for acquisition of more detailed information for localization of impacted tooth. The aim of this study was to evaluate the efficiency of tomography in localization of impacted maxillary tooth. In this descriptive study, nine orthodontic patients (5 males, 4 females, mean age 16.2 Years) with 12 impacted teeth (canine or supernumerary teeth) with diagnostically difficult impacted maxillary tooth who had undergone spiral tomography, were followed and received surgical treatment. Spiral tomography (2mm thickness with 1 and 3mm interval in mesial and distal directions) from marked point by cranex tome sordex machine (Helsinki, Finland) and Digora PSP (photostimulable phosphorus plates) were provided. After image transfer to computer, tomographic measurements were corrected by an enlargement factor×1.5. On the images, location of coronal portion of impacted tooth and the distance between tip or prominent point of coronal portion to tangent line of crestal bone in digital program to 0.1 mm accuracy was measured. The results of radiographic measurements were compared with surgical results. There was a 100% agreement between tomographic and surgical findings in localization of impacted teeth. The minimum and maximum differances between measurements of surgery and tomography were 0 and 1.5 mm respectively. The mean difference was 0.6 mm. Spiral tomography gives us additional information about location of impacted tooth compared with conventional radiography. This method facilitates the localization of impacted tooth and also measures the distance between impacted tooth and alveolar crest with minimum difference.