2D vs 3D- The truth within !

Objectives:The spiral CT technique presents an innovation of tomographic imaging systems and subsequent volumetric image reconstuction for dentistry.When compared with other methods of tomographic imaging spiral CT is characterized by rapid volumetric image acquisition from a single low radiation dose scan of the patient.The aim of this study was to evaluate the accuracy of leniar measurements on skull by comparing digital radiography and spiral CT.

Methods:15,linear measurements were made between the anatomic sites in three dimensions x,y,z in six skull using digital caliper.These were considered as real measurements.Subsequently spiral CT scan and digital radiography were taken.The CT data was recorded using Siemens Somatum Sensation CT scanner of 1mm thick slices and reconstructed using Mimics 11.02 software.The cephalometric records were taken using Planmeca and the data was compared by students t-test.

Results:The results showed that CT measurements were larger than direct skull measurements in ten out of fifteen parameters,but these differences were only significant in z axis.

Conclusion: Measurements made on spiral CT are comparable to anatomic truth in all three planes except in skull base structures.Measurements made on digital cephalograms show a significant variation except for midsagittal structures.