3D Computed Tomography vs. 2D radiography: comparison of 3D direct anthropometry with 2D norm calculations and analysis of differences in soft tissue measurements.

Objective: The aim of this study was twofold: (1) to compare soft tissue measurements of the same distances obtained from 3D computed tomography reconstructions with 2D cephalometric radiograms, (2) to compare data from 3D measurements from direct anthropometry and 2D "norms" for the facial measurements.

Patients And Methods: A total of 40 Caucasian patients that had their CBCT scans for various dental and dentoskeletal reasons were enrolled in this study. All the patients had large field of view (from the forehead to the chin). The data were stored in DICOM format and imported into a software for 3D reconstructions. After 3D facial soft tissue model generation, the distances between 18 soft tissue points were measured. The 3D soft tissue analysis was performed, and the facial indices were calculated. The mean 3D values were compared with 2D measurements performed on lateral cephalograms and Arnett's and Farkas' norms. The measurements were statistically compared using Student's t-test.

Results: Assessments from 2D and 3D measurements showed no statistical difference except for the distance Pogonion (for both male and female) and Labial superius prominence (females) to the True Vertical Line in 2D /Plane in case of 3D measurements. There was a significant difference between all 3D measurements and Arnett's and anthropometric Farkas' "norms". The mean difference between Farkas' "norms" and 3D measurements was within 3 mm for 70% of measurements.

Conclusions: According to the results, 3D soft tissue analysis allows for complete diagnostic determination. The 3D "norms" are to be verified on a greater sample.