Comparison of Digital and CBCT Synthesized Lateral Cephalograms

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Lee, Da
Lateral Cephalograms; Ricketts analysis; Digital Lateral Cephalogram; Synthesized Lateral Cephalogram; Orthodontics and Orthodontology; Other Dentistry; Cone-Beam Computed Tomography; Radiography, Dental, Digital; Orthodontics, Corrective;
thesis / dissertation description
Purpose: The purpose of this study was to compare the precision of lateral cephalometric Ricketts analysis measurements from NewTom 5G CBCT (NewTom) synthesized lateral cephalograms with Sirona Orthophos XG Plus (Sirona) digital lateral cephalograms. Materials & Methods: A Sirona digital lateral cephalogram and a NewTom synthesized lateral cephalogram of a phantom in the orthogonal and perspective projections were created. Metal washers in each plane of the phantom were measured in the vertical and horizontal dimensions and compared across the different imaging modalities. In Group 1, forty patients were randomly selected from the Loma Linda University Graduate Orthodontic Clinic who had both a NewTom synthesized lateral cephalogram and a Sirona digital lateral cephalogram. In Group 2, forty patients with both a NewTom and a Sirona lateral cephalogram were selected based exclusion criteria which included images with significant overlap of the first molars and/or border of the mandible, and missing first molars to limit error in cephalometric measurement. All of the lateral cephalograms were digitized into Dolphin 3D version 11.5 and traced using Ricketts cephalometric analysis. For both groups, six linear and nine angular measurements from each imaging modality were compared and analyzed using a paired-t test. Results: There is a statistical difference in % magnification of washer measurements in the horizontal and vertical dimensions amongst the caliper measurements versus various imaging modalities. In Group 1 and Group 2, all of the linear measurements except lower lip to E-plane were statistically different (P < 0.05). The angular measurements were not statistically different (P < 0.05) with the exception of Ricketts facial axis (P = 0.001), lower face height (P = 0.027), and mandibular arch (P = 0.029) for Group 1. The angular measurements were not statistically different (P > 0.05) with the exception of Ricketts facial axis (P = 0.020), interincisal angle (P = 0.044), and lower face height (P = 0.043) for Group 2. Conclusions: The statistical differences found in this study translate to clinically significant differences that will likely make superimpositions difficult and therefore the reference line used for calibrating magnification for the various image modalities should be recalibrated.