CBCT vs Conventional Lateral Cephalogram in Orthodontics: a Cephalometric Evaluation

INTRODUCTION: Despite the inherent magnification errors and difficulty in landmark identification, lateral cephalograms continue to be the primary diagnostic protocol in orthodontic offices today. Through the surfeit of technological progress, cone beam computer tomography (CBCT) is emerging as a powerful tool for diagnosis in the field of dentistry, allowing higher resolution, greater anatomic detail and visual access to three-dimensional perspectives of the soft and hard tissues of the face. To determine the diagnostic value of the CBCT with respect to orthodontic treatment planning, a comparative analysis of a three-dimensional imaging system to the conventional two-dimensional radiography in human subjects is necessary. OBJECTIVES: 1) To determine repeatability of landmark identification in the images from both systems 2) to ascertain the difference between cephalometric values obtained from traditional lateral cephalograms to those obtained from a CBCT generated lateral image. METHODS: 35 patients were selected by sequential self-sampling from the incoming pool of treatable cases at the University of Alberta Graduate Orthodontic Clinic in Edmonton. Traditional cephalograms (using Orthoceph OC100) and volumetric CBCT imaging (using Newtom QR-DVT 9000 Volume Scanner) were performed on each patient. Cephalometric analysis using Dolphin 3D was performed on the respective radiographic images. Ten angular measurements (SNA, SNB, ANB, MP-SN, MP-FH, SN-Ar, SGn-SN, U1-PP, L1-MP, UI-LI) were compared using paired MANOVA. RESULTS: A preliminary analysis of ten randomly selected patients demonstrated that there was insufficient evidence to support a significant difference in the cephalometric angular measurements between the two imaging systems (p>0.1, a=0.05). CONCLUSIONS: The enhanced visual accuity, detail and 3D accessibility of CBCT comes at price of increased radiation. However, ongoing technological advancements continue to adress this concern. Based on our preliminary findings, the results of cephalometric analysis performed on a lateral CBCT image is comparable to traditional cephalograms. Thus CBCT may have merit in orthodontic treatment planning.