Background: The current study aimed to compare the measurements of the mandible\nmorphology using 3D cone beam computed tomography (CBCT) images with those\nusing 2D CBCT-synthesized cephalograms; to quantify errors in measurements based\non 2D synthesized cephalograms; and to clarify the effects such errors have on the\ndescription of the mandibular growth.\nMethods: Mandibles of six miniature pigs were scanned monthly using CBCT over\n12 months and the data were used to reconstruct the 3D bone models. Five anatomical\nlandmarks were identified on each bone model, and the inter-marker distances and\nmonthly distance changes were calculated and taken as the gold standard. Synthetic 2D\ncephalograms were also generated for each bone model using a digitally reconstructed\nradiography (DRR)-generation method. Errors in cephalogram measurements were\ndetermined as the differences between the calculated variables in cephalograms and the\ngold standard. The variations between cephalograms and the gold standard were also\ncompared using paired t-tests.\nResults: While the inter-marker distance increases varied among the marker pairs, all\nmarker pairs increased their inter-marker distances gradually every month, reaching 50%\nof the total annual increases during the fourth and fifth months, and then slowing down\nin the subsequent months. The 2D measurements significantly underestimated most of\nthe inter-marker distances throughout the monitoring period, in most of the monthly\ninter-marker distance changes during the first four months, and in the total growth\n(p <0.05).\nConclusions: Significant errors exist in the measurements using 2D synthesized\ncephalogram, underestimating the mandibular dimensions and their monthly changes in\nthe early stages of growth, as well as the total annual growth. These results should be\nconsidered in dental treatment planning at the beginning of the treatment in order to\ncontrol more precisely the treatment process and outcome.
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