Measurement accuracy of a computer-assisted three-dimensional analysis and a conventional two-dimensional method

Abstract

Objective: To determine the differences between manual and cephalometric measurements on different sections of the human skull, which were obtained using computer-assisted threedimensional (3D) analysis and conventional two-dimensional (2D) techniques. Materials and Methods: Measurements were carried out on 13 dry human skulls, then 2D cephalograms and 3D computed tomographic (CT) images were obtained. Anatomic landmarks were determined and marked with clay before CT images were taken, and the same landmarks were marked with the help of metallic balls and pins for lateral and frontal cephalograms. Manual, lateral/frontal cephalometric, and computer-assisted 3D cephalometric measurements were compared statistically. One-way analysis of variance and Tukey Honestly Significant Difference tests were used to compare the results among the groups. Results: All measurements were statistically insignificant between the computer-assisted 3D and manual measurements. On the other hand, the differences between the conventional 2D and the manual measurements were statistically significant. The greatest amount of magnification was found at the Nasion-Menton distance (14.6%), which was located at the farthest distance from the central x-ray beam in the lateral cephalogram (P , .01). For the same reason, the greatest enlargement (16.2%) was observed in the distance between the zygomaticomaxillary sutures on the conventional frontal cephalogram (P , .01). Conclusions: The computer-aided 3D cephalometric measurements were found to be more accurate than the conventional cephalometric measurements. The results revealed that 3D cephalometric measurements were consistent with the manual measurements. In addition, the magnification and distortion might limit the results of conventional cephalometric measurements. (Angle Orthod. 2011;81:375-382.)

Evaluation of mandibular volume using cone-beam computed tomography and correlation with cephalometric values

“…22 Reliable and accurate evaluation is difficult because of this inherent geometric magnification, distortion, and superimposition of craniofacial structures. [23][24][25][26][27] The use of cephalometry as an adjunct to clinical examination as a basis for predicting craniofacial growth is thus questionable. 28,29 Imaging is increasingly favored for perceiving the size and form of craniofacial structures in orthodontics and has the advantage of replicating anatomical detail accurately in three dimensions.…”

3D landmarks of Craniofacial Imaging and subsequent considerations on superimpositions in orthodontics—The Aarhus perspective

“…Due to the complexity of some anatomical structures in 3D, errors in landmark identification represent a major source of cephalometric errors. 12 Therefore, comprehensive definitions of landmarks along all three directions (ie sagittal, vertical and transversal) are crucial to decrease the uncertainties in landmark identification. As done previously for 2D cephalometric analyses, it is essential to develop and validate standardized protocols to define and identify novel landmarks in 3D.…”

Korelasi indeks morfologi wajah dengan sudut interinsisal dan tinggi wajah secara sefalometri (Cephalometric correlation of facial morphology index with interincisal angle and facial height)

“…Dalam hal ini, tinggi wajah dapat membantu pihak pembuat sketsa untuk menggambarkan korban mendekati rupa aslinya, sementara besar sudut insisal dapat membantu menggambarkan pola konveksitas daerah sepertiga bawah dari tinggi wajah korban. [11][12][13] Temuan dalam penelitian ini, sebagaimana tertuang dalam Tabel 3, dengan nilai p<0,05 membuktikan bahwa terdapat hubungan bermakna antara indeks morfologi wajah dengan tinggi wajah pada analisis sefalometri lateral. Adanya korelasi bermakna ini diharapkan memberikan manfaat aplikatif dalam proses identifikasi individu yang hanya menyisakan tengkorak kepala.…”