Introduction: Study models are an essential part of an orthodontic record. Digital models are now available. One option for generating a digital model is cone-beam computed tomography (CBCT) scanning of orthodon- tic impressions and bite registrations. However, the accuracy of digital measurements from models generated by this method has yet to be thoroughly evaluated. Methods: A plastic typodont was modiﬁed with reference points for standardized intra-arch and interarch measurements, and 16 sets of maxillary and mandibular vinyl- polysiloxane and alginate impressions were made. A copper wax-bite registration was madewith the typodont in maximum intercuspal position to accompany each set of impressions. Continue reading Analysis of intra-arch and interarch measurements from digital models with 2 impression materials and a modeling process based on cone-beam computed tomography
Objective: To determine if measurements obtained from digital models from cone beam computed tomography (CBCT) images were comparable to the traditional method of digital study models by impressions.
Materials and Methods: Digital models of 30 subjects were used. InVivoDental (Anatomage, San Jose, Calif) software was used to analyze CBCT scans taken by a Galileos cone beam scanner (Sirona, Charlotte, NC) with a field of view of 15 3 15 3 15 cm3 and a voxel resolution of 0.125 mm. OrthoCAD (Cadent, Fairview, NJ) software was used to analyze impression scans of patients at different stages of orthodontic treatment. Impressions were taken using alginate and were mailed to OrthoCAD for digital conversion. The scans were then electronically returned in digital format for analysis. Continue reading Evaluation of CBCT Digital Models and Traditional Models Using the Little’s Index
Toma AM, Zhurov A, Playle R, Ong E, Richmond S. Reproducibility of facial soft tissue landmarks on 3D laser- scanned facial images. Orthod Craniofac Res 12:33-42, 2009.
Background – The three-dimensional (3D) measuring technology is useful to inspect facial shape in three planes of space (X, Y, and Z). Recent work has been directed to analyse craniofacial morphology using facial soft tissue landmarks to identify facial differences among population. The reproducibility of facial landmarks is almost necessary to ensure accurate 3D facial measurements.
Objective – The aim of this study is to assess the reproducibility of facial soft tissue landmarks using laser-scan 3D imaging technology.
Subjects and Methods – Facial landmarks were assessed for 30 15½-year-old British-Caucasian children (15 males and 15 females). The sample was recruited from the Avon Longitudinal Study of Parents and Children (ALSPAC). The 3D facial images were acquired for each subject using two high-resolution Konica ⁄ Minolta laser scanners. Twenty-one facial landmarks (63 X, Y, and Z coordinates) were identiﬁed and recorded on each 3D facial image by two examiners. The reproducibility of landmarks identiﬁcation at 2-week interval was assessed for one of the examiners (intra-examiner). In addition, the reproducibility of landmarks was assessed between the two examiners (inter-examiner). Using Bland-Altman plots, both intra- and inter-examiner assessments had evaluated landmarks reproducibility in three dimensions for the sample divided by gender. The reproducibility of the 3D-coordinates for each landmark was considered under three categories (<0.5 mm, <1 mm, and >1 mm) for both intra- and inter- examiner reproducibility assessments.
Continue reading Reproducibility of facial soft tissue landmarks on 3D laser- scanned facial images.
Korbmacher H, Kahl-Nieke B, Schöllchen M, Heiland M. Value of two cone-beam computed tomography systems from an orthodontic point of view. J Orofac Orthop 68:278- 289, 2007.
SUMMARY by Dr. DALIA BASYONI :
* CBCT cannot replace OPG, which remains our primary imaging modality.
* In complex cases involving multiple findings in different regions, CBCT is more desirable than conventional radiographs.
* Standard operating procedures (SOP) to use CBCT:
• clefts of the lip, jaw and palate and cases of impacted teeth. Continue reading Value of two cone-beam computed tomography systems from an orthodontic point of view.