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3-Dimensional Reproducibility of Natural Head Position
Uniformed Services University Of The Health Sciences Bethesda United States
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During orthodontic treatment, photographs or radiographs of patients are typically utilized to evaluate soft tissue growth and treatment change. As a means of assessing these changes, direct superimposition of images taken at different time points is traditionally accomplished. This study was accomplished in order to determine the reliability of using True Sagittal, Coronal and Frontal reference planes for image superimposition, based on a patients Natural Head Position NHP. The study was designed to evaluate the reproducibility of NHP over time in all planes of space using three-dimensional imaging. It was hypothesized that a patients NHP is reproducible in the Sagittal, Coronal and Frontal dimensions over time. Methods and Materials The experimental design included 28 adult subjects, 18-40 years of age. Two fixed laser lines iCAT , Imaging Sciences International, Hatfield, PA, oriented horizontally and vertically, were used as a reference to record NHP after a patient was asked to look into their own eyes in a mirror and assume a stable position after a series of oscillations. The patients NHP was recorded using semi-permanent markers Sharpie, Newell Rubbermaid Office Products, Oak Brook, IL placed on four points, coincident within the laser lines, on the head for registration. Using a 3-dimensional camera system 3dMD, Atlanta, GA, photographs were taken to capture the orientation of the respective points. By superimposing each of the five photographs on stable anatomic surfaces, changes in the position of the markers were recorded and then assessed for parallelism using 3dMDvultus 3dMD, Atlanta GA and Dolphin ImagingTM Dolphin Imaging and Management Solutions, Chatsworth, CA software packages. These systems allowed for quantification of angular differences. One subject was used to verify the reproducibility of the method and angles were calculated ten times at each time point and in all three angles.
APPROVED FOR PUBLIC RELEASE