Dana Nguyen

Abstract

Purpose: The purpose of this study was to determine the variability of lateral cephalometric landmark selection in two cone beam computed tomography (CBCT) lateral cephalometric simulations: 1) a mean projection image (MPI) and 2) a serial sagittal slice image (SSSI).

Methods: A MPI is a two-dimensional (2D) image obtained from the NewTom 3GTM CBCT that resembles the conventional lateral cephalogram. A SSSI is a 2D image also obtained from CBCT data, but is created by superimposing a series of selected thin sagittal slices containing the required cephalometric landmarks. This study compared the Ricketts and Steiner analysis of the MPI and SSSI from 35 consecutive patients of the Loma Linda University graduate orthodontic clinic. Three raters located the required landmarks on the MPI and SSSI for all patients. The landmarks wee digitized using QuickCeph2000TM. The MPI Ricketts and Steiner analysis measurements were compared with those of the SSSI.

Results: The results revealed that 4 of the 16 Ricketts measurements were significantly smaller in the MPI than the SSSI while none of the twelve Steiner measurements were significantly different. The results also showed no significant interrater differences in any of the measurements. The inter correlation coefficient (ICC) was greater in the SSSI than the MPI for all measurements except Sella to Nasion to B point (SNB).

Conclusions: The results indicated little variation in the Steiner analysis landmark identification. Both MPI & SSSI modes are equally successful in conducting a Steiner analysis. One fourth of the Ricketts analysis measurements were significantly smaller in the MPI relative to the SSSI. This discrepancy could be due to misidentification of the Frankfort horizontal plane (porion or orbitale), upper 6 distal, or pterygoid point on the MPI or to problems with the SSSI Ricketts analysis landmark definitions.

Even though there were few statistically significant differences between the mean measurements of the two image modes, there were clinically significant deviations in individual patient data that could potentially influence patient diagnosis. In addition, although there was generally good inter-rater agreement for landmark selection, there was more variability in landmark identification with the MPI mode.

LLU Discipline

Orthodontics and Dentofacial Orthopedics

Department

Orthodontics and Dentofacial Orthopedics

School

Graduate Studies

First Advisor

V. Leroy Leggitt

Second Advisor

Joseph M. Caruso

Third Advisor

James Farrage

Degree Name

Master of Science (MS)

Degree Level

M.S.

Year Degree Awarded

2006

Date (Title Page)

12-2006

Language

English

Library of Congress/MESH Subject Headings

Cephalometry -- statistics and numerical data; Tomography, X-Ray Computed; Imaging, Three-Dimensional; Diagnostic Imaging

Type

Thesis

Page Count

xiii; 55

Digital Format

PDF

Digital Publisher

Loma Linda University Libraries

Usage Rights

This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.

Collection

Loma Linda University Electronic Theses and Dissertations

Collection Website

http://scholarsrepository.llu.edu/etd/

Repository

Loma Linda University. Del E. Webb Memorial Library. University Archives

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