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External Root Resorption Associated with Maxillary Expansion Therapies as Evaluated via Cone Beam Computed Tomography: A Retrospective Randomized Clinical Trial Open Access


Other title
Cone Beam Computed Tomography
Maxillary Expansion
External Root Resorption
Type of item
Degree grantor
University of Alberta
Author or creator
Forst, Darren D
Supervisor and department
Lagravere, Manuel (Dentistry)
Examining committee member and department
Carey, Jason (Mechanical Engineering)
Flores-Mir, Carlos (Dentistry)
Secanell, Marc (Mechanical Engineering)
Martinez, Ysidora (Dentistry)
Medical Sciences-Orthodontics

Date accepted
Graduation date
Master of Science
Degree level
Objective: To investigate and develop an appropriate measurement protocol possessing adequate precision in both intra- and inter-rater reliability for in vivo maxillary first molar volume measurements using cone beam computed tomography (CBCT) images. To assess in vivo through the use of CBCT imaging whether the type of maxillary expansion appliance [BAME versus tooth-anchored maxillary expander (TAME)] impacts the amount of external root resorption in maxillary first molars as compared to a no treatment control group. Methods: 62 adolescents requiring maxillary expansion were randomly allocated to groups: TAME, BAME, and control. CBCT images were acquired at baseline and approximately 12-months. Segmentation procedures were investigated and developed to quantify maxillary first molar ERR. Dental volumes were measured on the CBCT images at both time points to assess maxillary first molar dental volume changes. Results: Excellent intra- and inter-rater agreement for segmentation. Automated thresholding with manual refinements on a 2D slice-by-slice basis, yielded the highest intra- and inter-rater reliability statistics. There lacked statistically significant evidence (p>0.05) of differences in external root resorption (both percentage and absolute volume) between TAME, BAME, and control groups. Conclusion: Whole tooth CBCT segmentation employing grayscale thresholding with 2D slice-by-slice manual refinements possesses excellent intra- and inter-rater reliability. There is no statistically significant evidence supporting increased ERR with TAME or BAME versus control.
Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.
Citation for previous publication
Forst D, Nijjar S, Flores-Mir C, Carey J, Secanell M, Lagravere M. Comparison of in vivo 3D cone-beam computed tomography tooth volume measurement protocols. Progress in Orthodontics 2014;15:69.Forst D, Nijjar S, Khaled Y, Manuel L, Flores-Mir C. Radiographic assessment of external root resorption associated with jackscrew-based maxillary expansion therapies: a systematic review. Eur J Orthod 2013 Dec 19.

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