The purpose of this research was to compare skeletal and dental changes assessed by digital volumetric images produced during and after rapid maxillary expansion (RME) between a bone-borne anchored expansion appliance and a conventional tooth-borne RME. Initial steps included the development of a methodology to analyze CBCT images. Reliability of traditional two dimensional (2D) cephalometric landmarks identified in CBCT images was explored, and new landmarks identifiable on the CBCT images were also evaluated. This methodology was later tested through a clinical trial with 62 patients where skeletal and dental changes found after maxillary expansion using either a bone-borne or tooth-borne maxillary expander and compared to a non-treated control group. The conclusions that were obtained from this thesis were that the NewTom 9” and 12” three dimensional (3D) images present a 1-to-1 ratio with real coordinates, linear and angular distances obtained by a coordinate measurement machine (CMM). Landmark intra- and inter-reliability (ICC) was high for all CBCT landmarks and for most of the 2D lateral cephalometric landmarks. Foramen Spinosum, foramen Ovale, foramen Rotundum and the Hypoglossal canal all provided excellent intra-observer reliability and accuracy. Midpoint between both foramen Spinosums (ELSA) presented a high intra-reliability and is an adequate landmark to be used as a reference point in 3D cephalometric analysis. ELSA, both AEM and DFM points presented a high intra-reliability when located on 3D images. Minor variations in location of these landmarks produced unacceptable uncertainty in coordinate system alignment. The potential error associated with location of distant landmarks is unacceptable for analysis of growth and treatment changes. Thus, an alternative is the use of vectors. Selection of landmarks for use in 3D image analysis should follow certain characteristics and modifications in their definitions should be applied. When measuring 3D maxillary complex structural changes during maxillary expansion treatments using CBCT, both tooth-anchored and bone-anchored expanders presented similar results. The greatest changes occurred in the transverse dimension while changes in the vertical and antero-posterior dimension were negligible. Dental expansion was also greater than skeletal expansion. Bone-anchored maxillary expanders can be considered as an alternative choice for tooth-anchored maxillary expanders. / Medical Sciences in Orthodontics
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:AEU.10048/504 |
| Date | 11 1900 |
| Creators | Lagravere Vich, Manuel Oscar |
| Contributors | Paul W. Major (Dentistry), Jason Carey (Mechanical Engineering), Paul W. Major (Dentistry), Jason Carey (Mechanical Engineering), Giseon Heo (Dentistry), Roger Toogood (Mechanical Engineering), Robert Lambert (Radiology and Diagnostic Imaging), Marc Secanell Gallart (Mechanical Engineering), Arthur J. Miller (Orofacial Sciences, Physiology) |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | en_US |
| Detected Language | English |
| Type | Thesis |
| Format | 4599296 bytes, application/pdf |
| Relation | Lagravère MO, Carey JPR, Toogood RR, Major PW. Three-dimensional accuracy of measurements made with software cone-beam computed tomography. Am J Orthod Dentofacial Orthop 2008;134:112-116, Lagravère MO, Low C, Flores-Mir C, Chung R, Carey J, Heo G, Major PW. Landmark intra- and inter-reliability obtained from digitized lateral cephalograms and formatted CBCT three-dimensional images. Am J Orthod Dentofacial Orthop in press, Lagravère MO, Major PW. Proposed reference point for 3-dimensional cephalometric analysis with cone-beam computerized tomography. Am J Orthod Dentofacial Orthop 2005;128(5):657-660, Lagravère MO, Gordon J, Guedes IH, Flores-Mir C, Carey J, Heo G, Major PW. Reliability of traditional cephalometric landmarks as seen in three-dimensional analysis in maxillary expansion treatments. Angle Orthod in press |
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