Award Date

5-1-2025

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Dental Medicine

First Committee Member

Brian Chrzan

Second Committee Member

Karl Kingsley

Third Committee Member

Charles Hill

Fourth Committee Member

Ying Guo

Number of Pages

63

Abstract

Background: Temporary anchorage devices (TADs) have changed the way many orthodontists practice orthodontics. TADs are mini-screw temporary implants made of titanium or stainless steel that are placed in the patient's bone in different locations to aid in complex biomechanical movements. This complete anchorage aids in distalization, intrusion, protraction, etc. with less reliance on patience compliance. While TADs have made many movements easier, there are limitations such as choice of where to place it, skill at placing them and patient individual physiology and anatomy that can limit the use of TADs.Objectives: Infrazygomatic crest (IZC) TADs are particularly useful for distalization and intrusion of the posterior maxillary dentition but often have limitations with root morphology in patients. The objective of this study is to analyze a new location, the zygomatico-maxillary buttress, for TAD placement to aid in these movements. This location would avoid the roots of the maxillary dentition, allowing for easier placement of the TAD and movement of the dentition. Methods: A total of 67 CBCT images were anonymized and analyzed to measure bone depth at 12 different sites per subject, assessing both the right and left sides. The cemento-enamel junction (CEJ) of the upper first molar was selected as the reference point due to its anatomical relationship with the zygomatico-maxillary buttress and its clinical relevance. Measurements were taken at the mesial, middle, and distal regions of the upper first molars. From each site, distances of 1, 3, 5, and 7 mm were marked perpendicularly from the CEJ towards the buccal. A vertical line was then extended from these points until it contacted the bone, at which the total bone depth was recorded. Results: The depth of the bone varied widely across patients ranging from 1.3 mm to 21.9 mm with an overall average of 4.19 mm. The difference is attributed to patients' individual anatomy and not any external factors. The mesial of the upper first molar had the highest average of 4.36 mm and the distal had the lowest average of 4.06. The averages varied more when distance from the CEJ was factored in, with the site 7 mm from the mesial CEJ having an average of 5.28 mm and the measurement 1 mm from the distal CEJ not having any measurable bone. Conclusion: Careful analysis of a CBCT radiograph is recommended prior to placing a TAD in the zygomatico-maxillary buttress area as patient anatomy seems to vary substantially. The highest probability of having adequate bone depth is 5-7 mm away from the mesial aspect of the upper first molar.

Keywords

Bone Depth; Orthodontics; TADs; Temporary Anchorage Device

Disciplines

Dentistry

File Format

pdf

File Size

3600 KB

Degree Grantor

University of Nevada, Las Vegas

Language

English

Rights

IN COPYRIGHT. For more information about this rights statement, please visit http://rightsstatements.org/vocab/InC/1.0/

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