Semester

Spring

Date of Graduation

2026

Document Type

Thesis

Degree Type

MS

College

School of Dentistry

Department

Orthodontics

Committee Chair

Peter Ngan

Committee Member

Khaled Alsharif

Committee Member

Guoqiang Guan

Abstract

ABSTRACT

 

Comparison of Three Methods in Diagnosing Maxillary Transverse Discrepancy

Thesis by Madison Smith, D.D.S.

Introduction

There are several different methods in determining the maxillary transverse discrepancy (MTD). In specific, MTD can be determined with the help of a cone beam computer tomography (CBCT), 3D scan and models, or simply a 2D occlusogram.  Do they provide the same MTD values for diagnosing transverse discrepancies? A patient may need a certain amount of skeletal and dental expansion based on a diagnosis of MTD, but this amount may vary depending on the diagnosis method used. There is a lack of knowledge in the literature comparing 2D and 3D methods in determining MTD. Currently, methods in measuring MTD include but not limited to utilizing posteroanterior (PA) cephalograms, digital scans, dental casts, and cone-beam computed tomography (CBCT) radiographs. In the current study, three different methods will be compared (Yonsei analysis on CBCT, Dr. Tim Tremont’s method on digital models, and a method by WVU faculty Dr. Khaled Alsharif using bony landmarks on digital models). The purpose of this study is to determine the difference among these three methods and inform orthodontists what methods similarly diagnose MTD.

Methods

The transverse dimension was measured and diagnosed using three methods. These included CBCT according to the Yonsei analysis as well as two separate methods using the dental casts via digital models, the Tremont analysis and the unpublished method used by WVU faculty, Dr. Khaled Alsharif. Once the measurements were taken and the MTD was determined for each of the three methods, a statistical analysis was performed to evaluate if there were any statistically significant differences in MTD among the three methods. Inclusion criteria included de-identified orthodontic patients 10 years old or above, no prior orthodontic treatment, CBCT capturing both the maxilla and mandible, and a digital scan of maxilla and mandible. Exclusion criteria included prior orthodontic treatment and patients with craniofacial abnormalities such as cleft lip/palate.

Results:

We performed repeated measures ANOVA followed by Tukey honesty significant difference (HSD) test to determine the differences in MTD scores using 3 MTD diagnostic methods. There was significant difference in mean MTD scores between at least two MTD diagnostic methods (F (2, 54) = 5.50, p=0.007). The post-hoc HSD test results showed significant differences in mean MTD scores between Alsharif method (-3.24 ± 2.51) and Tremont method (-2.44 ± 2.66), and between Tremont (-2.44 ± 2.66) method and Yonsei method (-3.39 ± 2.42). No significant difference was found between Alsharif method and Yonsei method.

Conclusions:

If a clinician would like to use a CBCT diagnostic analysis for the transverse dimension such as the Yonsei analysis but does not have access to CBCT, the unpublished method used by Dr. Khaled Alsharif can be used instead as they are statistically similar. The Tremont analysis diagnoses MTD to be approximately 1mm less than the Yonsei analysis and method used by Dr. Alsharif. While this is statistically significant, this is not clinically significant as most practitioners over-expand by a couple millimeters to account for relapse.

Intra-rater and inter-rater reliability were both excellent for all methods.

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