Document Type

Thesis

Date of Degree

Spring 2015

Degree Name

MS (Master of Science)

Degree In

Orthodontics

First Advisor

Robert N. Staley

Abstract

MAXILLARY CENTRAL INCISOR CROWN-ROOT RELATIONSHIPS IN CLASS I NORMAL OCCLUSIONS AND CLASS III OPEN AND DEEP MALOCCLUSIONS

By Jessica Fuller

M.S. Thesis Research Project

Introduction: The purposes of this thesis were several: (1) to examine a new crown-to-root angle based on anatomic points, the labial crown-root angle (LCRA), that was proposed in a recent University of Iowa thesis by Bauer, T.J. (2014) and correlate it with the collum angle (CA) values for Class I normal occlusions and Class III malocclusions; (2) to establish mean values for CA and LCRA for Class I normal occlusions and Class III open and deep bite malocclusions and statistically compare the groups; (3) to compare the significance of the correlation between overbite measures and CA and LCRA in the Class III sample. Only one study addressed the increased CA in Class III malocclusions however, the study did not include a normal occlusion control sample. Methods: 46 Class I normal samples, 20 Class III open bite samples and 22 Class III deep bite samples who met the inclusion criteria were measured cephalometrically. Relevant landmarks were placed, analyzed for reliability, and recorded for the measurements of interest. Results: A strong increasing correlation was found between CA and LCRA for all samples (Pearson's correlation coefficient = 0.82, p < .0001). The mean CA for the Class III deep bite group (9.32±4.46) was significantly different from the Class I normal core (3.38±1.70), Class I expanded (3.60±1.94) and Class III open bite (5.24±3.99) groups (ANOVA). The mean LCRA for the Class III deep bite group (39.67±5.64) was also significantly different from Class I normal core (31.97±4.25), Class I expanded (33.53±5.65) and Class III open bite (35.55±5.65) groups (ANOVA). There was no significant correlation between CA and overbite within Class III open (p=0.8029) and Class III deep bite groups (p=0.2089) or LCRA and overbite within Class III open (p=0.7529) and Class III deep bite groups (p=0.1864). Conclusions: LCRA and CA were highly correlated in Class III patients. Patients with Class III deep bites had statistically higher means for CA and LCRA than patients with Class I normal occlusions and Class III open bite malocclusions. There was no significant correlation between the measures for overbite and either CA or LCRA values in Class III patients.

Public Abstract

Introduction: The purpose of this study were several: (1) examine a new measurement for the angle of the maxillary central incisor called labial crown-root angle (LCRA) and correlate it with the accepted existing measurement, collum angle (CA), for different types of dental malocclusions; (2) establish average values for CA and LCRA for different types of dental malocclusions and compare them; (3) compare the amount of overbite and values for CA and LCRA for different dental malocclusions. Methods: 46 Class I samples, 20 Class III open bite samples and 22 Class III deep bite samples who met the criteria were examined using x-rays. Results: A strong correlation was found between CA and LCRA for all samples. The mean CA and LCRA for the Class III deep bite group was significantly different from the Class I normal core, Class I expanded and Class III open bite groups. There was no significant correlation between CA or LCRA and overbite within Class III open and Class III deep bite groups. Conclusions: LCRA and CA were highly correlated in Class III patients. Patients with Class III deep bites had statistically higher average CA and LCRA compared to Class I normal occlusions and Class III open bite malocclusions. There was no significant correlation between the measures for overbite and either CA or LCRA values in Class III patients. This information will help orthodontists identify and better treat patients with higher CA and LCRA values. We recommend LCRA as a better method of measuring the crown-root angle.

Keywords

publicabstract, Cephalometrics, Orthodontics, Tooth Anatomy

Pages

viii, 48

Bibliography

47-48

Copyright

Copyright 2015 Jessica Kay Fuller

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