Graduation Date

Fall 12-14-2018

Document Type


Degree Name

Master of Science (MS)


Medical Sciences Interdepartmental Area

First Advisor

Dr. Thyagaseely (Sheela) Premaraj


Purpose: The purpose of this investigation was to evaluate the immediate and long-term effects of palatal expansion on the transverse dimension of the nasomaxillary complex.

Materials and Methods: Twenty-eight patients’ CBCTs were obtained at four time points: pre-expansion (T1), post-expansion (T2), pre-treatment (T3), and middle or end of orthodontic treatment (T4). The patients’ age, sex, cervical vertebral maturation stage, and the number of instructed expander turns were recorded. Measurements of the nasal floor, nasal passage, maxillary sinus, maxillary first molar mesiolingual cusp, maxillary first molar palatal cusp, maxillary first molar buccal cortical bone, maxillary first molar palatal cortical bone, interorbital, and extraorbital widths were recorded.

Results: During expansion, all parameters except interorbital and extraorbital widths increased significantly. Post-expansion, most parameters continued to increase, with only the cusp tip width decreasing significantly. There were no significant differences between males and females except nasal floor, nasal passage, and interorbital widths during expansion (T1 to T2). Pre-expansion growth status did not influence changes except the extraorbital width during orthodontic treatment (T3 to T4).

Conclusions: Palatal expansion significantly changed the transverse width of nasomaxillary complex. Long-term retention showed all parameters except maxillary molar cusp and maxillary molar buccal cortical bone widths continued to increase to the T4 time point, likely due to the patients’ growth overcoming any relapse occurring.