Date of Award



Department of Orthodontics

First Advisor

Heesoo Oh

First Committee Member

Audrey Yoon

Second Committee Member

Joorok Park


Introduction: The aim of this study was to determine the types and prevalence of complications following MARPE protocol at University of the Pacific and to investigate the complication of asymmetry using CBCT analysis. Methods: In the first portion of this study, 97 patients who started treatment prior to July 2020 and who had MARPE expander treatment at the University of the Pacific were included. Chart review and evaluation of progress clinical photographs were used to report the following complications: inflammation, pain, appliance malfunction, broken microscrew, and pulpitis. In the second portion of this study, 77 patients from a private practice orthodontist who started treatment prior to January 2021 were included in this study. The complication of asymmetry was measured using CBCT measurements from T1 (prior to treatment start) and T2 (immediately following MARPE expansion). The change in U6 molar angulation changes was also assessed. Results: It was determined in the first portion of this study that the most common complication was inflammation around the MARPE site, with 82% of the study population exhibiting any severity of inflammation. 3 patients exhibited severe inflammation requiring removal of MARPE. 18% reported pain in the MARPE area. 9 patients exhibited appliance malfunction, 1 patient exhibited broken microscrew, and 1 patient exhibited pulpitis. It was determined in the second portion of this study that 47% of patients exhibited asymmetry greater than 1 mm and the average asymmetry at ANS was 1.47 mm. No correlation was exhibited between amount of asymmetric expansion and the following measures: age, molar inclination, palatal thickness, posterior screw expansion and palatal vault height. 3 Conclusions: Inflammation of the MARPE is the most common complication that can result in early removal of the expander. Other complications such as asymmetry and pain are common as well.

Journal Publication

This thesis has been published as a journal article here:

Audrey Yoon, Jacqui Payne, Heeyeon Suh, Linda Phi, Angela Chan, and Heesoo Oh. (2022) A retrospective analysis of the complications associated with miniscrew-assisted rapid palatal expansion. AJO-DO Clinical Companion, 2(5), pp 423-430.