Three-dimensional changes of the zygomaticomaxillary complex after mini-implant assisted rapid maxillary expansion

Kyeong-Tae Song; Jae Hyun Park; Won Moon; Jong-Moon Chae; Kyung-Hwa Kang

doi:10.1016/j.ajodo.2018.11.019

Three-dimensional changes of the zygomaticomaxillary complex after mini-implant assisted rapid maxillary expansion

Am J Orthod Dentofacial Orthop. 2019 Nov;156(5):653-662. doi: 10.1016/j.ajodo.2018.11.019.

Authors

Kyeong-Tae Song¹, Jae Hyun Park², Won Moon³, Jong-Moon Chae⁴, Kyung-Hwa Kang⁵

Affiliations

¹ Resident, Department of Orthodontics, School of Dentistry, University of Wonkwang, Iksan, South Korea.
² Professor and chair, Postgraduate Orthodontic Program, Arizona School of Dentistry & Oral Health, A.T. Still University, Mesa, Ariz; International Scholar, Graduate School of Dentistry, Kyung Hee University, Seoul, South Korea.
³ Associate professor, Center for Health Sciences, Section of Orthodontics, School of Dentistry, University of California, Los Angeles, Calif.
⁴ Professor, Department of Orthodontics, School of Dentistry, University of Wonkwang, Wonkwang Dental Research Institute, Iksan, South Korea; Visiting Scholar, Postgraduate Orthodontic Program, Arizona School of Dentistry and Oral Health, A.T. Still University, Mesa, Ariz.
⁵ Professor, Department of Orthodontics, School of Dentistry, University of Wonkwang, Wonkwang Dental Research Institute, Iksan, South Korea. Electronic address: pigtail@wonkwang.ac.kr.

PMID: 31677674
DOI: 10.1016/j.ajodo.2018.11.019

Abstract

Introduction: The aim of this study was to investigate 3-dimensional changes of the zygomaticomaxillary complex (ZMC) after mini-implant assisted rapid maxillary expansion (MARME).

Methods: A total of 15 pairs of cone-beam computed tomography 3-dimensional images taken before expansion (T0) and after expansion (T1) were analyzed by measuring changes in the coordinates of the landmarks of the ZMC.

Results: Changes in the x coordinates of the landmarks showed significant expansion (P <0.01) and greater expansion at the lower than upper portion of the ZMC (P <0.05) in the transverse dimension. All y coordinates of the landmarks except the jugal point (J) showed forward displacement (P <0.05), and the z coordinates of ANS, PNS, Alare, A, and ectocanine showed downward displacement (P <0.01) in the sagittal and vertical dimensions. Also, z coordinates of the landmarks that were closer to the midsagittal plane and in a more posterior portion of the ZMC displaced further downward (P <0.05). SNA and ANB angles increased (P <0.05 and P <0.001, respectively) and the SNB angle decreased (P <0.01). There was a significant correlation between changes in the x coordinates of the ectomolare and ectocanine and the amount of expansion measured from the center of resistance of the maxillary first molars (CR6; P <0.05). There was no significant correlation between the amount of CR6 expansion and changes in y and z coordinates of the landmarks.

Conclusions: 3-Dimensional changes of the ZMC after MARME showed expansion in a pyramidal shape from the coronal view, downward and forward displacement from the sagittal view, and parallel palatal expansion from the axial view. These findings might be useful for understanding skeletal expansion patterns using MARME.

MeSH terms

Cephalometry
Cone-Beam Computed Tomography
Humans
Imaging, Three-Dimensional
Maxilla* / diagnostic imaging
Palatal Expansion Technique*
Vertical Dimension