Comparison of Skeletal and Dental Changes Obtained from a Tooth-Borne Maxillary Expansion Appliance Compared to the Damon System Assessed through a Digital Volumetric Imaging: A Randomized Clinical Trial.

Hye Jin Nam,Giseon Heo,Paul W Major,Silvia Gianoni-Capenakas,Manuel O Lagravère

doi:10.3390/jcm9103167

Abstract

The purpose of this study was to evaluate and compare dental and skeletal changes associated with the Damon and Rapid Maxillary Expander (RME) expansion using Cone-Beam Computed Tomography (CBCT). Eighty-two patients, from The University of Alberta Orthodontic Clinic, were randomly allocated to either Group A or B. Patients in Group A received orthodontic treatment using the Damon brackets. Patients in Group B received treatment using the Hyrax (a type of RME) appliance. CBCT images were taken two times (baseline and after expansion). The AVIZO software was used to locate 18 landmarks (dental and skeletal) on sagittal, axial, and coronal slices of CBCT images. Comparison between two groups showed that transverse movement of maxillary first molars and premolars was much greater in the Hyrax group. The lateral movements of posterior teeth were associated with buccal tipping of crowns. No clinically significant difference in the vertical or anteroposterior direction between the two groups was noted. Alveolar bone next to root apex of maxillary first premolar and molar teeth showed clinically significant lateral movement in the Hyrax group only. The comparison between two groups showed significantly greater transverse expansion of the first molar and first premolars with buccal tipping in the RME group.

Highlights

A deficiency in maxillary transverse width has considerable implications in orthodontic treatment
Hyrax is one of the most commonly used Rapid Maxillary Expansion (RME) appliances, which has a screw device positioned across a palatal vault, and the device is activated by turning the screw until the desired maxillary expansion is achieved [3]
Comparison between these two treatment groups revealed that most clinically significant changes occurred in the dental landmarks. Skeletal landmarks such as right and left greater palatine foramen showed more lateral movement in the Hyrax group but the values were not clinically significant. This finding agrees with previous studies that treatment effects from the RME device are primarily on the dental structures compared to the skeletal structures [17,18]

Summary

Introduction

A deficiency in maxillary transverse width has considerable implications in orthodontic treatment. Having an inadequate transverse relationship between a maxilla and a mandible can lead to increased cervical wear (abfraction), dental arch crowding, and possible negative effects on patients’ smile esthetics and airways [1,2]. Rapid Maxillary Expansion (RME) is one method to treat narrow maxillary arches by separation of the midpalatal suture. Hyrax is one of the most commonly used RME appliances, which has a screw device positioned across a palatal vault, and the device is activated by turning the screw until the desired maxillary expansion is achieved [3]. Studies have shown side effects associated with the appliance such as active root resorption on the buccal side of the first premolars used for anchorage [4,5]. The device has been reported to expand the upper arch mainly by tipping and extruding the maxillary posterior teeth [6,7,8]

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Conclusion