Dentoskeletal outcomes of a rapid maxillary expander with differential opening in patients with bilateral cleft lip and palate: A prospective clinical trial

Abstract

Introduction: The purpose of this 2-arm parallel study was to evaluate the dentoskeletal effects of rapid maxillary expansion with differential opening (EDO) compared with the hyrax expander in patients with complete bilateral cleft lip and palate.

Methods: A sample of patients with complete bilateral cleft lip and palate was prospectively and consecutively recruited. Eligibility criteria included participants in the mixed dentition with lip and palate repair performed during early childhood and maxillary arch constriction with a need for maxillary expansion before the alveolar bone graft procedure. The participants were consecutively divided into 2 study groups. The experimental and control groups comprised patients treated with rapid maxillary expansion using EDO and the hyrax expander, respectively. Cone-beam computed tomography examinations and digital dental models of the maxillary dental arches were obtained before expansion and 6 months postexpansion. Standardized cone-beam computed tomography coronal sections were used for measuring maxillary transverse dimensions and posterior tooth inclinations. Digital dental models were used for assessing maxillary dental arch widths, arch perimeters, arch lengths, palatal depths, and posterior tooth inclinations. Blinding was used only during outcome assessment. The chi-square test was used to compare the sex ratios between groups (P <0.05). Intergroup comparisons were performed using independent t tests with the Bonferroni correction for multiple tests.

Results: Fifty patients were recruited and analyzed in their respective groups. The experimental group comprised 25 patients (mean age, 8.8 years), and the control group comprised 25 patients (mean age, 8.6 years). No intergroup significant differences were found for age, sex ratio, and dentoskeletal variables before expansion. No significant differences were found between the EDO and the hyrax expander groups regarding skeletal changes. The EDO promoted significantly greater increases of intercanine width (difference, 3.63 mm) and smaller increases in canine buccal tipping than the conventional hyrax expander. No serious harm was observed other than transitory variable pressure sensations on the maxillary alveolar process in both groups.

Conclusions: The EDO produced skeletal changes similar to the conventional hyrax expander. The differential expander is an adequate alternative to conventional rapid maxillary expanders when there is need for greater expansion in the maxillary dental arch anterior region.

Registration: This trial was not registered.

Protocol: The protocol was not published before trial commencement.

Funding: This study received financial support from FAPESP (process number 2009/17622-9). As a possible conflict of interest, a patent with an EDO was submitted in March 2011 to the National Institute of Industry Property and is still in process. However, we believe that this is a natural step of translational research (bench-to-bedside), and we guarantee that the scientific results are true.

Copyright © 2016 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.

Figures

Fig. 1

The EDO: A, preexpansion; B, postexpansion.

Fig. 2

A, CBCT transversal dimensions in the molar region; B, maxillary permanent first molar inclination. NCW, Nasal cavity width: width of the nasal cavity measured at the level of the intersection between the nasal cavity and the maxillary sinus floor; when the right and left intersections were not leveled, and only the right side was used as the reference for a measurement parallel to the horizontal plane. MxW, Maxillary width: maxillary width at the level of the hard palate. CW, Cleft width was measured from the right cleft border to the left cleft border parallel to the horizontal plane. ACW, Alveolar crest width: maxillary width at the level of the interpalatal alveolar crest. AW, Arch width: dental arch width measured at the level of the palatal cusp points. I, Tooth Inclination: the angle between lines passing through the buccal and lingual cusp tips of the first molars.

Fig. 3

Digital dental model measurements: A, maxillary arch widths were measured at the cervical level of the deciduous canines (C3-3), deciduous first molars or first premolars (C4-4), deciduous second molars or second premolars (C5-5), and permanent first molars (C6-6); B, arch perimeter was measured in 4 segments from the mesial aspect of the right permanent first molar to the mesial surface of the contralateral tooth; C, arch length was measured from the incisive papilla to the mesial aspect of the permanent first molars in the horizontal plane; D, palatal depth was measured from a line passing through the mesial gingival papilla of the permanent first molars to the deepest point on the palate, perpendicular to the line representing arch length.

Fig. 4

Posterior tooth inclination measurements between the crown long axis and the occlusal plane. The occlusal plane was defined as a plane passing bilaterally through the mesiobuccal cusp tip of the maxillary first molars and the mesioincisal point of the left central incisor. A–F, On a buccal view of each posterior tooth, the arrows was mesiodistally manipulated to represent tooth angulation (A, C, and E), according to facial axis point of Andrews. On the mesial view of each tooth, the arrow was buccolingually manipulated, representing crown torque (B, D, and F) according to Andrews. The variable was expressed as the external angle. After expansion, increasing values of the angle meant buccal inclination of the teeth.

Fig. 5

CONSORT diagram showing patient flow during the trial.

Fig. 6

Dispersion chart for all CBCT repeated measurements (Bland-Altman test).

Fig. 7

Dispersion chart for all repeated measurements on the digital dental models (Bland-Altman test).