<abstract xmlns="http://www.w3.org/1999/xhtml">

<sec>
<h3>Background</h3>
<p>To date, no study has determined if rapid followed by slow maxillary expansion (also termed ‘semi-rapid’ expansion) has the same effects on the dentofacial skeleton as rapid maxillary expansion.</p>
</sec>
<sec>
<h3>Objective</h3>
<p>To determine the vertical and sagittal changes in the facial skeleton during and following rapid then slow maxillary expansion (R-SME).</p>
</sec>
<sec>
<h3>Methods</h3>
<p>Bonded maxillary expansion appliances were used to separate the maxillae over six days by activating the midline screws twice a day. The screws were then activated three times a week until sufficient expansion was obtained (Mean: 3.4 months) and used as retainers for six months. Cephalometric measurements at the start of expansion (T1), end of expansion (T2) and end of retention (T3) were compared with paired <italic>t</italic>-tests. Pearson correlation coefficients were used to determine the associations between the expansion (dental and skeletal) and the cephalometric changes.</p>
</sec>
<sec>
<h3>Results</h3>
<p>The maxillae moved forward a small, but statistically significant, extent during expansion. The upper molars were extruded and the mandible ‘rotated’ downward and backward. Although the vertical height of the facial skeleton (SN/GoMe, S-Go, N-Me, ANS-Me) increased significantly during expansion, the changes were small and highly variable. Some dimensions (SN/GoMe) relapsed during retention, while others (S-Go, N-Me) increased.</p>
</sec>
<sec>
<h3>Conclusions</h3>
<p>Rapid then slow maxillary expansion caused a small, but statistically significant, forward movement of the upper facial skeleton, a small downward and backward rotation of the mandible and a small increase in face height. The changes were similar to those found during rapid maxillary expansion.</p>
</sec>
</abstract>

Background
To date, no study has determined if rapid followed by slow maxillary expansion (also termed ‘semi-rapid’ expansion) has the same effects on the dentofacial skeleton as rapid maxillary expansion.


Objective
To determine the vertical and sagittal changes in the facial skeleton during and following rapid then slow maxillary expansion (R-SME).


Methods
Bonded maxillary expansion appliances were used to separate the maxillae over six days by activating the midline screws twice a day. The screws were then activated three times a week until sufficient expansion was obtained (Mean: 3.4 months) and used as retainers for six months. Cephalometric measurements at the start of expansion (T1), end of expansion (T2) and end of retention (T3) were compared with paired t-tests. Pearson correlation coefficients were used to determine the associations between the expansion (dental and skeletal) and the cephalometric changes.


Results
The maxillae moved forward a small, but statistically significant, extent during expansion. The upper molars were extruded and the mandible ‘rotated’ downward and backward. Although the vertical height of the facial skeleton (SN/GoMe, S-Go, N-Me, ANS-Me) increased significantly during expansion, the changes were small and highly variable. Some dimensions (SN/GoMe) relapsed during retention, while others (S-Go, N-Me) increased.


Conclusions
Rapid then slow maxillary expansion caused a small, but statistically significant, forward movement of the upper facial skeleton, a small downward and backward rotation of the mandible and a small increase in face height. The changes were similar to those found during rapid maxillary expansion.

Effects of rapid-slow maxillary expansion on the dentofacial structures

Australasian Orthodontic Journal

This work is licensed under the Creative Commons Attribution 4.0 International License.

{"article-title":"Effects of rapid-slow maxillary expansion on the dentofacial structures"}

Background
To date, no study has determined if rapid followed by slow maxillary expansion (also termed ‘semi-rapid’ expansion) has the same effects on the...

Effects of rapid-slow maxillary expansion on the dentofacial structures

Published Online: Dec 14, 2023

Page range: 178 - 183

Received: Mar 01, 2010

Accepted: Aug 01, 2010

DOI: https://doi.org/10.2478/aoj-2010-0029

© 2010 Nihat Kilic et al., published by Sciendo

This work is licensed under the Creative Commons Attribution 4.0 International License.