Longitudinal stability of rapid and slow maxillary expansion

Abstract

OBJECTIVE: The aim of this retrospective study was to compare the longitudinal stability of two types of posterior crossbite correction: rapid maxillary expansion (RME) and slow maxillary expansion (SME). METHODS: Study casts of 90 adolescent patients were assessed for interdental width changes at three different periods: pretreatment (T1), post-treatment (T2) and at least, five years post-retention (T3). Three groups of 30 patients were established according to the treatment received to correct posterior crossbite: Group A (RME), group B (SME) and group C (control- Edgewise therapy only). After crossbite correction, all patients received fixed edgewise orthodontic appliances. Paired t-tests and one-way ANOVA were used to identify significant intra and intergroup changes, respectively (P < 0.05). RESULTS: Except for intercanine distance, all widths increased in groups A and B from T1 to T2. In the long-term, the amount of relapse was not different for groups A and B, except for 3-3 widths which showed greater decrease in group A. However, the percentage of clinically relapsed cases of posterior crossbite was similar for rapid and slow maxillary expansion. CONCLUSION: Rapid and slow maxillary expansion showed similar stability in the long-term.

Midpalatal Suture Density Evaluation after Rapid and Slow Maxillary Expansion with a Low-Dose CT Protocol: A Retrospective Study

“…This result might be explained by the greater variability of the results within the present sample. Slow protocols of expansion showed no significant differences in the skeletal rate of palatal expansion and stability in long-term follow-up, when compared to RME [33], and, according to the results of the present study, no significant differences on the midpalatal suture density. Moreover, a slower expansion rate would prevent the accumulation of large residual forces within the maxillary complex, which may result in the decrease in undesirable concomitant changes in the craniofacial sutures observed during RME [34] which can affect the whole cranio-facial region [35][36][37].…”

Bilateral or Unilateral Cross-Bite Treatment with Nickel Titanium Palatal Expander (NPE-2) in Young Adults

“…These results are comparable to those obtained with other devices that determine a slow expansion with evidence of separation of the median palatine suture radiologically detected in cases from 50% to 80% [21,22,23].…”

Evaluation of opening pattern and bone neoformation at median palatal suture area in patients submitted to surgically assisted rapid maxillary expansion (SARME) through cone beam computed tomography

“…It is worth emphasizing the indispensable role of post-expansion orthodontic retention of the midpalatal suture because at this period both bone neoformation and remodeling take place after disjunction, decreasing relapse possibilities 26 . According to a study which compared the stability between rapid and slow maxillary expansion, the dental arch transverse dimensions showed a more pronounced relapse maintaining approximately 40% of initial molar expansion with significant difference from control 21 . Progel, et al 22 (1992), Berger, et al 4 (1998) and Koudstaal, et al 13 (2005), reported 0.88 mm (12%), 1.01 mm (17.5%) and 0.5 mm (55%) of relapse, respectively, in a 12-month study period.…”