Immediate and Post-Retention Effects of Rapid Maxillary Expansion Investigated by Computed Tomography in Growing Patients

Abstract

Objective: To determine by low-dose computed tomography (CT) protocol the dental and periodontal effects of rapid maxillary expansion (RME). Materials and Methods: The sample comprised 17 subjects (7 males and 10 females), with a mean age at first observation of 11.2 years. Each patient underwent expansion of 7 mm. Multislice CT scans were taken before rapid palatal expansion (T0), at the end of the active expansion phase (T1), and after a retention period of 6 months (T2). On scanned images, measurements were performed at the dental and periodontal levels. Mean differences between measurements at T0, T1, and T2 were examined through analysis of variance (ANOVA) for repeated measures with post-hoc tests. Results: All interdental transverse measurements were significantly increased at both T1 and T2 with respect to T0. In the evaluation of T0-T1 changes, periodontal measurements were significant on the buccal aspect of banded teeth with a reduction in alveolar bone thickness corresponding to the mesial (−0.5 mm; P < .05) and distal (−0.4 mm; P < .05) roots of the right first molar and to the mesial root of the left first molar (−0.3 mm; P < .05). In the evaluation of overall T0-T2 changes, the lingual bone plate thickness of both first molars was found to be significantly increased (+0.6 mm; P < .05). Conclusions: RME therapy induces a significant increase in the transverse dimension of the maxillary arch in growing subjects without causing permanent injury to the periodontal bony support of anchoring teeth discernible on CT imaging.

CBCT of skeletal changes following rapid maxillary expansion to increase arch-length with a development-dependent bonded or banded appliance

“…This amount of expansion (Table 1) is similar to previous CBCT reports of a 3.6-mm increase 36 and 4.8 mm 37 of intermolar width. The effect of RME is not limited to the maxillary alveolar process but is also seen on adjacent structures, including the cranial and circummaxillary sutures.…”

“…19,20,33 However, there have been only a few studies that have focused on the effects of RME on craniofacial sutures by evaluating the frontal (coronal) dimension. [34][35][36][37] Overall, the present literature review suggests the bonded appliance is the optimal appliance before the maxillary first premolars (Mx4s) erupt, and the banded expander is more desirable thereafter. The aim of this study is to quantitatively evaluate the efficiency of a standardized activation (5 mm) in a consecutive series of children (6-15 years) treated with a developmentappropriate appliance.…”

Alveolar bone changes after asymmetric rapid maxillary expansion

“…11,18,19 Most studies showed that RME procedures reduce the amount of alveolar bone at different levels. 20,21 Garib et al 10 found a 3.8-mm decrease in the BABH of the first molar and observed that tooth-borne RME appliances decreased bone levels more than did tooth-tissue-borne appliances. To our knowledge, no studies have been published about the buccal alveolar bone effects of asymmetric RME.…”

Treatment and posttreatment skeletal effects of rapid maxillary expansion studied with low-dose computed tomography in growing subjects

“…The low-dose CT scan protocol was described previously. 14 Measurements were made on the scanned images at skeletal levels, according to definitions in previous studies by Sfondrini et al 6 and da Silva Filho et al 9 The transverse dimensions of the maxilla were measured on the axial scans parallel to the palatal plane at the midpalatal suture level.…”