TL;DR
In extraction cases, patients treated with CAs demonstrated a larger AW and greater lingual inclination of the anterior teeth than those treated with FAs, which may have implications for space management during treatment.
Asymmetric dental expansion is a preliminary goal in the treatment of a true unilateral crossbite (CB). The aim of this study was to investigate transverse dental changes following modified asymmetric rapid palatal expansion (ARPE) based on cone-beam computed tomography (CBCT) records. The dataset consisted of CBCT records obtained before and after treatment with a modified ARPE appliance in patients presenting with unilateral skeletal posterior CB and class I skeletal relationship. Eighteen linear and four angular measurements were analyzed based on CBCT images. The Shapiro–Wilk test, paired-samples t-test and Wilcoxon signed-rank test were used for statistical analyses. Maxillary interdental widths showed significant increments on both sides (p < 0.05). Maxillary posterior dental expansion was greater on the CB side compared to the non-crossbite (NCB) side. A significant increase was detected in the mandibular inter-first premolar width (p < 0.05). In addition, the inter-side difference in maxillary first molar inclination between the NCB and CB sides was also significant (p < 0.05). Modified ARPE may be beneficial for treatment of a unilateral CB.
The findings can help clinicians better understand the planning of space opening for PMLIs before clear aligner therapy commences and provide baseline information for future research.
Objective To compare the alignment efficiency, arch dimensional changes, and passive extraction space closure between between self‐ligating brackets (SLBs) and conventional brackets (CBs). Materials and Methods This randomized controlled trial on 70 participants (13–30 years) with moderate to severe crowding, skeletal Class I or mild to moderate Class II malocclusions, all requiring premolar extractions, who were randomly assigned to CB (n = 35) or SLB (n = 35) groups. Baseline age, gender, crowding, and malocclusion type were recorded. Standardized 0.022‐inch MBT brackets were bonded, with alignment started using 0.014‐inch nickel‐titanium (NiTi) archwires and monthly follow‐ups. Outcomes—Little’s Irregularity Index, intercanine and intermolar widths, and passive extraction space closure—were measured on blinded casts at baseline, 3, 6, and 9 months using digital calipers, with no active space‐closing auxiliaries. Data were analyzed using linear mixed‐effects models with repeated measures and covariates; regression coefficients with 95% CIs were reported, and p ≤ 0.05 was considered significant. Results Over the 9‐month observation period, both groups showed substantial improvement in alignment. SLBs demonstrated faster early alignment, with greater reductions in Little’s Irregularity Index at 3 months in both arches (maxilla: β = −0.91, p < 0.001; mandible: β = −0.60, p = 0.009), and in the maxilla at 6 months (β = −0.66, p = 0.005). Intercanine width increased in both groups, but expansion was consistently smaller with SLBs (β = −1.36 to −1.69 mm; all p < 0.001). In contrast, intermolar width was greater with SLBs throughout follow‐up in both arches (maxilla: β = 2.34–2.77 mm; mandible: β = 2.06–2.34 mm; all p < 0.001). Passive extraction space closure decreased significantly over time in both groups, with no significant effect of bracket type. Conclusion SLBs showed smaller increases in intercanine width, greater intermolar expansion, and faster early alignment. However, passive space closure was similar between groups. Differences were modest and may have limited clinical significance. Trial Registration: Retrospectively registered at ClinicalTrials.gov (NCT07503314)