Does Modifying a Palatal Expander with a Lingual Acrylic Block Create Asymmetric Dental Expansion? A Retrospective Study

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.