Mandibular Response in Class <scp>II</scp> Division 1 Growing Subjects: Clear Aligners vs. Rapid Maxillary Expansion Therapy. A Controlled Pilot Study

ABSTRACT Objectives The present study aimed to evaluate the skeletal and dental changes in two different groups of mixed dentition Class II division 1 patients treated with Clear Aligners and with Rapid Maxillary Expansion and to assess the post‐treatment mandibular response in comparison with an untreated control group. Materials and Method 33 subjects were recruited according to the following inclusion criteria: Caucasian ancestry, early mixed dentition with fully‐erupted first permanent molars, bilateral Class II division 1, posterior transverse interarch discrepancy &lt; 5 mm, CSV1–2, no previous orthodontic treatment/congenitally missing or extracted teeth/craniofacial syndromes. The Aligner Group (AG = 13, 6 males, 7 females, 9.2 ± 0.8 years) was treated with Clear Aligners following a standardized sequential expansion protocol “molars move first” without extractions and other auxiliaries than attachments; the RME group (RG = 10 patients, 5 males, 5 females, 9.6 ± 0.7 years) was treated with RME banded on second primary molars; the Control Group (CG = 10, 6 males, 4 females, 9.6 ± 0.9 years) was followed up for 1 year without treatment. Panoramic radiographs and lateral cephalograms were collected pre‐treatment (T0) and post‐treatment (T1) (T1–T0 = 15.7 ± 1.3 months). The Kruskal–Wallis one‐way test was used for the analysis of variance by ranks at T0 (baseline) and for the changes observed between T0 and T1 ( p &lt; 0.10). Results On the sagittal plane, no significant post‐treatment differences in mandibular response were found between the three analysed groups. On the vertical plane, the CA group showed a statistically significant reduction of SN‐GoMe when compared to the CG ( p = 0.023) and to the RG ( p = 0.067). Conclusions Clear Aligners and RME did not influence the sagittal skeletal relationship in prepubertal Class II division 1 patients treated during early mixed dentition, compared to the untreated control group. On the vertical plane, patients treated with Clear Aligners showed a statistically significant reduction of SN‐GoMe. Clinical Study Registration Number Protocol Number E00176‐2025