Effects On Palatal Surface Area In Mixed Dentition Patients Treated With Leaf Expander And Rapid Palatal Expander, Compared To Untreated Subjects: A Randomised Clinical Trial

Aim: To evaluate palatal surface effects induced by LE and RPE, alongside spontaneous changes in an untreated group, and to compare differences in canine and molar inclination among the three groups. Materials and Methods: This randomised clinical trial aimed to compare digital models pre- and post-treatment over 12 months in patients receiving tooth-borne Leaf Expander® (LE) and tooth-borne Hyrax-type maxillary expander (RPE) treatments, alongside untreated patients. Analysis included 24 LE patients (13 males, 11 females, mean age 8.5±1.5), 22 RPE patients (10 males, 12 females, mean age 7.9±1.6), and 17 untreated subjects (7 males, 10 females, mean age 8.1±1.2). Inclusion criteria comprised indications for maxillary expansion treatment, mixed dentition, CVMS ≤ 3, erupted first molars, and good oral hygiene. Digital models were obtained using an intraoral scanner pre- and post-treatment. Palatal surface, segmented into anterior, median, and posterior zones, and canine/molar inclination were measured at T0-T1 using VAM software as the primary and secondary endpoint. Statistical analyses involved paired-sample T-tests for intra-group comparisons and ANOVA tests with Bonferroni correction for inter-group comparisons. Results: Total surface increment for LE was 155.4 mm² (±49.92mm²); for RPE, it was 187.7 mm² (±58.06 mm²); and for the control group, it was 55.35 mm² (±18.69mm²), significant in all three groups. Statistically significant differences were observed in the anterior, median, and posterior zones, as well as in the total surface increment, between the LE and control groups, and between the RPE and control groups. No significant difference was found between the LE and RPE groups in surface increments. The RPE group exhibited a significant increase in vestibular inclination for molars and canines post-therapy. Conclusions: No significant difference in palatal surface increment was found between the two experimental groups (LE and RPE); both demonstrated a significant increase in palatal surface. The greatest increment occurred in the median palate zone for both experimental groups. The increment in the untreated control group was not significant. Furthermore, the RPE group showed a greater inclination of permanent molars compared to those treated with LE, indicating that expansion with lighter and continuous forces may lead to fewer dental side effects.