The Immediate Response of Craniofacial Structures and Soft Tissue Periodontium to the 2-Hinged Expander Activated by...

Background/Objectives: This study aimed to evaluate the immediate effects of a 2-hinged expander activated with the alternate rapid maxillary expansion-constriction (Alt-RAMEC) protocol on craniofacial structures and the soft tissue periodontium in adolescents with skeletal Class III malocclusion characterized by maxillary retrusion. Methods: Lateral cephalograms obtained at baseline (T0) and immediately after treatment (T1) from 15 adolescents (6 females, 9 males; mean ages 12.6-13.1 years) treated with a 2-hinged expander using a 9-week Alt-RAMEC protocol were analyzed. A control group consisted of 27 untreated Class III individuals (7 females, 20 males; mean ages 12.5-12.6 years). Sagittal and vertical skeletal, dental, and soft tissue measurements were assessed using a Cartesian coordinate system. Periodontal parameters of supporting teeth were evaluated at T0 and T1. Statistical analysis was performed using the Mann-Whitney U and Wilcoxon tests (p < 0.05). Results: Significant anterior maxillary displacement was observed in the treatment group compared with controls (p < 0.01), accompanied by increases in overjet and Wits appraisal (p < 0.05), while mandibular position remained unchanged. The upper lip advanced in accordance with skeletal changes (p < 0.05). Gingival index, bleeding index, and probing pocket depth increased significantly in supporting teeth (p < 0.05), whereas plaque index remained stable (p > 0.05). Conclusions: The 2-hinged expander combined with a 9-week Alt-RAMEC protocol induces immediate skeletal maxillary advancement in growing Class III patients with minimal dental compensation. Short-term periodontal changes suggest a transient inflammatory response associated with appliance therapy.