Early Expansion With Two Removable Appliances: A Randomized Clinical Trial

Objectives: To compare, after two years, dental arch and cephalometric changes in the early mixed dentition of Class I crowded patients treated with two expansion removable appliances. Methods: This is a prospective randomized clinical trial conducted by the Department of Orthodontics at the Universidad El Bosque, Bogota-Colombia, started in 2004. A total of 131 patients between 6 and 10 years old meeting the inclusion criteria were enrolled in the study. 44 were treated with the Frankel's function regulator 1 (FR-1), 46 with Schwarz, and 41 served as the control group. Skeletal changes and dental arch measurements were taken at baseline (T0) and a two year follow-up (T2). Results: Overall skeletal changes at the end of phase 1 were as follows: Changes in variables such as ANB, SN-MP, lower intercanine width and Little's irregularity index were related to normal growth. Decreased upper and lower arch perimeters were associated with the appliances and with normal growth. Statistical significant increments were observed at the upper intermolar and intercanine width in the FR-1 group (p<0.05). The need of a phase 2 (fixed appliances) was similar in all groups. Compliance and adherence was similar in both groups (Compliance: very good (0%), good (43.9%), fair (35.37%), and bad (19.51%). (Adherence: <56% with FR-1 and <36% with Schwarz). Conclusions: At the end of phase 1: There were no differences between the treated groups and the control group. The main difference between the appliances was with the FR-1 in the upper arch where it showed significant transverse increment. Little's irregularity index and lower intercanine width remain unchanged with the appliances. Need of the Phase 2 treatment with fixed appliances were similar in all groups. In general, treatment effects after 2 years with these removable appliances were associated with normal growth rather than with the appliances themselves.