Objectives

To compare, using cone-beam computed tomography, the dentoskeletal changes in rapid maxillary expansion with tooth-bone-borne (Hybrid Hyrax) and tooth-borne (Hyrax) appliances.

Setting and sample population

Forty-two patients who met the eligibility criteria (aged 11-14 years; transverse maxillary deficiency, posterior crossbite, and presence of upper first premolars and molars) were screened and allocated into two groups: HHG (treatment with Hybrid Hyrax); and HG (treatment with Hyrax).

Main outcome measures

The primary outcomes included nasomaxillary dimensional changes. CBCT was performed before and 3 months after the activation phase. Measurements were performed using Dolphin®. Baseline data were compared using one-way ANOVA. For intergroup comparison, ANCOVA was used to analyze the initial age, appliance activations (mm), and mid-palatal suture maturation data as covariates. Statistical significance was set at 5%.

Results

The premolar region in HHG showed increased skeletal changes than in HG, with the difference being 1.5 mm (0.5; 2.6) in the nasal cavity (p=0.004), 1.4 mm (0.3; 2.5) in the nasal floor (p=0.019), and 1.1 mm (0.2; 2.1) in the maxilla (p=0.022). The molar region in HHG showed increased skeletal changes with the difference being 0.9 mm (0.2; 1.5) in the nasal cavity (p=0.005), and 0.9 mm (0; 1.8) in the maxilla (p=0.042) than in HG. Premolar inclination was higher in HG.

Conclusion

Hybrid Hyrax showed more skeletal changes and fewer dental side effects, especially in the first premolar region. The amount of activation influenced the higher nasal skeletal changes in the Hybrid hyrax group.