Short-term treatment effects of the hybrid functional appliance SOS Activator in children with Class II skeletal discrepancy: A pilot study

In Class II skeletal discrepancies, functional appliances are commonly used for anterior mandibular repositioning. A functional appliance with an alternative design, named SOS Activator, has recently been introduced. This study aims to examine and document the short-term treatment effects of SOS Activator.

Initial and progress cephalometric radiographs of 24 patients treated with the SOS Activator were analyzed. All patients presented a Class II skeletal discrepancy with a retrognathic mandible. The control group comprised cephalometric radiographs of untreated children from the Bolton Growth Study. The radiographs were analyzed using the Miethke cephalometric analysis and the Viewbox 4 Cephalometric Software.

The results showed that patients treated with the SOS Activator, compared to the control group, exhibited a statistically significant increase in the SNB angle (P < 0.001), a decrease in the ANB and NA-APog angles (P < 0.0001, P ≤ 0.001), and a decrease in the Wits appraisal (P = 0.003). The proportion SGo: NMe × 100 was improved (P = 0.014). The Ptv-6s distance decreased, confirming the distalization of the upper first molars (P = 0.007). The soft tissue changes involved a decrease in the H angle (P = 0.017).

The SOS Activator is effective in the correction of Class II skeletal discrepancy by forward repositioning of the mandible. Additionally, due to its alternative design compared to other removable functional appliances, it presents the important advantage of concurrent distalization of the upper first molars and the simultaneous use of fixed appliances, such as braces and/or expansion devices, on the upper arch.