Short-term anteroposterior treatment effects of functional appliances and extraoral traction on class II malocclusion. A meta-analysis.

OBJECTIVE To evaluate the anteroposterior short-term skeletal and dental effects on Class II malocclusion in growing patients following treatment with functional appliances (activators or twin block), extraoral traction, or combination appliances (appliances with both functional and extraoral traction components), based on published data. MATERIALS AND METHODS A literature search was carried out identifying a total of nine prospective clinical trials. The data provided in the publications underwent meta-analysis using the random effects model with regard to SNA, SNB, ANB, and overjet. RESULTS All appliance groups showed an improvement in sagittal intermaxillary relationships (decrease in ANB) when compared to untreated subjects. Activators and twin block appliances accomplish this mainly by acting on the mandible (increases in SNB) while twin block appliances also seem to act on the maxilla (decrease in SNA). Extraoral traction appliances achieve this by acting on the maxilla (decreases in SNA). Combination appliances mainly act on the mandible (increase in SNB). Activators, twin block, and combination appliances also reveal a decrease in overjet, which is not the case in the singular use of extraoral traction. CONCLUSIONS Intermaxillary changes being present in all appliance groups, anteroposterior treatment response following the use of functional appliances and/or extraoral traction in growing class II malocclusion patients is most evident in one of the two jaws (mandible for activators and combination appliances and maxilla for extraoral traction) except for the twin block group, which shows changes on both jaws.