Treatment Effects of Twin-Block and Mandibular Protraction Appliance-IV in the Correction of Class II Malocclusion

OBJECTIVE: To evaluate the treatment effects of twin-block and Mandibular Protraction Appliance-IV (MPA-IV) in the treatment of Class II division 1 malocclusion. METHODS: Fifty North Indian girls with Class II division 1 malocclusion, in the age range of 9-13 years, were chosen. The subjects were divided among a control group (n = 10), a twin-block group (n = 25), and an MPA group (n = 15). Pre-follow-up and post-follow-up lateral cephalograms of control subjects and pretreatment and posttreatment lateral cephalograms of the treatment subjects were traced manually and subjected to a pitchfork analysis. RESULTS: Neither twin-block nor MPA-IV significantly restricted the forward growth of maxilla. Mandibular growth and improvement in the sagittal skeletal relation were significantly greater in the twin-block subjects. Distal movement of the maxillary dentition and mesial movement of the mandibular dentition were more prominent in the MPA-IV subjects. Molar correction and overjet reductions were significantly greater in the treatment subjects (P < .001). CONCLUSION: Twin-block and MPA-IV were effective in correcting the molar relationships and reducing the overjet in Class II division 1 malocclusion subjects. However, twin-block contributed more skeletal effects than MPA-IV for the correction of Class II malocclusion.