The study aimed to evaluate the dentoskeletal effects of twin block appliance and myobrace system in treating skeletal Class II Division I malocclusions in growing children taking into account the effects of normal growth in an untreated control group. Twenty subjects with Class II Division I malocclusion considered as study group were allocated randomly to two treatment groups of 10 each, consecutively treated with twin block appliances (mean age 10.850 ± 1.37 years) and myobrace system (mean age 10.40 ± 1.89 years). Ten children (mean age 10.60 ± 1.77 years) with untreated Class II Division I malocclusion were considered as a control group to eliminate possible growth effects. At the start of the treatment and end of the observation period of 18–24 months, lateral cephalograms were taken. All the angular and linear parameters measured were subjected to statistical analysis. Twin block group subjects produced more measurable and statistically significant skeletal and dentoalveolar changes at the end of the observation period, demonstrated by correction of full cuspal Class II molar relationship to Class I molar relationship and yielding mandibular growth in increments greater in magnitude than the myobrace system. Meanwhile, the myobrace system-induced favorable dentoalveolar changes by a significant reduction of overjet. The retrognathic profile, however, improved in both the intervention groups as the upper lip protrusion, mentalis strain, and the lower lip curl were eliminated in striking contrast to the untreated control group. The study demonstrates that with appropriate patient selection both myobrace system and twin block appliances can be used in conjunction with the fixed appliance therapy to achieve more stable Class II corrections.
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