A deficient mandibular growth on the sagittal plane is the most frequent diagnostic finding in dentoskeletal Class II malocclusion. Evidence indicated that functional treatment for such malocclusion is efficient only if performed during the pubertal growth spurt, as identified through radiographical growth indicators. With the aim of reducing the radiation to the patients and to follow longitudinally individual growth phases, the use of the sole third finger middle phalanx maturation (MPM), as a 5-stage method, has been proposed. Herein, three clinical cases of skeletal Class II malocclusion in growing patients treated by removable functional appliances (with or without full-fixed appliance treatment) are reported. Timing of intervention was strictly planned according to the MPM method, and skeletal effects have been recorded up to 21 months of follow-up. In all the cases, noteworthy skeletal effects have been achieved in terms of mandibular elongation, with relevant occlusal and aesthetic outcomes. It has also been showed that results are stable or slightly improved after functional treatment. These results would be achieved irrespective of the appliance used and support the use of the MPM method in everyday clinical practice.