INTERVENTION
overbite, overjet, Fatigue
ROTH
Clinical management in Group PE included extraction of maxillary first premolars and mandibular second premolars. Since subjects had varying pretreatment molar relationship, extractions were carried out in the mandibular arch in order to achieve similar molar relation bilaterally at the end of the treatment. The 0.018 x 0.028-in slot brackets (Roth prescription) were bonded, and levelling and alignment was carried out using 0.016-in nickel-titanium (NiTi) archwire, followed by 0.016 x 0.022-in NiTi. Working archwire (0.016 x 0.022-in stainless steel) was left In Group FF, similar bracket prescription was used and working archwire was 0.017 x 0.025-in stainless steel. Forsus™ (Fatigue Resistant Device, L-pin Spring Module, 3M), a fixed functional appliance, was used during the functional phase. The appliance selection and stepwise activation using 1.5-mm split rings was done according to the manufacturer’s instructions. Whenever more than one split ring was required for activation, the next size push rod was used. Average duration of the functional phase was 6.95±1.53 months. Functional phase continued until bilateral Class I molar and canine relation, optimized overbite and overjet were achieved. Following, non-activated appliance (i.e. spring module not compressed by the push rod as the patient bites down) was left All the subjects were scheduled every three weeks during the course of treatment. Post-debonding, patients were followed periodically during retention. 