Long term evaluation of Class II correction: A prospective study

Objectives: The purpose of this study was to evaluate the long-term results of the skeletal and dental changes obtained after Class II correction with a Twin Force Bite Corrector (TFBC). Methods: After the initial screening of 155 patients to be treated for their class II div 1 malocclusion, 45 patients with a mean age of 12.01 ± 1.24 years were selected on the basis of pre-set inclusion criteria for treatment with the TFBC appliance. All patients were treated with a Straight-Wire Appliance (0.022-inch slot appliance) under the guidance of two experienced clinicians who followed a well defined treatment protocol. Twenty-one patients were recalled for post retention evaluation from a minimum of 2 years to 7 years after treatment. Cephalograms were taken at three different time points: T1: before orthodontic treatment, T2; at the completion of treatment; and T3: at least 2 years after treatment. Linear and angular measurements were made to determine the skeletal and dental effects. Statistical analyses was performed using dependent analysis of variance (ANOVA). Results: On comparison of the changes between T2 and T1 significant (P˂0.05) restriction of growth of maxilla (SNA = -1.22°) and continued favourable growth of mandible (SNB = +1.01°) and proclination of lower incisors (IMPA = +3.5°) was observed. Comparision of T3 and T2 showed no significant difference in any of the skeletal or dental parameters observed (P > 0.05) except SNB = +1.05° (P˂ 0.05). A significant difference (P˂0.05) was also observed for palatal plane to mandibular plane angle between T2 and T1 (-1.43°) but not significant between T3 and T2 (P > 0.05). Conclusions: Class II correction with the TFBC appliance was achieved by a combination of skeletal and dental effects. The treatment changes appeared to be maintained over the retention period.