Postpubertal Assessment of Treatment Timing in Class II Malocclusion Treated with Twin Block Followed by Fixed Appliances: A Retrospective Observational Study.

Objectives: To evaluate the role of treatment timing in the management of Class II malocclusions with mandibular retrusion using Twin Block (TB) followed by fixed appliances (FAs). Methods: Forty-one Caucasian patients (22 females and 19 males) with Class II malocclusion treated consecutively with TB and FA were selected from the Orthodontic Clinic of the Careggi University Hospital, Florence, Italy and from a sample treated by a private practitioner in Auckland, New Zealand. According to the Cervical Vertebral Maturation (CVM) method, the subjects were divided into two groups: an early treated group (ETG) including 21 patients (mean age 10.8 ± 2.1 years) who began treatment before the pubertal growth peak (CS1-CS2), and a late treated group (LTG) including 20 patients (mean age 12.4 ± 1.1 years) treated at the growth peak (CS3-CS4). Cephalometric skeletal, dento-alveolar and soft tissue parameters were evaluated before treatment with TB (T0) and at the mid-term observation (at a postpubertal stage CS4-CS6) after FA (T1). Independent samples t-tests were performed to compare intergroup differences at T0 and T1 while Fisher's exact test was used to assess differences for gender. Results: At T0, the groups showed statistically significant differences in mandibular dimensions, in accordance with the different age distribution. At T1, significant differences between ETG and LTG were observed in Co-Gn (5.0 mm, p = 0.048, 95% Confidence Interval (CI) -9.8 mm; -0.1 mm), Co-Go (3.7, p = 0.009, 95%CI -6.3 mm; -0.9 mm), and Pg'-TVL SN10 (2.7 mm, p = 0.039, 95%CI -5.2 mm; -0.1 mm). Conclusions: Class II treatment with TB and FA confirmed that including the pubertal phase in the functional-orthopedic treatment led to more favorable mandibular growth and chin projection when evaluated at a postpubertal observation.