Comparative Evaluation of Twin Block Appliance and Fixed Orthodontic Appliance in Early Class II Malocclusion Treatment: A Randomized Controlled Trial

Abstract

Aims: To compare skeletal, dentoalveolar, and soft tissue changes between Twin block and early fixed orthodontic appliance for class II division 1 malocclusion treatment through a randomized controlled trial.

Materials and methods: Sample and randomization: This study was a randomized controlled trial with a 1:1 allocation ratio in which 40 patients were divided equally into two groups: control and experimental; each group had an equal number of boys and girls. Randomization was achieved using random blocks of 20 patients with allocation concealed in sequentially numbered, opaque, and sealed envelopes. Blinding was only applicable for data analysis of radiographic measurements. Intervention: Twin block appliance was used in the experimental group for 1 year. However, control group was treated with fixed appliance. Inclusion criteria: Skeletal class II division 1 malocclusion with mandibular retrognathism; cephalometric angular measurements: SNA ≥ 82, SNB ≤ 78, ANB ≥ 4; overjet ≥6 mm; and patient in circumpubertal stage cervical vertebral maturation (CVM2 and CVM3). Parameters for evaluation: Cephalometric skeletal, dental, and soft tissue angular and linear measurements were used for evaluation.

Results: SNB increased remarkably by 4° in the Twin block group, but only by 0.68 in the control group. There was a significant decrease in vertical dimensions (SN-GoGn) in the Twin block group compared to control group (p = 0.002). Significant enhancement in the facial profile of the patients was observed.

Conclusions: The Twin block appliance induced significant skeletal and dental changes. These changes were more obvious relative to the slight changes induced by natural growth.

Clinical significance: Early treatment of Class II due to mandibular retrusion with Twin block functional appliance is recommended due to its favourable skeletal effect. Early treatment with fixed appliance affects mainly the dentoalveolar component. Long term follow-up is needed for further insights.

Keywords: Mandibular retrusion; Skeletal class II Twin block..