Evaluation of the effects of Twin-block appliances in children with skeletal ClassⅡmalocclusion and mandibular retrusion: a randomized controlled study

doi:10.19439/j.sjos.2026.05.008

Abstract

Abstract: PURPOSE: To evaluate the effects of Twin-block appliance in children with skeletal ClassⅡmalocclusion and mandibular retrusion. METHODS: A total of 85 children with skeletal ClassⅡmalocclusion and mandibular retrusion admitted from March 2022 to March 2024 were selected and randomly divided into the straight-wire group (n=42) and the Twin-block group (n=43). The straight-wire group was treated with straight-wire appliance, while the Twin-block group was treated with Twin-block appliance. The clinical efficacy, masticatory function, bite force, mandibular changes, aesthetic outcomes and facial soft tissue profile indices were compared between the two groups. RESULTS: The clinical efficacy of the Twin-block group was significantly higher than that of the straight-wire group (P<0.05). After the treatment, the masticatory function and bite force in the Twin-block group were significantly greater than those in the straight-wire group (P<0.05). The condylar length, mandibular body length, mandibular ramus height and SNB angle in the Twin-block group were significantly greater than those in the straight-wire group (P<0.05). The proportions of favorable anterior overjet/overbite and good posterior occlusion in the Twin-block group were significantly higher than the straight-wire group, while U1-SN and L1-MP angles were significantly lower (P<0.05). The nasolabial angle (NLA) and facial angle of the Twin-block group were significantly higher than those of the straight-wire group, and the Holdaway angle (H angle) was significantly lower than that of the straight-wire group (P<0.05). CONCLUSIONS: Twin-block appliance can effectively improve the masticatory function and bite force, promote the growth of the mandible and the improvement of the sagittal position, and significantly improve the facial soft tissue profile in the treatment of skeletal Class Ⅱ children with mandibular retrusion.

Key words: Twin-block appliance, Skeletal Class Ⅱ malocclusion with mandibular retrusion, Bite force, Mandibular changes

CLC Number:

R783.5

Niu Yirui, Ji Xiaoting, Qi Kun. Evaluation of the effects of Twin-block appliances in children with skeletal ClassⅡmalocclusion and mandibular retrusion: a randomized controlled study[J]. Shanghai Journal of Stomatology, 2026, 35(5): 491-496.

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