The effect of two types of functional appliance on soft tissue profile: a randomized clinical trial

Aim: The objective of this study was to compare and evaluate the effects of two functional appliances including modified activator and modified twin block appliances on the profiles of facial soft tissue.
This study included 30 patients suffering from skeletal class II abnormalities. Participants were randomly allocated into one of two treatment groups for functional appliances, the modified twin block group and the modified activator group (ten girls and five boys, with a mean age of 10.4± 0.82 years in the modified twin block group; nine girls and six boys, with a mean age of 9.8± 0.94 years in the modified activator group). The mean duration of treatment was 20.4± 6 months in the modified activator group, and 17.9 ± 5 months in the modified twin block group which included the eight months of aftertreatment maintenance. Data were analyzed using a paired t-test and an independent samples t-test.
In the modified activator treatment group, changes in the labiomental angle (p=0.02), the angle of facial convexity (p=0.004), the Ls-S vertical (p=0.034), the distance between the labial surface of the upper central incisor and the upper lip (p=0.012), the Li-E Line (p=0.029), the total anterior facial height (p=0.008) and the pog’-S vertical (p=0.013) were significant. The difference between two groups was significant only in Li-E line.
The effects of modified activators and modified twin block appliances on the soft tissue profile was almost the same, and both resulted in significant alterations to the soft tissue profile.