Soft tissue profile changes after Twin Block functional appliance therapy in malocclusion Cl II patients using photographs based on NHP

Abstract

Class II malocclusion due to mandibular deficiency is one of the most common malocclusion. The treatment of choice has been functional therapy during growth period of life. By now studies have been based on retrospective cephalometric studies; and there has been a serious controversy among reported studies with respect to dental and skeletal components of the outcomes of treatment. The purpose for this study was to evaluate post treatment soft tissue profile changes on NHP profile photographs, in patients treated with functional appliances. Material and methods: This is a clinical trial performed in Tabriz dental faculty in 2008. The subjects of this study consisted of 25 skeletal class II patients with mandibular deficiency that was treated using a modified Twin Block appliance. All subjects were chosen from a private practice office of the main author. Pre and post-treatment profile photographs were taken in NHP to compare 19 soft tissue measurements, before and after treatment. Data analysis was done using SPSS 16 software and paired T-test to obtain mean values and comparisons of the pre and post-treatment findings. p-values less than 0.05 were considered significant statistically. Results: The estimated values showed a positive influence of 2 degrees reduction in facial convexity, 8 degrees in Z-Merrifield angle, lower jaw protrusion of 4 mm (p=0.001) and soft tissue pogonion protrusion of 3.18 mm (p=0.001) respectively. There was a noticeable reduction in lip in-competency corroborated by an increase in lower lip height estimated as 5.36 mm mean value p=0.001, inter-labial gap mean value reduction of 6.82 mm (p=0.001) and mentolabial angle increase of 10 degrees (p=0.001). Besides all these positive effects, the estimated values for some other landmarks indicated backward changes in the midface and upper lip protrusion. Also, an increase in the nasolabial angle (p=0.001) and a decrease in upper lip sulcus and upper lip (p=0.001) were observed. There was no statistically significant pre and post treatment changes in other estimated facial and nasal variables. Conclusion: Using Twin Block appliance during growth period, cause a clinical positive changes in soft tissue profile of the treated patients. A reduction of facial convexity would be an important outcome along with correction of lip in-competency that would be the result of an increase in the prominence of the soft tissue of the chin, and improvement of the lips lengths and reduction of the inter-labial gap.