Objective: To evaluate changes in pharyngeal airway dimensions after treatment of Skeletal Class II with mandibular retrognathia using Twinblock functional appliance compared to Skeletal Class II untreated subjects.
Materials and Methods: 24 skeletal Class II patients with an age range 9-12 years old were selected from the outpatient clinic of the Department of Orthodontics, Cairo University.
The patients were divided into two groups: a control group of untreated individuals (Group 1-Control, n=12) and a functional appliance group (Group 2-TwinBlock, n=12). Digital lateral cephalograms were made at the beginning (T1) and at the end of the observational period (T2) for Group 1 and at the end of the twinblock active treatment period for Group 2. Treatment duration in both groups was 7.5 months. Angular and linear lateral cephalometric measurements were done to identify skeletal relationship (SNA, SNB, ANB and Witts appraisal) as well as the widths of the upper and lower pharyngeal airways at T1 and T2 (Nasopharynx, oropharynx and hypopharynx). The data was evaluated and compared using Paired t-test and Independent sample t-test.
Results: The mean ages for Groups 1 and 2 were 10.53 ± 1.32 and 10.89 ± 1.17 years respectively. At T1, there were no statistically significant differences between the skeletal measurements and pharyngeal airway dimensions between the two study groups (p >0.05). However, at T2, statistically significant differences were observed between Groups 1 and 2 (p 0.05).
Conclusions: Twinblock is effective in increasing the sagittal dimensions of the pharyngeal airway. Hence, this appliance can be useful in improving the respiratory function of growing individuals with reduced airway size due to mandibular deficiency.