Effectiveness of twin-block and Mandibular Protraction Appliance-IV in the improvement of pharyngeal airway passage dimensions in Class II malocclusion subjects with a retrognathic mandible

摘要

Objective: To test the hypothesis that twin-block and Mandibular Protraction Appliance-IV (MPA-IV) are not effective in improving the pharyngeal airway passage (PAP) dimensions among Class II malocclusion subjects with a retrognathic mandible. Materials and Methods: Eighty-three subjects ranging in age from 8 to 14?years were divided into four groups. Group I included 30 Class I malocclusion subjects (healthy controls); group II consisted of 16 Class II malocclusion subjects (Class II controls); group III had 16 subjects in whom Class II malocclusion was treated by MPA-IV; and the remaining 21 subjects formed group IV, whose Class II malocclusions were corrected by twin-block appliance. Lateral cephalograms recorded at the beginning of orthodontic treatment in group I subjects and at the beginning and end of follow-up/treatment with functional appliance in group II, III, and IV subjects were analyzed to determine the PAP dimensions. Paired t-test, one-way analysis of variance, and Tukey tests were applied for statistical analysis, and a P-value .05 was considered statistically significant. Results: Soft palate length was decreased significantly in group III (P P P P P P P P Conclusions: The twin-block appliance was more efficient than the MPA-IV in the improvement of PAP dimensions among Class II malocclusion subjects with retrognathic mandible.