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 < .05) and group IV (P < .001) subjects. Soft palate thickness in group IV subjects was increased significantly as compared to group II (P < .05) and group III (P < .01) subjects. The improvement in soft palate inclination in group III and group IV subjects was significant (P < .01). The oropharynx depth was increased significantly in group III (P < .05) and group IV (P < .001) subjects. The depth of the hypopharynx was increased significantly (P < .01) in group IV subjects.

 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.

 Source: The Angel Orthodontists

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