Comparison of Equivalency of Volumetric Expansion Between Nasopharynx and Oropharynx in Patients with Class II Malocclusion Subjected to Rapid Maxillary Expansion using Cone Beam Computed Tomography – A Prospective Study.

Abstract

Objective: The purpose of this study is to analyse the change in the total volume of the oropharynx and nasopharynx after the maxillary expansion done with HYRAX (Hygienic Rapid Expander) and its proportionality with each other. Materials and method: 20 patients were selected for the study. Midline diastema, intermolar width, the volumetric change in the nasopharyngeal and oropharyngeal airway, and McNamara Airway analysis to measure the airway was measured on CBCT Scans before and after expansion. We have evaluated some angular measurements such as saddle angle, articular angle and the gonial angle to evaluate changes in the position of the mandible. Results: Results of paired t-test showed the volume of the nasopharynx has increased with a mean of -3.0200±1.46; p-value =0.001. The volume of the oropharynx has increased with a mean of -7.7600±5.082; p-value =0.001. Increase in the nasal width with mean of -2.0800±0.71642; p-value =0.001. Increase in the intermolar width mean of -4.86000±1.694; p-value = 0.001. McNamara analysis done for upper and lower pharyngeal airways with mean = -1.80100±0.713 p-value = 0.001, mean = -2.37000±0.857 p-value = 0.001 for upper and lower pharyngeal airway respectively. The saddle angle shows a significant reduction with the mean= 3.1000±2.22 p-value=0.001. Articular angle shows an increase (p=0.001) with a mean difference of 3.500±2.60. The Gonial angle decreased with the mean difference=2.40±1.3 p= 0.001. Conclusion: Use of RME results in increase in the volume of oropharynx and nasopharynx, nasal cavity width and the intermolar width which was statistically significant too.