A cephalometric study on the velopharyngeal changes after maxillary protraction

Lee, Nam Ki; Cha, Bong Kuen

Abstract

The purpose of this study was to investigate cephalometrically the short term static velopharyngeal changes in 25 patients (10 boys and 15 girls, aged from 5 years 9 months to 12 years 10 months in the beginning of treatment) with skeletal Class III malocclusions who underwent nonsurgical maxillary protraction therapy with a facemask. The linear, angular and ratio measurements were made on lateral cephalograms. Only the change in hard palatal plane angle was negatively correlated with the change in maxillary depth or N-perp to A (p < 0.01). The change in velar angle showed a statistically significant increase (p < 0.001). This change was influenced more by the soft palatal plane angle than by the hard palatal plane angle (p < 0.001). The changes in soft tissue nasopharyngeal depth and hard tissue nasopharyngeal depth showed statistically significant increases (p < 0.001). Correlations between the changes in soft tissue (or hard tissue) nasopharyngeal depth and the change in soft palatal plane angle were significant (p < 0.05). The increase in hard palate length was statistically significant (p < 0.001). The change in hard palate length was negatively correlated with the change in soft tissue nasopharyngeal depth (p < 0.05). The change in need ratio S (C) showed a statistically significant increase (p < 0.001). But this difference was within the normal range reported by previous studies. These findings indicate that the velopharyngeal competence was maintained even if the anatomical condition of the static velopharyngeal area were changed after maxillary protraction.