The Skeletal Effects to the Maxilla after Rapid Maxillary Expansion using CBCT
The purpose of this study was to use cone beam computed tomography (CBCT) to quantitatively evaluate and compare skeletal expansion and alveolar tipping of the maxilla at the maxillary canine (Cl), first premolar (PI), second premolar (P2) and first molar (Ml) after rapid maxillary expansion (RME). Transverse effects to the maxillary suture, nasal width and maxillary sinus were also assessed. Included in the study were thirty consecutive patients (17 males and 13 females; mean age = 13.8 + 1.7 years) requiring RME using Hyrax appliances as part of their comprehensive orthodontic treatment. The pre-RME and post-RME measurements of palatal and buccal maxillary widths (PMW and BMW), palatal alveolar angle (PAA), nasal width (NW), nasal floor width (NEW), and maxillary sinus width (MSW) at Cl, PI, P2 and Ml were compared using Wilcoxon signed-rank, Kruskall-Wallis and Wilcoxon rank sum tests at the significant level of a = .05. To evaluate the level of association, Pearson correlation analyses were performed (a = .05). The results of this study suggest that skeletal expansion of the maxilla exhibits a triangular pattern with the wide base in the anterior, accounting for 55% of total expansion at PI, 45% at P2, and 38% at Ml. An additional alveolar bending/tipping component accounts for 6% of total expansion at PI, 9% at P2, and 13% at Ml. The remaining orthodontic (dental tipping) portion of total expansion is 39% at PI, 46% at P2, and 49% at Ml. RME also produces a statistically significant increase in nasal width and decrease in maxillary sinus width (p < .0001). Retention time showed a significant negative correlation to the change in palatal maxillary width at Cl, P2 and Ml (p < .05), rate of appliance expansion only displayed a significant correlation with palatal maxillary expansion at PI and P2 (p < .05), and age exhibited no statistically significant association with any parameters (p > .05).
Other Dentistry, Palatial Expansion Technique; Cone-Beam Computed Tomography; Maxillary Sinus; Orthodontics, Corrective; Nasal Cavity -- radiography
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