Three dimensional evaluation of the effect of rapid maxillary expansion on maxillary sinus volume.

Aim: To compare the maxillary sinus volume (MSV) of posterior cross bite (PCB) patients before and after rapid maxillary expansion (RME) by cone-beam computed tomography (CBCT).

Methods: A total of 24 patients' CBCT scans that underwent RME therapy for their orthodontic treatment were used. CBCTs were obtained before (T1), immediately after (T2), and 6 months after (T3) RME. MSVs were calculated by using the 3D module of Dolphin 11.0 software. Repeated measures ANOVA (RMANOVA) was used to identify the MSV differences.

Results: The results showed no significant differences between the right and left MSVs of the T1 group (p>.05). No significant differences were found between the right and left side MSV of the T2 group (p>.05). There were no significant differences between the right and left side MSV of the T3 group (p>.05). According to the intergroup comparisons, the RMANOVA test results revealed statistically significant right (F = 459.37, p<.001), left (F = 409.34, p<.001), and mean (F = 489.33, p<.001) MSV differences between groups. Multiple comparisons of the right, left, and mean MSV between the T1 and T2, T2 and T3, and T1 and T3 groups with Bonferroni's test revealed no significant differences between the T1 and T2 (p>.05) and T2 and T3 (p>.05) groups. However, significant differences were found in the right (p<.05), left (p<.05), and mean (p<.05) MSV between the T1 and T3 groups. The right, left, and mean MSV of the T3 group were significantly higher than those of the T1 group.

Conclusion: No significant change was detected in the MSV immediately after RME. However, MSV was significantly increased at the end of the retention period.