Effects of maxillary expansion rate on the nasopharyngeal airway in the mixed dentition

Objective: To evaluate the effects of maxillary expansion rate on nasopharyngeal airway in the mixed dentition period. Materials and Methods: Three groups of the patients were individually treated with semi-rapid maxillary expansion (SRME), rapid maxillary expansion (RME), and removable appliance without expansion (control group). Mean age values were 8.63 ΁ 1.09 years for the SRME group (18 patients: 11 girls and 7 boys), 8.78 ΁ 1.21 years for the RME group (17 patients: 11 girls and 6 boys), and 10.5 ΁ 1.01 years for the control group (16 patients: 6 girls and 10 boys). Screw activation was conducted two-quarter turns per day during the treatment in RME group. Same activation order was used for SRME group for the first week, followed by one-quarter turn every 2 days. Intragroup comparisons were evaluated by paired samples t -test and intergroup changes were analyzed with an analysis of variance (ANOVA). Post-hoc multiple comparisons were done by Tukey's Honestly Significance Difference (HSD) test. Results: For both SRME and RME groups, changes in aerial and total airway measurements were statistically significant when compared to the control group (SRME vs. control: P = 0.049 in aerial, P = 0.038 total airway; RME vs. control: P = 0.048 in aerial, P = 0.011 total airway). When both treatment groups were compared, no statistically significant differences were found in any of the measurements. Conclusions: SRME and RME had significant effects on craniofacial airway dimensions when compared to initial values or untreated control values. Changes in airway dimension were similar in the SRME and RME groups.