Objective: To evaluate the influence of the rapid maxillary expansion on the natural head position and the upper airway, and to analyze if there is any relationship between the variation of these two variables. Study design: Cephalograms of 34 patients were used. The treatment group comprised 17 subjects and the control group also 17 subjects. The cephalograms were taken before (T0) and after treatment (T1) to evaluate the cranium-cervical and the upper airway measurements. Results: There were no significant changes in the cranium-cervical angles after the rapid maxillary expansion except for palatal plane/odontoid line (it was 95.4 ± 6.0° for the control group and 98.2 ± 8.2° for the treatment group at T0; and it was 90.1 ± 4.9° for the control group and 95.8 ± 7.4° for the treatment group at T1). However, there was no association between these changes and the rapid maxillary expansion. There was an increment in the upper airway for the treatment group (this distance was 11.2 ± 3.4 mm at T0, while it was 13.9 ± 2.4 mm at T1). A variation could be also found in the control group (the average was 13.0 ± 4.9 mm at T0 and 13.1 ± 4.7 mm at T1). There was no correlation between the variation in the craniocervical measures and the changes in the upper airway. Conclusions: There is not any change in the natural head position after the rapid maxillary expansion, but there is an increment in the upper airway.
(Rev Esp Ortod. 2015;45(3):136-141)