The effect of rapid maxillary expansion on nasal airway resistance.

The purpose of this investigation was to provide quantitative data describing the effects of rapid palatal expansion on nasal airway resistance. Rapid palatal expansion is an orthodontic procedure which is commonly used to widen the maxilla to correct maxillary narrowing resulting in the orthodontic abnormality of crossbite and to provide more space for alignment of crowded teeth. Recordings of nasal airway resistance were taken prior to expansion, immediately after expansion (approximately one month), after a retention period of approximately 4 months and approximately one year after initiation of treatment. Findings indicate an average reduction in nasal airway resistance of 48.7 per cent which was statistically significant at the 0.005 level. The reduction also appeared stable throughout the post treatment observation period (maximum one year) as each series of readings was statistically significantly lower than the initial reading, but not significantly different from each other. Reduction of nasal airway resistance was highly correlated to the initial nasal resistance level prior to rapid maxillary expansion. Those individuals with the greater initial resistance tended to have greater reductions in airway resistance following the expansion.