Effects of semirapid maxillary expansion on conductive hearing loss

Introduction: Conductive hearing loss is affected by physical changes imposed on the mechanical system of the outer or middle ear. Maxillary expansion can affect conductive hearing loss, and the changes have been investigated with pure-tone audiograms. Semirapid and slow methods of maxillary expansion have some advantages over rapid maxillary expansion, but the effects on conductive hearing loss have not been investigated. The purpose of this study was to investigate long-term effects of semirapid maxillary expansion (SRME) with an acrylic bonded appliance on conductive hearing loss by using audiometric and tympanometric records. Methods: The effects of SRME with a bonded appliance were studied in 19 growing subjects who had narrow maxillary arches and conductive hearing loss. Hearing levels were determined with pure-tone audiometric and tympanometric records. Four records were taken from each subject. The first records were taken before SRME, the second after maxillary expansion (mean, 3.4 months later), the third after retention (mean, 6 months later), and the fourth after fixed-appliance treatment (approximately 2 years later). The data were analyzed with ANOVA. The least-significant difference test was also used to determine when the changes in the measurements were significant. Results: Hearing improved and air-bone gaps decreased at a statistically significant level after active expansion, and these changes remained relatively stable during the last 2 periods. Middle-ear volume increased at a statistically significant level after maxillary expansion and continued to increase until the end of treatment. No significant change was observed in the static compliance value. Conclusions: SRME treatment has a positive and statistically significant effect on both hearing and normal functioning of the eustachian tubes in patients with transverse maxillary deficiency and conductive hearing loss.