Effects of Rapid Maxillary Expansion on Serum Insulin-Like Growth Factor I and Apnea Hypopnea Index Scores in a Prepubertal Population with Maxillary Constriction

Abstract

Introduction: Insulin-like Growth Factor 1 (IGF-1) is a potent mitogenic hormone that is critical for normal growth and metabolism. In some cases, children with pediatric obstructive sleep apnea (POSA) may demonstrate lower serum IGF-1 levels and growth. A narrow maxilla is one morphological feature reported in a subgroup of POSA individuals. Surgical removal of enlarged adenoids and palatine tonsils in POSA individuals has been shown to increase IGF-1, normalize apnea-hypopnea index (AHI) scores, and allow catch-up growth while non-surgical maxillary expansion treatment has so far shown to improve AHI scores, at least short-term. No studies to date have assessed the effect of maxillary expansion on serum IGF-1 levels. Objective: To determine the effect of non-surgical maxillary expansion on serum IGF-1 and AHI score in non-syndromic, prepubertal children with maxillary transverse deficiency compared to untreated controls over a period of approximately 12 months. Methods: Sixty-five prepubertal children (ages 7 – 12) from the graduate orthodontic clinics of the Universities of Alberta and Insubria were admitted and randomly assigned to either a treatment group (intra-oral fixed maxillary expander followed by a fixed retainer) or a delayed treatment follow-up control group. Blood samples, home sleep apnea tests, body mass index score, dental models, and hand-wrist radiographs were acquired at the start and end of the trial. Multivariate and univariate statistical testing was performed to assess for interactions, covariates, and to compare means between groups iii Conclusions: The control group experienced a significant increase in serum IGF-1 but the treatment group experienced a significantly larger increase over the trial period. Severity of maxillary deficiency and skeletal age significantly interacted with time to explain the variance of both outcomes. There were significant interactions between treatment group and time. Subgroup analysis showed the University of Insubria cohort had a significant but lower increase in IGF-1 levels for the treatment group and no change for the control group, and the average maxillary deficiency was significantly less for the University of Alberta cohort. AHI scores significantly decreased in the treatment group but increased slightly but significantly in the control group.