Changes in hyoid bone position in skeletal Class II children post-functional appliance therapy.

IntroductionThe hyoid bone is deeply involved in three important body functions: deglutition, phonation and respiration. Several studies have shown that changes in the position of the hyoid bone may influence in pharyngeal size with mandibular advancement, thus a forward positioned hyoid bone may be an indicator of wide upper airways. ObjectiveTo determine the changes in the position of the hyoid bone after functional appliance treatment. Subjects and methods20 children (aged 9-13) that currently visit Hiroshima University Hospital actively undergoing FKO activator therapy volunteered for this study. Several lateral cephalometric radiographs were indicated and traced to assess hyoid bone position changes that might have occurred when actively complying with the FKO therapy, said radiographs were procured before active functional treatment (T0), during it (T1), and a year after continuous use of this appliance (T2). ANOVA tests were done to find statistical significance. ResultsThe results of these tests were analyzed and compared; it was found that, the hyoid bone is at a lower position from the mandibular plane and Frankfurt horizontal plane after FKO treatment, also the mandible is more forward after activator therapy, bringing the hyoid bone forward with it thus widening the lowest section of the upper airways. ConclusionThe FKO not only induces the proper development of the mandible, it also potentially advances the position of the hyoid bone, thus affecting positively in the opening of airways providing an improvement in the childrens breathing functions. O_LIAuthors report no conflict of interest. C_LI FundingThis research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. Conflicts of interest/Competing intereststhe authors have no conflicts of interest to declare. Ethics approvalThis research has been approved by the Ethics Review Committee of Hiroshima University (No. E - 56). Consent to participateAll subjects needed to have provided informed consent from the parent or guardian prior all evaluations. This study has followed the guidelines stated in the Helsinki Declaration for clinical investigations. Consent for publicationAll subjects have provided informed consent from the parent or guardian to allow publication of acquired data.