# Hyoid bone position with bone-borne or tooth-borne surgically assisted rapid palatal expansion: a retrospective cohort study

## TL;DR

This study found that surgically assisted palatal expansion causes minimal and likely clinically insignificant changes in hyoid bone position, with no major differences between two appliance types.

## Contribution

The study provides empirical evidence on hyoid bone position changes following SARPE, comparing bone-borne and tooth-borne appliances.

## Key findings

- Hyoid bone position remained generally stable with changes not exceeding 2 mm.
- The Hyrax group showed a significant vertical downward shift in hyoid position, while the TPD group showed a slight upward shift.
- Changes in hyoid position were not significantly related to the amount of maxillary expansion or appliance type.

## Abstract

There is a lack of evidence whether hyoid bone position changes with surgically assisted rapid palatal expansion (SARPE), which could improve the airway. The aim of this study was to (1) evaluate the differences in hyoid bone position with SARPE, (2) assess whether there are differences between bone-borne or tooth-borne expansion appliances, and (3) investigate possible relationships between expansion values and hyoid bone position.

Eligible for inclusion in this retrospective cohort study were adult patients who underwent SARPE using bone-borne or tooth-borne expansion appliances. The Hyrax group (n=32; female/male 20/12; mean age 26.0 ± 9.1 years) was treated with a hyrax appliance and the TPD group (n=33; female/male 15/18; mean age 25.0 ± 8.0 years) was treated with a transpalatal distractor. The position of the hyoid bone was determined on lateral cephalograms before (\documentclass[12pt]{minimal}
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Hyoid bone position remained generally stable, with changes not exceeding 2 mm. The only statistically significant change in the overall cohort was observed for the sagittal distance Hy-Me, which decreased from 44.23 mm to 43.40 mm (\documentclass[12pt]{minimal}
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\begin{document}$${p}\, {=0.005}$$\end{document}). Significant differences between groups were noted for the vertical distance Hy-Me’, with the Hyrax group showing a mean change of -1.95 mm (\documentclass[12pt]{minimal}
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\begin{document}$$^{\circ }$$\end{document} in the TPD group (\documentclass[12pt]{minimal}
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\begin{document}$${p}\, {=0.036}$$\end{document}). All other measurements showed no significant changes and possible correlations between the expansion values and the position of the hyoid bone were inconclusive.

While the results indicate small, statistically significant, but probably clinically negligible movements of the hyoid bone after SARPE, the hyoid position remained generally stable and changes were not dependent on the appliance used or the amount of expansion.

Overall, the observed changes were not substantial enough to support any clinically meaningful effects of SARPE on airway function through hyoid bone movements.