The hyoid bone position in mouth breathers and tongue-thrusters.

In 1981 Bibby and Preston commented on the uniqueness of the anatomic relationships of the hyoid bone, notably that it was not fixed in space by bony articulations. This fact alone makes it a potential indicator of certain individual features of importance in orthodontic diagnosis and treatment. This study investigates the effect of mouth breathing and tongue-thrusting on the hyoid bone position by means of the hyoid triangle analysis. Three groups of eighteen subjects formed the sample, one group of mouth breathers, one group of tongue-thrusters, and a control group of subjects who exhibited neither of these. Preorthodontic lateral cephalometric radiographs were taken, and the position of the hyoid bone was analyzed from these. The groups were compared statistically by means of t tests and showed no statistically significant difference. These results show that the hyoid bone has a stable position and is independent of any posture alterations due to tongue-thrusting or mouth breathing.