Tongue Measurement by Ultrasound in East African Open Bite Patients

OBJECTIVE: The role of the tongue in the pathophysiology of anterior open bite (AOB) is poorly understood. This study characterized tongue shape and motion in East African children with and without AOB.

METHODS: Ten children of East African descent, ages 9-12, were recruited. Five (2 males, 3 females) with negative overbite or overbite less than 1.0 mm were categorized to AOB or AOB tendency group; the other 5 with overjet larger than 1.0 mm were taken as controls. Ultrasound imaging of the tongue was performed with the subject seated in a dental chair for three conditions: rest, gum chewing, and command-initiated water-swallowing, in sagittal and coronal projections. The orientation and probe location were recorded by a spatial tracking system in the submandibular region. Two-dimensional tongue contours were traced and analyzed with custom MATLAB software to create 3D visualizations of the tongue.

RESULTS: No significant differences were observed for the average thicknesses of the AOB and control groups during rest, swallowing and chewing. However, average range of motion in the middle-tongue region showed a unique difference over all subjects: 11.5mm for chewing and 18.7mm for swallowing. In general, AOB subjects had a larger range of motion and average maximum velocity than the control group. From cephalometric analysis, one finding is that the gonial angle was positively correlated with average thickness during swallowing in AOB subjects alone (p<0.05).

CONCLUSIONS: These results suggest that 1) the tongue may need to move more and faster during chewing and swallowing to meet the functional demands in the AOB; 2) the tongue thickness may be dependent upon the inclination of the mandible in the AOB and 3) ultrasound imaging is a safe and useful tool for the study of tongue morphology and function.

Supported by NIH Grants of T32-DE007132, U54-DE14254, and UW Royalty Research Fund.