The role of the tongue in the pathophysiology of anterior open bite (AOB) is poorly understood. This study characterized tongue morphology and functional motion, craniofacial skeletal pattern and upper airway space, and speech function in East African children with and without AOB.
Ten 9-12 year-old children of East African descent were recruited, five with AOB and five as control. Cone-beam CT scans, ultrasound imaging of the tongue during chewing and swallowing, and inter-labial pressure and lip muscle activity during lip closure and speech were taken in all subjects.
No significant differences were identified in most linear and angular measurements between the two groups except for the smaller mandibular and combined airway volumes in AOB (p < 0.10). Mandibular volume was positively associated with total face and ramus heights, and bilateral condylar width. The oral airway volume was associated with total face and anterior lower face heights. The combined oral and pharyngeal airway volume was associated with anterior lower face height. No significant differences were identified for the average tongue thicknesses between the two groups during swallowing and chewing. However, AOBs had a larger range of motion and average maximal velocity than controls. Significant associations between the tongue and skeletal variables were most often seen in tongue thickness during chewing. The average raw score of articulation tests was higher in AOBs than controls, and more isolated efforts of sound production with an extended duration and less corresponding muscle activity in speech intelligibility tests were identified in AOBs than those of controls. AOBs also presented significantly lower lip muscle activity during lip closure.
1) Craniofacial skeletal patterns are similar between AOBs and controls, but AOBs have smaller volumes of mandibular and upper airway spaces; 2) The tongue moves farther and faster during chewing and swallowing in AOBs; 3) The tongue thickness in chewing is more related to skeletal variables than other tongue features; 4) AOBs are more likely to have articulatory deficiencies and speech disorders.