Application of a barometer for assessment of oral functions: Donders space.

We developed a barometer applicable to a small space, to assess oral and pharyngeal functions. Negative oral pressure during rest and pressure changes during swallowing were measured in a space between the palate and tongue (STP). Twenty volunteers were asked to sit in a chair in a relaxed upright position. A sensor was placed on the posterior midline of hard palate. Recording commenced just before subjects closed their lips and continued. Subjects were asked to swallow saliva and keep the apposition. Finally, subjects were asked to open their mouth. Recordings were performed five times, and 5 s of continuous data in each phase was averaged. To verify the reliability of the system, the same procedure was accomplished with twin sensors. When the jaw and lips were closed, the pressure slightly decreased from atmospheric pressure (-0·17 ± 0·24-kPa). After swallowing, the pressure in STP showed more negative value (-0·50 ± 0·59-kPa). There is a significant difference between the values in open condition and after swallowing (P < 0·001) and between values after swallowing and final open condition (P < 0·05). Twin sensor showed almost the same trajectories of pressure changes for all the recordings. Obtained negative pressure might generate about 0·71-N of force and would be enough to keep the tongue in the palatal fossa at rest. The system detected large negative/positive pressure changes during swallowing. We conclude this system may be a tool to evaluate oral functions.