Abstract
This study investigated the influence of the passage of air throughthe space between the upper and lower incisal teeth on phonetics.
Three experimental resin pontics with different horizontal overlaps-2, 4, 8 mm-were in turn temporarily cemented to the abutment teeth in two subjects. Phonetic test were performed with and without the experimental pontics and the resulting objective speech disorders, sound spectrograms, palatograms and mandibular positions were examined.
The results were as follows:
1. Regardless of the change of the horizontal overlap, objective speech disorders were not found in any of the subjects.
2. The sound spectrograms showed a decrease in the energy of the voice sounds /s/, /∫/ and /t∫/ as well as a lowering of frequency when the horizontal overlap was increased.
3. The contour of the anterior region of the tongue palate contact area decreased in one subject when the horizontal overlap was increased.
4. During the articulation of Is/ and /tf/ sounds, the mandibular position altered in one of the subjects by changes in the horizontal overlap.
5. The influence of the horizontal overlap on phonetics differed according to the individual.
