The effect of obturator bulb height on speech in maxillectomy patients.

The purpose of this study was to compare the speech function of low height bulb obturators with that of high height bulb obturators. Thirteen maxillectomy patients, who underwent post-operative prosthodontic rehabilitations, were included. Two obturators of the same design except for different bulb heights were fabricated for each maxillectomy patient. One of the two obturators had high bulb design and the other had low bulb design. After one of the obturators was used for a period of 3 weeks, the patient's speaking functions were evaluated by measuring nasalance scores, formant frequencies, and vowel working space areas. The same procedures were repeated with the second obturator following another 3-week period of usage. In addition, the effect of delivery sequence and anatomic conditions related to maxillectomy were analysed. The results demonstrated that the nasalance scores with the low bulb obturators were significantly higher than those with the high bulb obturators. There were no significant differences in formant frequencies based on the bulb height of the obturators. The vowel working spaces for the two obturators were similar in shape and there were no significant differences between the vowel working space areas created by the two obturators. The delivery sequence affected the results. However, there were no significant differences related to the other anatomical variables. Although low bulb obturators might function similarly with high bulb obturators in terms of the articulation of speech, they would exhibit a difficulty in controlling hypernasality in maxillectomy patients.