Evaluation of speech improvement following obturator prostheses for patients with palatal defect.

Palatal defect is a common maxillofacial defect after maxillectomy that can be repaired by obturator prostheses, which can effectively improve patients' speech. However, comprehensive evaluation methods for speech recovery are still controversial and remain undefined. A prospective cohort study on 34 patients with palatal defect and 34 healthy controls was performed. Patients received obturator prostheses and their speech was recorded without and then with obturators. Participants pronounced six Chinese vowels and 100 syllables for recording. This paper evaluated the recovery of speech function of patients through the combination of subjective and objective assessment methods. Recruited listeners evaluated the speech intelligibility (SI) of 100 syllables. Vowel formant frequency and quantified vowel nasalization were measured using analysis software. The SI of patients improved significantly after wearing obturators. F2 values of six vowels in patients with obturators were higher than patients without obturators and close to the corresponding values in normal controls. The differences in F2 of /i/ and /u/, (A1-P1) of /i/ and /u/ for patients without and with obturator use were significant. Patients' ability to control the pronunciation of /i/ and /u/ improved greatly with obturators. These provide clinical evidence of the treatment outcomes in patients with palatal defect who received obturators.